Safety cabinet and photocatalytic filter unit used therein

Abstract

Provided is a safety cabinet capable of reliably preventing a situation in which an anticancer agent in a workspace is diffused into an installation chamber by an external discharge airflow, thereby exposing an operator to the anticancer agent.　A housing 51 has provided therein a photocatalyst filter 52 and a black light 53, as well as a plenum 57 that causes a first external discharge airflow Z1 to flow into the photocatalyst filter 52 at a desired filter inflow air velocity while satisfying a prescribed air velocity condition pertaining to the air velocity of an unpurified airflow X. The desired filter inflow air velocity is selected from an appropriate range in which the anticancer agent decomposing action of the photocatalyst filter 57 is attained at a desired level or higher. The inflow-side cross-sectional area Aa of the plenum 57 is set to be the same as or larger than the opening area Ac of an exhaust port 19. The outflow-side cross-sectional area Ab of the plenum 57 is set according to the air volume of a second external discharge airflow Z2 such that the first external discharge airflow Z1 flows into the photocatalyst filter 57 at the desired filter inflow air velocity.

Description

[Technical Field]

[0001] The present invention relates to a safety cabinet and a photocatalytic filter unit used in industrial fields such as medicine, regenerative medicine, and pharmaceuticals, and more specifically, to a safety cabinet that can reliably prevent workers from being exposed to anticancer drugs by diffusing the anticancer drug being handled by workers in the workspace into the installation room by an external exhaust airflow discharged from the exhaust port, and to a photocatalytic filter unit suitably used in said safety cabinet. [Background technology]

[0002] Safety cabinets are equipment designed to prevent biohazards and create a safe working environment. They are mandatory in laboratories and research facilities at universities, research institutes, and medical institutions that handle biohazards such as pathogens and genetically modified organisms. Safety cabinets typically have a sealed (semi-sealed) workspace inside, except for the work opening. To ensure that contaminated aerosols generated within the workspace do not leak outside the safety cabinet, the workspace is kept under negative pressure, and the contaminated air containing the aerosols is purified using a HEPA filter (High Efficiency Particulate Air Filter) or ULPA filter (Ultra Low Penetration Air Filter) before being discharged outside the safety cabinet.

[0003] Safety cabinets with the above-described structure are classified into Class I, Class II, and Class III depending on the substance or organism used, and the structure differs according to each class. A Class I safety cabinet is equipped with a HEPA or ULPA filter only at its exhaust port, while a Class II safety cabinet is equipped with a HEPA or ULPA filter not only at its exhaust port but also at its air intake port. Furthermore, the airflow purified by the HEPA or ULPA filter at the air intake port is configured to form an air curtain (air barrier) at the work opening, preventing contamination of samples handled in the work space due to unpurified external airflow entering the work space through the work opening.

[0004] Class II safety cabinets are classified according to their structure and airflow method. There are two types: "Type A1," "Type A2," and "Type B1," which are indoor circulation types (partial circulation and partial exhaust) in which the exhaust air (external exhaust airflow) purified by the HEPA or ULPA filter at the exhaust port is discharged into the room in which the safety cabinet is installed (hereinafter also referred to as the installation room) and circulates within the installation room; and "Type B2," which is a full exhaust type in which the exhaust air (external exhaust airflow) purified by the HEPA or ULPA filter at the exhaust port is discharged to the outside of the building through an exhaust duct installed in the building where the safety cabinet is located, without circulating within the installation room. The difference between "Type A1" and "Type A2" lies in the inflow air velocity into the work space. The inflow air velocity for "Type A1" is 0.4 m / s or more, while that for "Type A2" is 0.5 m / s or more. The difference between the "A1 type," "A2 type," and "B1 type" lies in the circulation rate (the ratio of purified airflow, cleaned by the HEPA or ULPA filter at the air intake, that circulates inside the safety cabinet). The circulation rate for the "A1 type" and "A2 type" is approximately 70%, while the circulation rate for the "B1 type" is approximately 50%. The "B1 type" and "B2 type" both share the feature of outdoor exhaust through a sealed exhaust duct.

[0005] A Class III safety cabinet has a configuration (glove box) in which the workspace is completely isolated from the worker and the external environment by a partition, and the worker is required to work using gloves attached to the glove box. The supply of air to the workspace (supply of the purified airflow) is carried out via an air supply duct connected to the outside of the building, and the exhaust from the workspace is carried out via an exhaust duct connected to the outside of the building.

[0006] An example of the "Class II" "Type A2" safety cabinet described above is disclosed in Patent Document 1 (Japanese Patent No. 6228040). The safety cabinet of Patent Document 1 comprises a safety cabinet body and an exhaust recirculation unit disposed on the safety cabinet body. The safety cabinet body supplies clean air to the internal working space via an air supply HEPA filter, circulates the air in the working space within the safety cabinet body, and discharges a portion of the circulating air to the outside of the safety cabinet body via an exhaust HEPA filter, thereby maintaining negative pressure in the working space and taking in outside air through the opening of the front shutter to create a barrier air (air barrier). The exhaust recirculation unit takes in the air discharged from the safety cabinet body via the HEPA filter through an exhaust intake port provided at the rear of the bottom surface, and blows the taken-in air downward along the shutter from an exhaust outlet provided at the front of the bottom surface. The air descending along the shutter is drawn into the negatively pressurized workspace through an opening at the lower end of the shutter, thereby being recycled as all or part of the barrier air that prevents the air in the workspace from leaking out through the opening (see Claim 1, paragraphs 0009-0017, Figures 1-9).

[0007] The safety cabinet of Patent Document 1, having the above configuration, has the following effects: (a) The air exhausted from the air exhaust passage of the safety cabinet can be uniformly blown downward from the top of the safety cabinet body to the front of the safety cabinet body as a rectified flow with a uniform flow and reduced wind speed, so that the air exhausted from the air exhaust passage of the safety cabinet body can be taken back into the workspace from the front opening of the workspace as clean air, and the amount of clean air taken into the cleanroom, which is a biosafety facility, can be reduced according to the amount of clean air taken in; (b) The air that has been decontaminated by the exhaust HEPA filter passes through the exhaust recirculation unit and its flow is uniformly regulated, and it becomes a downward laminar flow with a reduced wind speed, so that it is blown downward from the top along the shutter on the front of the cabinet body, so that turbulence does not occur in the cleanroom, and air that has come into contact with the sample in the workspace does not leak out of the safety cabinet from the front of the workspace (see paragraph 0007).

[0008] Incidentally, in safety cabinets installed in laboratories, research institutes, and medical institutions that handle biohazards, when handling "anticancer drugs" widely used in cancer treatment in the medical field, it has traditionally been recommended to install "Class III" safety cabinets, which can handle anticancer drugs in a sealed state, or "Class IIB2" safety cabinets with full exhaust, considering that anticancer drugs are dangerous drugs that can cause health damage to healthy people. However, in reality, in some buildings where safety cabinets are planned to be installed, it may not be possible to install either "Class III" or "Class IIB2" safety cabinets due to reasons such as difficulty in installing ducts leading to the outside of the building. In such cases, it becomes necessary to install "Class IIA1, A2, or B1" safety cabinets with indoor circulation as an alternative. In light of this situation, there has been a strong demand from universities, research institutes, and medical institutions that handle biohazards for the realization of "Class IIA1, A2, or B1" safety cabinets with indoor circulation capable of handling anticancer drugs.

[0009] As is well known, "anticancer drugs" are medications designed to act on the cell proliferation process of cancer cells, inhibiting their growth and promoting their death. According to Non-Patent Literature 1 (Report on the Anticancer Drug Exposure Countermeasures Seminar, held on August 25, 2018), the following points (a) to (g) have been clarified regarding anticancer drugs. That is, (a) Many anticancer drugs have cytotoxic properties and include "mutagenicity: chromosomal abnormalities," "carcinogenicity: properties that promote the development or carcinogenic process of cancer," and "teratogenicity: properties that cause fetal morphological defects through pregnant women." (b) There is a risk of unintentional entry of anticancer drugs into the body through "inhalation: breathing contaminated air," "skin contact: touching contaminated surfaces," "hand-to-mouth contact," "needle stick injuries, etc.," (c) The outer surface of the anticancer drug vial is contaminated. (d) Many anticancer drugs are shaken in a container to mix with the solution during preparation, but this inevitably generates aerosols in the vial of the anticancer drug, and there is also a possibility that the anticancer drug will vaporize, and there is a risk that these will leak out of the vial when the needle is inserted. (e) HEPA filters typically incorporated into safety cabinets are largely ineffective at removing vaporized anticancer drugs. (f) When processing anticancer drugs in an indoor circulating safety cabinet ("Class IIA1, A2, or B1"), the anticancer drugs being processed on the workbench of the safety cabinet may diffuse in an aerosol or gaseous state within the room in which the safety cabinet is installed, and there is a risk that workers working in the safety cabinet may be exposed to the anticancer drugs being processed. (g) Even in a completely sealed "Class III" safety cabinet, the workspace is filled with a large amount of vaporized anticancer drugs, and if an infusion bag is placed inside, its exterior will be contaminated with the anticancer drugs. Therefore, there are already "Class III" safety cabinets that are equipped with a device to wash the exterior of the infusion bag with ozonated water.

[0010] Furthermore, regarding the treatment of anticancer drugs, Non-Patent Literature 2 (a paper by Lowe et al., "Formation of Nitrate and Ammonium Ions in Titanium Dioxide-Mediated Photocatalytic Decomposition of Nitrogen-Containing Organic Compounds") reports test results showing that anticancer drugs were decomposed into inorganic substances by the photocatalytic activity of titanium dioxide (TiO2). In this report, the photocatalytic oxidation of a series of primary, secondary, and tertiary amines, as well as other nitrogen and sulfur-containing organic compounds, by photocatalysis using ultraviolet light on a thin film of titanium dioxide was studied. The compounds tested in this report were 15 types: n-pentylamine, piperidine, pyridine, phenylalanine, desipramine, thioridazine, penicillamine, isosorbide disnitrate, 4-nitrocatechol, 2,4-dinitrophenol, cyclophosphamide, 5-fluorouracil, atrazine, ethylenediaminetetraacetic acid, and tetrabutylammonium phosphate. A titanium dioxide thin film coated on a spiral-shaped borosilicate glass was irradiated with ultraviolet light to activate the photocatalytic action of titanium dioxide, and the oxidation state of the above-mentioned compounds due to this photocatalytic action was observed. As a result, it was reported that both ammonium ions and nitrate ions were generated for all of the above-mentioned compounds, and that the relative concentrations of these two ions were influenced not only by the properties of nitrogen in the compound, but also by the ultraviolet light irradiation time to the solute and the concentration of the solute.

[0011] The 15 compounds targeted in the report in Non-Patent Document 2 include cyclophosphamide and 5-fluorouracil, which are used as anticancer drugs. Therefore, the report suggests the possibility that anticancer drugs can be converted into harmless inorganic substances by utilizing the photocatalytic action of titanium dioxide, or in other words, that anticancer drugs can be rendered harmless.

[0012] However, in order to utilize the photocatalytic oxidation effect of titanium dioxide, irradiation with ultraviolet light as the activation light for titanium dioxide is essential. For this reason, it is necessary that when a titanium dioxide film is formed on an air filter (e.g., a HEPA filter or ULPA filter) installed in a safety cabinet and then irradiated with ultraviolet light, no problems arise in the air filter as a result. However, there are concerns regarding the air filter in this regard. The reason is that air filters installed in safety cabinets are generally made from glass fiber filter paper, which has excellent broad chemical resistance and heat resistance, but it is known that glass fibers lose strength when exposed to ultraviolet light for a long time, leading to deterioration of the air filter, such as the formation of pinholes (see, for example, Non-Patent Document 3).

[0013] Therefore, it is conceivable that metal fibers could be used instead of glass fibers, and that air filters installed in safety cabinets could be made of metal fibers to prevent a decrease in strength due to prolonged irradiation with ultraviolet light. An example of a photocatalyst support for air filters based on this idea is disclosed in Patent Document 2 (Japanese Patent Application Publication No. 2000-262903).

[0014] Disclosed in Patent Document 2 is a photocatalytic carrier used in air purifiers, air conditioners, etc., in which a photocatalytic substance (e.g., fine particles of titanium dioxide) is fixed to the surface of a metal substrate with a binder (e.g., an adhesive substance such as a silicon compound, silicon resin, or fluororesin). The metal substrate is formed from a nonwoven fabric-like fibrous structure having a highly permeable three-dimensional structure by depositing metal fibers (e.g., aluminum fibers). This photocatalytic carrier is provided with sufficient voids for air circulation to increase the contact efficiency between the photocatalytic substance and malodorous substances and harmful substances, thereby enabling the removal of malodorous substances and harmful substances by oxidative decomposition. Furthermore, it is possible to easily and efficiently regenerate it after deterioration by washing it with hot water (see Claim 1, paragraphs 0002-0004, 0012-0018, Figures 1 and 2).

[0015] Furthermore, Patent Document 3 discloses an example in which titanium dioxide particles having photocatalytic activity and containing 50 ppm or more of OH groups (more than conventionally) are used as photocatalytic particles. These photocatalytic particles can form a thicker photocatalytic layer than conventionally on the surface of a substrate (e.g., ceramics having fine irregularities on the surface) without peeling off, without using an inorganic binder, and without the surface of the photocatalytic particles being coated with an inorganic binder, and can sufficiently exhibit a photocatalytic effect (see Claim 1, Paragraphs 0004 to 0010, 0018, FIGS. 1 and 2).

Prior Art Documents

Patent Documents

[0016]

Patent Document 1

Patent Document 2

Patent Document 3

Non-Patent Documents

[0017]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

[0018] As described above, from the information relating to the prior art mentioned above, the idea can be derived to "combine a photocatalytic filter and a light source (a light source that emits activation light) for exhibiting the photocatalytic activity of the photocatalytic filter, and install them, for example, in the exhaust port of a safety cabinet, so that the anticancer agent used in the working space of the safety cabinet passes through the photocatalytic filter by the airflow inside the safety cabinet, thereby decomposing and rendering harmless the anticancer agent in aerosol or gaseous state using the photocatalytic filter before discharging it to the outside of the safety cabinet." If this idea can be realized, the situation in which "the anticancer agent discharged from the exhaust port diffuses into the room (installation room) where the safety cabinet is installed, and workers working in the safety cabinet are exposed to the anticancer agent" can be prevented, and thus the above-mentioned requests from universities, research institutes, and medical institutions that handle biohazards can be met. In other words, it is possible to provide an indoor circulating type "Class IIA1, A2, or B1" safety cabinet capable of processing anticancer agents.

[0019] However, for indoor circulation type "Class II" safety cabinets, strict standards are set, as described in JIS K 3800 "Class II Safety Cabinets for Biohazard Countermeasures" issued by the Japanese Standards Association. According to these standards, for "Class II A1, A2, or B1" safety cabinets, A portion of the airflow discharged from the workspace is sent to an "air intake" where an air filter is installed, purified by the air filter, and then circulated inside the safety cabinet. The remaining airflow discharged from the workspace is sent to an "exhaust port" equipped with an air filter, purified by the air filter, and then discharged into the room (installation room) where the safety cabinet is installed. The amount of unpurified airflow equivalent to the airflow discharged from the exhaust port into the installation chamber is replenished through the front opening of the safety cabinet, so that the total amount of air circulating inside the safety cabinet is maintained at a constant value. This is the resulting airflow configuration.

[0020] As can be seen from the three requirements related to the airflow configuration described above, in the case of an indoor circulating "Class II" safety cabinet, all airflow inside and outside the safety cabinet mutually influences each other. Therefore, extremely delicate adjustment and setting are required for the balance of supply and exhaust air (wind speed and airflow volume) related to the airflow described in the three requirements above.

[0021] In fact, when a safety cabinet is shipped from the manufacturer's factory, each unit undergoes a process in which the required wind speed and airflow are measured, and auxiliary components such as supply and exhaust adjustment plates are used to carefully adjust for variations in the performance of the blower and air filters built into the safety cabinet, bringing them into line with the specified design values. This process is the same not only for "Class II" safety cabinets, but also for "Class I" and "Class III" safety cabinets.

[0022] This invention was made in consideration of the above-mentioned prior art and circumstances, with the aim of realizing the above-mentioned idea, and its purpose is to provide a safety cabinet and a photocatalytic filter unit to be used therein that can reliably prevent a situation in which an anticancer drug being processed by an worker in the workspace is diffused into the installation room by the external exhaust airflow discharged from the exhaust port, resulting in the worker being exposed to the anticancer drug.

[0023] Another object of the present invention is to provide a safety cabinet and a photocatalytic filter unit for use therein that can be operated as a safety cabinet with the function of decomposing and neutralizing anticancer drugs contained in the external exhaust airflow discharged from the exhaust port, with little to no change to the airflow design of a "conventional safety cabinet" that does not have the function of decomposing and neutralizing anticancer drugs contained in the external exhaust airflow discharged from the exhaust port.

[0024] Another object of the present invention is to provide a safety cabinet and a photocatalytic filter unit for use therein that can be operated as a safety cabinet with the function of decomposing and neutralizing anticancer drugs by adding a photocatalytic filter and light source for decomposing and neutralizing anticancer drugs to a "conventional safety cabinet" that does not have the function of decomposing and neutralizing anticancer drugs contained in the external exhaust airflow discharged from the exhaust port, without hardly changing the airflow design of the "conventional safety cabinet".

[0025] Further objects of the present invention not explicitly stated herein will become apparent from the following description and accompanying drawings. [Means for solving the problem]

[0026] (1) According to a first aspect of the present invention, a safety cabinet is provided. This safety cabinet is A main body having a front opening that functions as a work opening and an air intake for unpurified airflow (X), a work space communicating with the front opening, an internal passage communicating with the work space, and an exhaust port communicating with the internal passage, The first blower installed inside the main body, An air filter for supplying purified airflow (Y) to the workspace is installed inside the main body, An exhaust air filter installed inside the main body, which purifies the unpurified airflow (X) supplied to the working space through the front opening and the purified airflow (Y) supplied to the working space by the supply air filter after they move from the working space to the internal flow path, and discharges them from the exhaust port as a first external exhaust airflow (Z1), A photocatalytic filter installed in the external flow path through which the first external exhaust airflow (Z1) flows decomposes the anticancer agent contained in the first external exhaust airflow (Z1) by photocatalytic action, and then discharges it to the outside of the safety cabinet as a second external exhaust airflow (Z2). A light source installed in the external channel emits activation light to activate the photocatalytic action of the photocatalytic filter, The external flow path is provided with a plenum for allowing the first external exhaust airflow (Z1) to flow into the photocatalytic filter at a desired filter inflow velocity while satisfying predetermined wind velocity conditions (e.g., 0.53 m / s or more) for the wind velocity of the unpurified airflow (X), The photocatalytic filter has an appropriate range of air velocity at filter inflow that allows for an anticancer drug decomposition effect of a desired level or higher for each anticancer drug, and the desired air velocity at filter inflow of the first external exhaust airflow (Z1) is set to fall within the appropriate range. The inlet cross-sectional area of ​​the plenum is set to be the same as or larger than the opening area of ​​the exhaust port. The cross-sectional area of ​​the outlet side of the plenum is set according to the airflow rate of the second external exhaust airflow (Z2) so that the first external exhaust airflow (Z1) flows into the photocatalytic filter at the desired filter inflow velocity. It is characterized by the following:

[0027] In the safety cabinet according to the first aspect of the present invention, since it has the above-described configuration, the unpurified airflow (X) supplied to the workspace through the front opening and the purified airflow (Y) supplied to the workspace by the supply air filter move from the workspace to the internal flow path, are purified by the exhaust air filter, and are discharged from the exhaust port as the first external exhaust airflow (Z1). Therefore, fine particles present in the workspace are removed by the exhaust air filter and are not included in the first external exhaust airflow (Z1) discharged from the exhaust port. However, anticancer agents (usually in aerosol or gaseous state) present in the workspace are not removed by the exhaust air filter, so unless a process to remove the anticancer agent is performed inside the safety cabinet, they will be discharged to the outside of the safety cabinet by the first external exhaust airflow (Z1).

[0028] However, in a safety cabinet according to the first aspect of the present invention, the photocatalytic action of the photocatalytic filter installed in the external channel through which the first external exhaust airflow (Z1) flows is activated by the activation light from the light source installed in the external channel, thereby decomposing and neutralizing the anticancer agent contained in the first external exhaust airflow (Z1) flowing through the external channel. In other words, by passing the first external exhaust airflow (Z1) through the photocatalytic filter with activated photocatalytic action before it is discharged outside the safety cabinet, the anticancer agent can be removed from the first external exhaust airflow (Z1). The first external exhaust airflow (Z1), from which the anticancer agent has been removed, is then discharged outside the safety cabinet as the second external exhaust airflow (Z2). This means that there is no risk of the anticancer agent present in the workspace being diffused into the room where the safety cabinet is installed.

[0029] Therefore, (a) the effect is obtained that the anticancer drug being processed by the worker in the workspace is reliably prevented from being diffused into the installation room by the first external exhaust airflow (Z1) discharged from the exhaust port, and the worker being exposed to the anticancer drug.

[0030] Furthermore, the photocatalytic filter and the light source, which decompose and neutralize the anticancer drug contained in the first external exhaust airflow (Z1), are installed in the external flow path, which is the flow path through which the first external exhaust airflow (Z1) discharged from the exhaust port flows. The external flow path has a plenum formed therein, and the first external exhaust airflow (Z1) flows into the photocatalytic filter at a desired filter inflow velocity while satisfying the predetermined wind speed condition (for example, 0.53 m / s or more) for the wind speed of the unpurified airflow (X). The desired filter inflow velocity is set to fall within the appropriate range of the photocatalytic filter for each anticancer drug. This is to ensure that the photocatalytic filter reliably achieves an anticancer drug decomposition effect of a desired level or higher for each anticancer drug.

[0031] Furthermore, the inlet cross-sectional area of ​​the plenum is set to be the same as or larger than the opening area of ​​the exhaust port. This is to prevent the airflow rate and velocity of the first external exhaust airflow (Z1) discharged from the exhaust port from being limited by the inlet cross-sectional area of ​​the plenum. As a result, there is virtually no need to change the airflow design within the main body relating to the unpurified airflow (X), the purified airflow (Y), and the first external exhaust airflow (Z1), which was carried out assuming that the photocatalytic filter and the light source are not installed in the external flow path.

[0032] Furthermore, the outlet-side cross-sectional area of ​​the plenum is set according to the airflow rate of the second external exhaust airflow (Z2) so that the first external exhaust airflow (Z1) flows into the photocatalytic filter at the desired filter inflow velocity. This is because, according to JIS K 3800, the airflow rate of the second external exhaust airflow (Z2) is determined by the airflow rate of the unpurified airflow (X), and also because the predetermined airflow velocity condition (e.g., 0.53 m / s or more) for the unpurified airflow (X) must be satisfied. Thus, since the airflow rate of the second external exhaust airflow (Z2) that flows out of the photocatalytic filter (i.e., passes through the photocatalytic filter) and is discharged to the outside of the safety cabinet is determined in advance, the filter inflow velocity of the first external exhaust airflow (Z1) must be specified within the appropriate range of the photocatalytic filter in order to match the determined airflow rate, and as a result, the outlet-side cross-sectional area of ​​the plenum is naturally determined.

[0033] Therefore, in a safety cabinet according to the first aspect of the present invention, it is possible to use an airflow design that was performed without installing the photocatalytic filter and the light source for decomposing and neutralizing anticancer drugs contained in the first external exhaust airflow (Z1) discharged from the exhaust port in the external flow path, with almost no changes.

[0034] Therefore, (b) it is possible to operate a "conventional safety cabinet" that does not have the function of decomposing and neutralizing anticancer drugs contained in the first external exhaust airflow (Z1) discharged from the exhaust port as a safety cabinet that has the function of decomposing and neutralizing anticancer drugs, with almost no change to the airflow design of the conventional safety cabinet.

[0035] Furthermore, in the safety cabinet according to the first aspect of the present invention, as described above, it is possible to use the airflow design performed without installing the photocatalytic filter and the light source in the external flow path with almost no changes. Therefore, even if the photocatalytic filter and the light source are added to the external flow path through which the first external exhaust airflow (Z1) flows, it is virtually unnecessary to change the airflow design.

[0036] Therefore, (c) by adding a photocatalytic filter and a light source for decomposing and neutralizing anticancer drugs to a "conventional safety cabinet" that does not have the function of decomposing and neutralizing anticancer drugs contained in the first external exhaust airflow (Z1) discharged from the exhaust port, it is possible to operate the "conventional safety cabinet" as a safety cabinet with the function of decomposing and neutralizing anticancer drugs without changing the airflow design of the "conventional safety cabinet" at all.

[0037] (2) In a preferred example of a safety cabinet according to a first aspect of the present invention, an opening area changing means is provided for changing the opening area of ​​the exhaust port, The opening area of ​​the exhaust port can be changed as needed using the opening area changing means.

[0038] In this example, the opening area of ​​the exhaust port can be easily changed by the opening area changing means in response to changes in the airflow volume and velocity of the first external exhaust airflow (Z1) caused by the addition of the photocatalytic filter unit and the light source. This has the advantage that adjusting the airflow velocity of the filter inlet of the first external exhaust airflow (Z1) to stay within the appropriate range becomes easier than when the opening area changing means is not provided.

[0039] (3) In yet another preferred example of a safety cabinet according to the first aspect of the present invention, the opening area changing means is a cover or lid that allows adjustment of the degree of opening of the exhaust port.

[0040] This example has the advantage that the means for changing the opening area can be implemented in a simple manner. (4) In another preferred example of a safety cabinet according to the first aspect of the present invention, if the air velocity of the first external exhaust airflow (Z1) at the time of inflow to the filter is set to fall within the appropriate range of the photocatalytic filter, and the airflow rate of the second external exhaust airflow (Z2) discharged from the photocatalytic filter unit is Q1, then the outflow side cross-sectional area Ab of the plenum is: Ab=Q1 / V1 It is given by.

[0041] This example has the advantage that it is very easy to calculate the outflow cross-sectional area Ab of the plenum.

[0042] (5) In yet another preferred example of a safety cabinet according to a first aspect of the present invention, the light source is positioned between the photocatalytic filter and the exhaust air filter, A breathable activation light blocking means is placed between the light source and the exhaust air filter to prevent the activation light emitted from the light source from irradiating the exhaust air filter.

[0043] In this example, the activation light blocking means prevents the activation light emitted from the light source from irradiating the exhaust air filter, thus suppressing the risk of the exhaust air filter deteriorating due to the activation light. Furthermore, since the activation light blocking means is permeable, it has the advantage of suppressing the influence of the activation light blocking means on the first external exhaust airflow (Z1).

[0044] (6) In yet another preferred example of a safety cabinet according to a first aspect of the present invention, a photocatalytic filter having the same photocatalytic activity as the photocatalytic filter is used as the activation light blocking means.

[0045] In this example, the activated light blocking means can be implemented in a simple manner, and moreover, the photocatalytic filter used as the activated light blocking means exhibits the same anticancer drug decomposition effect as the photocatalytic filter, thus offering the advantage of significantly improving anticancer drug decomposition performance compared to the case where the activated light blocking means is not used.

[0046] (7) In yet another preferred example of a safety cabinet according to a first aspect of the present invention, the light source comprises a plurality of linear discharge tubes (e.g., black lights) arranged at intervals along the inlet surface of the photocatalytic filter, Near each of the multiple discharge tubes, a strip-shaped light-shielding member is arranged that extends along the corresponding discharge tube. Multiple of the light-shielding members function as the activation light blocking means, The breathability of the activation light blocking means is achieved by the gaps between the multiple light-shielding members.

[0047] In this example, the activation light blocking means can be implemented in a simple manner, and it has the advantage of being less expensive than when a photocatalytic filter is used as the activation light blocking means.

[0048] (8) In yet another preferred example of a safety cabinet according to a first aspect of the present invention, the light source comprises a plurality of strip-shaped LED devices arranged at intervals along the inlet surface of the photocatalytic filter.

[0049] In this example, the activation light emitted from each of the multiple LED devices is limited to the direction toward the photocatalytic filter and is not emitted toward the exhaust air filter. Therefore, there is an advantage in that the same effect as when the activation light blocking means is installed can be obtained without installing the activation light blocking means.

[0050] (9) In yet another preferred example of a safety cabinet according to a first aspect of the present invention, the light source is composed of a plurality of strip-shaped LED devices arranged at intervals along the inlet surface of the photocatalytic filter, An opaque member (e.g., a substrate) included in each of the multiple LED devices functions as the activation light blocking means. The ventilation of the activation light blocking means is achieved by the spacing between the multiple LED devices.

[0051] In this example, the opaque member (e.g., substrate) included in each of the multiple LED devices functions as the activation light blocking means, which has the advantage of eliminating the need to separately provide the activation light blocking means.

[0052] (10) In yet another preferred example of a safety cabinet according to a first aspect of the present invention, the internal flow path is A predetermined portion (e.g., 70%) of the unpurified airflow (X) and the purified airflow (Y) discharged from the internal space and moving through the internal flow path is purified by the supply air filter and then supplied again to the working space as the purified airflow (Y), and The remaining portion (e.g., 30%) of the unpurified airflow (X) and the purified airflow (Y) moving through the internal flow path is discharged from the outlet as the first external exhaust airflow (Z1). It is formed in such a way, This allows the safety cabinet to function as an indoor circulation type safety cabinet.

[0053] In this example, there is the advantage that the safety cabinet according to the first aspect of the present invention can be operated as an indoor circulation type safety cabinet.

[0054] (11) In yet another preferred example of a safety cabinet according to a first aspect of the present invention, the external passage is formed inside a duct which has one end connected to the exhaust port and the other end connected to the outside of the building. The photocatalytic filter and the light source are arranged inside the duct, and the plenum is formed inside the duct. The internal flow path is configured such that all of the unpurified airflow (X) and purified airflow (Y) discharged from the internal space and moving through the internal flow path are discharged from the exhaust port as the first external exhaust airflow (Z1), and further discharged to the outside of the building through the inside of the duct. The first external exhaust airflow (Z1) is configured to flow through the plenum into the photocatalytic filter with assistance from a second blower installed inside the duct. This allows the safety cabinet to function as a fully exhausted safety cabinet.

[0055] In this example, there is the advantage that the safety cabinet according to the first aspect of the present invention can be operated as a fully exhausted safety cabinet.

[0056] (12) According to a second aspect of the present invention, a photocatalytic filter unit for a safety cabinet is provided that makes it possible to add the function of decomposing and neutralizing anticancer drugs to a "conventional safety cabinet" that does not have such a function. This photocatalytic filter unit is A photocatalytic filter unit used by being attached to the main body of a safety cabinet so as to cover its exhaust port, A housing having an inlet opening at one end for receiving the first external exhaust airflow (Z1) discharged from the exhaust port of the safety cabinet, and an outlet opening at the other end for decomposing the anticancer agent contained in the first external exhaust airflow (Z1) by photocatalytic action and then discharging it to the outside of the photocatalytic filter unit as a second external exhaust airflow (Z2), A photocatalytic filter installed inside the aforementioned housing, A light source is installed inside the housing near the photocatalytic filter, which emits activation light to activate the photocatalytic action of the photocatalytic filter, The enclosure comprises a plenum formed in the flow path of the first external exhaust airflow (Z1) inside the enclosure, which allows the first external exhaust airflow (Z1) to flow into the photocatalytic filter at a desired filter inflow velocity while satisfying predetermined wind velocity conditions (e.g., 0.53 m / s or more) for the wind velocity of the unpurified airflow (X) inside the main body of the safety cabinet, The photocatalytic filter has an appropriate range of air velocity at filter inflow that allows for an anticancer drug decomposition effect of a desired level or higher for each anticancer drug, and the desired air velocity at filter inflow of the first external exhaust airflow (Z1) is set to fall within the appropriate range. The inlet cross-sectional area of ​​the plenum is set to be the same as or larger than the opening area of ​​the exhaust port. The cross-sectional area of ​​the outlet side of the plenum is set according to the airflow rate of the second external exhaust airflow (Z2) so that the first external exhaust airflow (Z1) flows into the photocatalytic filter at the desired filter inflow velocity. It is characterized by the following:

[0057] In the photocatalytic filter unit according to the second aspect of the present invention, the photocatalytic filter and the light source are provided inside the housing, which has an inlet opening at one end and an outlet opening at the other end. When the photocatalytic filter unit is mounted on the main body such that the inlet opening covers the exhaust port of the safety cabinet, the first external exhaust airflow (Z1) discharged from the exhaust port enters the housing through the inlet opening and flows through the flow path. By activating the photocatalytic action of the photocatalytic filter installed inside the housing with the activation light from the light source also installed inside the housing, anticancer agents contained in the external exhaust airflow (Z1) flowing through the flow path can be decomposed and rendered harmless. In other words, anticancer agents can be removed from the external exhaust airflow (Z1) before it is discharged outside the photocatalytic filter unit. The external exhaust airflow (Z1) from which the anticancer agents have been removed is then discharged outside the photocatalytic filter unit as the second external exhaust airflow (Z2). This means that there is no risk of the anticancer drug present inside the safety cabinet diffusing into the room where the safety cabinet is installed.

[0058] Therefore, the effect is obtained that (a) the anticancer drug being processed by the worker in the workspace of the safety cabinet is diffused into the installation room by the first external exhaust airflow (Z1) discharged from the exhaust port, and the worker is exposed to the anticancer drug.

[0059] Furthermore, the photocatalytic filter and the light source, which decompose and neutralize the anticancer agent contained in the first external exhaust airflow (Z1), are installed in the flow path inside the housing. The flow path in which these are installed is the flow path through which the first external exhaust airflow (Z1) discharged from the exhaust port flows. The external flow path has a plenum formed therein, and the first external exhaust airflow (Z1) flows into the photocatalytic filter at a desired filter inflow velocity while satisfying the predetermined wind speed condition (for example, 0.53 m / s or more) for the wind speed of the unpurified airflow (X) of the safety cabinet. The desired filter inflow velocity is set to fall within the appropriate range of the photocatalytic filter for each anticancer agent. This is to ensure that the photocatalytic filter reliably achieves an anticancer agent decomposition effect of a desired level or higher for each anticancer agent.

[0060] Furthermore, the inlet cross-sectional area of ​​the plenum is set to be the same as or larger than the opening area of ​​the exhaust port. This is to ensure that the airflow rate and velocity of the first external exhaust airflow (Z1) discharged from the exhaust port are not limited by the inlet cross-sectional area of ​​the plenum. As a result, there is virtually no need to change the airflow design for the unpurified airflow (X) and the first external exhaust airflow (Z1) inside the main body of the safety cabinet, which was carried out assuming that the photocatalytic filter and the light source were not installed in the flow path.

[0061] Furthermore, the outlet cross-sectional area of ​​the plenum is set according to the airflow rate of the second external exhaust airflow (Z2) so that the first external exhaust airflow (Z1) flows into the photocatalytic filter at the desired filter inflow velocity. This is because, according to JIS K 3800, the airflow rate of the second external exhaust airflow (Z2) is determined by the airflow rate of the unpurified airflow (X), and also because the predetermined airflow velocity condition (e.g., 0.53 m / s or more) for the unpurified airflow (X) must be satisfied. Thus, since the airflow rate of the second external exhaust airflow (Z2) that flows out of the photocatalytic filter (i.e., passes through the photocatalytic filter) and is discharged to the outside of the photocatalytic filter unit is predetermined, the airflow velocity of the first external exhaust airflow (Z1) at the time of inflow into the filter must be specified within the appropriate range of the photocatalytic filter in order to match the predetermined airflow rate, and as a result, the cross-sectional area of ​​the outlet side of the plenum is naturally determined.

[0062] Accordingly, in the photocatalytic filter unit according to the second aspect of the present invention, the photocatalytic filter and the light source for decomposing and neutralizing anticancer agents contained in the first external exhaust airflow (Z1) discharged from the exhaust port can be used with almost no change to the airflow design performed without installing them in the flow path.

[0063] Therefore, (b) it is possible to operate a "conventional safety cabinet" that does not have the function of decomposing and neutralizing anticancer drugs contained in the first external exhaust airflow (Z1) discharged from the exhaust port as a safety cabinet that has the function of decomposing and neutralizing anticancer drugs, with almost no change to the airflow design of the conventional safety cabinet.

[0064] Furthermore, in the photocatalytic filter unit according to the second aspect of the present invention, as described above, it is possible to use the airflow design performed without installing the photocatalytic filter and the light source in the flow path with almost no changes. Therefore, even if the photocatalytic filter and the light source are added to the flow path through which the first external exhaust airflow flows using the photocatalytic filter unit, it is virtually unnecessary to change the airflow design.

[0065] Therefore, (c) by adding a photocatalytic filter and light source for decomposing and neutralizing the anticancer drug contained in the first external exhaust airflow (Z1) discharged from the exhaust port to a "conventional safety cabinet" that does not have the function of decomposing and neutralizing the anticancer drug, it is possible to operate the "conventional safety cabinet" as a safety cabinet with the function of decomposing and neutralizing the anticancer drug without changing the airflow design of the "conventional safety cabinet" with almost no change.

[0066] (13) In a preferred example of a photocatalytic filter unit according to a second aspect of the present invention, the opening area of ​​the exhaust port is adjustable, The inlet-side opening of the housing is set to a size that can accept all of the first external exhaust airflow (Z1) discharged from the exhaust port, even if the opening area of ​​the exhaust port is changed.

[0067] In this example, the inlet-side opening of the housing is set to a size that can accommodate all of the first external exhaust airflow (Z1) discharged from the exhaust port, even if the opening area of ​​the exhaust port is changed (between its maximum and minimum values). Therefore, by appropriately changing the opening area of ​​the exhaust port, it is possible to mitigate changes in the airflow volume and velocity of the first external exhaust airflow (Z1) caused by the addition of the photocatalytic filter unit and the light source. This has the advantage that adjusting the filter inlet velocity of the first external exhaust airflow (Z1) to fall within the appropriate range becomes easier than when the opening area of ​​the exhaust port cannot be changed.

[0068] (14) In yet another preferred example of a photocatalytic filter unit according to a second aspect of the present invention, the entirety of the first external exhaust airflow (Z1) discharged from the exhaust port is received by the inlet-side opening of the housing, whether the opening area of ​​the exhaust port is set to its maximum value or to its minimum value.

[0069] In this example, with the photocatalytic filter unit attached to the main body, the opening area of ​​the exhaust port can be expanded or contracted to its limit, which has the advantage of making it easier to adjust the filter inflow velocity of the first external exhaust airflow (Z1) to stay within the appropriate range.

[0070] (15) In yet another preferred example of a photocatalytic filter unit according to a second aspect of the present invention, if the air velocity of the first external exhaust airflow (Z1) at the time of inflow to the filter is set to fall within the appropriate range of the photocatalytic filter, and the airflow rate of the second external exhaust airflow (Z2) discharged from the photocatalytic filter unit is Q1, then the outflow side cross-sectional area Ab of the plenum is: Ab=Q1 / V1 It is given by.

[0071] This example has the advantage that it is very easy to calculate the outflow cross-sectional area Ab of the plenum.

[0072] (16) In yet another preferred example of a photocatalytic filter unit according to a second aspect of the present invention, the light source is positioned between the photocatalytic filter and the exhaust air filter, A breathable activation light blocking means is placed between the light source and the exhaust air filter to prevent the activation light emitted from the light source from irradiating the exhaust air filter.

[0073] In this example, the activation light blocking means prevents the activation light emitted from the light source from irradiating the exhaust air filter, thus suppressing the risk of the exhaust air filter deteriorating due to the activation light. Furthermore, since the activation light blocking means is permeable, it has the advantage of suppressing the influence of the activation light blocking means on the first external exhaust airflow (Z1).

[0074] (17) In yet another preferred example of a photocatalytic filter unit according to a second aspect of the present invention, a photocatalytic filter having the same photocatalytic activity as the photocatalytic filter is used as the activation light blocking means.

[0075] In this example, the activated light blocking means can be implemented in a simple manner, and moreover, the photocatalytic filter used as the activated light blocking means exhibits the same anticancer drug decomposition effect as the photocatalytic filter, thus offering the advantage of significantly improving anticancer drug decomposition performance compared to the case where the activated light blocking means is not used.

[0076] (18) In yet another preferred example of a photocatalytic filter unit according to a second aspect of the present invention, the light source comprises a plurality of linear discharge tubes (e.g., black lights) arranged at intervals along the inlet surface of the photocatalytic filter, Near each of the multiple discharge tubes, a strip-shaped light-shielding member is arranged that extends along the corresponding discharge tube. Multiple of the light-shielding members function as the activation light blocking means, The breathability of the activation light blocking means is achieved by the gaps between the multiple light-shielding members.

[0077] In this example, the activation light blocking means can be implemented in a simple manner, and it has the advantage of being less expensive than when a photocatalytic filter is used as the activation light blocking means.

[0078] (19) In yet another preferred example of a photocatalytic filter unit according to a second aspect of the present invention, the light source comprises a plurality of strip-shaped LED devices arranged at intervals along the inlet surface of the photocatalytic filter.

[0079] In this example, the activation light emitted from each of the multiple LED devices is limited to the direction toward the photocatalytic filter and is not emitted toward the exhaust air filter. Therefore, there is an advantage in that the same effect as when the activation light blocking means is installed can be obtained without installing the activation light blocking means.

[0080] (20) In yet another preferred example of a photocatalytic filter unit according to a second aspect of the present invention, the light source is composed of a plurality of strip-shaped LED devices arranged at intervals along the inlet surface of the photocatalytic filter, An opaque member (e.g., a substrate) included in each of the multiple LED devices functions as the activation light blocking means. The ventilation of the activation light blocking means is achieved by the spacing between the multiple LED devices.

[0081] In this example, the opaque member (e.g., substrate) included in each of the multiple LED devices functions as the activation light blocking means, which has the advantage of eliminating the need to separately provide the activation light blocking means.

[0082] (21) In yet another preferred example of a photocatalytic filter unit according to a second aspect of the present invention, the photocatalytic filter is mounted in the housing in a manner that it can be attached to the housing by a pair of filter holding members, The pair of filter holding members are configured to function as guides for the photocatalytic filter when attaching the photocatalytic filter to or detaching it from the housing.

[0083] In this example, there is the advantage that the photocatalytic filter can be easily attached to and detached from the housing. [Effects of the Invention]

[0084] The safety cabinet according to the first aspect of the present invention and the photocatalytic filter unit according to the second aspect of the present invention provide the following effects: (a) It is possible to reliably prevent a situation in which an anticancer agent being handled by an worker in the workspace is diffused into the installation room by the external exhaust airflow discharged from the exhaust port, thereby exposing the worker to the anticancer agent; (b) It is possible to operate a "conventional safety cabinet" that does not have a function to decompose and neutralize anticancer agents contained in the external exhaust airflow discharged from the exhaust port as a safety cabinet with a function to decompose and neutralize anticancer agents with almost no change to the airflow design of the "conventional safety cabinet" that does not have a function to decompose and neutralize anticancer agents contained in the external exhaust airflow discharged from the exhaust port; and (c) By adding a photocatalytic filter and a light source for decomposing and neutralizing anticancer agents to a "conventional safety cabinet" that does not have a function to decompose and neutralize anticancer agents contained in the external exhaust airflow discharged from the exhaust port, it is possible to operate a "conventional safety cabinet" with a function to decompose and neutralize anticancer agents with almost no change to the airflow design of the "conventional safety cabinet". [Brief explanation of the drawing]

[0085] [Figure 1] This is a schematic cross-sectional diagram illustrating the overall configuration of a safety cabinet according to the first embodiment of the present invention. [Figure 2] This is a schematic front view illustrating the overall configuration of a safety cabinet according to the first embodiment of the present invention. [Figure 3] This is a conceptual diagram showing a photocatalytic filter unit used in a safety cabinet according to the first embodiment of the present invention, viewed from diagonally to the upper right front. [Figure 4] This is a front view of a photocatalytic filter unit used in a safety cabinet according to the first embodiment of the present invention, showing the unit with the front and rear walls of the housing removed. [Figure 5] This is a front view of a photocatalytic filter unit used in a safety cabinet according to the first embodiment of the present invention, showing the state with the photocatalytic filter removed from Figure 4. [Figure 6] This is a conceptual diagram of a photocatalytic filter used in a photocatalytic filter unit of a safety cabinet according to the first embodiment of the present invention. [Figure 7] This graph conceptually shows the relationship between pressure loss and airflow at the exhaust port of a safety cabinet according to the first embodiment of the present invention, and the static pressure characteristics of the blower of the safety cabinet. [Figure 8] This graph shows the change in the rate of decomposition of anticancer drugs with respect to operating time, obtained in an effectiveness verification test of a safety cabinet according to the first embodiment of the present invention. [Figure 9] This is a front view of a photocatalytic filter unit used in a safety cabinet according to a second embodiment of the present invention, showing the unit with the front and rear walls of the housing removed. [Figure 10] This is a front view of a photocatalytic filter unit used in a safety cabinet according to a third embodiment of the present invention, showing the unit with the front and rear walls of the housing removed. [Figure 11] This is a front view of a photocatalytic filter unit used in a safety cabinet according to a fourth embodiment of the present invention, showing the unit with the front and rear walls of the housing removed. [Figure 12] This is a schematic cross-sectional diagram illustrating the overall configuration of a safety cabinet according to a fifth embodiment of the present invention. [Figure 13] This is a performance comparison table of safety cabinets according to the first and second embodiments of the present invention, a safety cabinet according to a modified example of the first embodiment of the present invention, and a conventional safety cabinet, Comparative Example 1, and Comparative Example 2. [Figure 14] This is a conceptual diagram illustrating a test method for the air purification performance of a safety cabinet according to the first embodiment of the present invention. [Figure 15] This graph shows the test results of the air purification performance of a safety cabinet according to the first embodiment of the present invention. [Figure 16] This is a conceptual diagram showing another configuration (using two photocatalytic filters) of the photocatalytic filter unit used in the safety cabinet according to the first embodiment of the present invention. [Figure 17]This is a conceptual diagram showing another configuration (using two photocatalytic filters) of the photocatalytic filter unit used in the safety cabinet according to the first embodiment of the present invention. [Figure 18] This is a conceptual diagram showing another configuration (using four photocatalytic filters) of the photocatalytic filter unit used in the safety cabinet according to the first embodiment of the present invention. [Figure 19] This is a conceptual diagram showing another configuration (using two photocatalytic filters) of the photocatalytic filter unit used in the safety cabinet according to the first embodiment of the present invention. [Figure 20] This is a conceptual diagram showing another configuration (using four photocatalytic filters) of the photocatalytic filter unit used in the safety cabinet according to the first embodiment of the present invention. [Figure 21] This is a conceptual diagram showing another configuration (using two photocatalytic filters) of the photocatalytic filter unit used in the safety cabinet according to the first embodiment of the present invention. [Figure 22] This is a conceptual diagram showing another configuration (using four photocatalytic filters) of the photocatalytic filter unit used in the safety cabinet according to the first embodiment of the present invention. [Modes for carrying out the invention]

[0086] Hereinafter, preferred embodiments of the present invention will be described with reference to the attached drawings.

[0087] (First Embodiment) Figures 1 and 2 show the overall configuration of the safety cabinet 1 according to the first embodiment of the present invention, and Figures 3 to 5 show the configuration of the photocatalytic filter unit 50 incorporated into the safety cabinet 1.

[0088] (Configuration of Safety Cabinet 1) The safety cabinet 1 according to the first embodiment of the present invention is configured as an indoor circulation type "Class IIA2" safety cabinet and is installed inside an installation room (not shown) (for example, a laboratory or testing room in a university, research institute, medical institution, etc.). As shown in Figures 1 and 2, the safety cabinet 1 comprises a main body 10 and a photocatalytic filter unit 50 fixed to the upper outer surface of the main body 10.

[0089] (Configuration of main unit 10) The main body 10 is supported by a base 11 fixed to its lower part. As shown in Figures 1 and 2, the main body 10 comprises a front wall 16 that slopes forward from the upper edge to the lower edge at a predetermined angle, a rear wall 15 that extends vertically and is positioned opposite the front wall 16 at a predetermined distance, a bottom wall 12 that extends horizontally and is connected to the lower edge of the front wall 16 and the lower edge of the rear wall 15, an upper wall 14 that extends horizontally and is connected to the upper edge of the front wall 16 and the upper edge of the rear wall 15, a left side wall 13a that extends vertically and is connected to the left edge of the front wall 16 and the left edge of the rear wall 15, respectively, and a right side wall 13b that extends vertically and is connected to the right edge of the front wall 16 and the right edge of the rear wall 15, respectively. Thus, the main body 10 has an overall hollow box shape with only the front surface sloped.

[0090] The front wall 16 has a roughly rectangular front opening 16a that functions as a work opening. The front opening 16a also functions as an air intake for unpurified airflow X. The front opening 16a can be opened and closed by moving a transparent shutter 18, which is slidably mounted on the outer surface of the front wall 16, up and down along the outer surface.

[0091] Inside the main body 10, a workbench 17 extending horizontally is installed near the bottom wall 12. The front edge of the workbench 17 is connected to the front wall 16 near the lower edge of the front opening 16a. The rear edge of the workbench 17 is connected to the lower edge of the back panel 17c, which extends vertically inward from the front wall 16 at a predetermined interval. The left edge of the workbench 17 is connected to the lower edge of the left side panel 17e, which extends vertically inward from the left side wall 13a at a predetermined interval. The right edge of the workbench 17 is connected to the lower edge of the right side panel 17f, which extends vertically inward from the right side wall 13b at a predetermined interval. A top panel 17d extending horizontally at a predetermined interval is positioned directly above the workbench 17. The front edge of the top panel 17d is connected to the front wall 16, the rear edge of the top panel 17d is connected to the upper edge of the back panel 17c, the left edge of the top panel 17d is connected to the upper edge of the left side panel 17e, and the right edge of the top panel 17d is connected to the upper edge of the right side panel 17e. The workbench 17, the back panel 17c, the left side panel 17e, the right side panel 17f, and the top panel 17d, and the portion of the front wall 16 of the main body 10 facing the back panel 17c form (define) a workspace 20. The worker can insert their arm into the workspace 20 through the front opening 16a and place instruments, samples, etc. on the workbench 17 located below the workspace 20 to perform various tasks.

[0092] As described above, a workspace 20 communicating with the front opening 16a is formed inside the main body 10. Therefore, an internal flow path 30 is formed between the partition wall defining the workspace 20, i.e., the workbench 17, the back panel 17c, the left side panel 17e, the right side panel 17f, and the top panel 17d, and the inner wall surface of the main body 10. In this first embodiment, the internal flow path 30 is formed from a lower flow path 31 formed between the workbench 17 and the bottom wall 12, a rear side flow path 32 formed between the back panel 17c and the rear wall 15, and an upper flow path 33 formed between the top panel 17d and the top wall 14.

[0093] The workbench 17 has multiple front intake ports 17a formed near the front wall 16 and multiple rear intake ports 17b formed away from the front wall 16 and closer to the rear wall 15, arranged in parallel at intervals. As a result, the work space 20 is in communication with the lower flow path 31 via the multiple front intake ports 17a and the multiple rear intake ports 17b. Consequently, gas (usually air) inside the work space 20 enters the lower flow path 31 directly below the work space 20 via the front intake ports 17a and the rear intake ports 17b, moves backward along the lower flow path 31 to reach the rear side flow path 32 behind the work space 20, and then rises up the rear side flow path 32 to reach the upper flow path 33 directly above the work space 20.

[0094] An exhaust port 19 is formed on the upper wall 14 of the main body 10 to discharge a portion (in this case, 30%) of the gas present in the upper flow path 33 to the outside of the main body 10. As shown in Figure 3, a cover (lid) 19a is provided over the exhaust port 19 so as to slide. By moving the cover 19a in the direction of the arrow in Figure 3, the exhaust port 19 can be opened and closed as needed, and the amount of exhaust can also be adjusted by changing the degree of opening of the cover 19a (the opening area of ​​the exhaust port 19). In other words, the exhaust port 19 with the cover 19a has the function of discharging a portion of the gas present in the upper flow path 33 to the outside of the main body 10, as well as the function of adjusting the amount of air supplied to the photocatalytic filter unit 50 (exhaust volume adjustment port).

[0095] The upper wall 14 is further equipped with an exhaust HEPA filter unit 42, which houses an exhaust HEPA filter 42a. The exhaust HEPA filter 42a is installed in the exhaust HEPA filter unit 42 so that it can be replaced when necessary. The exhaust HEPA filter 42a is installed in a position that overlaps with the exhaust port 19 (see Figures 1 and 2) and has the function of purifying a portion (in this case, 30%) of the gas present in the upper flow path 33. The gas purified by the exhaust HEPA filter 42a is then discharged to the outside of the main body 10 through the exhaust port 19 and sent into the photocatalytic filter unit 50 installed in the exhaust port 19.

[0096] The gas discharged from the exhaust port 19 to the outside of the main unit 10 may contain anticancer drugs in aerosol or gaseous form. However, as described later, these drugs are decomposed and rendered harmless by the photocatalytic filter unit 50 before being discharged into the installation room from the unit 50. Therefore, there is no risk of workers performing tasks in the safety cabinet 1 being exposed to the anticancer drugs.

[0097] The upper panel 17d, which is a partition wall defining the workspace 20, is equipped with an air intake port (not shown) and an air intake HEPA filter unit 41 containing an air intake HEPA filter 41a. This unit 41 is located below the exhaust HEPA filter unit 42. The air intake HEPA filter 41a is installed in the air intake HEPA filter unit 41 so that it can be replaced when necessary. The air intake HEPA filter 41a has the function of introducing and purifying the gas present in the upper flow path 33 that is not exhausted from the exhaust port 19 (in this case, 70%) through the air intake port. The purified gas is then supplied directly to the workspace 20 below.

[0098] A blower 40 is installed on the upper wall 14 of the main body 10. The blower 40 is provided to generate a desired airflow in the working space 20 and internal passages 30 (lower passage 31, rear passage 32, and upper passage 33) inside the main body 10. The airflow output by the blower 40 causes gas to circulate inside the main body 10 through the working space 20 and internal passages 30 (lower passage 31, rear passage 32, and upper passage 33). This point will be described later.

[0099] In this example, the blower 40 is fixed to the upper wall 14 of the main body 10, but the present invention is not limited to this. For example, it may be placed directly below or behind the work chamber 30. In short, it can be installed in any location as long as it can generate the desired airflow to circulate within the work space 20 and internal flow path 30 of the main body 10. Also, although one blower 40 is installed here, it goes without saying that two or three or more blowers may be installed as needed.

[0100] The airflow circulating inside the main body 10 through the working space 20 and the internal flow paths 30 (i.e., the lower flow path 31, the rear flow path 32, and the upper flow path 33) is set as follows, in accordance with the provisions of JIS K 3800. Specifically, an unpurified airflow X is supplied to the working space 20 from the outside through the front opening 16a, and a purified airflow Y is supplied from the upper flow path 33 through the supply air HEPA filter 41a. The unpurified airflow X also functions as an air curtain (air barrier) to prevent contamination of the sample handled in the working space 20. The unpurified airflow X and the purified airflow Y supplied to the working space 20 become a single airflow W (=X+Y), which moves through the lower flow path 31 and the rear flow path 32 and reaches the upper flow path 33. A predetermined percentage (30% in this case) of the airflow W that reaches the upper flow path 33 is purified by the exhaust HEPA filter 42a, and then becomes the first external exhaust airflow Z1, which is discharged from the exhaust port 19 to the outside of the main body 10 and reaches the inside of the photocatalytic filter unit 50. Inside the photocatalytic filter unit 50, all of the anticancer agents contained in the first external exhaust airflow Z1 are removed, and then it is discharged as the second external exhaust airflow Z2 to the outside of the photocatalytic filter unit 50, i.e., to the installation room of the safety cabinet 1. The remaining airflow W that reaches the upper flow path 33 (70% in this case) is purified by the supply air HEPA filter 41a and supplied again to the working space 20 as purified airflow Y. The process is repeated thereafter. These airflows X, Y, W, Z1 and Z2 operate in the same circulating manner throughout the operation of the safety cabinet 1.

[0101] As described above, a predetermined percentage (30% in this case) of the airflow W (=X+Y) leaving the work space 20 is constantly discharged as the first external exhaust airflow Z1 from the exhaust port 19 to the outside of the main unit 10 (i.e., inside the photocatalytic filter unit 50), and further discharged as the second external exhaust airflow Z2 from the photocatalytic filter unit 50 to the outside of the safety cabinet 1. To replenish this, an unpurified airflow X is supplied to the work space 20 from the outside through the front opening 16a. Consequently, the airflow rate of the second external exhaust airflow Z2 (the amount of gas passing per unit time) is the same as the airflow rate of the unpurified airflow X. As a result, the gas pressure in each part inside the main unit 10 is constantly maintained at approximately the set value.

[0102] Herein, an example of specific dimensions relating to the main body 10 of the safety cabinet 1 according to the first embodiment having the configuration described above is as follows:

[0103] In other words, the front opening 16a is, for example, a rectangle with a width (horizontal) of 0.9 m and a height (vertical) of 0.25 m. The wind velocity of the unpurified airflow X supplied from the front opening 16a to the work space 20 is, for example, 0.55 m / s, and the airflow volume of the unpurified airflow X supplied from the front opening 16a (which is equal to the airflow volume of the first external exhaust airflow Z1 discharged from the exhaust port 19) is, for example, 445 m 3 The value is / h. In addition, the airflow rate of the unpurified airflow X (and the first external exhaust airflow Z1) supplied from the front opening 16a and the airflow rate of the purified airflow Y supplied to the work space 20 via the supply air HEPA filter 41a are set in a ratio of 3 to 7. That is, the airflow rates of the unpurified airflow X and the first external exhaust airflow Z1 are (3 / 10) of the airflow W (=X+Y), and the airflow rate of the purified airflow Y is (7 / 10) of the airflow W (=X+Y).

[0104] Furthermore, as described above, since the airflow rates of the unpurified airflow X and the first external exhaust airflow Z1 are set to be greater than the airflow rate of the purified airflow Y, the opening area of ​​the exhaust port 19, which functions as an exhaust volume adjustment port (an air supply volume adjustment port for the photocatalytic filter unit 50), is generally set to be smaller than the opening area of ​​the front opening 16a. Therefore, the exhaust port 19 is made into a rectangle, for example, with a width (horizontal) of 0.2m and a depth (vertical) of 0.25m, so as to be sufficiently smaller than the front opening 16a (0.9m × 0.25m). The airflow velocity of the first external exhaust airflow Z1 discharged from the exhaust port 19 and supplied to the inside of the photocatalytic filter unit 50 is set to, for example, 2.4m / s.

[0105] (Configuration of photocatalytic filter unit 50) Next, we will explain the configuration of the photocatalytic filter unit 50.

[0106] As can be easily understood from Figures 1 and 2, the photocatalytic filter unit 50 is installed on the outside of the main body 10, in a position that overlaps with the exhaust port 19 (including the cover 19a) formed on the upper wall 14 of the main body 10. In other words, the photocatalytic filter unit 50 has an external structure attached to the main body 10.

[0107] As shown in Figures 3 to 6, the photocatalytic filter unit 50 comprises a hollow rectangular parallelepiped housing 51, a rectangular flat photocatalytic filter 52 installed inside the housing 51, four linear black lights 53 that function as activation light sources for the photocatalytic action of the photocatalytic filter 52, and a plenum 57 for directing a first external exhaust airflow Z1 into the photocatalytic filter 52 at a desired filter inflow velocity.

[0108] As shown in Figure 3, the housing 51 is a rectangular tube enclosed by a front wall 51a, a left side wall 51b, a right side wall 51c, and a rear wall 51d. The inlet end of the housing 51 (the lower end in Figures 3 and 4) is open, forming a rectangular inlet opening 51e. Similarly, the outlet end of the housing 51 (the upper end in Figures 3 and 4) is also open, forming a rectangular outlet opening 51f. The inlet opening 51e is fixed in a position that overlaps with the exhaust port 19 (including the cover 19a) of the main body 10, surrounding the entire exhaust port 19 including the cover 19a. Therefore, whether the opening area of ​​the exhaust port 19 is set to its maximum value or its minimum value, all of the first external exhaust airflow Z1 discharged from the exhaust port 19 is received by the inlet-side opening 51e of the housing 51. Consequently, with the photocatalytic filter unit 50 mounted on the main body 10, the opening area of ​​the exhaust port 19 can be expanded or contracted to its limit, making it easier to adjust the airflow velocity of the first external exhaust airflow Z1 when it enters the filter. A photocatalytic filter 52 is installed near the outlet-side opening 51f using a pair of filter holding members 54.

[0109] As shown in Figure 6, the photocatalytic filter 52 is formed as a rectangular flat plate, with a rectangular planar inlet surface 52a on one side (the bottom surface in Figure 6) into which the external exhaust airflow Z1 flows, and a rectangular planar outlet surface 52b on the other side (the top surface in Figure 6) into which the external exhaust airflow Z2 flows out. The left end 52c and the right end 52d of the photocatalytic filter 52 are inserted into corresponding grooves 54d of a pair of filter holding members 54, respectively, and are fixed inside the housing 51 near its outlet side opening 51f (see Figures 3 and 4).

[0110] The photocatalytic filter 52 possesses both breathability and photocatalytic properties. In other words, it has a filtering function that captures and removes fine particles in the first external exhaust airflow Z1, and an anticancer drug decomposition function by a photocatalyst (e.g., titanium dioxide) immobilized on the photocatalytic filter 52. As the photocatalytic filter 52, for example, a metal honeycomb filter, a nonwoven fabric filter, or a porous ceramic filter with photocatalytically active titanium dioxide (or other photocatalytically active substance) immobilized on it can be suitably used, but the present invention is not limited to these. In short, any configuration can be used as long as it possesses both a filtering function that captures and removes fine particles and an anticancer drug decomposition function by photocatalysis.

[0111] Each of the pair of filter holding members 54 is a straight, rail-shaped member having an inner groove 54d into which the left end 52c or right end 52d of the photocatalytic filter 52 can be engaged, as shown in Figure 5, and its cross-sectional shape is approximately U-shaped. Each of the pair of filter holding members 54 is fixed to the outflow-side ends (upper ends in Figures 3 to 5) of the left wall 51b and right wall 51c of the housing 51, respectively. The pair of filter holding members 54 extend along the left wall 51b and right wall 51c, respectively, and extend parallel to each other in the same plane. By inserting the left and right ends 52c and 52d of the photocatalytic filter 52 into the corresponding grooves 54d of the filter holding member 54 and pushing them in, the photocatalytic filter 52 can be engaged and mounted to the housing 51 in the state shown in Figures 3 and 4. Conversely, the photocatalytic filter 52, which is mounted on the housing 51 in the state shown in Figures 3 and 4, can be easily removed from the housing 51 by pulling it forward or backward along the grooves 54d of the pair of filter holding members 54 as shown in Figures 3 and 4.

[0112] As is clear from the above, each of the pair of filter holding members 54 also functions as a "guide" when attaching and detaching the photocatalytic filter 52 to the housing 51. This has the advantage of making it easy to attach and detach the photocatalytic filter 52.

[0113] Furthermore, it is preferable to attach lids (not shown) to the ends of each of the pair of filter holding members 54 in a removable manner. In this case, when installing the photocatalytic filter 52 into the housing 51, it is sufficient to simply remove the lids (not shown) attached to the ends of each of the pair of filter holding members 54, insert the left and right ends 52c and 52d of the photocatalytic filter 52 into the corresponding grooves 54d of the filter holding member 54, and push them in all the way. The photocatalytic filter 52 is then correctly installed in the housing 51, and after that, the removed lids can be reattached to the ends of the corresponding filter holding members 54. Therefore, for the person in charge of maintenance work on the photocatalytic filter unit 50, it is extremely convenient to replace the photocatalytic filter 2 by simply attaching and detaching the lids (not shown) provided at each end of the pair of filter holding members 54 and inserting and removing the photocatalytic filter 52.

[0114] Generally, photocatalytic filters 52 have hydrophilic properties and self-cleaning capabilities, making it possible to remove dirt by washing them with water. Therefore, maintenance of the photocatalytic filter 52 can be performed by the operator of the safety cabinet 11 themselves, at any time they wish, without having to call a maintenance company or perform complicated procedures such as conventional sterilization gas filling methods. As a result, the risk of the system being unable to operate due to maintenance work on the photocatalytic filter 52 is virtually eliminated, and the anticancer drug decomposition effect of the photocatalytic filter 52 can be utilized to the fullest extent.

[0115] As shown in Figure 4, the dimensions are set such that a predetermined gap 55 (with a width of G) is created between the end faces of the left end 52c and the right end 52d of the photocatalytic filter 52 and the bottom surface of the groove 54d of the corresponding filter holding member 54, making it easy for an operator to insert and remove the photocatalytic filter 52 by inserting their finger into the gap 55. In addition, the side wall 54a on the inlet side (lower side in Figure 4) that supports the photocatalytic filter 52 of each filter holding member 54 is formed to be slightly longer (wider) than the side wall 54b on the outlet side (upper side in Figure 4) that supports the photocatalytic filter 52 of the filter holding member 54, but its width Wb is set to be long enough to adequately support the photocatalytic filter 52 even if the photocatalytic filter 52 is placed off-center on either side of the filter holding member 54. Therefore, not only can the external exhaust airflow Z1 that flows into the housing 51 be passed through the photocatalytic filter 52 without any leakage, but there is also the advantage that the risk of the photocatalytic filter 52 falling out of the filter holding member 54 when an operator inserts or removes the photocatalytic filter 52 is suppressed.

[0116] Furthermore, in order to reduce the risk of the photocatalytic filter 52 falling when it is inserted or removed, for example, a wire mesh (not shown) with almost no air resistance may be placed on the inlet side of the photocatalytic filter 52 (directly below it in Figures 3 and 4), and the entire surface of the wire mesh may catch the photocatalytic filter 52 if it falls.

[0117] The blacklights 53 are linear fluorescent lamps and are installed inside the housing 51 near the photocatalytic filter 52, which is mounted in the outlet-side opening 51f inside the housing 51 in the manner shown in Figures 3 and 4. The blacklights 53 are positioned at a predetermined distance from the inlet surface 52a (bottom surface in Figures 3 and 4) of the photocatalytic filter 52 to the exhaust port 19 (inlet-side opening 51e). Multiple linear blacklights 53 extend parallel to the pair of filter holding members 54 in a plane parallel to the photocatalytic filter 52, and are arranged at equal intervals at predetermined intervals in a direction perpendicular to the pair of filter holding members 54.

[0118] Generally, the shorter the wavelength of light emitted by the black light 53, the higher its ability to activate the photocatalytic action of the photocatalytic filter 52. Therefore, here we use a black light (fluorescent lamp type) emitting ultraviolet A (UV-A) rays (wavelength: 320nm~400nm), which has a high photocatalytic activation ability and low impact on the human body. Specifically, for example, a black light manufactured by Toshiba Lighting & Technology Corporation, with a power consumption of 8W and a peak wavelength of 352nm, can be used. However, the present invention is not limited to this. Any light source that has the ability to activate the photocatalytic action of the photocatalytic filter 52 is acceptable, and there are no restrictions on its shape, number, or the wavelength of the activated light emitted.

[0119] The plenum 57 is designed to direct the first external exhaust airflow Z1, which moves inside the housing 51, into the photocatalytic filter 52 at a desired filter inflow velocity. The plenum 57 refers to the portion from the inflow-side opening 51e of the housing 51 to the inflow surface 52a of the photocatalytic filter 52 (the plane on the side closer to the exhaust port 19). The velocity and pressure of the first external exhaust airflow Z1, which reaches the inflow-side opening 51e of the housing 51 via the exhaust port 19 of the main body 10, are adjusted (optimized) by the plenum 57, and the filter inflow velocity of the first external exhaust airflow Z1 when it flows into the inflow surface 52a of the photocatalytic filter 52 is set to a desired value, that is, a value that allows the photocatalytic filter 52 to exhibit an anticancer drug decomposition effect at or above the desired level (as far as possible). This value is selected from the appropriate range of filter inflow velocity (described later) of the photocatalytic filter 52.

[0120] (Details of Plenum 57) Next, I will explain the aforementioned Plenum 57 in more detail.

[0121] The plenum 57 requires that various conditions related to the plenum 57, such as the inlet cross-sectional area Aa at the inlet end of the plenum 57, the outlet cross-sectional area Ab at the outlet end of the plenum 57, the wind speed when the first external exhaust airflow Z1 moving inside the plenum 57 flows into the plenum 57 (wind speed at plenum inflow), and the wind speed when it flows into the photocatalytic filter 52 (wind speed at filter inflow), be set to appropriate values. The conditions required for this are as follows.

[0122] (i) First, in order to obtain an anticancer drug decomposition effect of the photocatalytic filter 52 at a desired level or higher, it is necessary to set the airflow velocity of the first external exhaust airflow Z1 flowing into the filter 52 to within the appropriate range of the filter 52. This appropriate range of airflow velocity at filter inflow varies greatly depending on the type of photocatalyst fixed to the photocatalytic filter 52 and the type of anticancer drug being targeted, and is specific to the photocatalyst on the photocatalytic filter 52 and the target anticancer drug.

[0123] (b) The wind speed when the first external exhaust airflow Z1 leaves the exhaust port 19 and reaches the inlet end of the plenum 57, that is, the inlet opening 51e of the housing 51 (wind speed at plenum inflow) and the wind speed when it moves along the plenum 57 and finally reaches the inlet surface 52a of the photocatalytic filter 52 (wind speed at filter inflow) do not usually coincide. Nor do they fall within the appropriate range for the wind speed at filter inflow.

[0124] (h) The air velocity at the time the first external exhaust airflow Z1 reaches the inlet surface 52a of the photocatalytic filter 52 must fall within the appropriate range specific to the photocatalytic filter 52. Therefore, "the air velocity at the time the first external exhaust airflow Z1 enters the filter must be set to a desired value selected from within the appropriate range specific to the photocatalytic filter 52." This is the first condition.

[0125] (ii) The wind velocity of the first external exhaust airflow Z1 when it enters the plenum is determined by the airflow rate of the first external exhaust airflow Z1 when it is discharged from the exhaust port 19 and reaches the inlet end of the plenum 57, and the inlet cross-sectional area Aa of the inlet end of the plenum 57. In order to suppress the pressure loss caused by the addition of the photocatalytic filter 52 and to ensure that the airflow design of the "previous safety cabinet" which does not have the function of decomposing and neutralizing anticancer drugs does not change significantly due to the addition of the photocatalytic filter 52, "the airflow rate of the first external exhaust airflow Z1 at the inlet end of the plenum 57 should not be changed, and the inlet cross-sectional area Aa of the plenum 57 should be the same as or larger than the opening area Ac of the exhaust port 19, according to the airflow rate of the second external exhaust airflow Z2." This is the second condition.

[0126] (e) The airflow rate when the second external exhaust airflow Z2 is discharged from the outlet surface 52b of the photocatalytic filter 52 is determined by the airflow rate of the unpurified airflow X supplied to the work space 20 from the front opening 16a. However, the wind speed of the unpurified airflow X must satisfy certain wind speed conditions (e.g., 0.53 m / s or more) according to JIS K 3800. Therefore, in order to suppress pressure loss caused by the addition of the photocatalytic filter 52 and to prevent the airflow design of the "previous safety cabinet" which does not have the function of decomposing and neutralizing anticancer drugs from changing significantly due to the addition of the photocatalytic filter 52, "the outlet side cross-sectional area Ab of the plenum 57 should be set according to the airflow rate of the second external exhaust airflow Z2 so that the first external exhaust airflow Z1 flows into the photocatalytic filter 52 at the desired wind speed when it enters the filter, while ensuring that the wind speed of the unpurified airflow X satisfies the aforementioned wind speed conditions according to JIS K 3800." This is the third condition.

[0127] Next, I will explain why the first to third conditions mentioned above are necessary. 1. Appropriate air velocity range when the first external exhaust airflow Z1 enters the filter. 2. Resolving the discrepancy between the wind speed at plenum inflow and filter inflow of the first external exhaust airflow Z1. 3. Suppression of pressure loss caused by the installation of the first photocatalytic filter unit 50. 4. Setting the airflow velocity of the first external exhaust airflow Z1 at the time of filter inflow within the appropriate range. I will explain in that order.

[0128] [1. Appropriate air velocity range when the first external exhaust airflow Z1 enters the filter] When the photocatalytic filter 52 is irradiated with ultraviolet light emitted by the black light 53, the action of the photocatalyst (e.g., titanium dioxide (TiO2)) immobilized on the photocatalytic filter 52 is activated. In this state, when the first external exhaust airflow Z1 containing an anticancer agent is passed through the photocatalytic filter 52, the anticancer agent comes into contact with the photocatalyst on the photocatalytic filter 52 and is decomposed into harmless inorganic substances by the action of the photocatalyst. The amount of decomposition of the anticancer agent per unit volume at that time, that is, the amount (percentage) of the anticancer agent decomposed by the photocatalyst from a unit volume of the anticancer agent, changes depending on the wind speed of the first external exhaust airflow Z1 when it flows into the photocatalytic filter 52 (wind speed when it flows into the filter). This is because the contact time between the anticancer agent and the photocatalyst varies depending on the magnitude of the wind speed of the first external exhaust airflow Z1 when it flows into the filter.

[0129] For example, the slower (lower) the wind speed of the first external exhaust airflow Z1 when it enters the filter, the longer the contact time between the photocatalyst fixed to the photocatalytic filter 52 and the anticancer agent, making it possible to increase the amount of decomposition of the anticancer agent per unit volume. However, if the wind speed of the first external exhaust airflow Z1 when it enters the filter is too fast (too high), the decomposition process of the anticancer agent by the photocatalytic filter 52 cannot keep up, and the anticancer agent remains in the second external exhaust airflow Z2 discharged from the photocatalytic filter unit 50, potentially causing the anticancer agent to diffuse into the installation chamber of the safety cabinet 1. Conversely, if the wind speed of the first external exhaust airflow Z1 when it enters the filter is too slow (too low), the first external exhaust airflow Z1 may stagnate inside the housing 51 or plenum 57 housing the photocatalytic filter 52, causing the airflow state inside the main body 10 of the safety cabinet 1 to deviate from the design state, potentially impairing the original air circulation function.

[0130] Furthermore, the above-mentioned situation in which the first external exhaust airflow Z1 stagnates inside the housing 51 or plenum 57, impairing the air circulation function, can be avoided, for example, by increasing the filtering area of ​​the inlet surface 52a of the photocatalytic filter 52 (the area of ​​the inlet surface 52a that substantially performs filtering). However, doing so would make the size of the plenum 57 (and consequently the photocatalytic filter unit 50) excessively large, making it difficult to install it in the safety cabinet 1, thus there are practical limits to increasing the filtering area of ​​the photocatalytic filter 52. Increasing the filtering area also presents the problem of excessive costs related to the photocatalytic filter 52. Consequently, the minimum value of the wind speed of the first external exhaust airflow Z1 when it enters the filter will also be limited, similar to its maximum value.

[0131] Experiments conducted by the inventors, taking the above points into consideration, have shown that the wind speed of the first external exhaust airflow Z1 containing the anticancer drug at the time of filter inflow is preferably in the range of 0.3 m / s to 2.0 m / s, and more preferably in the range of 0.5 m / s to 1.5 m / s. When the wind speed of the first external exhaust airflow Z1 at the time of filter inflow is in the latter range (0.5 m / s to 1.5 m / s) rather than the former range (0.3 m / s to 2.0 m / s), a higher anticancer drug decomposition effect can be obtained, and the size of the plenum 57 can also be prevented from becoming excessively large. Since the highest level of anticancer drug decomposition effect can be obtained in the latter range, it can be understood that the latter range is the optimal range for the photocatalytic filter 52 used in the experiment, as it balances the plenum size and the intensity of the anticancer drug decomposition effect. The former range can also be understood as a suitable range that balances the plenum size and the intensity of the anticancer drug decomposition effect. Therefore, both of these ranges can be considered the "appropriate range of airflow velocity at filter inflow" for the photocatalytic filter 52 used in the experiment.

[0132] Therefore, if the air velocity of the first external exhaust airflow Z1 at the time of filter inflow can be set to the "appropriate range of air velocity at filter inflow" described above, it becomes possible to maximize the decomposition amount of the anticancer agent per unit volume while preventing the anticancer agent from remaining in the second external exhaust airflow Z2 discharged from the photocatalytic filter unit 50, or the first external exhaust airflow Z1 from accumulating inside the housing 51 or plenum 57 housing the photocatalytic filter 52. This means that by setting the air velocity of the first external exhaust airflow Z1 at the time of filter inflow to the "appropriate range of air velocity at filter inflow" described above, the photocatalytic filter 52 can always exert an anticancer agent decomposition effect at a desired level or higher. In other words, after starting operation of the safety cabinet 1, it is possible to remove (reduce to zero) all of the anticancer agent contained in the second external exhaust airflow Z2 discharged from the photocatalytic filter unit 50 in a short time (for example, 10 minutes).

[0133] [2. Resolution of the discrepancy between the wind speed at plenum inflow and filter inflow of the first external exhaust airflow Z1] As described above, the photocatalytic filter 52 has an appropriate range for the airflow velocity of the first external exhaust airflow Z1 at the time of filter inflow. Therefore, it is necessary to set the airflow velocity of the first external exhaust airflow Z1 at the time of filter inflow within that appropriate range.

[0134] However, the wind velocity of the first external exhaust airflow Z1 at plenum inflow is never within the aforementioned appropriate range for the wind velocity of the first external exhaust airflow Z1 at filter inflow. This is because the design of the internal airflow of the main unit 10 does not anticipate the situation in which the first external exhaust airflow Z1 discharged from the exhaust port 19 of the main unit 10 passes through the photocatalytic filter 52. In other words, the effect of pressure loss due to the addition of the photocatalytic filter 52 is not considered. Therefore, it is necessary to somehow bring the wind velocity of the first external exhaust airflow Z1 at plenum inflow within the aforementioned appropriate range.

[0135] One method to keep the wind velocity of the first external exhaust airflow Z1 at filter inflow within the aforementioned appropriate range is to change the wind velocity of the external exhaust airflow Z1 at plenum inflow itself so that it falls within the aforementioned appropriate range. In this case, it is necessary to change the existing settings of the various devices incorporated into the main body 10 of the safety cabinet 1, such as the wind power setting of the blower 40 and the opening amount (opening area) of the exhaust port 65. However, since the existing settings related to the various devices incorporated into the main body 10 were determined after detailed consideration to achieve the desired air purification performance inside the main body 10, changing the wind velocity of the first external exhaust airflow Z1 at plenum inflow requires adjusting and resetting all other existing settings that become necessary as a result. This is a much more difficult task than one might imagine.

[0136] For example, if the output airflow of the blower 40 or the opening size (opening area) of the exhaust port 65 is changed in order to alter the airflow velocity of the first external exhaust airflow Z1 when it enters the plenum, the set values ​​for the total supply and exhaust volume of the safety cabinet 1, the set value for the inflow velocity of the unpurified airflow X from the front opening 16a, and the supply and exhaust balance set at 7:3 will change, requiring these values ​​to be readjusted and set again. In the worst case, the desired air purification performance may not be achieved inside the main unit 10.

[0137] Therefore, changing the wind speed of the first external exhaust airflow Z1 at plenum inflow in order to keep the wind speed of the first external exhaust airflow Z1 at filter inflow within the above-mentioned appropriate range is not practical and cannot be adopted. It is necessary to ensure that the wind speed at filter inflow of the first external exhaust airflow Z1 falls within the above-mentioned appropriate range by some method without changing the wind speed at plenum inflow of the first external exhaust airflow Z1. Therefore, the inventors came up with the idea that "the wind speed of the first external exhaust airflow Z1 at plenum inflow changes during the process until it reaches the inflow surface 52a of the photocatalytic filter 52, so that when it finally flows into the inflow surface 52a of the photocatalytic filter 52, the wind speed at filter inflow falls within the above-mentioned appropriate range." The above-mentioned plenum 57 was provided to realize this idea.

[0138] [3. Suppression of pressure loss caused by the installation of the photocatalytic filter unit 50] JIS K 3800 "Class II safety cabinets for biohazard countermeasures" stipulates that the wind speed of the unpurified airflow X introduced into the workspace 20 through the front opening 16a should be set to a value of 0.53 m / s or higher.

[0139] Generally, wind speed V, as the speed at which air moves, can be expressed using the following formula (1), where Q is the amount of air that passes (moves) per unit time, and A is the area over which the air passes.

[0140] Q = A × V (1) In the safety cabinet 1 according to this first embodiment, as described above, if the front opening 16a is a rectangle with a width (horizontal) of 0.9m and a height (vertical) of 0.25m, then the opening area A of the front opening 16a is 0.225m². 2 Furthermore, if the output strength of the blower 40 is set so that the wind speed V of the unpurified airflow X introduced through the front opening 16a is 0.55 m / s (= 1,980 m / h), then the airflow Q of the unpurified airflow X introduced through the front opening 16a is, from the above formula (1), 445 m 3 It becomes / h.

[0141] Furthermore, since the safety cabinet 1 according to this first embodiment is an indoor circulation type Class II, the airflow rate of the first external exhaust airflow Z1 sent from the exhaust port 19 to the photocatalytic filter unit 50 is the same as the airflow rate of the unpurified airflow X, which is 445 m³. 3 It is / h.

[0142] Here, we consider the pressure loss P caused by installing the photocatalytic filter unit 50 directly above the exhaust port 19 of the safety cabinet 1.

[0143] The pressure loss P caused by the installation of the photocatalytic filter unit 50 can be calculated using the Darcy-Weisbach formula, where Cp is the drag coefficient, A is the cross-sectional area, L is the filter thickness, and ρ is the air density (approximately 1.2 kg / m³).3 ) is given by the following formula (2) using the wind speed V.

[0144] P = (1 / 2)Cp × (L / A) × ρ × V 2 (2) Also, from the above formula (1) and the above formula (2), the following formula (3) holds.

[0145] P = (1 / 2)Cp × (L / A) × ρ × (Q / A) 2 (3) The above formula (3) can be transformed as follows into the following formula (4).

[0146] P = (1 / 2)Cp × (L / A 3 ) × ρ × Q 2 (4) From the above formula (4), it can be seen that the pressure loss P increases as the air volume Q increases, as the filter thickness L increases, and as the cross-sectional area A decreases.

[0147] FIG. 7 is a conceptual diagram showing the graphs K1, K2, K3 of the relationship between the pressure loss P and the air volume Q based on the above formula (4) and the graph M of the static pressure characteristic (P-Q curve) of the blower, superimposed.

[0148] The graph M in FIG. 7 is the static pressure characteristic (P-Q curve) of the blower 40 built into the main body 10 of the safety cabinet 1. The air volume Q when the pressure loss P is 0 is the maximum air volume, and the pressure loss P when the air volume Q is 0 is the maximum static pressure. From the graph M, it can be seen that as the pressure loss P increases from 0, the air volume Q decreases. The static pressure characteristic represented by the graph M is a characteristic specific to the blower 40, and actually draws various curves, but only an example is shown in FIG. 4.

[0149] Graphs K1, K2, and K3 in Figure 7 all show that, as can be seen from the above formula (4), the pressure loss P is a function proportional to the square of the airflow rate Q. Graph K1 shows the pressure loss P when the photocatalytic filter unit 50 is not installed (i.e., when the photocatalytic filter unit 50 is removed from the safety cabinet 1 according to this first embodiment) (hereinafter this configuration will also be referred to as the conventional example). The airflow rate Qp1 at the intersection (point p1 in the figure) of graph K1, which shows the pressure loss P of the conventional example, and graph M, which shows how much airflow rate Q can be produced when a pressure loss P is given, represents the supply and exhaust airflow rate in the conventional example (the airflow rate of the unpurified airflow X supplied from the outside and the airflow rate of the first external exhaust airflow Z1 discharged to the outside).

[0150] Graph K2 in Figure 7 shows the pressure loss P when the photocatalytic filter 52 is simply fitted into the exhaust port 19 to add the photocatalytic filter 52 to the safety cabinet 1 (hereinafter this configuration will also be referred to as Comparative Example 1), when filtering the air discharged from the exhaust port 19 with the photocatalytic filter 52. In Comparative Example 1, since there is no plenum 57, the first external exhaust airflow Z1, which is exhausted from the exhaust port 19 at, for example, the wind speed of 2.4 m / s as described above, flows directly into the inlet surface 52a of the photocatalytic filter 52. The pressure loss P depends on the opening area Ac of the exhaust port 19 and is at least greater than in the conventional example by the amount of pressure loss caused by the photocatalytic filter 52. In Figure 7, it can be seen that the airflow Qp2 at the intersection of graph K2 and graph M (p2 in the figure), which shows the pressure loss P of Comparative Example 1, is less than the airflow Qp1 of the conventional example described above. Thus, by simply installing the photocatalytic filter 52 in the exhaust port 19, the airflow Q decreases. From equation (1) above, this means that in Comparative Example 1, the wind speed V of the unpurified airflow X flowing in from the front opening 16a decreases. If the wind speed V of the unpurified airflow X decreases in this way, and the condition that the wind speed of the unpurified airflow X from the front opening 16a must be "0.53 m / s or more" can no longer be guaranteed, it will deviate from the JIS K 3800 standard and will not be able to operate as a safety cabinet.

[0151] In the safety cabinet 1 according to this first embodiment, unlike Comparative Example 1, a plenum 57 is provided inside the housing 51 to direct the first external exhaust airflow Z1 discharged from the exhaust port 19 toward the photocatalytic filter 52. The outflow side cross-sectional area Ab of the plenum 57, that is, the opening area of ​​the inlet surface 52a of the photocatalytic filter 52, is larger than the opening area Ac of the exhaust port 19. By doing so, the effect of pressure loss P caused by the installation of the photocatalytic filter unit 50 is reduced, and the decrease in airflow Q of the first external exhaust airflow Z1 (and consequently the second external exhaust airflow Z2) caused by the installation of the unit 50 can be suppressed. This is clear from Figure 7.

[0152] In other words, the relationship between the pressure loss P and airflow Q of the safety cabinet 1 according to this first embodiment is shown in graph K3 of Figure 7. From the above formula (4), the pressure loss P is greatly reduced by increasing the outlet cross-sectional area Ab of the plenum 57, so graph K3 is closer to graph K1 of the conventional example than graph K2 of Comparative Example 1. In other words, in the configuration of this first embodiment, by providing the plenum 57 and increasing its outlet cross-sectional area Ab to be larger than the opening area Ac of the exhaust port 19, the effect of the pressure loss P caused by the installation of the photocatalytic filter unit 50 can be greatly suppressed compared to Comparative Example 1 (graph K2), and therefore the decrease in airflow Q (and the resulting decrease in the wind velocity V of the unpurified airflow X) that was a problem in Comparative Example 1 can be greatly suppressed.

[0153] [4. Setting the airflow velocity of the first external exhaust airflow Z1 at the time of filter inflow within the appropriate range] As described above, by significantly suppressing the effect of pressure loss P caused by the installation of the photocatalytic filter unit 50, the supply and exhaust airflow Qp3 (i.e., the airflow of the unpurified airflow X and the airflow of the first external exhaust airflow Z1) (see Figure 7) of the safety cabinet 1 according to this first embodiment can be secured. In that case, the wind velocity Vp3 of the first external exhaust airflow Z1 flowing into the photocatalytic filter 52 will be as follows.

[0154] In other words, as described above, there is an appropriate range for the wind speed V of the first external exhaust airflow Z1 flowing into the photocatalytic filter 52 that allows the photocatalyst on the photocatalytic filter 52 to easily exhibit its anticancer drug decomposition performance. If we let Vp3 be the value of the wind speed V of the first external exhaust airflow Z1 flowing into the photocatalytic filter 52 at the time of filter inflow, and Ap3 be the value of the outlet side cross-sectional area Ab of the plenum 57, then the value Qp3 of the supply and exhaust airflow (i.e., the airflow of the unpurified airflow X and the airflow of the first external exhaust airflow Z1) of the safety cabinet 1 according to this first embodiment is given by the following formula (5) from the above formula (1).

[0155] Qp3 = Ap3 × Vp3 (5) From the above formula (5), it can be seen that by changing the value Ap3 of the outlet side cross-sectional area Ab of the plenum 57 according to the value Qp3 of the supply and exhaust airflow Q of the safety cabinet 1 according to this first embodiment, it is possible to set the value Vp3 of the wind velocity V at filter inflow of the first external exhaust airflow Z1 to a desired value. In other words, by providing a plenum 57 inside the housing 51 of the photocatalytic filter unit 50 and adjusting the value Ap3 of its outlet side cross-sectional area Ab according to the value Qp3 of the supply and exhaust airflow Q of the safety cabinet 1 according to this first embodiment, it becomes possible to set the value Vp3 of the wind velocity V at filter inflow of the first external exhaust airflow Z1 so that the photocatalytic effect (anti-cancer drug decomposition performance) of the photocatalytic filter 52 is maximized.

[0156] Herein, an example of the specific dimensions of the photocatalytic filter unit 50 of the safety cabinet 1 according to the first embodiment having the configuration described above is as follows.

[0157] In other words, for example, a rectangular plate-shaped photocatalytic filter 52 with a width (horizontal) of 300 mm, a depth (vertical) of 300 mm, and a thickness of 20 mm can be used. The distance Wa between the pair of filter holding members 54 (distance between the left wall 51b and the right wall 51c of the housing 51) can be, for example, 320 mm, and the width Wb of the lower wall 54a of the filter holding member 54 can be, for example, 25 mm. Since the external exhaust airflow Z1 does not flow into the portion of the inlet surface 52a of the photocatalytic filter 52 that faces and contacts the lower wall 54a of the filter holding member 54 (for example, 10 mm wide), the width of the inlet surface 52a of the photocatalytic filter 52 into which the external exhaust airflow Z1 flows is, for example, 280 mm (= 300 mm - 10 mm × 2). Therefore, the outflow side cross-sectional area Ab of the plenum 57 is, for example, width (horizontal) 280 mm × depth (vertical). Furthermore, the outflow cross-sectional area Ab of the plenum 57 is equal to the filtering area of ​​the inflow surface 52a of the photocatalytic filter 52 (the area of ​​the inflow surface 52a that effectively performs the filtering operation).

[0158] (Performance comparison) Figure 13 shows a performance comparison table. This table shows the measurement results of the wind velocity V of the unpurified airflow X from the front opening 16a (opening area A), and the wind velocity V of the first external exhaust airflow Z1 at filter inflow at the plenum 57 (opening area A, i.e., outlet side cross-sectional area Ab), as well as the verification results of air purification performance and anticancer drug decomposition performance, in a manner that allows comparison between the safety cabinet 1 according to the first embodiment, a conventional example, and comparative example 1.

[0159] In the table in Figure 13, regarding air purification performance, if the wind speed V of the unpurified airflow X from the front opening 16a is guaranteed to be "0.53 m / s or more" according to JIS K 3800, then the air purification performance as a safety cabinet can be guaranteed, indicated by "○". If the wind speed V is less than 0.53 m / s, it is indicated by "×".

[0160] Regarding the anticancer drug decomposition performance, if the wind speed V of the first external exhaust airflow Z1 flowing into the photocatalytic filter 52 is within the range of 0.5 to 1.5 m / s (one of the two appropriate ranges mentioned above), it is indicated with a "○" that the photocatalytic filter 52 (the photocatalyst above) can exert its maximum anticancer drug decomposition performance. If the wind speed V is too slow or too fast, and although there is some effect, the photocatalytic filter 52 cannot exert its maximum anticancer drug decomposition performance, it is indicated with a "△" and if it does not have any anticancer drug decomposition performance at all, it is indicated with a "×".

[0161] The wind speed V was measured using an anemometer manufactured by Nippon Kanomax Co., Ltd. The safety cabinet used for the measurement was the same in this first embodiment, the conventional example, and Comparative Example 1, except for the modified example. The airflow Q was calculated from the opening area A of the front opening 16a, as shown in the table in Figure 13, and the measured wind speed V of the unpurified airflow X from the front opening 16a. Similarly, it was calculated from the outlet side cross-sectional area Ab of the plenum 57, as shown in the table in Figure 13, and the measured wind speed V of the first external exhaust airflow Z1 at filter inflow.

[0162] The conventional example does not have a photocatalytic filter unit 50 (the configuration of the previous safety cabinet), and therefore does not have anticancer drug decomposition performance. However, the wind speed V of the unpurified airflow X from the front opening 16a is 0.55 m / s, so the air purification function was guaranteed. Therefore, the air purification function is marked as "✓".

[0163] Comparative Example 1 is a configuration in which the photocatalytic filter 52 is fitted directly into the exhaust port 19 in order to ensure that the first external exhaust airflow Z1 from the exhaust port 19 passes through the photocatalytic filter 52 without leakage, and a black light 53 is installed upstream of it. In Comparative Example 1, the opening area Ac of the exhaust port 19 is small at 0.9m × 0.25m, resulting in a large pressure loss, which reduced the airflow Q of the first external exhaust airflow Z1 discharged from the exhaust port 19. As a result, the wind velocity of the unpurified airflow X from the front opening 16a was 0.51m / s, and the air purification function specified in JIS K 3800 could not be guaranteed. Therefore, the air purification performance is marked as "×".

[0164] Comparative Example 2 is an example where only the output of the blower 40 is increased in the configuration of Comparative Example 1. Since the highest priority is to enable operation as a safety cabinet, the output of the blower 40 was increased to raise the wind velocity V of the unpurified airflow X from the front opening 16a, which was insufficient in Comparative Example 1, to 0.55 m / s. However, in this configuration, the wind velocity of the first external exhaust airflow Z1 at the time of filter inflow naturally rises above the desired value, so the vaporized anticancer drug will pass through the photocatalytic filter 52 at high speed, and there is a high possibility that the decomposition of the anticancer drug will not proceed sufficiently and the anticancer drug will leak out from the photocatalytic filter 52. Therefore, the anticancer drug decomposition performance is rated as "△".

[0165] In the safety cabinet 1 according to this first embodiment, unlike the others, a photocatalytic filter unit 50 having a plenum 57 is provided in a position that overlaps with the exhaust port 19 of the main body 10. The airflow Q of the unpurified airflow X from the front opening 16a (which is equal to the airflow Q of the first external exhaust airflow Z1 flowing into the plenum 57) is 445 m³. 3 / h, and the conventional example is 455m 3 Since it is slightly smaller than / h, a small pressure loss is observed. However, the wind velocity V of the unpurified airflow X from the front opening 16a is 0.54 m / s, which was confirmed to meet the requirement of "0.53 m / s or more" specified in JIS K 3800. This is because by providing the plenum 57 and increasing its outlet cross-sectional area Ab compared to the opening area Ac of the exhaust port 19, the pressure loss caused by the photocatalytic filter 52 was significantly suppressed. Furthermore, this significantly increased the filtering area (the area where filtering is actually performed) of the inlet surface 52a of the photocatalytic filter 52 into which the first external exhaust airflow Z1 flows. Therefore, the air purification function is rated as "○".

[0166] Furthermore, in the safety cabinet 1 according to this first embodiment, by providing a plenum 57 in the photocatalytic filter unit 50, it is possible to control the airflow velocity of the first external exhaust airflow Z1 flowing into the photocatalytic filter 52 at the time of filter inflow, regardless of the shape or size of the exhaust port 19. Therefore, by adjusting the outlet-side cross-sectional area Ab of the plenum 57 according to the supply and exhaust airflow of the safety cabinet 1 (airflow of unpurified airflow X from the front opening 16a and airflow of the first external exhaust airflow Z1 flowing into the plenum 57), the value of the airflow velocity V of the first external exhaust airflow Z1 at the time of filter inflow can be easily set to an appropriate range that maximizes the photocatalytic decomposition performance of the photocatalytic filter 52.

[0167] The table in Figure 13 shows a modified example of the safety cabinet 1 according to this first embodiment, where the airflow Q of the unpurified airflow X from the front opening 16a is the same as that of this first embodiment (445 m³). 3 600m (greater than / h) 3 An example in which the rate was increased to / h is also shown. In this modified example, the airflow rate Q of the unpurified airflow X is higher than in the first embodiment, so in order to suppress the wind velocity V of the unpurified airflow X, the opening area of ​​the front opening 16a is set to 0.5m × 0.3m, which is larger than in the first embodiment (0.3m × 0.28m). In this modified example as well as in the first embodiment, it is possible to suppress the pressure loss P caused by the photocatalytic filter 52 by changing the outlet side cross-sectional area Ab of the plenum 57 according to the airflow rate Q of the unpurified airflow X. Therefore, in this modified example as well as in the first embodiment, it is possible to optimize the wind velocity V of the first external exhaust airflow Z1 at the time of filter inflow (for example, by setting it to 1.11m / s) while complying with the requirement of JIS K 3800 that the wind velocity V of the unpurified airflow X is "0.53m / s or more".

[0168] (Method for confirming the decomposition performance of anticancer drugs) Next, we will explain the method for confirming the degradation performance of anticancer drugs as shown in the table in Figure 13.

[0169] The degradation performance of anticancer drugs shown in the table in Figure 13 was confirmed by the following method. The following description mainly focuses on the safety cabinet 1 according to the first embodiment of the present invention described above, but it goes without saying that the conventional example, comparative examples 1 and 2, and modifications of this first embodiment were also confirmed in the same manner.

[0170] First, a safety cabinet 1 according to the first embodiment of the present invention, having the configuration described above, was actually manufactured. In this safety cabinet 1, the front opening 16a was a rectangle with a width of 0.9 m and a height of 0.25 m. The wind speed and airflow rate of the unpurified airflow X supplied from the front opening 16a were 0.54 m / s and 445 m³, respectively. 3 The setting was changed to / h. The airflow rate of the unpurified airflow X supplied from the front opening 16a and the airflow rate of the purified airflow Y supplied to the work space 20 via the supply air HEPA filter 41a were set to a ratio of 3 to 7. The exhaust port 19 is a rectangle with a width of 0.2m and a depth of 0.25m, and the airflow velocity of the external exhaust airflow Z1 discharged from the exhaust port 19 was set to 2.4m / s.

[0171] The housing 51 of the photocatalytic filter unit 50 was made of a 1.0 mm thick stainless steel plate. The width Wf of the photocatalytic filter 52 was 300 mm, the total width Wa of the filter holding member 54 was 320 mm, the width Wb of the lower wall 54a of the pair of filter holding members 54 was 25 mm, and the width G of the gap between the left side 52c and right side 52d of the photocatalytic filter 52 and the bottom surface of the groove 54d of the corresponding filter holding member 54 was 10 mm. As the photocatalytic filter 52, a photocatalytic ceramic foam manufactured by Renatec Co., Ltd., with a porosity of 80-90%, a width of 300 mm, a depth of 300 mm, and a thickness of 20 mm was used. Cyclophosphamide was used as the anticancer drug, due to the particularly strong concern of occupational exposure of workers to anticancer drugs.

[0172] The safety cabinet 1 according to the first embodiment of the present invention, manufactured as described above, was placed inside a sealed chamber (see Figure 14), and a petri dish containing an acetone solution of the anticancer drug cyclophosphamide was placed on its workbench 17. After confirming that the acetone solution on the petri dish had completely vaporized and the sealed chamber was filled with cyclophosphamide (the operating time of the safety cabinet 1 up to this point was 0 hours, and therefore the anticancer drug decomposition rate was 0%), the safety cabinet 1 was operated. The effectiveness of the safety cabinet 1 (the decomposition performance of cyclophosphamide) was confirmed by measuring and comparing the cyclophosphamide concentration before and after operation of the safety cabinet 1. This was because there was no means to stably and steadily supply cyclophosphamide gas as an anticancer drug.

[0173] While the safety cabinet 1 was in operation, the air in the sealed chamber was drawn out at a rate of 1 liter per minute using a known air pump and bubbled into the acetone solution to recover cyclophosphamide from the solution. The bubbling air was then recirculated back into the sealed chamber. Cyclophosphamide was recovered from the solution before and during the operation of the safety cabinet 1. During operation, recovery was performed every 30 minutes.

[0174] The recovered acetone solution containing cyclophosphamide was dissolved in diethyl ether with an internal standard and derivatized with trifluoroacetic anhydride. After drying under nitrogen gas, the solution was dissolved in toluene to obtain a sample. The cyclophosphamide in this sample was quantitatively analyzed using a gas chromatograph-mass spectrometer under the following analytical conditions.

[0175] For cyclophosphamide, we used Endoxan for injection, manufactured by Shionogi & Co., Ltd. We used an Agilent Technologies gas chromatograph-mass spectrometer (7890A) and a column (DB-5) manufactured by the same company (length 30m, inner diameter 0.25mm, film thickness 0.25μm). Helium gas (airflow rate 24mL / min) was used as the carrier gas. The oven temperature was heated from 70°C to 250°C with a temperature gradient of 15°C / min, held for 3 minutes, and then heated to 300°C with a temperature gradient of 30°C / min.

[0176] Figure 8 shows the results of calculating the "decomposition rate" for the safety cabinet 1, based on measurements of the residual concentration inside the sealed chamber over time, with the pre-operation measurement value set to 100%.

[0177] As is clear from the graph of the first embodiment of the present invention in Figure 8, the cyclophosphamide decomposition rate reached 100% after 120 minutes of operation of the safety cabinet 1, and thereafter, it was found that no cyclophosphamide was present in the acetone solution of cyclophosphamide in the petri dish placed on the workbench 17 of the safety cabinet 1. As a result, it was confirmed that the photocatalytic decomposition performance of anticancer drugs can be efficiently demonstrated with the safety cabinet 1 according to the first embodiment of the present invention.

[0178] Figure 8 shows the test results for safety cabinet 1 according to the first embodiment, along with the test results for safety cabinets of Comparative Example 1 and Comparative Example 2.

[0179] As described above, the safety cabinet of Comparative Example 1 is configured such that the photocatalytic filter 52 is fitted directly into the exhaust port 19 of the safety cabinet 1 according to the first embodiment, and a black light 53 is placed upstream of it, in order to ensure that the exhaust from the exhaust port 19 of the safety cabinet 1 passes through the photocatalytic filter 52 without leakage. In the safety cabinet of Comparative Example 1, it can be seen that the cyclophosphamide decomposition rate does not reach 100% even after 120 minutes of operation of the safety cabinet 1. Therefore, it is presumed that the vaporized cyclophosphamide slips through the photocatalytic filter 52 and leaks out of the safety cabinet, and it is clear that it cannot be used for the purpose of preventing the anticancer drug being processed in the work space 20 from diffusing into the installation room (in aerosol or gaseous state) via the exhaust port 19 and exposing workers to the anticancer drug.

[0180] In the safety cabinet of Comparative Example 1, the shape and size of the front opening 16a are the same as in the first embodiment, but the wind speed of the unpurified airflow X supplied from the front opening 16a is 0.51 m / s, which is slightly smaller than in the first embodiment (0.54 m / s). Also, the airflow volume of the unpurified airflow X from the front opening 16a is 413 m³ 3 / h, and this is also the first embodiment (445m 3 It is slightly smaller than ( / h). In the safety cabinet of Comparative Example 1, the photocatalytic filter 52 is installed by fitting it directly into the exhaust port 19, so the first external exhaust airflow Z1 that passes through the opening of the exhaust port 19 (a rectangle with a width of 0.3m and a depth of 0.28m) flows directly into the photocatalytic filter 52. For this reason, the airflow Q of the first external exhaust airflow Z1 flowing into the photocatalytic filter 52 is 413m³ 3 / h, in this first embodiment (445m 3 Although slightly lower than the value in the first external exhaust airflow Z1 at filter inflow, the wind speed of the first external exhaust airflow Z1 at filter inflow is 2.29 m / s, which is considerably higher than in the first embodiment (1.45 m / s). Therefore, it is presumed that the excessive wind speed of the first external exhaust airflow Z1 at filter inflow is the cause of the vaporized cyclophosphamide passing through the photocatalytic filter 52 and leaking out of the safety cabinet.

[0181] The safety cabinet of Comparative Example 2 has the same configuration as the safety cabinet of Comparative Example 1, but the output of the blower 40 is increased to raise the wind speed of the unpurified airflow X supplied from the front opening 16a, which was insufficient in Comparative Example 1, to 0.55 m / s. In the safety cabinet of Comparative Example 2, it can be seen that the cyclophosphamide decomposition rate does not reach 100% even after 120 minutes of operation. Therefore, similar to the safety cabinet of Comparative Example 1, it is presumed that the vaporized cyclophosphamide slips through the photocatalytic filter 52 and leaks out, and it can be seen that it cannot be used for the purpose of preventing the anticancer drug being processed in the work space 20 from diffusing into the installation room via the exhaust port 19 and exposing workers to the anticancer drug.

[0182] In the safety cabinet of Comparative Example 2, the shape and size of the front opening 16a are the same as in the first embodiment, but the wind speed of the unpurified airflow X supplied from the front opening 16a is 0.55 m / s, which is almost the same as in the first embodiment (0.54 m / s). Also, the airflow volume of the unpurified airflow X from the front opening 16a is 445 m³ 3 / h is the same as in the first embodiment. In the safety cabinet of Comparative Example 2, as in the case of Comparative Example 1, the photocatalytic filter 52 is installed by fitting it directly into the exhaust port 19 of the safety cabinet 1. Therefore, the first external exhaust airflow Z1 that passes through the opening of the exhaust port 19 (a rectangle with a width of 0.3m and a depth of 0.28m) flows directly into the photocatalytic filter 52. For this reason, the airflow Q of the first external exhaust airflow Z1 flowing into the photocatalytic filter 52 is 445m³ 3 The value is the same as in the first embodiment, but the wind speed of the first external exhaust airflow Z1 at the time of filter inflow is 2.47 m / s, which is much larger than in the first embodiment (1.45 m / s). Therefore, as in Comparative Example 1, it is presumed that the excessive wind speed of the first external exhaust airflow Z1 at the time of filter inflow is the cause of the vaporized cyclophosphamide passing through the photocatalytic filter 52 and leaking out of the safety cabinet.

[0183] (Method for verifying the removal performance of volatile organic compounds) Next, we will describe the test results of the steady-state volatile organic compound removal performance of the safety cabinet 1 according to the first embodiment of the present invention.

[0184] The steady-state removal (decomposition) performance of volatile organic compounds by the safety cabinet 1 according to this first embodiment was confirmed by checking the decomposition performance of acetaldehyde (gas) using the following test procedure. This was done to supplement the above-mentioned test of anticancer drug decomposition performance, as it was impossible to continuously supply a constant amount of gaseous anticancer drug, and therefore the test had to be conducted with a constant amount of anticancer drug in the chamber. In other words, in the above-mentioned test of anticancer drug decomposition performance, it was confirmed that the anticancer drug in the chamber was decomposed, but it was not necessarily clear whether the anticancer drug contained in the first external exhaust airflow Z1 of the safety cabinet 1 was steadily 100% decomposed.

[0185] After placing the safety cabinet 1 inside a chamber (see Figure 14) capable of receiving clean air equivalent to or better than that of the safety cabinet 1 according to this first embodiment, acetaldehyde (gas) was supplied to the chamber so that the acetaldehyde concentration in the chamber was 5 ppm, and it was confirmed that the acetaldehyde concentration in the chamber was 5 ppm. Subsequently, acetaldehyde gas with a concentration of 5 ppm was generated using a gas mixer equipped with a compressor and a clean air inlet mechanism, and introduced into the work space 20 through the front opening 16a at an airflow rate of 1 L / min. At this time, the same amount of exhaust gas (acetaldehyde gas) as that supplied to the chamber was set to maintain the acetaldehyde concentration in the chamber at 5 ppm. Then, the blower 40 was operated, and the black light 52 was also operated to generate ultraviolet A light (UV-A light). Then, 10 minutes after the start of operation of the blower 40 and the black light 52, the acetaldehyde concentration in the chamber was measured. For comparison, the same measurements were performed with the Blacklight 53 device stopped. The test results are shown in Figure 15.

[0186] As a result, when the operation of the black light 53 was stopped, the acetaldehyde concentration in the chamber remained at 5 ppm, but when the operation of the black light 53 was started, the acetaldehyde concentration in the chamber decreased to 1 ppm after 10 minutes (see graph in Figure 15). This demonstrates that the safety cabinet 1 according to this first embodiment has sufficient steady-state decomposition performance of volatile organic compounds.

[0187] Therefore, by combining the test results for volatile organic compound removal performance obtained in this manner with the test results for anticancer drug decomposition performance described above, it was found that the safety cabinet 1 according to this first embodiment can decompose all anticancer drugs contained in the first external exhaust airflow Z1 that is continuously discharged from the exhaust port 19 without impairing its air purification performance.

[0188] Furthermore, the photocatalytic filter 52 becomes contaminated over time by decomposition products of anticancer drugs and dust that has slipped through the exhaust HEPA filter 55. If dirt adheres to the titanium dioxide surface, the photocatalytic activity will be impaired, so the photocatalytic filter 2 needs to be replaced as needed or cleaned to keep it in a clean state at all times. If the maintenance procedure is complicated, maintenance may not be performed sufficiently, and the anticancer drug decomposition function of the photocatalyst may not be fully exhibited. For this reason, it is preferable to use a photocatalytic filter based on porous ceramic that can be washed with water by the worker during maintenance, is lightweight, has high rigidity and is easy to handle. For example, a photocatalytic ceramic foam manufactured by Renatec Co., Ltd., with a porosity of 80-90%, a width of 0.3m, a depth of 0.3m, and a thickness of 0.02m, is suitable for use.

[0189] (Effects of the safety cabinet 1 according to the first embodiment) As described in detail above, in the safety cabinet 1 according to the first embodiment of the present invention, the main body 10 is provided with a front opening 16a that functions as a work opening and an air intake for unpurified airflow X, a work space 20 communicating with the front opening 16a, an internal flow path 30 communicating with the work space 20, and an exhaust port 19 communicating with the internal flow path 30. The main body 10 is further equipped with a blower 40, an air supply HEPA filter 41a that supplies purified airflow Y to the work space 20, and an exhaust HEPA filter 42a that purifies the unpurified airflow X and purified airflow Y discharged from the work space 20 and discharges them from the exhaust port 19 as a first external exhaust airflow Z1.

[0190] Up to this point, the configuration is the same as that of a "conventional safety cabinet." However, in the safety cabinet 1 according to this first embodiment, the photocatalytic filter unit 50 is installed on the outside of the main body 10 in a position that overlaps with the exhaust port 19 (including the cover 19a) formed on the upper wall 14 of the main body 10. In other words, the photocatalytic filter unit 50 is externally attached to the main body 10.

[0191] The externally attached photocatalytic filter unit 50 is located in the external flow path through which the first external exhaust airflow Z1 flows, that is, in the internal space of the housing 51. The photocatalytic filter 52 decomposes the anticancer drug contained in the first external exhaust airflow Z1 through photocatalytic action and discharges it to the outside of the safety cabinet 1 as the second external exhaust airflow Z2. A black light 53 is installed near the photocatalytic filter 52 to emit activation light in order to activate the photocatalytic action of the photocatalytic filter 52.

[0192] Furthermore, a plenum 57 is formed in the external flow path through which the first external exhaust airflow Z1 flows, that is, in the internal space of the housing 51. The plenum 57 is configured such that the first external exhaust airflow Z1 flows into the photocatalytic filter 52 at a desired filter inflow velocity selected to fall within an appropriate range (for example, 0.5 m / s to 1.5 m / s) of the filter inflow velocity of the photocatalytic filter 52, which allows for an anticancer drug decomposition effect of a desired level or higher for each anticancer drug. To this end, the inflow side cross-sectional area Aa of the plenum 57 is set to be the same as or larger than the opening area Ac of the exhaust port 19, and the outflow side cross-sectional area Ab of the plenum 57 is set according to the airflow rate of the second external exhaust airflow Z so that the first external exhaust airflow Z1 flows into the photocatalytic filter 52 at a filter inflow velocity selected to fall within the appropriate range.

[0193] As the safety cabinet 1 according to this first embodiment has the configuration described above, the unpurified airflow X supplied to the work space 20 through the front opening 16a and the purified airflow Y supplied to the work space 20 by the supply air HEPA filter 41a move from the work space 20 to the internal flow path 30, are purified by the exhaust HEPA filter 42a, and discharged from the exhaust port 19 as the first external exhaust airflow Z1. Therefore, fine particles present in the work space 20 are removed by the exhaust HEPA filter 42a and are not included in the first external exhaust airflow Z1 discharged from the exhaust port 19. However, anticancer agents (usually in aerosol or gaseous state) present in the work space 20 are not removed by the exhaust HEPA filter 42a, so unless a process to remove the anticancer agents is performed inside the safety cabinet 1, they will be discharged to the outside of the safety cabinet 1 by the first external exhaust airflow Z1.

[0194] However, in the safety cabinet 1 according to this first embodiment, the photocatalytic action of the photocatalytic filter 52 installed in the external flow path (i.e., the internal space of the housing 51) through which the first external exhaust airflow Z1 flows is activated by ultraviolet light from a black light 53 installed in the external flow path, thereby decomposing and neutralizing the anticancer agent contained in the first external exhaust airflow Z1 flowing through the external flow path. In other words, by passing the first external exhaust airflow Z1 through the activated photocatalytic filter 52 before it is discharged to the outside of the safety cabinet 1, the anticancer agent can be removed from the first external exhaust airflow Z1. The first external exhaust airflow Z1, from which the anticancer agent has been removed, is then discharged to the outside of the safety cabinet 1 as the second external exhaust airflow Z2. This means that there is no risk of the anticancer agent present in the work space 20 being diffused into the room where the safety cabinet 1 is installed.

[0195] Therefore, (a) the effect is obtained that the anticancer drug being processed by the worker in the workspace 20 is diffused into the installation room by the first external exhaust airflow Z1 discharged from the exhaust port 19, and the worker is exposed to the anticancer drug.

[0196] Furthermore, the photocatalytic filter 52 and black light 53, which decompose and neutralize the anticancer drug contained in the first external exhaust airflow Z1, are installed in the external flow path (i.e., the internal space of the housing 51). This external flow path is the flow path through which the first external exhaust airflow Z1 discharged from the exhaust port 19 flows. A plenum 57 is formed in the external flow path, and the first external exhaust airflow Z1 flows into the photocatalytic filter 52 at a desired filter inflow velocity while satisfying the predetermined wind speed condition (e.g., 0.53 m / s or more) for the wind speed of the unpurified airflow X. The desired filter inflow velocity is set to fall within the appropriate range of the photocatalytic filter 52 for each anticancer drug. This is to ensure that the photocatalytic filter 52 reliably achieves an anticancer drug decomposition effect of a desired level or higher for each anticancer drug.

[0197] Furthermore, the inlet cross-sectional area Aa of the plenum 57 is set to be the same as or larger than the opening area Ac of the exhaust port 19. This is to prevent the airflow rate and velocity of the first external exhaust airflow Z1 discharged from the exhaust port 19 from being limited by the inlet cross-sectional area Aa of the plenum 57. As a result, there is almost no need to change the airflow design for the unpurified airflow X, purified airflow Y, and first external exhaust airflow Z1 inside the main unit 10, which was carried out assuming that the photocatalytic filter 52 and black light 53 were not installed in the external flow path.

[0198] Furthermore, the outlet-side cross-sectional area Ab of the plenum 57 is set according to the airflow rate of the second external exhaust airflow Z2 so that the first external exhaust airflow Z1 flows into the photocatalytic filter 52 at the desired filter inflow velocity. This is because, according to JIS K 3800, the airflow rate of the second external exhaust airflow Z2 is determined by the airflow rate of the unpurified airflow X, and also because the predetermined airflow velocity condition (e.g., 0.53 m / s or more) for the unpurified airflow X must be satisfied. Thus, since the airflow rate of the second external exhaust airflow Z2 that flows out of the photocatalytic filter 52 (i.e., passes through the photocatalytic filter 52) and is discharged to the outside of the safety cabinet 1 is determined in advance, the filter inflow velocity of the first external exhaust airflow Z1 must be specified within the appropriate range of the photocatalytic filter 52 in order to match the determined airflow rate, and as a result, the outlet-side cross-sectional area Ab of the plenum 57 is naturally determined.

[0199] Therefore, in the safety cabinet 1 according to this first embodiment, it is possible to use an airflow design that was created without installing the photocatalytic filter 52 and black light 53 for decomposing and neutralizing anticancer drugs contained in the first external exhaust airflow Z1 discharged from the exhaust port 19 in the external flow path, with almost no changes.

[0200] Therefore, (b) the effect is obtained that the airflow design of the "previous safety cabinet," which does not have the function of decomposing and neutralizing anticancer drugs contained in the first external exhaust airflow Z1 discharged from the exhaust port 19, can be operated as a safety cabinet that has the function of decomposing and neutralizing the anticancer drugs with almost no change.

[0201] Furthermore, in the safety cabinet 1 according to this first embodiment, as described above, it is possible to use the airflow design performed without installing the photocatalytic filter 52 and black light 53 in the external flow path with almost no changes. Therefore, even if the photocatalytic filter 52 and black light 53 are added to the external flow path through which the first external exhaust airflow Z1 flows, it is virtually unnecessary to change the airflow design.

[0202] Therefore, (c) by adding a photocatalytic filter 52 and a black light 53 for decomposing and neutralizing anticancer drugs to a "conventional safety cabinet" that does not have the function of decomposing and neutralizing anticancer drugs contained in the first external exhaust airflow Z1 discharged from the exhaust port 19, it is possible to operate the "conventional safety cabinet" as a safety cabinet that has the function of decomposing and neutralizing anticancer drugs without changing the airflow design of the "conventional safety cabinet" at all.

[0203] (Second Embodiment) Next, with reference to Figure 9, the safety cabinet 1 according to the second embodiment of the present invention described above will be explained.

[0204] The configuration of the safety cabinet 1 according to the second embodiment of the present invention is the same as that of the safety cabinet 1 according to the first embodiment, except that the photocatalytic filter unit 50A according to the second embodiment, having the configuration shown in Figure 9, is incorporated in place of the photocatalytic filter unit 50 according to the first embodiment, having the configuration shown in Figures 3 and 4. Therefore, in the following, the differences between the photocatalytic filter unit 50A according to the second embodiment and the photocatalytic filter unit 50 according to the first embodiment will be described in detail, and the same points between the two will be omitted and denoted by the same reference numerals as those used in the safety cabinet 1 according to the first embodiment.

[0205] As shown in Figure 9, the configuration of the photocatalytic filter unit 50A in this second embodiment corresponds to the photocatalytic filter unit 50 of the first embodiment (see Figures 3 and 4) with the addition of a flat plate-shaped photocatalytic filter 52A. In this case, the photocatalytic filter 52A is identical to that of the photocatalytic filter unit 50 of the first embodiment in terms of shape, size, material, and function, including the fixed photocatalyst. However, the present invention is not limited to this type of photocatalytic filter.

[0206] The hollow rectangular casing 51A is shaped like the hollow rectangular casing 51 of the photocatalytic filter unit 50 according to the first embodiment, slightly extended toward the opposite side (downward in Figure 9) from the photocatalytic filter unit 50 in order to create space for the additional installation of the photocatalytic filter 52A. Consequently, the total height of the casing 51A of the photocatalytic filter 52A, that is, the distance between the rectangular outlet opening 51Ae and the rectangular inlet opening 51Af, is larger than that of the casing 51 according to the first embodiment. The casing 51A is a rectangular tube surrounded by a front wall 51a, a left side wall 51Ab, a right side wall 51Ac, and a rear wall 51d, which is the same as the casing 51 according to the first embodiment. The outlet opening 51Ae is positioned to overlap with the exhaust port 19 (including the cover 19a) and to encompass the entire exhaust port 19 (including the cover 19a). This is also the same as the casing 51 according to the first embodiment.

[0207] A photocatalytic filter 52 is installed at the inlet opening 51Af using a pair of filter holding members 54 used in the first embodiment. In addition, a photocatalytic filter 52A identical to the photocatalytic filter 52 in the first embodiment, i.e., identical in shape, size, material, and function, is installed using a pair of filter holding members 54A having the same configuration as the pair of filter holding members 54 in the first embodiment. The photocatalytic filter 52A is positioned below the black light 53, parallel to the photocatalytic filter 52, and approximately symmetrical to the photocatalytic filter 52 with respect to the black light 53.

[0208] Similar to the photocatalytic filter 52 according to the first embodiment described above, the inlet surface 52Aa of the photocatalytic filter 52A is on the side of the inlet opening 51Af (lower in Figure 9), and its outlet surface 52Ab is on the side of the outlet opening 51Ae (upper in Figure 9). Furthermore, a gap 55A exists between the left side surface 52Ac of the photocatalytic filter 52A and the inner surface of the groove 54Ad of the corresponding filter holding member 54A, and a gap 55A also exists between the right side surface 52Ad of the photocatalytic filter 52A and the inner surface of the groove 54Ad of the corresponding filter holding member 54A. This is also the same as in the case of the photocatalytic filter 52.

[0209] The photocatalytic filter 52A is positioned as a light-shielding member (activation light blocking member) to prevent ultraviolet light emitted from the black light 53 from irradiating the exhaust HEPA filter 42a installed at the exhaust port 19 of the safety cabinet 1. As the photocatalytic filter 52A, as a light-shielding member, is installed in the flow path of the first external exhaust airflow Z1 sent from the exhaust port 19 toward the photocatalytic filter 52, it needs to have sufficient air permeability so as not to obstruct the flow of the airflow Z1. However, since the photocatalytic filter 52A is identical in shape, size, material, and function to the photocatalytic filter 52 according to the first embodiment, there are no problems related to air permeability. However, the air velocity of the first external exhaust airflow Z1 at the time of filter inflow toward the photocatalytic filter 52 will fluctuate slightly compared to the first embodiment in which the photocatalytic filter 52A is absent, so countermeasures are necessary. This will be described later.

[0210] In the safety cabinet 1 of the first embodiment described above, while the safety cabinet 1 is in operation, ultraviolet light (activation light for the photocatalytic filter 52) emitted from the black light 53 is constantly irradiated not only to the photocatalytic filter 52 but also to the exhaust HEPA filter 42a inside the safety cabinet 1 via the exhaust port 19. This is because, due to the characteristics of the black light 53, ultraviolet light is emitted radially around its entire circumference. The exhaust HEPA filter 42a is generally formed from glass fiber filter paper, which has excellent broad chemical resistance and heat resistance, but it is known that the glass fibers forming the filter paper can experience a decrease in strength due to prolonged irradiation with the aforementioned ultraviolet light (activation light) (see Non-Patent Literature 3). For example, pinholes may occur in areas where the strength of the exhaust HEPA filter 42a has decreased. As a result, the collection performance of the exhaust HEPA filter 42a may decrease earlier than in the "previous safety cabinet," and there is a high risk that the replacement time for the exhaust HEPA filter 42a will be earlier than in the "previous safety cabinet."

[0211] Furthermore, it is well known that ultraviolet light can have adverse effects on the human body, such as causing skin aging. Therefore, if the black light 53 built into the photocatalytic filter unit 50 is positioned in a location visible through the exhaust port 19, as in the safety cabinet 1 according to the first embodiment, there is a risk that a person performing maintenance work on the safety cabinet 1 according to the first embodiment may inadvertently be exposed to ultraviolet light and suffer adverse effects on their body.

[0212] In the safety cabinet 1 according to this second embodiment, as described above, a photocatalytic filter 52A, which acts as a light-shielding member (activation light blocking member), is added inside the housing 51A of the photocatalytic filter unit 50A. As a result, the ultraviolet light is blocked by the photocatalytic filter 52A, and the ultraviolet light is no longer irradiated toward the exhaust port 19 of the main body 10. In other words, the ultraviolet light is no longer leaked out from the photocatalytic filter unit 50A. As a result, there is no risk that the exhaust HEPA filter 42a will deteriorate prematurely due to the ultraviolet light, and that its replacement time will be earlier than in the "previous safety cabinet". Furthermore, since the ultraviolet light is no longer irradiated toward the exhaust HEPA filter 42a through the exhaust port 19 (no leakage), there is no risk that the person performing maintenance work on the safety cabinet 1 according to this second embodiment will be adversely affected by the ultraviolet light.

[0213] However, in the photocatalytic filter unit 50A according to this second embodiment, a photocatalytic filter 52A is added as a light-shielding member (activation light blocking member). As a result, the pressure loss caused by the photocatalytic filter 52A causes the air velocity of the first external exhaust airflow Z1 at the time of filter inflow to decrease compared to that of the photocatalytic filter unit 50 according to the first embodiment, in which the photocatalytic filter 52A is absent. This means that the air velocity of the unpurified airflow X flowing into the work space 20 through the front opening 16a of the safety cabinet 1 according to this second embodiment also decreases. If this air velocity decreases too much and fails to meet the requirement of "0.53 m / s or more", it will fall outside the JIS K 3800 standard and will not be able to operate as a safety cabinet. Therefore, some measures must be taken to address the decrease in air velocity of the first external exhaust airflow Z1 and the unpurified airflow X.

[0214] Therefore, in the safety cabinet 1 according to this second embodiment, the outflow-side cross-sectional area Ab of the plenum 57 of the photocatalytic filter unit 50A (which is equal to the opening area of ​​the inflow surface 52a of the photocatalytic filter 52) is enlarged compared to the first embodiment. Specifically, the width of the outflow-side cross-sectional area Ab of the plenum 57 of the photocatalytic filter unit 50A is set to 0.52m, which is wider than the first embodiment (0.3m), and its depth is set to 0.3m, which is larger than the first embodiment (0.28m). As a result, in the safety cabinet 1 according to this second embodiment, the outflow-side cross-sectional area Ab of the plenum 57 is 0.52m × 0.3m = 0.156m 2 As described above, in the case of the first embodiment (0.3m × 0.28m = 0.084m 2 This is expanded compared to the previous configuration. This compensates for the decrease in wind speed of the first external exhaust airflow Z1 when it enters the filter. In fact, the wind speed of the unpurified airflow X entering the work space 20 through the front opening 16a is 0.54 m / s, which is the same wind speed as in the first embodiment described above.

[0215] The table in Figure 13 shows the effects of the safety cabinet 1 according to this second embodiment, including the wind velocity V of the unpurified airflow X from the front opening 16a of the safety cabinet 1, the measured wind velocity Vp3 of the first external exhaust airflow Z1 at filter inflow to the photocatalytic filter 52, the values ​​of each cross-sectional area A, and the air purification performance and anticancer drug decomposition performance by the photocatalyst as a safety cabinet. The meaning of the "○", "△", and "×" indications for air purification performance and anticancer drug decomposition performance is the same as that used for the safety cabinet 1 according to the first embodiment.

[0216] As can be seen from the table in Figure 13, in the safety cabinet 1 of this second embodiment, the airflow Q of the first external exhaust airflow Z1 discharged from the photocatalytic filter unit 50A is 435 m³. 3 / h, and the above first embodiment (445m 3It is slightly lower than ( / h). This indicates that there is a slight pressure loss due to the addition of the catalytic filter 52A. However, the wind velocity V of the unpurified airflow X from the front opening 16a is maintained at 0.54 m / s, the same as in the first embodiment, and satisfies the requirement of "0.53 m / s or more" according to JIS K 3800. This is because the downstream cross-sectional area Ab of the plenum 57 has been enlarged from (0.3 m × 0.28 m) in the first embodiment to (0.52 m × 0.3 m).

[0217] In other words, the pressure loss caused by the addition of the photocatalytic filter unit 50A to the main body 1 is greater than in the first embodiment by the amount of the added photocatalytic filter 52A, and as a result, the airflow rate of the first external exhaust airflow Z1 is slightly lower than in the first embodiment. Therefore, the airflow rate of the unpurified airflow X, which matches the airflow rate of the first external exhaust airflow Z1, also decreases. Consequently, the airflow velocity of the unpurified airflow X flowing into the work space 20 through the front opening 16a would decrease. However, because the opening area of ​​the front opening 16a is enlarged from the first embodiment (0.3m × 0.28m) to (0.52m × 0.3m), the decrease in the airflow velocity of the unpurified airflow X is mitigated, and the same 0.54m / s as in the first embodiment can be maintained.

[0218] In the safety cabinet 1 of this second embodiment, the increased pressure loss due to the addition of the photocatalytic filter 52A to the photocatalytic filter unit 50 of the first embodiment is mitigated by the enlargement of the opening area of ​​the front opening 16a. Therefore, the air purification performance obtained in the safety cabinet 1 according to this second embodiment is the same as that of the safety cabinet 1 according to the first embodiment. Accordingly, in the table in Figure 13, the air purification performance of this second embodiment is indicated as "○".

[0219] In the table in Figure 13, the anticancer drug decomposition performance obtained in the safety cabinet 1 of this second embodiment is also marked with "○". This is for the following reason. In this second embodiment, the wind speed of the first external exhaust airflow Z1 at the time of filter inflow is 0.77 m / s, which is lower than that of the first embodiment (1.45 m / s). On the other hand, the outflow side cross-sectional area Ab of the plenum 57 of the photocatalytic filter unit 50A is set to (0.52 m × 0.3 m), which is larger than that of the first embodiment (0.3 m × 0.28 m). Therefore, the decrease in the anticancer drug decomposition performance of the photocatalytic filter 52 that is expected due to the decrease in the wind speed of the first external exhaust airflow Z1 at the time of filter inflow is compensated for by the increase in the outflow side cross-sectional area Ab of the plenum 57 (the opening area of ​​the inflow surface 52a of the photocatalytic filter 52). Furthermore, the wind speed of the first external exhaust airflow Z1 at filter inflow, which is 0.77 m / s, falls within the appropriate range required to achieve an anticancer drug decomposition effect at or above the desired level.

[0220] As described above, the safety cabinet 1 according to the second embodiment of the present invention is equivalent to replacing the photocatalytic filter unit 50 of the safety cabinet 1 according to the first embodiment with a photocatalytic filter unit 50A having the above-described configuration. Therefore, similar to the safety cabinet 1 according to the first embodiment, (a) It is possible to reliably prevent a situation in which the anticancer drug being processed by the worker in the work space 20 is diffused into the installation room by the first external exhaust airflow Z1 discharged from the exhaust port 19, and the worker is exposed to the anticancer drug. (b) It is possible to operate the "previous safety cabinet," which does not have the function of decomposing and neutralizing anticancer drugs contained in the first external exhaust airflow Z1 discharged from the exhaust port 19, as a safety cabinet with the function of decomposing and neutralizing said anticancer drugs with almost no change to its airflow design, and (c) Compared to the "conventional safety cabinet" which does not have the function of decomposing and neutralizing anticancer drugs contained in the first external exhaust airflow Z1 discharged from the exhaust port 19, by adding a photocatalytic filter 52 and a black light 53 for decomposing and neutralizing the anticancer drugs, it is possible to operate the "conventional safety cabinet" as a safety cabinet with the function of decomposing and neutralizing the anticancer drugs without changing the airflow design of the "conventional safety cabinet" with almost no change. This is the effect that can be achieved.

[0221] Furthermore, in the safety cabinet 1 according to this second embodiment, in addition to the above effects (a) to (c), (d) The effect is that there is no risk of the exhaust HEPA filter 42a needing to be replaced sooner than in the "previous safety cabinet" due to its premature deterioration, (e) Another benefit is that the person performing maintenance work on the safety cabinet 1 is not at risk of being adversely affected by the ultraviolet light.

[0222] (Third embodiment) Next, with reference to Figure 10, a safety cabinet 1 according to a third embodiment of the present invention will be described.

[0223] The configuration of the safety cabinet 1 according to the third embodiment of the present invention is the same as that of the safety cabinet 1 according to the first embodiment, except that the photocatalytic filter unit 50B according to the third embodiment, which has the configuration shown in Figure 10, is incorporated in place of the photocatalytic filter unit 50 according to the first embodiment, which has the configuration shown in Figures 3 and 4. Therefore, in the following, the differences between the photocatalytic filter unit 50B according to the third embodiment and the photocatalytic filter unit 50 according to the first embodiment will be described in detail, and the same points between the two will be omitted and denoted by the same reference numerals as those used in the safety cabinet 1 according to the first embodiment.

[0224] As shown in Figure 10, the configuration of the photocatalytic filter unit 50B according to this third embodiment is equivalent to adding a plurality of breathable light-shielding members (activation light blocking members) 59 with a V-shaped cross-section and extending in a band to the photocatalytic filter unit 50 according to the first embodiment (see Figures 3 and 4).

[0225] These light-shielding members 59 are each positioned directly below and along the corresponding black light 53 to prevent ultraviolet light emitted from the black light 53 from irradiating the exhaust HEPA filter 42a installed in the exhaust port 19 of the safety cabinet 1 according to this third embodiment. Each light-shielding member 56 and the corresponding black light 53 are not in contact with each other, and a small gap is provided between them.

[0226] The V-shaped cross-section of each light-shielding member 59 makes it possible to ensure light shielding against ultraviolet light while suppressing the increase in resistance (pressure loss occurring inside the photocatalytic filter unit 50B) to the first external outflow airflow Z1 flowing inside the housing 51, in other words, inside the plenum 57, and in other words, while ensuring the ease of flow (air permeability) of the first external outflow airflow Z1. However, it goes without saying that these light-shielding members 59 do not need to have a V-shaped cross-section as long as they can ensure air permeability to the first external outflow airflow Z1.

[0227] As a simple example of the light-shielding member 59, for example, a "mountain-shaped louver" with an opening ratio of 50% can be used. However, the present invention is not limited to this. The light-shielding member 56 can have any configuration and material as long as it has both breathability (ease of flow of the first external outflow airflow Z1) and light-shielding properties, and therefore, any other configuration can be used.

[0228] Preferably, the light-shielding member 59 has the function of reflecting ultraviolet light emitted from the black light 53. In this case, the ultraviolet light radiated from the black light 53 toward the exhaust port 19 (downward in Figure 10) of the main unit 10 is reflected by the light-shielding member 59 and irradiated onto the photocatalytic filter 52, so the total amount of ultraviolet light irradiated onto the photocatalytic filter 52 increases compared to when the light-shielding member 59 does not have a reflective function. This has the advantage that the ability of the photocatalyst on the photocatalytic filter 52 to decompose anticancer drugs is increased by an amount equivalent to the amount of ultraviolet light reflected by the light-shielding member 59.

[0229] The photocatalytic filter unit 50B according to the third embodiment of the present invention, like the photocatalytic filter unit 50A according to the second embodiment, has a plurality of light-shielding members (activation light blocking members) 59 added inside the housing 51B of the photocatalytic filter unit 50B. As a result, the ultraviolet light is blocked by the light-shielding members 59, and the ultraviolet light is no longer irradiated toward the exhaust port 19 of the main body 10. In other words, the ultraviolet light is no longer leaked out of the photocatalytic filter unit 50B. As a result, similar to the photocatalytic filter unit 50A according to the second embodiment, there is no risk that the exhaust HEPA filter 42a will deteriorate prematurely due to the ultraviolet light, and that its replacement time will be earlier than that of the "previous safety cabinet". Furthermore, since the ultraviolet light is no longer irradiated toward the exhaust HEPA filter 42a through the exhaust port 19 (no leakage), there is also the advantage that the person performing maintenance work on the safety cabinet 1 according to this third embodiment will not be adversely affected by the ultraviolet light.

[0230] As described above, the safety cabinet 1 according to the third embodiment of the present invention is equivalent to replacing the photocatalytic filter unit 50A of the safety cabinet 1 according to the second embodiment with a photocatalytic filter unit 50B having the above-described configuration, and therefore it is clear that the same effects (a) to (e) as those of the safety cabinet 1 according to the second embodiment can be obtained.

[0231] (Fourth Embodiment) Next, referring to FIG. 11, the safety cabinet 1 according to the fourth embodiment of the present invention will be described.

[0232] The configuration of the safety cabinet 1 according to the fourth embodiment of the present invention is the same as that of the safety cabinet 1 according to the first embodiment having the configuration shown in FIGS. 3 and 4, except that the photocatalyst filter unit 50C according to the fourth embodiment having the configuration shown in FIG. 11 is incorporated instead of the photocatalyst filter unit 50 according to the first embodiment. Therefore, hereinafter, the differences between the photocatalyst filter unit 50C according to the fourth embodiment and the photocatalyst filter unit 50 according to the first embodiment will be described in detail, and the description of the same points between the two will be omitted with the same reference numerals as those of the safety cabinet 1 according to the first embodiment.

[0233] As shown in FIG. 11, the configuration of the photocatalyst filter unit 50C according to the fourth embodiment corresponds to that in which a plurality of LED devices 58 that emit the same ultraviolet light as the black light 53 are installed instead of the plurality of linear black lights 53 in the photocatalyst filter unit 50 (refer to FIGS. 3 and 4) according to the first embodiment.

[0234] The hollow rectangular parallelepiped housing 51C of the photocatalyst filter unit 50C according to the fourth embodiment has a shape in which the lower end of the hollow rectangular parallelepiped housing 51 of the photocatalyst filter unit 50 according to the first embodiment is slightly shortened upward. Therefore, the overall height of the housing 51C, that is, the distance between the rectangular lower opening 51Ce and the rectangular upper opening 51Cf, is smaller than that of the housing 51. The housing 51C according to the fourth embodiment is a square cylinder surrounded by a front wall 51a, a left side wall 51Cb, a right side wall 51Cc, and a rear wall 51d, which is the same as the housing 51 according to the first embodiment. The lower opening 51Ce is positioned at a position overlapping the exhaust port 19 (including the cover 19a) so as to include the entire exhaust port 19 (including the cover 19a). This is also the same as the housing 51.

[0235] Each LED device 58 has a plurality of light-emitting diode (LED) elements 58a arranged in a linear or matrix pattern in a predetermined pattern on a strip-shaped substrate 58b, and the whole is formed in an elongated strip shape, and is mounted so as to span between the left side wall 51Cb and the right side wall 51Cc of the housing 51C. In FIG. 11, a plurality of LED devices 53A are arranged in parallel at a predetermined interval in the front-rear direction with respect to the paper surface. The layout of these LED devices 58 is the same as that of the black light 53 of the photocatalyst filter unit 50 according to the first embodiment. A predetermined gap is provided between adjacent LED devices 58, thereby suppressing the pressure loss generated inside the photocatalyst filter unit 50C to the same extent as in the case of the photocatalyst filter unit 50 according to the first embodiment. Therefore, the photocatalyst filter unit 50C can obtain the same anticancer agent decomposition performance as that of the photocatalyst filter unit 50 according to the first embodiment.

[0236] Unlike the black light 53, the LED device 58 emits ultraviolet light only from the light-emitting surface of the substrate 58b, that is, the surface on which the LED elements 58a are arranged. Therefore, by installing the light-emitting surface inside the housing 51C facing the photocatalyst filter 52, it is possible to block the ultraviolet light heading toward the exhaust HEPA filter 42a while ensuring air permeability. That is, it is possible to prevent the ultraviolet light from irradiating the exhaust HEPA filter 42a installed at the exhaust port 19 of the main body 10. For this reason, there is an advantage that the photocatalyst filter 52A as a light-shielding member of the photocatalyst filter unit 50A according to the second embodiment and the light-shielding member 59 of the photocatalyst filter unit 50B according to the third embodiment become unnecessary.

[0237] Since the substrate 58b of each LED device 58 is not formed in a V-shaped cross section like the light-shielding member 59 in the third embodiment, it is expected that the pressure loss in the photocatalyst filter unit 50C will increase slightly more than in the case of the third embodiment. However, by making the outflow-side cross-sectional area Ab of the plenum 57 slightly wider than in the case of the third embodiment, it is possible to easily compensate for the increase.

[0238] As described above, the safety cabinet 1 according to the fourth embodiment of the present invention is equivalent to replacing the photocatalytic filter unit 50 of the safety cabinet 1 according to the first embodiment with a photocatalytic filter unit 50C having the above-described configuration, and therefore it is clear that the same effects (a) to (c) as those of the safety cabinet 1 according to the first embodiment can be obtained.

[0239] Furthermore, in the safety cabinet 1 according to the fourth embodiment of the present invention, since a photocatalytic filter unit 50C with an LED device 58 installed in place of the black light 53 is installed, it is clear that in addition to the same effects (a) to (c) as the safety cabinet 1 according to the first embodiment, the same effects (d) and (e) as the safety cabinet 1 according to the second embodiment can also be obtained. Moreover, (f) the effect that there is no need to separately install a light-shielding member (activation light blocking member) can also be obtained.

[0240] (Fifth embodiment) Next, with reference to Figure 12, a safety cabinet 1D according to the fifth embodiment of the present invention will be described.

[0241] The safety cabinet 1D according to the fifth embodiment of the present invention, shown in Figure 12, is configured as a fully exhausted "Class IIB2 type" using a configuration similar to the safety cabinet 1 of the first embodiment, which is configured as an indoor circulation type "Class IIA2 type". Therefore, in the following, the differences between the safety cabinet 1D according to the fifth embodiment and the safety cabinet 1 according to the first embodiment will be described in detail, and explanations of the same points between the two will be omitted and denoted by the same reference numerals as the safety cabinet 1 according to the first embodiment.

[0242] In the fifth embodiment of the present invention, the safety cabinet 1D is as shown in Figure 12, (i) In order to prevent the airflow W(=X+Y) discharged from the working space 20 from returning to the upper flow path 33 directly above the working space 20 via the lower flow path 31 directly below the working space 20 and the rear flow path 32 located at the rear of the working space 20, the rear flow path 32 located at the rear of the working space 20 of the main body 10D is isolated from the upper flow path 33. The airflow W(=X+Y) is directed outwards.

[0243] (ii) The exhaust port 19 (including the cover 19a) is located not on the upper wall 14 of the main body 10, but at the discharge end (upper end in Figure 12) of the rear side flow path 32, which is separated from the upper flow path 33. The exhaust HEPA filter 42a is installed slightly inward from the discharge end of the rear side flow path 32, adjacent to the exhaust port 19 (including the cover 19a).

[0244] (iii) To send the airflow W (=X+Y) to the outside, a duct 45 is connected to the upper end (discharge end) of the rear side passage 32. The inlet end of the duct 45 is connected to the upper end (exhaust end) of the rear side passage 32, and the outlet end of the duct 45 is connected to the outside (outside) of the building where the installation room of the safety cabinet 1D is located.

[0245] (iv) The duct 45 also functions as the housing for the photocatalytic filter unit 50D. A photocatalytic filter 52 is installed near the outlet end of the duct 45, and a plurality of black lights 53 are arranged inside (upstream of) the photocatalytic filter 52, and an exhaust-only blower 44 is installed inside (upstream of) the black lights 53. A plenum 57D is formed in the region from the inlet end of the duct 45 to the inlet surface 52a of the photocatalytic filter 52. Therefore, the photocatalytic filter unit 50D according to this fifth embodiment comprises a duct 45 that functions as a housing, a photocatalytic filter 52, a plurality of black lights 53, an exhaust-only blower 44, and a plenum 57D provided inside the duct 45, and the configuration of the unit 50D is the same as the photocatalytic filter unit 50 according to the first embodiment, except that the duct 45 is used as the housing and an exhaust-only blower 44 is added.

[0246] (v) The cross-sectional area of ​​the inlet end of the duct 45, which serves as the housing for the photocatalytic filter unit 50D, in other words, the inlet cross-sectional area Aaa of the plenum 57D of the unit 50D, corresponds to the inlet cross-sectional area Aa of the plenum 57 of the photocatalytic filter unit 50 according to the first embodiment, and the cross-sectional area of ​​the outlet end of the duct 45, in other words, the outlet cross-sectional area Abb of the plenum 57D, corresponds to the outlet cross-sectional area Ab of the plenum 57 of the photocatalytic filter unit 50 according to the first embodiment.

[0247] (vi) An air intake (not shown) is formed in the upper wall 14 of the main body 10D, and the upper flow path 33 communicates with the outside of the main body 10D (inside the installation room) through the air intake. When the safety cabinet 1D is in operation, an unpurified airflow U is supplied to the upper flow path 33 from the outside of the main body 10D through the air intake.

[0248] (vii) The blower 40 is fixed not to the upper wall 14 of the main body 10D, but to the upper panel 17d which forms part of the partition wall of the work space 20.

[0249] (viii) The plenum 57D inside the photocatalytic filter unit 50D is configured to allow the first external exhaust airflow Z1 to flow into the photocatalytic filter 52 at a desired filter inflow velocity while satisfying predetermined wind speed conditions (e.g., 0.53 m / s or more) for the wind speed of the unpurified airflow X. To this end, the inflow side cross-sectional area Aaa of the plenum 57D is set to be the same as or larger than the opening area Ac of the exhaust port 19, and the outflow side cross-sectional area Abb of the plenum 57D is set according to the airflow rate of the second external exhaust airflow Z2 so that the first external exhaust airflow Z1 flows into the photocatalytic filter 52 at the desired filter inflow velocity. This is the same as the photocatalytic filter unit 50 according to the first embodiment described above.

[0250] As described above, in the safety cabinet 1D according to this fifth embodiment, an unpurified airflow U is supplied from outside the main body 10D to the upper flow path 33 via an air intake port (not shown) on the upper wall 14 of the main body 10D. Since the upper flow path 33 is separated from the rear flow path 32, the unpurified airflow U does not flow into the rear flow path 32. The unpurified airflow U is purified by the air supply HEPA filter 42a and then supplied to the work space 20 as purified airflow Y. In the work space 20, an unpurified airflow X is supplied via the front opening 16a, and this unpurified airflow X functions as an air curtain (air barrier), similar to the safety cabinet 1 according to the first embodiment.

[0251] The unpurified airflow X and purified airflow Y supplied to the workspace 20 become a single airflow W (=X+Y) and move through the lower flow path 31 to the rear flow path 32. The airflow W then rises further up the rear flow path 32 and reaches the exhaust HEPA filter 42a located at its discharge end (upper end in Figure 12). After being purified by the exhaust HEPA filter 42a, the airflow W is discharged from the exhaust port 19 as the first external exhaust airflow Z1. The discharged first external exhaust airflow Z1 then enters the plenum 57D inside the duct 45 from its inlet end (lower left end in Figure 12). After that, it moves through the inside of the duct 45 (plenum 57D) towards the photocatalytic filter 52 installed at the outlet end of the duct 45 (plenum 57D).

[0252] The exhaust fan 44 is provided to efficiently deliver the first external exhaust airflow Z1, which has traveled through the duct 45 (plenum 57D), to the photocatalytic filter 52. The installation of the duct 45, or in other words, the movement of the first external exhaust airflow Z1 to the photocatalytic filter 52 via the duct 45, results in a pressure loss. Therefore, this pressure loss is compensated for by the airflow output by the exhaust fan 44.

[0253] The airflow rate of the unpurified airflow X supplied to the workspace 20 through the front opening 16a and the airflow rate of the purified airflow Y supplied to the workspace 20 after the unpurified airflow U introduced from outside the main body 10D into the upper flow path 33 is purified by the supply air HEPA filter 41a are set to a ratio of 3:7 by adjusting the output balance with the exhaust fan 44. This is the same as in the case of the safety cabinet 1 according to the first embodiment described above.

[0254] Here, an example of specific dimensions for the safety cabinet 1D according to the fifth embodiment having the configuration described above is as follows.

[0255] In the safety cabinet 1D according to this fifth embodiment, with the photocatalytic filter unit 50D not installed, the front opening 16a has a width of 0.9m and a height of 0.25m, and the wind speed and airflow rate of the unpurified airflow X supplied from the front opening 16a to the work space 20 are 0.55m / s and 445m, respectively. 3 The airflow rate of the first exhaust airflow Z1 discharged from exhaust port 19 to duct 45 (plenum 57D) is 1480 m³ / h. 3 It is / h.

[0256] The airflow rate of the first exhaust airflow Z1 is 1480 m³ 3Since it is / h, in order to set the wind speed at the time of filter inflow of the first exhaust air flow Z1 flowing into the photocatalyst filter 52 within the appropriate range (0.5 m / s to 1.5 m / s) in which the photocatalyst filter 52 exhibits its anti-cancer agent decomposition performance at a high level by its photocatalyst, the inflow side cross-sectional area Aaa of the plenum 57D was set to be the same as or larger than the opening area Ac of the exhaust port 19, and the outflow side cross-sectional area Abb of the plenum 57D was set to (700 mm × 600 mm). When the wind speed at the time of filter inflow of the first exhaust air flow Z1 flowing into the photocatalyst filter 52 was measured, it was 0.98 m / s. It is clear that this value is within the above-mentioned appropriate range of the wind speed at the time of filter inflow of the first exhaust air flow Z1. As a result, it was confirmed that all the anti-cancer agents contained in the first external exhaust air flow Z1 constantly discharged from the exhaust port 19 can be decomposed and detoxified and then discharged outside the building as the second external exhaust air flow Z2. Also, the wind speed and air volume of the unpurified air flow X supplied from the front opening 16a were 0.55 m / s and 444 m 3 / h, respectively. As a result, it was also confirmed that the air purification performance as a safety cabinet can be maintained.

[0257] As described above, in the safety cabinet 1D according to the fifth embodiment of the present invention, the photocatalyst filter unit 50D having the above-described configuration is installed in the main body 10D having the above-described configuration. Similar to the case of the safety cabinet 1 according to the first embodiment described above, the inflow side cross-sectional area Aaa of the plenum 57D is set to be the same as or larger than the opening area Ac of the exhaust port 19, and further, the outflow side cross-sectional area Abb of the plenum 57D is set according to the air volume of the second external exhaust air flow Z2 so that the first external exhaust air flow Z1 flows into the photocatalyst filter 52 at the desired wind speed at the time of filter inflow.

[0258] Therefore, it is clear that the same effects (a) to (c) as those of the safety cabinet 1 according to the first embodiment configured as an indoor circulation type "Class IIA2 type" can be obtained even in the safety cabinet 1D according to the fifth embodiment of the present invention configured as a full exhaust type "Class IIB2 type".

[0259] Furthermore, it is clear that the same effects (a) to (e) as those of the safety cabinet 1 according to the second or third embodiment can be obtained by replacing the photocatalytic filter unit 50D used in the safety cabinet 1 according to the fifth embodiment with the photocatalytic filter unit 50A or 50B incorporated in the safety cabinet 1 according to the second or third embodiment.

[0260] Furthermore, it is clear that the same effects (a) to (f) as those of the safety cabinet 1 according to the fourth embodiment can be obtained by replacing the photocatalytic filter unit 50D used in the safety cabinet 1 according to the fifth embodiment with the photocatalytic filter unit 50C incorporated in the safety cabinet 1 according to the fourth embodiment.

[0261] (Other configuration examples of photocatalytic filter units) Figures 16 to 22 are conceptual diagrams showing other configuration examples of the photocatalytic filter unit 50. As can be seen from these figures, the shape of the plenum 57 (housing 51) that makes up the photocatalytic filter unit 50, as well as the number and layout of the photocatalytic filter 52 and light sources (black light 53, LED device 58, etc.) can be changed in various ways.

[0262] The configuration shown in Figure 16 is a photocatalytic filter unit 50 used in the safety cabinet 1 according to the first embodiment described above, in which two identical rectangular flat photocatalytic filters 52 are arranged in an inverted V shape at an angle of approximately 90° near the outlet opening 51f inside the rectangular cylindrical housing 51. Each photocatalytic filter 52 is at an angle of approximately 45° to the right wall 51b and the left wall 51c of the housing 51. A total of seven black lights 53 are arranged in a similar inverted V shape along each photocatalytic filter 52.

[0263] In this configuration, the airflow passing through the inside of the housing 51 (plenum 57) is as shown by the arrows in the figure. The first external exhaust airflow Z1 branches into two directions inside the plenum 57, passes through each photocatalytic filter 52, and is discharged as the second external exhaust airflow Z2 from the outlet side opening 51f of the housing 51. Therefore, the inlet side cross-sectional area Aa of the plenum 57 is the same as that of the photocatalytic filter unit 50 according to the first embodiment described above, but the outlet side cross-sectional area Ab of the plenum 57 is the sum of the outlet side cross-sectional areas Ab1 and Ab2 of each photocatalytic filter 52. That is, Ab = Ab1 + Ab2.

[0264] The configuration in Figure 17 is similar to that in Figure 16, in the photocatalytic filter unit 50 of the first embodiment described above, with two identical rectangular flat photocatalytic filters 52 placed on the side of the outflow opening 51f inside the rectangular cylindrical housing 51. However, it differs from the configuration in Figure 16 in that both photocatalytic filters 52 are arranged parallel to the right wall 51b and the left wall 51c of the housing 51. A total of four black lights 53 are arranged linearly between the two photocatalytic filters 52, along them.

[0265] In this configuration, the airflow passing through the inside of the housing 51 (plenum 57) is as shown by the arrows in the figure. The first external exhaust airflow Z1 branches into two directions inside the plenum 57, passing through each photocatalytic filter 52, and is discharged as the second external exhaust airflow Z2 from the outlet side opening 51f of the housing 51. Therefore, the inlet side cross-sectional area Aa of the plenum 57 is the same as that of the photocatalytic filter unit 50 according to the first embodiment described above, but the outlet side cross-sectional area Ab of the plenum 57 is the sum of the outlet side cross-sectional areas Ab1 and Ab2 of each photocatalytic filter 52, similar to the configuration in Figure 16. That is, Ab = Ab1 + Ab2.

[0266] The configuration shown in Figure 18 is that of the photocatalytic filter unit 50 in the first embodiment described above, in which four identical rectangular flat photocatalytic filters 52 are arranged parallel to the right wall 51b and left wall 51c of the rectangular cylindrical housing 51 on the side of the outflow opening 51f inside the housing 51. Two of the photocatalytic filters 52 are arranged closer to the left wall 51c with their opposing ends connected to each other, and the other two photocatalytic filters 52 are arranged closer to the right wall 51b with their opposing ends connected to each other. A total of eight black lights 53 are arranged in a straight line along the space between the two photocatalytic filters 52 arranged closer to the left wall 51c and the two photocatalytic filters 52 arranged closer to the right wall 51b.

[0267] In this configuration, the airflow passing through the inside of the housing 51 (plenum 57) is as shown by the arrows in the figure. The first external exhaust airflow Z1 branches into four directions inside the plenum 57, passing through each of the photocatalytic filters 52, and is discharged as the second external exhaust airflow Z2 from the outlet side opening 51f. Therefore, the inlet side cross-sectional area Aa of the plenum 57 is the same as that of the photocatalytic filter unit 50 according to the first embodiment described above, but the outlet side cross-sectional area Ab of the plenum 57 is the sum of the outlet side cross-sectional areas Ab1, Ab2, Ab3, and Ab4 of each of the photocatalytic filters 52. That is, Ab = Ab1 + Ab2 + Ab3 + Ab4.

[0268] The configuration shown in Figure 19 is a photocatalytic filter unit 50 from the first embodiment described above, but using a tapered rectangular cylindrical housing 51, with two identical rectangular flat photocatalytic filters 52 placed near the outlet opening 51f inside the housing. The outlet opening 51f of the housing 51 has a larger opening area than the inlet opening 51e. The two photocatalytic filters 52 are arranged parallel to the outlet opening 51f of the housing 51 with their opposing ends connected to each other, which differs from the configurations in Figures 16 and 17. A total of eight black lights 53 are arranged in a straight line along both photocatalytic filters 52.

[0269] In this configuration, the airflow passing through the inside of the housing 51 (plenum 57) is as shown by the arrows in the figure. The first external exhaust airflow Z1, while gradually expanding inside the plenum 57 according to the inclination of the front wall 51a, right side wall 51b, left side wall 51c, and rear wall 51d of the housing 51, branches into two directions, passes through each photocatalytic filter 52, and is discharged from the outlet side opening 51f as the second external exhaust airflow Z2. Therefore, the inlet side cross-sectional area Aa of the plenum 57 is the same as that of the photocatalytic filter unit 50 according to the first embodiment described above, but the outlet side cross-sectional area Ab of the plenum 57 is the sum of the outlet side cross-sectional areas Ab1 and Ab2 of each photocatalytic filter 52. That is, Ab = Ab1 + Ab2.

[0270] The configuration shown in Figure 20 is a photocatalytic filter unit 50 in the first embodiment described above, but using a tapered rectangular cylindrical housing 51, with four identical rectangular flat photocatalytic filters 52 arranged on the side of the outlet opening 51f inside the housing 51. Similar to the configuration in Figure 19, the outlet opening 51f of this housing 51 has a larger opening area than the inlet opening 51e. Two of the photocatalytic filters 52 are arranged in an inverted V shape at an angle of approximately 60° and positioned closer to the left wall 51c, and a total of seven black lights 53 are arranged in a similar inverted V shape along these two photocatalytic filters 52. The other two photocatalytic filters 52 are arranged in an inverted V shape at an angle of approximately 60° and positioned closer to the right wall 51b, adjacent to the central two photocatalytic filters 52, and a total of seven black lights 53 are arranged in a similar inverted V shape along these two photocatalytic filters 52.

[0271] In this configuration, the airflow passing through the inside of the housing 51 (plenum 57) is as shown by the arrows in the figure. The first external exhaust airflow Z1, while gradually expanding within the plenum 57 according to the inclination of the front wall 51a, right side wall 51b, left side wall 51c, and rear wall 51d of the housing 51, branches into four directions, passes through each photocatalytic filter 52, and is discharged from the outlet side opening 51f as the second external exhaust airflow Z2. Therefore, the inlet side cross-sectional area Aa of the plenum 57 is the same as that of the photocatalytic filter unit 50 according to the first embodiment described above, but the outlet side cross-sectional area Ab of the plenum 57 is the sum of the outlet side cross-sectional areas Ab1, Ab2, Ab3, and Ab4 of each photocatalytic filter 52. That is, Ab = Ab1 + Ab2 + Ab3 + Ab4.

[0272] The configuration shown in Figure 21 is the same as that of the photocatalytic filter unit 50 in the first embodiment described above, but with identical rectangular flat photocatalytic filters 52 positioned at approximately 30° inclination relative to the right wall 51b and left wall 51c of the rectangular cylindrical housing 51, on the side of the inlet opening 51e and the side of the outlet opening 51f, respectively. This differs from the configurations shown in Figures 16 and 17. The four black lights 53 are arranged in a straight line along the photocatalytic filter 52 positioned on the side of the inlet opening 51e. Similarly, the other four black lights 53 are arranged in a straight line along the photocatalytic filter 52 positioned on the side of the outlet opening 51f.

[0273] In the configuration shown in Figure 21, a gap exists between the end of the photocatalytic filter 52 located near the outlet opening 51f on the side of the inlet opening 51e and the end of the photocatalytic filter 52 located near the inlet opening 51e on the side of the outlet opening 51f. Therefore, there is a risk that a portion of the first external exhaust airflow Z1 may pass through this gap and move to the outlet opening 51f without passing through both photocatalytic filters 52. To address this, the gap is closed by an appropriate closing member.

[0274] Furthermore, the through-holes between the point where the end of the photocatalytic filter 52 located near the outlet opening 51f intersects with the outlet opening 51f, and between the front wall 51a, right side wall 51b, and rear wall 51d of the housing 51, are closed by appropriate closing members. In addition, the through-holes between the point where the end of the photocatalytic filter 52 located near the inlet opening 51e intersects with the inlet opening 51e, and between the front wall 51a, left side wall 51c, and rear wall 51d of the housing 51, are also closed by appropriate closing members. This is to prevent a portion of the first external exhaust airflow Z1 from passing through each of the through-holes and moving to the outlet opening 51f without passing through both photocatalytic filters 52.

[0275] In this configuration, the airflow passing through the inside of the housing 51 (plenum 57) is as shown by the arrows in the figure. The first external exhaust airflow Z1 branches into two directions inside the plenum 57, passes through each photocatalytic filter 52, and is discharged as the second external exhaust airflow Z2 from the outlet side opening 51f of the housing 51. Therefore, the inlet cross-sectional area Aa at the inlet end of the plenum 57 is the same as that of the photocatalytic filter unit 50 according to the first embodiment described above. However, the outlet cross-sectional area Ab at the outlet end of the plenum 57 is the sum of the outlet cross-sectional areas Ab1 and Ab2 of each photocatalytic filter 52, similar to the configuration in Figures 16 and 17. That is, Ab = Ab1 + Ab2.

[0276] The configuration in Figure 22 corresponds to using two sets of the layout of two photocatalytic filters 52 and a total of eight black lights 53 used in the configuration of Figure 21, arranged symmetrically with respect to the center line of the housing 51. In other words, the configuration in Figure 22 is the photocatalytic filter unit 50 of the first embodiment described above, in which the layout of two photocatalytic filters 52 and a total of eight black lights 53 used in the configuration of Figure 21 is placed near the left side wall 51c inside the rectangular cylindrical housing 51, and the same layout used in the configuration of Figure 21 is placed near the right side wall 51b inside the housing 51, arranged symmetrically with respect to the center line of the housing 51. Therefore, in the configuration of Figure 22, a total of four photocatalytic filters 52 and a total of sixteen black lights 53 are used.

[0277] In this configuration, the airflow passing through the inside of the housing 51 (plenum 57) is as shown by the arrows in the figure. The first external exhaust airflow Z1 branches into four directions inside the plenum 57, passing through each photocatalytic filter 52, and is discharged as the second external exhaust airflow Z2 from the outlet side opening 51f of the housing 51. Therefore, the inlet side cross-sectional area Aa of the plenum 57 is the same as that of the photocatalytic filter unit 50 according to the first embodiment described above. However, the outlet side cross-sectional area Ab at the outlet side end of the plenum 57 is the sum of the outlet side cross-sectional areas Ab1, Ab2, Ab3, and Ab4 of each photocatalytic filter 52, similar to the configuration in Figures 18 and 20. That is, Ab = Ab1 + Ab2 + Ab3 + Ab4.

[0278] As described above, by changing the shape of the housing 51 provided in the photocatalytic filter unit 50 in the first embodiment described above, or by changing the number and / or layout of the photocatalytic filters 52 installed inside the housing 51, or by changing the shape of the plenum 57, it is possible to expand the adjustable range of the outlet cross-sectional area Ab of the plenum 57 without changing the inlet cross-sectional area Aa of the plenum 57. Therefore, there are a wide range of methods for adjusting and setting the outlet cross-sectional area Ab of the plenum 57 according to the airflow rate of the second external exhaust airflow Z2 so that the first external exhaust airflow Z1 flows into one or more photocatalytic filters 52 at a desired filter inflow velocity. This is also true in the second to fifth embodiments described above.

[0279] (Other embodiments) In the first to fifth embodiments described above, examples were shown of using a linear black light 53 (fluorescent lamp) and an LED device as light sources for exhibiting the photocatalytic performance of the photocatalytic filter. However, it goes without saying that any other light source capable of emitting the desired activation light may be used.

[0280] Furthermore, in the first embodiment described above, the pair of filter holding members 54 are fixed to the upper edges of the left wall 51b and the right wall 51c of the housing 51, but it goes without saying that the present invention is not limited thereto. This configuration was adopted to allow the attachment and detachment of a lid that is detachably attached to the ends of the pair of filter holding members 54 without processing the housing 51. Therefore, if the lid is not used, the pair of filter holding members 54 may be fixed at a position slightly below the upper edges of the left wall 51b and the right wall 51c of the housing 51, as long as the function of the plenum 57 is not lost, so that the outlet surface 52b of the photocatalytic filter 52 is lower than the upper edge of the housing 51 (the upper edges of the front wall 51a, the left wall 51b, the right wall 51c, and the rear wall 51d), and both the pair of filter holding members 54 and the photocatalytic filter 52 are housed (built inside) the housing 51.

[0281] Furthermore, as long as the function of the plenum 57 is not lost, the outlet surface 52b of the photocatalytic filter 52 may be higher (protruding), lower (recessed), or at the same level as the upper edge of the housing 51 (the upper edges of the front wall 51a, left wall 51b, right wall 51c, and rear wall 51d).

[0282] Furthermore, in the first embodiment described above, in order to simplify the configuration, the inlet-side cross-sectional area Aa of the plenum 57 is made approximately the same as the opening area of ​​the lower opening 51e of the housing 51. This is because the opening area of ​​the lower opening 51e of the housing 51 is sufficiently larger than the opening area Ac of the exhaust port 65. This shape of the housing 51 corresponds to extending the housing of an existing photocatalytic filter unit that is not optimized for safety cabinets in the direction of airflow (perpendicular to the photocatalytic filter 52). However, the present invention is not limited to this. For example, the shape of the lower opening 51e of the housing 51 may be the same as that of the exhaust port 19, and the housing 51 may be locked to the upper wall 14 of the main body 10 so that the lower opening 51e engages with the exhaust port 19, thereby interconnecting the lower opening 51e and the exhaust port 19. Such a configuration has the advantage that it is possible to suppress the generation of pressure loss and turbulence caused by the sudden widening of the airflow path from the exhaust port 19.

[0283] Furthermore, in the safety cabinets 1 and 1D according to the first to fifth embodiments described above, it is preferable that the power supply for the black light 53 and LED device 58, which serve as light sources emitting activation light, be shared with the power supply for the fluorescent lamps installed inside the main body 10 to prevent workers from forgetting to turn on the black light 53 and LED device 58. However, the configuration is not limited to this, and for example, an airflow sensor may be provided to turn on the black light 53 and LED device 58 when it detects airflow inside the main body 10. Also, a locking mechanism (not shown) may be used to prevent the lids (not shown) that are locked to the ends of the pair of filter holding members 54 from ever opening while the black light 53 and LED device 58 are lit. This has the advantage of reliably preventing a situation in which a worker removes the photocatalytic filter 52 while the black light 53 and LED device 58 are lit and is exposed to ultraviolet light irradiated from the black light 53 and LED device 58.

[0284] Furthermore, it goes without saying that there are no particular limitations on the type of anticancer drug that is processed by the safety cabinet and photocatalytic filter unit according to the present invention. [Industrial applicability]

[0285] The present invention is widely applicable to safety cabinets in which anticancer drugs are used as one of the items to be processed (pharmaceuticals), and can be used in various industrial fields such as medicine, regenerative medicine, and pharmaceuticals where this type of safety cabinet is used. [Explanation of Symbols]

[0286] 1. 1D Safety Cabinet 10, 10D body 11 Base 12 Bottom wall 13a Left side wall 13b Right side wall 14 Upper wall 15 Back wall 16 Front wall 16a Front opening 17 Workbench 17a Front suction port 17b Rear intake port 17c back plate 17d Top plate 17e Left side plate 17f Right side plate 18 Transparent Shutter 19 Exhaust vent 20 workspace 30 Internal flow path 31 Lower channel as internal channel 32 Rear side channel as internal channel 33 Upper channel as internal channel 40 Blower 41. HEPA filter unit for air intake 41a HEPA filter for air intake 42 Exhaust HEPA filter unit 42a Exhaust HEPA filter 44 Blower 45 duct 50, 50A, 50B, 50C Photocatalytic Filter Unit 51, 51A, 51B, 51C enclosure 51a Front wall of the enclosure Left side wall of the 51b, 51Ab, 51Bb, and 51Cb enclosures. Right side wall of the 51c, 51Ac, 51Bc, and 51Cc enclosures. 51d Rear wall of the enclosure 51e, 51Ae, 51Be, 51Ce Enclosure Inlet Opening 51f, 51Af, 51Bf, 51Cf Outlet side opening of the enclosure 52 Photocatalytic Filters 52A Photocatalytic filter as a light-shielding member (activation light blocking member) 52a, 52Aa Inlet surface of photocatalytic filter 52b, 52Ab Outlet surface of photocatalytic filter 52c, 52Ac Photocatalytic filter left end 52d, 52Ad Right end of photocatalytic filter 53 Blacklight 54, 54A Filter holding member 54a, 54Aa Lower wall of filter holding member 54b, 54Ab Upper wall of filter holding member 54c, 54Ac Side walls of filter holding members 54d, 54Ad Recess of filter holding member 55, 55A gap 57 Exhaust Plenum 58 LED device 58a LED element 58b Circuit board 59 Light-shielding member (activation light blocking member) U,X Unpurified Airflow Y Purifying Airflow Z1 First external exhaust airflow Z2 Second external exhaust airflow W Airflow consisting of unpurified airflow and purified airflow Aa Cross-sectional area of ​​the inflow side of the plenum Ab Outflow cross-sectional area of ​​the plenum AC exhaust port opening area Ad duct outlet cross-sectional area

Claims

1. A main body having a front opening that functions as a work opening and an air intake for unpurified airflow, a work space connected to the front opening, an internal passage connected to the work space, and an exhaust port connected to the internal passage, The first blower installed inside the main body, An air filter for supplying purified airflow to the workspace is installed inside the main unit, An exhaust air filter installed inside the main body, which purifies the unpurified airflow supplied to the workspace through the front opening and the purified airflow supplied to the workspace by the air supply filter after they move from the workspace to the internal flow path, and discharges them from the exhaust port as a first external exhaust airflow; A photocatalytic filter is installed in the external flow path through which the first external exhaust airflow discharged from the exhaust port flows, which decomposes the anticancer agent contained in the first external exhaust airflow by photocatalytic action and then discharges it to the outside of the safety cabinet as a second external exhaust airflow. A light source installed in the external channel emits activation light to activate the photocatalytic action of the photocatalytic filter, The external flow path is provided with a plenum formed therein for causing the first external exhaust airflow to flow into the photocatalytic filter at a desired filter inflow velocity while satisfying predetermined wind velocity conditions for the wind velocity of the unpurified airflow, The photocatalytic filter has an appropriate range of air velocity at filter inflow that allows for an anticancer drug decomposition effect of a desired level or higher for each anticancer drug, and the desired air velocity at filter inflow of the first external exhaust airflow is set to fall within the appropriate range. The inlet cross-sectional area of ​​the plenum is set to be the same as or larger than the opening area of ​​the exhaust port. The cross-sectional area of ​​the outlet side of the plenum is set according to the airflow rate of the second external exhaust airflow so that the first external exhaust airflow flows into the photocatalytic filter at the desired filter inflow velocity. The photocatalytic filter, the light source, and the plenum are integrally configured as a photocatalytic filter unit, and the housing of the photocatalytic filter unit is formed such that part or all of its internal space functions as the external flow path. The plenum is formed in the region from the inlet-side opening of the housing in the internal space to the inlet surface of the photocatalytic filter. The wind velocity at the time the first external exhaust airflow flows into the plenum changes as the first external exhaust airflow flows through the plenum, so that the wind velocity of the first external exhaust airflow at the time it flows into the filter falls within the appropriate range of wind velocity at the time it flows into the filter of the photocatalytic filter. A safety cabinet characterized by the following features.

2. An opening area changing means for changing the opening area of ​​the exhaust port is further provided. The safety cabinet according to claim 1, wherein the opening area of ​​the exhaust port can be changed as needed using the opening area changing means.

3. The safety cabinet according to claim 2, wherein the means for changing the opening area is a cover or lid that allows the degree of opening of the exhaust port to be adjusted.

4. If the airflow velocity of the first external exhaust airflow at the time of inflow into the filter is set to fall within the appropriate range of the photocatalytic filter, and the airflow rate of the second external exhaust airflow discharged from the photocatalytic filter unit is Q1, then the outflow side cross-sectional area Ab of the plenum is, Ab = Q1 / V1 A safety cabinet according to any one of claims 1 to 3, as provided by [the relevant source].

5. The light source is positioned between the photocatalytic filter and the exhaust air filter. A safety cabinet according to any one of claims 1 to 3, wherein a breathable activation light blocking means for preventing the activation light emitted from the light source from irradiating the exhaust air filter is disposed between the light source and the exhaust air filter.

6. The safety cabinet according to claim 5, wherein a photocatalytic filter having the same photocatalytic action as the photocatalytic filter is used as the activation light blocking means.

7. The light source is composed of a plurality of linear discharge tubes arranged at intervals along the inlet surface of the photocatalytic filter, Near each of the multiple discharge tubes, a strip-shaped light-shielding member is arranged that extends along the corresponding discharge tube. Multiple of the light-shielding members function as the activation light blocking means, The safety cabinet according to claim 5, wherein the breathability of the activation light blocking means is achieved by gaps between the plurality of light-shielding members.

8. The safety cabinet according to any one of claims 1 to 3, wherein the light source is composed of a plurality of strip-shaped LED devices arranged at intervals along the inlet surface of the photocatalytic filter.

9. The light source is composed of a plurality of strip-shaped LED devices arranged at intervals along the inlet surface of the photocatalytic filter. Each of the multiple LED devices contains an opaque member that functions as the activation light blocking means. The safety cabinet according to claim 8, wherein the ventilation of the activation light blocking means is achieved by the spacing between the plurality of LED devices.

10. The aforementioned internal flow path The unpurified airflow and a predetermined portion of the purified airflow, which are discharged from the workspace and travel through the internal flow path, are purified by the supply air filter and then supplied back into the workspace as the purified airflow. The unpurified airflow and the remaining purified airflow moving through the internal flow path are configured to be discharged from the outlet as the first external exhaust airflow and flow into the external flow path. The safety cabinet according to any one of claims 1 to 3, wherein the safety cabinet functions as an indoor circulation type safety cabinet.

11. The present invention provides a duct that functions as the housing of the photocatalytic filter unit, with one end connected to the exhaust port and the other end connected to the outside of the building, wherein part or all of the internal space of the duct is formed to function as the external flow path, The photocatalytic filter and the light source are arranged inside the duct. The plenum is formed in the region from the inlet-side opening of the duct in the internal space to the inlet surface of the photocatalytic filter. The internal flow path is configured such that all of the unpurified airflow and purified airflow discharged from the working space and moving through the internal flow path are discharged from the exhaust port as the first external exhaust airflow, and further discharged to the outside of the building through the inside of the duct. The first external exhaust airflow is configured to flow into the photocatalytic filter through the plenum, with assistance from a second blower installed inside the duct. The safety cabinet according to any one of claims 1 to 3, wherein the safety cabinet functions as a fully exhausted safety cabinet.

12. A photocatalytic filter unit used by being attached to the main body of a safety cabinet so as to cover its exhaust port, A housing having an inlet opening at one end for receiving a first external exhaust airflow discharged from the exhaust port of the safety cabinet, and an outlet opening at the other end for decomposing the anticancer agent contained in the first external exhaust airflow by photocatalytic action and then discharging it to the outside of the photocatalytic filter unit as a second external exhaust airflow, A photocatalytic filter installed inside the aforementioned housing, A light source is installed inside the housing near the photocatalytic filter, which emits activation light to activate the photocatalytic action of the photocatalytic filter, The enclosure comprises a plenum formed in the flow path of the first external exhaust airflow, which allows the first external exhaust airflow to flow into the photocatalytic filter at a desired filter inflow velocity while satisfying predetermined wind velocity conditions for the wind velocity of the unpurified airflow inside the main body of the safety cabinet, The photocatalytic filter has an appropriate range of air velocity at filter inflow that allows for an anticancer drug decomposition effect of a desired level or higher for each anticancer drug, and the desired air velocity at filter inflow of the first external exhaust airflow is set to fall within the appropriate range. The inlet cross-sectional area of ​​the plenum is set to be the same as or larger than the opening area of ​​the exhaust port. The cross-sectional area of ​​the outlet side of the plenum is set according to the airflow rate of the second external exhaust airflow so that the first external exhaust airflow flows into the photocatalytic filter at the desired filter inflow velocity. The enclosure is formed such that part or all of its internal space functions as an external flow path for the safety cabinet through which the first exhaust airflow flows. The plenum is formed in the region of the internal space from the inlet-side opening of the housing to the inlet surface of the photocatalytic filter. The wind velocity at the time the first external exhaust airflow flows into the plenum changes as the first external exhaust airflow flows through the plenum, so that the wind velocity of the first external exhaust airflow at the time it flows into the filter falls within the appropriate range of wind velocity at the time it flows into the filter of the photocatalytic filter. A photocatalytic filter unit characterized by the following features.

13. The opening area of ​​the exhaust port can be changed. The photocatalytic filter unit according to claim 12, wherein the inlet-side opening of the housing is set to a size that can accept all of the first external exhaust airflow discharged from the exhaust port, even if the opening area of ​​the exhaust port is changed.

14. The photocatalytic filter unit according to claim 13, configured such that all of the first external exhaust airflow discharged from the exhaust port is received by the inlet-side opening of the housing, whether the opening area of ​​the exhaust port is set to its maximum value or to its minimum value.

15. If the airflow velocity of the first external exhaust airflow at the time of inflow into the filter is set to fall within the appropriate range of the photocatalytic filter, and the airflow rate of the second external exhaust airflow discharged from the photocatalytic filter unit is Q1, then the outflow side cross-sectional area Ab of the plenum is, Ab = Q1 / V1 A photocatalytic filter unit according to any one of claims 12 to 14.

16. The light source is positioned between the photocatalytic filter and the exhaust air filter. The photocatalytic filter unit according to any one of claims 12 to 14, wherein a breathable activation light blocking means for preventing the activation light emitted from the light source from irradiating the exhaust air filter is disposed between the light source and the exhaust air filter.

17. The photocatalytic filter unit according to claim 16, wherein a photocatalytic filter having the same photocatalytic action as the photocatalytic filter is used as the activation light blocking means.

18. The light source is composed of a plurality of linear discharge tubes arranged at intervals along the inlet surface of the photocatalytic filter, Near each of the multiple discharge tubes, a strip-shaped light-shielding member is arranged that extends along the corresponding discharge tube. Multiple of the light-shielding members function as the activation light blocking means, The photocatalytic filter unit according to claim 16, wherein the breathability of the activation light blocking means is achieved by gaps between the plurality of light-shielding members.

19. The photocatalytic filter unit according to any one of claims 12 to 14, wherein the light source is composed of a plurality of strip-shaped LED devices arranged at intervals along the inlet surface of the photocatalytic filter.

20. The light source is composed of a plurality of strip-shaped LED devices arranged at intervals along the inlet surface of the photocatalytic filter. Each of the multiple LED devices contains an opaque member that functions as the activation light blocking means. The photocatalytic filter unit according to claim 19, wherein the permeability of the activation light blocking means is achieved by the spacing between the plurality of LED devices.

21. The photocatalytic filter is attached to the housing in a manner that allows it to be detachably attached by a pair of filter holding members. The photocatalytic filter unit according to any one of claims 12 to 14, wherein the pair of filter holding members are configured to function as guides for the photocatalytic filter when the photocatalytic filter is attached to or removed from the housing.

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