Cover, test guide, and filter unit

Abstract

To provide a cover and test guide that assists in conducting efficient and more accurate leak tests. [Solution] A cover 4 for a filter unit including a filter 1 and a storage container 2 for the filter, comprising a perforated plate 41 arranged to cover the opening O of the storage container 2, a porous section 41a formed in the perforated plate 41 to allow air supplied from the opening O side of the storage container 2 to pass through, and a frame-shaped test guide 42 arranged to surround the entire periphery of the porous section 41a and extending vertically from the porous section 41a, wherein the height of the test guide 42 is 20 mm or more and 200 mm or less.

Description

[Technical Field]

[0001] The present invention relates to a cover and test guide for a filter unit, and to a filter unit. [Background technology]

[0002] Clean rooms are used as the work environment in pharmaceutical manufacturing plants and other facilities. Clean air is supplied to clean rooms through, for example, HEPA filters. Leak testing is mandatory for HEPA filters installed in clean rooms, both at the time of completion and periodically as validation. HEPA leak testing methods are specified in ISO 14644-3 (2019) and JIS B 9917-3 (2009). However, JIS B 9917-3 (2009) is scheduled to be revised to JIS B 9920-3 in the future. On-site leak testing is often performed by testers moving a suction probe while scanning to check the number of particles downstream of the HEPA filter.

[0003] The container that houses the HEPA filter has an opening that serves as an outlet for supplying clean air toward the target space. This opening is fitted with, for example, a perforated cover. When conducting a leak test for a HEPA filter, the perforated cover is usually removed and the area around the opening is covered with an anti-contamination sheet to prevent fine particles from being drawn into the container. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-223199 Summary of the Invention [Problem to be solved by the invention]

[0005] In conventional leak tests, it was necessary to remove the punched cover, which could result in fine particles being generated during the process, which could affect the results of the leak test. Also, after removing the punched cover, the tester would scan a position about 30 mm away from the HEPA filter with a suction probe. At this time, the suction probe could come into contact with the HEPA filter, which could damage it.

[0006] The present invention has been proposed to solve the problems of the prior art as described above, and its purpose is to provide a cover and test guide that assist in carrying out leak tests efficiently, more accurately, and safely. [Means for solving the problem]

[0007] In order to achieve the above object, the cover of the present invention has the following features. (1) A cover for a filter unit including a filter and a storage container for the filter, comprising a perforated plate arranged to cover the opening of the storage container, a porous portion formed in the perforated plate through which air supplied from the opening side of the storage container can pass, and a frame-shaped test guide arranged to surround the entire periphery of the porous portion and extending vertically from the porous portion, wherein the height of the test guide is 20 mm or more and 200 mm or less.

[0008] (2) The height of the test guide may be 30 mm or more and 100 mm or less.

[0009] (3) The height of the test guide may be 50 mm.

[0010] (4) The porous portion may be provided with a trace marking that indicates the path along which the suction probe scans during the leak test.

[0011] (5) The test guide may be provided with height markings that indicate the height at which the suction probe scans during the leak test.

[0012] (6) The height marking may be provided at a position spaced 10 mm or more from the porous portion.

[0013] In order to achieve the above object, the test guide of the present invention has the following features. (1) A test guide applicable to a filter unit including a filter, a storage container for the filter, and a cover for the storage container, wherein the cover includes a perforated plate arranged to cover the opening of the storage container, and a porous portion formed in the perforated plate through which air supplied from the opening side of the storage container can pass, and the test guide is a frame-shaped member extending vertically from the porous portion arranged to surround the entire periphery of the porous portion, and the height of the frame-shaped member is 20 mm or more and 200 mm or less.

[0014] (2) The height of the frame-shaped member may be 30 mm or more and 100 mm or less.

[0015] (3) The frame-shaped member may have a height of 50 mm.

[0016] In order to achieve the above object, the filter unit of the present invention has the following features. (1) A filter unit including a filter, a storage container for the filter, and a cover for the storage container, wherein the cover includes a perforated plate arranged to cover the opening of the storage container, a porous portion formed in the perforated plate through which air supplied from the opening side of the storage container can pass, and a frame-shaped test guide arranged to surround the entire periphery of the porous portion and extending vertically from the porous portion, and the height of the test guide is 20 mm or more and 200 mm or less. [Effects of the Invention]

[0017] The present invention provides a cover and test guide that assists in conducting leak tests efficiently, more accurately, and safely. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic diagram showing a schematic configuration of a filter unit according to a first embodiment. [Figure 2] 4 is a photograph for explaining a cover and a test guide according to the first embodiment. [Figure 3] 4 is a photograph for explaining a cover and a test guide according to the first embodiment. [Figure 4] FIG. 2 is a schematic diagram for explaining particle concentration measurement conditions. [Figure 5] This is a photograph that visualizes the behavior of fine particles. [Figure 6] FIG. 2 is a schematic diagram for explaining particle concentration measurement conditions. [Figure 7] 10 is a photograph for explaining particle concentration measurement. [Figure 8] FIG. 1 is a schematic diagram of a clean room. DETAILED DESCRIPTION OF THE INVENTION

[0019] [1. First embodiment] [1.1 Configuration] The cover and test guide according to the present invention will be described together with an example of a filter unit including a filter and its storage container. While the filter may be a HEPA filter, the present invention is also applicable to other filters such as ULPA filters. In the following description, the floor side of a target space such as a clean room may be referred to as "downward," and the ceiling side of the target space may be referred to as "upward."

[0020] As shown in Figure 1, the HEPA filter 1 is stored in a storage container 2 called a HEPA box. The HEPA filter 1 is a filter that captures fine particles contained in air supplied from upstream. The HEPA filter 1 is filled with filter paper made of glass fiber that is folded accordion-style. The HEPA filter 1 supplies clean air to the downstream side of the HEPA filter 1, i.e., the target space side. The upstream surface of the HEPA filter 1 where air is supplied is called the ventilation surface 1a, and the downstream surface that supplies clean air is called the intake surface 1b.

[0021] The storage container 2 is a box-shaped container with an opening O facing the target space. In this embodiment, an opening into which the storage container 2 can be installed is provided in a ceiling board constituting the ceiling C of the target space, and the storage container 2 is disposed by being embedded inside the opening of the ceiling C. The box-shaped storage container 2 is fitted and fixed into the opening of the ceiling C with the surface of the storage container 2 facing the opening O positioned upward so that the opening O is positioned downward and facing the target space. In the following description, the surface of the storage container 2 facing the opening O will be referred to as the top surface of the storage container 2. The opening O of the storage container 2 may be disposed so as to be flush with the ceiling C of the target space, or may be configured to protrude downward from the ceiling C.

[0022] The HEPA filter 1 is held and fixed by a clamp or the like provided inside the storage container 2 at a position above the opening O of the storage container 2. Therefore, in the example of Fig. 1, the air intake surface 1b of the HEPA filter 1 is not flush with the ceiling C of the target space. Note that there is no intention to exclude a configuration in which the air intake surface 1b of the HEPA filter 1 is flush with the ceiling C or a configuration in which it protrudes below the ceiling C. However, the HEPA filter 1 is fixed to the storage container 2 so that the air intake surface 1b faces toward the target space, i.e., downward.

[0023] A space is provided between the ventilation surface 1a of the HEPA filter 1 and the upper surface of the storage container 2. A supply duct 3 that supplies air to this space is connected to the storage container 2. The supply duct 3 is an airway that circulates and supplies air from within a target space to the ventilation surface 1a of the HEPA filter 1. However, it is not intended to exclude the air supplied via the supply duct 3 from being outside air.

[0024] A pre-filter, fan, and the like (not shown) may be connected to the supply duct 3. The supply duct 3 may be located upstream of the HEPA filter 1 in the storage container 2, and may be connected to the top surface of the storage container 2, for example. The HEPA filter 1, storage container 2, and supply duct 3 described above are an example of a filter unit to which the cover 4 of this embodiment is applied, and are not intended to limit the configuration. The HEPA filter 1, storage container 2, supply duct 3, and cover 4 may also be considered together as a filter unit.

[0025] The cover 4 of this embodiment is a removable lid for the storage container 2 that is provided to cover the opening O of the storage container 2. FIG. 2 shows a photograph of the cover 4. The planar shape of the cover 4 may be, for example, rectangular, but is not limited to this. The cover 4 includes a perforated plate 41 and a test guide 42. The perforated plate 41 and the test guide 42 of this embodiment are integrally formed, for example, by welding. The perforated plate 41 and the test guide 42 may also be fixed with a fixture. However, the test guide 42 alone may be added to a cover included in a pre-made filter unit.

[0026] The perforated plate 41 is a flat plate-like member formed so as to have a larger planar area than the opening O of the storage container 2. The perforated plate 41 may be made of a metal such as iron or stainless steel. Considering strength and deflection, the perforated plate 41 is preferably made of metal, but there is no intention to exclude the perforated plate 41 being made of resin or the like. In consideration of aesthetics, the perforated plate 41 may be colored, for example, to be similar in color to the ceiling C. Furthermore, the perforated plate 41 is not limited to being flat, and may be formed in the shape of a quadrangular pyramid at the center of the opening O of the storage container 2 so as to protrude toward the target space.

[0027] The perforated plate 41 includes a perforated portion 41a and a peripheral portion 41b. The perforated portion 41a and the peripheral portion 41b may be formed from the same metal plate. The perforated portion 41a is formed to allow clean air supplied from the air intake surface 1b of the HEPA filter 1 through the opening O of the storage container 2 to pass through. The perforated portion 41a may have, for example, multiple holes formed therein. A mesh board such as a punching board or a metal net may be used as the perforated portion 41a. The perforated portion 41a may have multiple holes at least in a portion facing the opening O of the storage container 2. Therefore, if the opening O of the storage container 2 is rectangular, the perforated plate 41 may have multiple holes formed therein over an area substantially equal to the rectangular shape of the opening O to form the perforated portion 41a.

[0028] The aperture ratio of the porous portion 41a due to the plurality of holes provided therein is not particularly limited, but should be sufficient to allow passage of clean air supplied from the air intake surface 1b of the HEPA filter 1. In other words, the porous portion 41a may have an aperture ratio similar to that of the porous portion of a perforated plate used in a cover included in a commercially available filter unit.

[0029] The porous portion 41a may be provided with trace markings M1 that indicate the trajectory of the suction probe scanning during a leak test. The trace markings M1 are lines drawn on the surface of the porous portion 41a facing the target space so that they are visible to the leak tester. If the trace markings M1 were protruding, they could collide with the suction probe, cause changes in the airflow, or become a source of dust, so it is preferable to draw lines. Figure 2 shows an example of trace markings M1 assuming a suction probe tip shape of 80 x 10 mm. The porous portion 41a is provided with multiple straight lines spaced 70 mm apart as trace markings M1. When the suction probe tip shape is 80 x 10 mm, providing trace markings M1 at 70 mm intervals allows the scanning area to overlap by 5 mm, ensuring reliable scanning.

[0030] The tracing markings M1 are provided so that the entire surface of the porous portion 41a can be scanned by the tester scanning the suction probe by tracing each straight line. The tester can also scan the tracing markings M1 with the suction probe by positioning a marker, such as an arrow, in the center of the suction probe at the tracing marking M1. The tracing markings M1 are not limited to being linear, and may be, for example, a smallest square in the center of the porous portion 41a, surrounded by multiple squares of gradually increasing area, or may be spiral-shaped.

[0031] The peripheral edge portion 41b is a non-porous portion that surrounds the periphery of the porous portion 41a. When the porous portion 41a is formed in a rectangular shape, the peripheral edge portion 41b is formed in a rectangular frame shape. The peripheral edge portion 41b covers the periphery that forms the opening O in the storage container 2, and has a size that reaches the ceiling C of the target space around the opening O of the storage container 2. As shown in FIG. 2, the peripheral edge portion 41b of the perforated plate 41 may be fixed to the storage container 2 or the ceiling C with a fixing device S.

[0032] The test guide 42 is a plate-like member extending vertically from the perforated plate 41 toward the target space. The test guide 42 is formed so as to surround the entire periphery of the perforated portion 41a and hang down from between the perforated portion 41a and the peripheral portion 41b. Therefore, the test guide 42 is formed in a frame shape. In the example of Figure 2, the test guide 42 is a rectangular frame-like member that matches the shape of the perforated portion 41a. The shape of the test guide 42 is not limited to this; if the planar shape of the perforated portion 41a is circular, a circular frame-like test guide 42 may be provided. The thickness of the test guide 42 is not particularly limited, but is preferably about several millimeters. Since an increase in the thickness of the test guide 42 increases the weight of the test guide 42, it is preferable to set the thickness appropriately taking into account the weight and strength of the test guide 42.

[0033] The height of the test guide 42 is preferably configured to be 20 mm or more and 200 mm or less. By making the height of the test guide 42 20 mm or more, the effect of suppressing the intrusion of particles during a leak test is achieved. Note that even if the height of the test guide 42 is 20 mm or less, the effect of suppressing the intrusion of particles can be achieved. However, during a leak test, the test must be performed with the tip of the suction probe at least 10 mm away from the porous portion 41a of the porous plate 41. Furthermore, to reliably suppress the intrusion of particles, it is preferable to perform the leak test at a position at least 10 mm higher than the end of the test guide 42. For these reasons, the height of the test guide 42 is set to 20 mm or more.

[0034] If the height of the test guide 42 is less than 20 mm, it will not be able to adequately cover the test suction probe, and the possibility of particles getting around the suction probe cannot be completely ruled out. Also, because the cover 4 is installed even during normal operation of the filter unit, it is more preferable to set the height of the test guide 42 to 100 mm or less, as this will keep it out of the sight of workers working in the clean room.

[0035] It is more preferable that the height of the test guide 42 be 30 mm or more. By making the height of the test guide 42 30 mm or more, the effect of preventing the intrusion of fine particles can be improved. It is even more preferable that the height of the test guide 42 be 50 mm or more. For example, if the height of the test guide 42 is 30 mm, it is necessary to maintain the tip of the suction probe approximately 10 mm away from the porous portion 41a of the porous plate 41 during the leak test.

[0036] The filter unit may be placed on a ceiling C with a ceiling height of 3 m or more. If the ceiling height is high, it may be difficult for the tester to manually move the suction probe while maintaining the measurement distance of the suction probe at 10 mm. In such cases, the suction probe may collide with the perforated plate 41, causing dust to be generated.

[0037] On the other hand, when the height of test guide 42 is 50 mm, the tip of the suction probe should be kept about 10 to 30 mm away from porous portion 41a of porous plate 41 during the leak test. Therefore, even when the filter unit is placed on a high ceiling C, the possibility of the suction probe colliding with the porous plate can be reduced. Also, when the height of test guide 42 is 100 mm, the tip of the suction probe should be kept about 10 to 50 mm away from porous portion 41a of porous plate 41 during the leak test.

[0038] From the viewpoint of preventing collisions of the suction probe, it is preferable that the height of test guide 42 be 100 mm or more. However, in addition to the aesthetic aspect, it is considered sufficient to have a clearance to separate the suction probe from perforated plate 41 by approximately 10 to 30 mm, so the most preferable height of test guide 42 is 50 mm.

[0039] As shown in FIG. 3, the test guide 42 may be provided with a height marking M2 that indicates the height at which the suction probe scans during the leak test. The height marking M2 is a line drawn on the inner surface of the test guide 42 so that it is visible to the tester performing the leak test. If the height marking M2 were a protrusion, it could collide with the suction probe, cause changes in the airflow, or become a source of dust, so it is preferable to draw a line. For example, if the height of the test guide 42 is 15 to 30 mm, the height marking M2 may be positioned, for example, 10 mm away from the porous portion 41a of the porous plate 41.

[0040] For example, if the height of the test guide 42 is 50 mm, two height markings M2 may be provided, for example, at a position 10 mm and a position 30 mm away from the porous portion 41a of the perforated plate 41, or the area between 10 and 30 mm may be filled in. Furthermore, for example, if the height of the test guide 42 is 100 mm, two height markings M2 may be provided, for example, at a position 10 mm and a position 50 mm away from the porous portion 41a of the perforated plate 41, or the area between 10 and 50 mm may be filled in.

[0041] By aligning the tip height of the suction probe with the height marking M2 while scanning, the tester can help prevent collisions between the suction probe and porous portion 41a. Furthermore, as described below, on the inner periphery of test guide 42, near the end of test guide 42, particles are likely to become trapped. Therefore, by providing height marking M2 on test guide 42 and maintaining the tip height of the suction probe within a predetermined range, leak testing can be performed without being affected by particles trapped at the end of test guide 42.

[0042] [1.2 Visualization and concentration measurement of fine particles] (Verification facilities, etc.) The test guide 42 of this embodiment was verified by measuring the concentration of fine particles. The results of various studies are explained below. The following verification was carried out by installing a filter unit including a quarter-sized storage container in a clean booth with an FFU (manufactured by Nippon Muki Co., Ltd., 2100W x 1400D x 2100H).

[0043] Visualization photography was performed on the air blown out from the cover of the filter unit. A rectangular frame-shaped test guide was attached to the perforated plate of the cover using a 2 mm thick acrylic plate. The test guide was verified with heights L (mm) of 0, 50, 100, 150, and 200 mm. Visualization photography was performed using a particle visualization system, Particle Viewer PV2-VLD (manufactured by Kato Koken Co., Ltd.).

[0044] The specific specifications of the visualization system are shown in Table 1. [Table 1]

[0045] Polystyrene latex (PSL) particles (maximum particle size distribution: 0.33 μm) were introduced using a Collison atomizer as the microparticles for visualization. The introduction position of the PSL particles is shown in Figure 4. An LSAPC (Model 3889, manufactured by Nippon Kanomax Co., Ltd., ≥ 0.3 μm, 0.1 cf / min) was used to measure the microparticle concentration.

[0046] (Verification procedure) The visualization of particles and measurement of particle concentration were carried out by the following verification procedure. (1) The FFU was operated and the inside of the clean booth was cleaned. (2) 50% of the rated airflow was blown onto the HEPA filter, and PSL particles were introduced from the Collison atomizer. (3) A red laser light sheet was formed close to the air outlet of the cover, parallel to the filter surface, and the scattered light from the particles was photographed with a highly sensitive camera. The image was then processed using dedicated software to visualize the behavior of the particles. (4) The particle concentration was measured on the inner and outer periphery of the test guide at the positions shown in Figure 4.

[0047] (Measurement results) First, visualization confirmed that when the test guide height was 0 mm, i.e., when no test guide was provided, fine particles flowed downstream of the porous portion, which is the outlet of the cover. On the other hand, when the test guide height L was 50 mm or more, fine particles did not flow downstream of the porous plate. Figure 5 shows a photograph visualizing the behavior of fine particles when the test guide height L was 50 mm. It is clear from the photograph in Figure 5 that fine particles did not flow downstream of the porous plate.

[0048] Next, the results of measuring the particle concentration are shown in Table 2. [Table 2]

[0049] As is clear from Table 2, when no test guide was provided, particulates were measured on the inner periphery of the test guide, i.e., downstream of the porous portion of the cover. On the other hand, when a test guide was provided on the cover, no particulates were measured on the inner periphery of the test guide for all test guides with heights between 50 and 200 mm, confirming that leak testing is possible. These results confirmed that the test guide prevents particulates from entering.

[0050] [1.3 Measuring particle concentration in clean rooms] (Verification facilities, etc.) The particle concentration was measured for a full-size (610 x 610 mm) filter unit installed on the ceiling of an actual non-unidirectional flow clean room. In this verification, the height L (mm) of the test guide was set to 0, 30, 50, and 100 mm, and the air volume Q (m 3 / h) is 500, 1000m 3 Measurements were carried out under the conditions of / h.

[0051] (Verification procedure) The particle concentration was measured using the following verification procedure. (1) As shown in Figure 6, poly-α-olefin (PAO) was generated as fine particles from an aerosol generator on the upstream side of the HEPA filter and on the outer periphery of the test guide. (2) Particles are measured on the upstream side of the filter, the outer periphery of the test guide, and the inner periphery of the test guide. The specifications of the LSAPC used for the measurements are as follows: Upstream side of filter and outer side of test guide: MET ONE 6003 type 2.83 L / min ≧ 0.3 μm Test guide inner circumference: MET ONE 6013 type 28.3 L / min ≧ 0.3 μm

[0052] (Measurement results) First, when the test guide is 0 mm, that is, when no test guide is provided, the air volume Q (m 3 / h) is 1000m 3 / h. This particle measurement was performed with the measurement distance H, which is the distance from the perforated plate to the tip of the suction probe, fixed at 10 mm. Then, particle measurement was performed while changing the separation distance D, which is the distance from the test guide to the central axis of the suction probe, to 10, 30, 60, 90, 120, and 320 mm. This measurement was used to examine whether there was a difference in the inflow of particles between the central and peripheral parts of the perforated section when no test guide was present.

[0053] Table 3 shows the particle measurement results for each separation distance. [Table 3]

[0054] As is clear from Table 3, particles were measured at distances of 10 to 30 mm, which indicates the peripheral area of ​​the porous portion. These results confirmed that without a test guide, the leak test could not be performed because particles were entrapped in the peripheral area of ​​the porous portion. On the other hand, it was also revealed that when the distance D was 60 mm or more and the suction probe was close to the center of the porous portion, there was no effect of particle entrapment, etc.

[0055] Next, when the height of the test guide is 100 mm, the air volume Q (m 3 / h) is 500m 3 / h. This particle measurement was performed with the separation distance D, which is the distance from the test guide to the center axis of the suction probe, fixed at 10 mm. Then, the measurement distance H, which is the distance from the perforated plate to the tip of the suction probe, was changed to 10, 30, 50, and 100 mm, and particle measurements were performed. This measurement was used to investigate whether there was a difference in the inflow of particles depending on the height of the suction probe that fits within the test guide when a 100 mm high test guide is present. Figure 7 shows a photograph of the measurement.

[0056] The results of each particle measurement are shown in Table 4. [Table 4]

[0057] As is clear from Table 4, it was confirmed that no fine particles flowed in when the measurement distance H of the suction probe was 10 to 50 mm. On the other hand, when the measurement distance H of the suction probe was 100 mm, the same as the height L of the test guide, it was revealed that fine particles on the outer periphery of the test guide were being inhaled.

[0058] In addition, when the height of the test guide is set to 50 mm, the air volume Q (m 3 / h) is 500m 3 / h. This particle measurement was performed with the separation distance D, which is the distance from the test guide to the central axis of the suction probe, fixed at 10 mm. Then, the measurement distance H, which is the distance from the perforated plate to the tip of the suction probe, was moved to 10, 30, and 50 mm, and particle measurement was performed. This measurement was used to investigate whether there was a difference in the inflow of particles depending on the height of the suction probe that fits into the test guide when a 50 mm high test guide was present.

[0059] The results of each particle measurement are shown in Table 5. [Table 5]

[0060] As is clear from Table 5, it was confirmed that no fine particles flowed in when the measurement distance H of the suction probe was 10 to 30 mm. On the other hand, when the measurement distance H of the suction probe was 50 mm, which is the same as the height L of the test guide, it was revealed that fine particles on the outer periphery of the test guide were being inhaled.

[0061] Furthermore, when the height of the test guide is 30 mm, the air volume Q (m 3 / h) is 500m 3 / h. This particle measurement was performed with the separation distance D, which is the distance from the test guide to the central axis of the suction probe, fixed at 10 mm. Then, the measurement distance H, which is the distance from the perforated plate to the tip of the suction probe, was moved to 10, 30, and 50 mm, and particle measurement was performed. This measurement was used to investigate whether there was a difference in the inflow of particles depending on the height of the suction probe that fits into the test guide when a 30 mm high test guide was present.

[0062] The results of each particle measurement are shown in Table 6. [Table 6]

[0063] As is clear from Table 6, when the measurement distance H of the suction probe was 10 mm, no particles were seen to flow in. On the other hand, when the measurement distance H of the suction probe was 30 mm, the same as the height L of the test guide, it was clear that particles on the outer periphery of the test guide were being inhaled. Furthermore, when the measurement distance H of the suction probe was outside the range of the test guide, the number of particles flowing in further increased.

[0064] Finally, when the height of the test guide is 20 mm, the air volume Q (m 3 / h) is 500m 3 / h. This particle measurement was performed with the separation distance D, which is the distance from the test guide to the central axis of the suction probe, fixed at 10 mm. Then, the measurement distance H, which is the distance from the perforated plate to the tip of the suction probe, was moved to 10 and 20 mm, and particle measurement was performed. This measurement was used to investigate whether there was a difference in the inflow of particles depending on the height of the suction probe that fits into the test guide when a test guide with a height of 20 mm was present.

[0065] The results of each particle measurement are shown in Table 7. [Table 7]

[0066] As is clear from Table 7, it was confirmed that no fine particles flowed in when the measurement distance H of the suction probe was 10 mm. On the other hand, when the measurement distance H of the suction probe was 20 mm, which is the same as the height L of the test guide, it was revealed that fine particles on the outer periphery of the test guide were inhaled.

[0067] [1.4 Consideration of cleanroom cleanliness] The above verification revealed that the test guide included in the cover of this embodiment is effective in preventing the entrapment of fine particles during leak testing. Meanwhile, the cover with the test guide also serves as a cover for the filter unit during normal operation of the clean room. The inventors investigated whether the test guide affects the cleanliness of the clean room during normal operation.

[0068] The height of the test guide used in the cleanliness study was 50 mm. First, PAO was generated as simulated particles in the clean room at a pump flow rate of 0 to 2.5 L / min. Then, particle concentration measurements were performed at measurement point A shown in the clean room schematic diagram in Figure 8. The particle concentration measurements were performed both with and without the test guide installed.

[0069] The results of the particle concentration measurements are shown in Table 8. The particle concentration is measured in units of 0.3 μm particles / cf. [Table 8]

[0070] As is clear from Table 8, under all PAO generation conditions, the particle concentration was about the same regardless of whether or not a guide was used. Therefore, it was thought that the test guide did not affect the cleanliness of the clean room during normal operation.

[0071] Next, to determine whether the test guide was causing unevenness in cleanliness, the particle concentration was measured at multiple points around the test guide. Specifically, particle concentration measurements were performed at measurement points A, B, C, and D shown in Figure 8. The PAO generation condition was 2 L / min.

[0072] The results of the particle concentration measurements are shown in Table 9. The particle concentration is measured in units of 0.3 μm particles / cf. [Table 9]

[0073] As is clear from Table 9, there were changes in the particle concentration at measurement points A to D. However, even without the test guide, the particle concentrations at measurement points A to D changed in the same way. These results confirmed that the test guide does not affect the cleanliness of the clean room during normal operation.

[0074] [1.5. Effects of the First Embodiment] The cover of this embodiment has the following advantages.

[0075] (1) A cover 4 for a filter unit including a filter and a storage container 2 for the filter, comprising a perforated plate 41 arranged to cover the opening O of the storage container 2, a perforated portion 41a formed in the perforated plate 41 to allow air supplied from the opening O side of the storage container 2 to pass through, and a frame-shaped test guide 42 arranged to surround the entire periphery of the perforated portion 41a and extending vertically from the perforated portion 41a, wherein the height of the test guide 42 is 20 mm or more and 200 mm or less.

[0076] When the test guide 42 is provided on the cover 4, it is possible to perform a leak test without removing the cover 4. Conventionally, there was a possibility that fine particles generated by removing the cover could affect the leak test, but since the cover 4 of this embodiment does not need to be removed, no fine particles are generated and an accurate leak test can be performed. In addition, the workload of removing the cover as in the conventional method is eliminated, improving work efficiency. Furthermore, there is no impact on the cleanliness of the clean room during normal operation.

[0077] Even if the tester accidentally hits the suction probe against the cover 4 during a leak test, it is highly safe and will not damage the HEPA filter 1. By providing a frame-shaped test guide 42 with a height of 20 mm to 200 mm around the porous portion 41a, it is possible to prevent fine particles from being caught in the leak test, enabling a more accurate leak test.

[0078] Furthermore, the above experimental results reveal that when the measurement distance of the suction probe is approximately the same as the height of the test guide 42, fine particles on the outer periphery of the test guide are inhaled. Therefore, when the test guide 42 is provided, the tester can perform a leak test while making sure that the measurement distance is shorter than the height of the test guide 42. Simply providing the test guide 42 allows the tester to know the approximate position of the measurement distance of the suction probe, making it possible to perform an accurate test.

[0079] (2) The height of the test guide may be 30 mm or more and 100 mm or less.

[0080] By making the height of the test guide 42 30 mm or more, it is possible to reliably prevent particles from getting around. Furthermore, by making the height of the test guide 42 100 mm or less, the height is such that it is out of the sight of the workers working in the clean room during normal operation of the clean room, improving the appearance.

[0081] (3) The height of the test guide may be 50 mm.

[0082] When the height of the test guide 42 is 50 mm, the tip of the suction probe can be maintained approximately 10 to 30 mm away from the porous portion 41a of the porous plate 41 during the leak test. Therefore, even when the filter unit is placed on a high ceiling C, the possibility of the suction probe colliding with the porous plate can be reduced. Furthermore, since the test guide 42 is attached to the cover 4 even during normal operation of the clean room, setting the height to 50 mm or less makes it less visible to workers working in the clean room, which is aesthetically pleasing.

[0083] (4) The porous portion 41a may be provided with trace markings M1 that indicate the path of scanning by the suction probe during a leak test.

[0084] The tester can reliably test the entire surface of the porous portion 41a by aligning a marker such as an arrow in the center of the suction probe with the tracing marking M1 and scanning the tracing marking M1 with the suction probe, thereby improving workability.

[0085] (5) The test guide 42 may be provided with a height marking M2 that indicates the height at which the suction probe scans during the leak test.

[0086] By aligning the tip height of the suction probe with the height marking M2 and scanning, the tester can perform the test without causing the suction probe to collide with the porous portion 41a. If the suction probe and porous portion 41a collide, there is a risk of fine particles being generated, so the height marking M2 supports accurate leak testing. Furthermore, if the measurement distance between the suction probe and porous portion 41a becomes larger than necessary, there is a risk that the suction probe will catch surrounding fine particles. By having the tester perform measurements using the height marking M2 as a guide, the accuracy of the leak test is improved.

[0087] (6) The height marking M2 may be provided at a position spaced 10 mm or more from the porous portion 41a.

[0088] To perform an accurate leak test, it is preferable to set the measurement distance of the suction probe so that it is positioned near the porous portion 41a. At the same time, it is necessary to avoid collision between the suction probe and the porous portion 41a. For these reasons, by positioning the height marking M2 at least 10 mm away from the porous portion 41a, both accuracy and safety can be achieved.

[0089] [2. Other embodiments] (1) In the above embodiment, the cover 4 has been mainly described. However, a configuration in which only the test guide 42 is added to a cover included in a pre-made filter unit may also be adopted. In this case, the test guide 42 may be considered to be a frame-like member extending perpendicularly from the porous portion 41a and surrounding the entire periphery of the porous portion 41a. If the cover included in the pre-made filter unit is made of a steel plate, the test guide 42 can be fixed to the cover using a magnet. If the cover is made of stainless steel, for example, the test guide 42 can be fixed using a fixture.

[0090] (2) In this embodiment, the trace marking M1 and the height marking M2 are provided on the cover 4. In addition, a light-emitting unit such as a laser pointer may be provided on the suction probe. By providing a light-emitting unit at a predetermined position on the suction probe and scanning while pointing at the marking, the accuracy of the test operation is improved. In such a configuration, the light-emitting unit alone or the suction probe with the light-emitting unit can be considered as an auxiliary tool for leak testing. In other words, the configuration may include both a cover and an auxiliary tool for testing.

[0091] (3) The test aid may include a mechanism to assist in maintaining the suction probe at the correct height. For example, the suction probe may be equipped with a distance detection function using a laser beam. For example, if the height of the test guide 42 is 50 mm, the measurement distance may be set to 30 mm, and an alarm may be sounded if the measurement distance deviates by 10 mm or more from 30 mm. This configuration can help ensure that the suction probe fits securely within the test guide 42. [Explanation of symbols]

[0092] C:Ceiling S: Fixture 1: HEPA filter 2: Storage container O: Opening 3: Supply duct 4: Cover 41: Perforated plate 41a: Porous part M1: Trace marking 41b: Periphery 42: Exam Guide M2: Height marking

Claims

1. A cover for a filter unit including a filter and a container for the filter, a perforated plate provided to cover the opening of the storage container; a porous portion formed in the porous plate, through which air supplied from an opening side of the storage container can pass; a frame-shaped test guide extending perpendicularly from the porous portion and surrounding the entire periphery of the porous portion; The height of the test guide is 20 mm or more and 200 mm or less. cover.

2. 2. The cover of claim 1, wherein the height of the test guide is 30 mm or more and 100 mm or less.

3. 10. The cover of claim 1, wherein the test guide has a height of 50 mm.

4. 2. The cover according to claim 1, wherein the porous portion is provided with trace markings that indicate a path along which a suction probe scans during a leak test.

5. 5. The cover according to claim 1, wherein the test guide is provided with height markings that indicate the height at which a suction probe scans during a leak test.

6. The cover according to claim 5 , wherein the height marking is provided at a position spaced apart from the porous portion by 10 mm or more.

7. A test guide for use with a filter unit including a filter, a container for the filter, and a cover for the container, comprising: The cover is a perforated plate provided to cover the opening of the storage container; a porous portion formed in the porous plate, through which air supplied from the opening side of the storage container can pass; the test guide is a frame-shaped member that is provided so as to surround the entire periphery of the porous portion and extends perpendicularly from the porous portion, The height of the frame-shaped member is 20 mm or more and 200 mm or less. Exam guide.

8. 8. The test guide of claim 7, wherein the height of the frame-shaped member is 30 mm or more and 100 mm or less.

9. 8. The test guide of claim 7, wherein the frame-like member has a height of 50 mm.

10. A filter unit including a filter, a container for the filter, and a cover for the container, The cover is a perforated plate provided to cover the opening of the storage container; a porous portion formed in the porous plate, through which air supplied from an opening side of the storage container can pass; a frame-shaped test guide extending perpendicularly from the porous portion and surrounding the entire periphery of the porous portion; The height of the test guide is 20 mm or more and 200 mm or less. Filter unit.

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