Cover, test guide, and filter unit

Abstract

We provide covers and test guides to support the efficient and more accurate conduct of leak testing. [Solution] A filter unit cover 4 including a filter 1 and a filter storage container 2, comprising: a perforated plate 41 provided to cover the opening O of the storage container 2; a perforated portion 41a formed in the perforated plate 41, through which air supplied from the opening O side of the storage container 2 can pass; and a frame-shaped test guide 42 provided to surround the entire perimeter 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.

Description

[Technical Field]

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

[0002] In pharmaceutical manufacturing plants and similar facilities, cleanrooms are used as the working environment. Clean air is supplied to the cleanroom, for example, through a HEPA filter. Leak testing is mandatory for HEPA filters installed in cleanrooms, both upon completion of construction and as part of periodic validation. The HEPA leak test method is specified in ISO 14644-3 (2019) and JIS B9917-3 (2009). However, JIS B9917-3 (2009) is scheduled to be revised to JIS B9920-3 in the future. In practice, leak testing is often performed by a tester scanning while moving a suction probe to check the number of particulate matter downstream of the HEPA filter.

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

[0004] [Patent Document 1] Japanese Patent Publication No. 2016-223199 [Overview of the project] [Problems that the invention aims to solve]

[0005] In conventional leak tests, the removal of the perforated cover was necessary, and the fine particles generated during the removal process could potentially affect the leak test results. Furthermore, after removing the perforated cover, the tester scans a point approximately 30 mm away from the HEPA filter using a suction probe. At this time, the suction probe could come into contact with the HEPA filter, potentially damaging it.

[0006] This invention was proposed to solve the problems of the prior art described above. Its objective is to provide a cover and test guide that support the efficient, more accurate, and safer conduct of leak testing. [Means for solving the problem]

[0007] To achieve the above objective, the cover of the present invention has the following features. (1) A filter unit cover including a filter and a container for the filter, comprising: a perforated plate provided to cover the opening of the container; a perforated portion formed in the perforated plate, through which air supplied from the opening side of the container can pass; and a frame-shaped test guide provided to surround the entire perimeter of the perforated portion, extending vertically from the perforated 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 trace markings that indicate the trajectory of the suction probe during the leak test.

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

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

[0013] Furthermore, in order to achieve the above objectives, 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 provided to cover the opening of the storage container, and a perforated 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 provided to surround the entire perimeter of the perforated portion and extending vertically from the perforated portion, the height of the frame-shaped member being 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 height of the frame-shaped member may be 50 mm.

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

[0017] According to the present invention, it is possible to provide covers and test guides that support the efficient, more accurate, and safer conduct of leak tests. [Brief explanation of the drawing]

[0018] [Figure 1] It is a schematic diagram showing a schematic configuration of a filter unit according to the first embodiment. [Figure 2] It is a photograph for explaining a cover and a test guide according to the first embodiment. [Figure 3] It is a photograph for explaining a cover and a test guide according to the first embodiment. [Figure 4] It is a schematic diagram for explaining particle concentration measurement conditions. [Figure 5] It is a photograph visualizing the behavior of fine particles. [Figure 6] It is a schematic diagram for explaining particle concentration measurement conditions. [Figure 7] It is a photograph for explaining particle concentration measurement. [Figure 8] It is a schematic diagram of a clean room.

Mode for Carrying Out the Invention

[0019] [1. First Embodiment] [1.1 Configuration] The cover and the 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. Examples of the filter include a HEPA filter, but the present invention is also applicable to other filters such as an ULPA filter. In the following description, the floor side of a target space such as a clean room may be described as downward and the ceiling side of the target space may be described as upward.

[0020] As shown in Figure 1, the HEPA filter 1 is housed in a storage container 2 called a HEPA box. The HEPA filter 1 is a filter that captures fine particles contained in the air supplied from the upstream side. The HEPA filter 1 is filled with filter paper made of glass fibers that is folded in an accordion-like manner. The HEPA filter 1 supplies clean air to the downstream side of the HEPA filter 1, that is, to the target space side. In the HEPA filter 1, the upstream side to which air is supplied is referred to as the ventilation surface 1a, and the downstream side to which clean air is supplied is referred to as the supply surface 1b.

[0021] The storage container 2 is a box-shaped container having an opening O facing the target space. In this embodiment, an opening is provided in the ceiling panel that constitutes the ceiling C of the target space, into which the storage container 2 can be installed, and the storage container 2 is embedded inside the opening in the ceiling C. The box-shaped storage container 2 is fitted and fixed into the opening in the ceiling C with the surface of the storage container 2 facing the opening O positioned upwards, so that the opening O is located downwards 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 positioned flush with the ceiling C of the target space, or it may be configured to protrude downwards from the ceiling C.

[0022] The HEPA filter 1 is held and fixed by clamps 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 in Figure 1, the air supply 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 configurations in which the air supply surface 1b of the HEPA filter 1 is flush with the ceiling C or protrudes downward from the ceiling C. However, the HEPA filter 1 is fixed to the storage container 2 so that the air supply surface 1b faces towards the target space, i.e., downward.

[0023] A space is provided between the ventilation surface 1a of the HEPA filter 1 and the top surface of the storage container 2. A supply duct 3 is connected to the storage container 2 to supply air to this space. The supply duct 3 is an air passage for circulating and supplying, for example, air from within the target space to the ventilation surface 1a of the HEPA filter 1. However, there is no intention to exclude the possibility that the air supplied via the supply duct 3 is outside air.

[0024] The supply duct 3 may be connected to a pre-filter, fan, etc. (not shown). The supply duct 3 only needs to 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 just one example of a filter unit to which the cover 4 of this embodiment is applied, and there is no intention to limit its configuration. Furthermore, the HEPA filter 1, storage container 2, supply duct 3, and cover 4 can also be considered together as a filter unit.

[0025] The cover 4 in this embodiment is a removable lid for the storage container 2, provided to cover the opening O of the storage container 2. A photograph of the cover 4 is shown in Figure 2. The planar shape of the cover 4 may be, for example, rectangular, but is not limited thereto. The cover 4 includes a perforated plate 41 and a test guide 42. In this embodiment, the perforated plate 41 and the test guide 42 are integrally formed, for example, by welding. Alternatively, the perforated plate 41 and the test guide 42 may be fixed together with fasteners. However, the test guide 42 may be added to a cover included in a commercially available filter unit.

[0026] The perforated plate 41 is a flat plate-shaped member formed to have a larger planar area than the opening O of the storage container 2. The perforated plate 41 may be made of metal such as iron or stainless steel. Considering strength and deflection, it is preferable for the perforated plate 41 to be made of metal, but there is no intention to exclude the possibility of forming the perforated plate 41 with resin or other materials. Considering aesthetics, the perforated plate 41 may be colored to match the color of the ceiling C, for example. Furthermore, the perforated plate 41 is not limited to a flat plate shape, and may be formed in a pyramidal pyramidal shape so as to protrude toward the target space in the central part of the opening O of the storage container 2.

[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 so that clean air supplied from the air supply surface 1b of the HEPA filter 1 through the opening O of the storage container 2 can pass through. The perforated portion 41a may have, for example, multiple holes. A mesh-like board such as a perforated board or a metal mesh may be used as the perforated portion 41a. The perforated portion 41a only needs to have multiple holes in the 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 in an area approximately the same as the rectangle of the opening O to form the perforated portion 41a.

[0028] The aperture ratio of the porous portion 41a, which is provided by the multiple holes in the porous portion 41a, is not particularly limited, but it should be sufficient to allow clean air supplied from the air supply surface 1b of the HEPA filter 1 to pass through. In other words, the porous portion 41a may have an aperture ratio similar to that of the porous portion of a porous plate used in a cover included in a commercially available filter unit.

[0029] The porous section 41a may be provided with trace markings M1 that indicate the trajectory scanned by the suction probe during a leak test. Trace markings M1 are lines drawn on the surface of the porous section 41a facing the target space so that they can be seen by the tester performing the leak test. If the trace markings M1 were protrusions, there is a possibility of collision with the suction probe, a possibility of changes in airflow, and a possibility of dust generation, so it is preferable to draw lines. Figure 2 shows an example of trace markings M1 assuming the tip shape of the suction probe is 80 × 10 mm. For example, multiple straight lines spaced 70 mm apart are provided as trace markings M1 on the porous section 41a. When the tip shape of the suction probe is 80 × 10 mm, by providing trace markings M1 at 70 mm intervals, the scanning areas can be overlapped by 5 mm each, enabling reliable scanning.

[0030] Trace markings M1 are provided so that the entire surface of the porous portion 41a can be scanned by the tester scanning the suction probe along each straight line. Alternatively, the tester can scan the trace markings M1 with the suction probe so that a marker, such as an arrow marked on the central part of the suction probe, is positioned on the trace markings M1. Trace markings M1 are not limited to straight lines; for example, they may be shown by providing a smallest square in the central part of the porous portion 41a and surrounding it with multiple squares of gradually increasing area, or they may be spiral in shape.

[0031] The peripheral portion 41b is a non-perforated portion surrounding the perforated portion 41a. If the perforated portion 41a is formed in a rectangular shape, the peripheral portion 41b will be formed in a rectangular frame shape. The peripheral portion 41b covers the periphery that forms the opening O in the storage container 2 and is large enough to reach the ceiling C of the target space around the opening O of the storage container 2. As shown in Figure 2, the peripheral portion 41b of the perforated plate 41 may be fixed to the storage container 2 or the ceiling C by fasteners S.

[0032] The test guide 42 is a plate-shaped member that extends perpendicularly from the perforated plate 41 toward the target space. The test guide 42 is formed to surround the entire periphery of the perforated portion 41a, hanging downward from between the perforated portion 41a and the peripheral edge 41b. Therefore, the test guide 42 is formed in a frame shape. In the example in Figure 2, a rectangular frame-shaped test guide 42 is provided to match 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-shaped test guide 42 may be provided. The thickness of the test guide 42 is not particularly limited, but it is good to have a thickness of a few millimeters. Since the weight of the test guide 42 increases with its thickness, it is good to choose an appropriate thickness considering the weight and strength of the test guide 42.

[0033] The height of the test guide 42 should be set to be between 20 mm and 200 mm. Setting the height of the test guide 42 to 20 mm or more will have the effect of suppressing the leakage of fine particles during the leak test. Note that even if the height of the test guide 42 is less than 20 mm, the effect of suppressing the leakage of fine particles can still be achieved. However, during the leak test, it is necessary to perform the test with the tip of the suction probe at least 10 mm away from the porous portion 41a of the porous plate 41. Furthermore, in order to reliably suppress the leakage of fine particles, it is preferable to perform the leak test at a position at least 10 mm above the end of the test guide 42. For the above reasons, the height of the test guide 42 should be 20 mm or more.

[0034] If the height of the test guide 42 is less than 20 mm, it may not adequately cover the test suction probe, and the possibility of fine particles entering the suction probe position cannot be completely ruled out. Furthermore, since the cover 4 is installed even during normal operation of the filter unit, setting the height of the test guide 42 to 100 mm or less is preferable, as it will be at a height that does not obstruct the view of workers in the cleanroom.

[0035] It is more preferable that the height of the test guide 42 be 30 mm or more. Setting the height of the test guide 42 to 30 mm or more improves the effect of preventing the leakage of fine particles. 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, during the leak test it is necessary to maintain a distance of about 10 mm from the tip of the suction probe to the porous portion 41a of the porous plate 41.

[0036] The filter unit may be installed in a ceiling C with a ceiling height of 3m or more. If the tester is manually moving the suction probe, it may be difficult to maintain a measurement distance of 10mm for the suction probe when the ceiling height is high. In such cases, the suction probe may collide with the perforated plate 41, potentially generating dust.

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

[0038] Based on the above, from the viewpoint of preventing collision of the suction probe, it is preferable that the height of the test guide 42 be 100 mm or more. However, in addition to the aesthetic aspect mentioned above, it is considered sufficient to have enough clearance to allow the suction probe to be separated from the perforated plate 41 by about 10 to 30 mm, so the most preferable height for the test guide 42 is 50 mm.

[0039] As shown in Figure 3, the test guide 42 may be provided with height markings M2 indicating the height to which the suction probe scans during a leak test. The height markings M2 are lines drawn on the inner surface of the test guide 42 so that they can be seen by the tester performing the leak test. It is preferable to draw lines for the height markings M2, as protrusions could potentially collide with the suction probe, cause changes in airflow, or become a source of dust. For example, if the height of the test guide 42 is 15 to 30 mm, the height markings M2 may be shown at a position, 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 placed at positions, for example, 10 mm and 30 mm apart from the perforated portion 41a of the perforated plate 41, or the area between 10 and 30 mm may be filled in. Also, for example, if the height of the test guide 42 is 100 mm, two height markings M2 may be placed at positions, for example, 10 mm and 50 mm apart from the perforated portion 41a of the perforated plate 41, or the area between 10 and 50 mm may be filled in.

[0041] By scanning the tip height of the suction probe to match the height marking M2, the tester can help prevent collision between the suction probe and the porous section 41a. Furthermore, as described later, on the inner circumference of the test guide 42, near the end of the test guide 42, the entrapment of fine particles is likely to occur. Therefore, by providing a height marking M2 on the 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 fine particles entrapped at the end of the test guide 42.

[0042] [1.2 Visualization and concentration measurement of particulate matter] (Verification equipment, etc.) The test guide 42 of this embodiment was verified by measuring the concentration of particulate matter. The results of various studies are described below. The following verification was performed by incorporating a filter unit including a quarter-size storage container into a clean booth with an FFU (manufactured by Nippon Muki Co., Ltd., 2100W x 1400D x 2100H).

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

[0044] Table 1 shows the specific specifications of the visualization system. [Table 1]

[0045] Polystyrene latex (PSL) particles (maximum distributed particle size 0.33 μm) were introduced as microparticles for visualization using a Collison atomizer. Figure 4 shows the introduction positions of the PSL particles. An LSAPC (Model 3889, ≥0.3 μm, 0.1 cf / min) was used to measure the microparticle concentration.

[0046] (Verification procedure) The following verification procedure was used to visualize the fine particles and measure their concentration. (1) The FFU was operated to clean the inside of the clean booth. (2) PSL particles were introduced from the Collison atomizer by blowing air at 50% of the rated volume onto the HEPA filter. (3) A red laser light sheet was formed adjacent to the air outlet of the cover and parallel to the filter surface. The scattered light from the fine particles was captured with a high-sensitivity camera, and the behavior of the fine particles was visualized by image processing with dedicated software. (4) The concentration of particulate matter was measured on the inner and outer sides of the test guide at the positions shown in Figure 4.

[0047] (Measurement results) First, visualization revealed that when the height of the test guide was 0 mm, i.e., when no test guide was provided, fine particles flowed downstream of the porous section, which is the air outlet of the cover. On the other hand, when the height L of the test guide was 50 mm or more, no fine particles flowed downstream of the porous plate. Figure 5 shows a photograph visualizing the behavior of fine particles when the height L of the test guide is 50 mm. It is clear from the photograph in Figure 5 that no fine particles flowed downstream of the porous plate.

[0048] Next, the results of the particulate matter concentration measurement are shown in Table 2. [Table 2]

[0049] As is clear from Table 2, when no test guide was provided, fine particles were measured on the inner circumference side 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 fine particles were measured on the inner circumference side of the test guide for all test guides with heights from 50 to 200 mm, confirming that leak testing was possible. From these results, it was confirmed that the test guide prevents the inflow of fine particles.

[0050] [1.3 Measurement of particulate matter concentration in a cleanroom] (Verification equipment, etc.) Particulate matter concentration measurements were performed on a full-size (610 x 610 mm) filter unit installed on the ceiling of an actual non-unidirectional flow cleanroom. In this verification, the height L (mm) of the test guide was set to 0, 30, 50, and 100 mm, and the airflow Q (m³) was measured. 3 ( / h) is 500, 1000m 3 Measurements were performed under the condition of / h.

[0051] (Verification procedure) The particulate matter concentration was measured using the following verification procedure. (1) As shown in Figure 6, poly-α-olefin (PAO) is generated as fine particles from an aerosol generator on the upstream side of the HEPA filter and on the outer circumference of the test guide, respectively. (2) Measurement of fine particles is performed on the upstream side of the filter, the outer circumference of the test guide, and the inner circumference of the test guide. The specifications of the LSAPC used for measurement are shown below. Upstream side of filter and outer circumference 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 airflow Q(m 3 ( / h) is 1000m 3 Particle measurements were performed under the condition of / h. The measurement distance H, which is the distance from the porous plate to the tip of the suction probe, was fixed at 10 mm. Then, the separation distance D, which is the distance from the test guide to the central axis of the suction probe, was moved to 10, 30, 60, 90, 120, and 320 mm, and particle measurements were performed. This measurement investigated whether there was a difference in particle inflow between the central and peripheral parts of the porous area when the test guide was absent.

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

[0054] As is clear from Table 3, fine particles were detected at a separation distance of 10-30 mm, which represents the peripheral area of ​​the porous section. From these results, it was confirmed that without a test guide, leak testing cannot be performed because fine particles are trapped in the peripheral area of ​​the porous section. On the other hand, it was also found that when the separation distance D is 60 mm or more, and the suction probe is close to the center of the porous section, the test is not affected by fine particle trapping.

[0055] Next, assuming the height of the test guide is 100 mm, the airflow Q (m³) 3 ( / h) is 500m 3 Particle measurements were performed under the condition of / h. The separation distance D, the distance from the test guide to the central axis of the suction probe, was fixed at 10 mm. Then, the measurement distance H, the distance from the perforated plate to the tip of the suction probe, was moved to 10, 30, 50, and 100 mm, and particle measurements were performed. This measurement investigated whether there were differences in the inflow of particle material due to differences in the height of the suction probe that fits within the test guide, given the presence of a 100 mm high test guide. Figure 7 shows a photograph of the measurement process.

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

[0057] As is clear from Table 4, it was confirmed that no particulate matter entered when the measurement distance H of the suction probe was between 10 and 50 mm. On the other hand, when the measurement distance H of the suction probe was the same as the height L of the test guide, 100 mm, it became clear that particulate matter from the outer circumference of the test guide was being drawn in.

[0058] Furthermore, if the height of the test guide is set to 50 mm, the airflow Q(m 3 ( / h) is 500m 3 Particle measurements were performed under the condition of / h. The separation distance D, the distance from the test guide to the central axis of the suction probe, was fixed at 10 mm. Then, the measurement distance H, the distance from the perforated plate to the tip of the suction probe, was moved to 10, 30, and 50 mm, and particle measurements were performed. This measurement investigated whether, given the presence of a 50 mm high test guide, differences in the height of the suction probe within the test guide resulted in differences in the inflow of particles.

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

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

[0061] Furthermore, when the height of the test guide was 30 mm, fine particle measurement was carried out under the condition that the air volume Q (m 3 / h) was 500 m 3 / h. This fine particle measurement was carried out 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 fine particle measurement was carried out. By this measurement, when there was a test guide with a height of 30 mm, it was examined whether there were differences in the inflow of fine particles due to differences in the height of the suction probe within the test guide.

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

Table 6

[0063] As is clear from Table 6, it was confirmed that there was no inflow of fine particles 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 30 mm, which was the same as the height L of the test guide, it was revealed that fine particles on the outer peripheral side of the test guide were being inhaled. And when the measurement distance H of the suction probe was outside the range of the test guide, the number of fine particles flowing in further increased.

[0064] Finally, when the height of the test guide was 20 mm, fine particle measurement was carried out under the condition that the air volume Q (m 3 / h) was 500 m 3Particle measurements were performed under the condition of / h. The separation distance D, the distance from the test guide to the central axis of the suction probe, was fixed at 10 mm. Then, the measurement distance H, the distance from the perforated plate to the tip of the suction probe, was moved to 10 mm and 20 mm, and particle measurements were performed. This measurement investigated whether there was a difference in the inflow of particle material due to differences in the height of the suction probe that fits within the test guide, given the presence of a 20 mm high test guide.

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

[0066] As is clear from Table 7, it was confirmed that no particulate matter entered 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, the same as the height L of the test guide, it became clear that particulate matter from the outer edge of the test guide was being drawn in.

[0067] [1.4 Examination 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. On the other hand, the cover with the test guide also serves as a cover for the filter unit during normal operation of the cleanroom. The inventors investigated whether the test guide affects the cleanliness level during normal operation of the cleanroom.

[0068] The height of the test guide used for the cleanliness study was set to 50 mm. First, PAO was generated in the cleanroom as simulated particulate matter using a pump flow rate of 0 to 2.5 L / min. Then, the particulate matter concentration was measured at measurement point A, as shown in the cleanroom schematic diagram in Figure 8. The particulate matter concentration measurement was performed both with and without the test guide.

[0069] The results of the particulate concentration measurement are shown in Table 8. The unit of particulate concentration is 0.3 μm particles / cf. [Table 8]

[0070] As is clear from Table 8, the particulate matter concentration was similar under all PAO generation conditions, regardless of whether the guide was present or not. Therefore, it was concluded that the test guide did not affect the cleanliness of the cleanroom during normal operation.

[0071] Next, to examine whether the test guide was causing inconsistencies in cleanliness, particulate matter concentrations were measured at multiple points around the test guide. Specifically, particulate matter concentrations were measured at measurement points A, B, C, and D shown in Figure 8. The PAO generation condition was set to 2 L / min.

[0072] The results of the particulate concentration measurement are shown in Table 9. The unit of particulate concentration is 0.3 μm particles / cf. [Table 9]

[0073] As is clear from Table 9, changes in particulate matter concentration occurred at measurement points A to D. However, even without the test guide, the particulate matter concentration at measurement points A to D changed similarly. From these results, it was confirmed that the test guide does not affect the cleanliness of the cleanroom during normal operation.

[0074] [1.5. Effects of the First Embodiment] The effects and benefits of the cover of this embodiment are as follows.

[0075] (1) A filter unit cover 4 including a filter and a filter storage container 2, comprising a perforated plate 41 provided to cover the opening O of the storage container 2, a perforated portion 41a formed in the perforated plate 41 through which air supplied from the opening O side of the storage container 2 can pass, and a frame-shaped test guide 42 provided to surround the entire perimeter 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] If the test guide 42 is provided on the cover 4, the leak test can be performed without removing the cover 4. Conventionally, particulate matter generated by removing the cover could affect the leak test, but since the cover 4 in this embodiment is not removed, no particulate matter is generated, and an accurate leak test can be performed. In addition, the workload of removing the cover itself is eliminated, improving work efficiency. Furthermore, it does not affect the cleanliness level during normal operation of the cleanroom.

[0077] Even if the tester accidentally collides the suction probe with the cover 4 during the leak test, the HEPA filter 1 will not be damaged, ensuring high safety. By providing a frame-shaped test guide 42 with a height of 20 mm to 200 mm around the porous section 41a, it is possible to prevent the entrapment of fine particles during the leak test, enabling more accurate leak testing.

[0078] Furthermore, the experimental results above clearly show that when the measurement distance of the suction probe is approximately the same as the height of the test guide 42, fine particles from the outer circumference of the test guide are being drawn in. Therefore, when the test guide 42 is provided, the tester can perform the leak test while being mindful to keep the measurement distance shorter than the height of the test guide 42. The mere presence of the test guide 42 allows the tester to know the approximate position of the measurement distance of the suction probe, thus enabling accurate testing.

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

[0080] By setting the height of the test guide 42 to 30 mm or more, the intrusion of fine particles can be reliably prevented. Furthermore, if the height of the test guide 42 is 100 mm or less, it will be at a height that does not obstruct the view of workers in the cleanroom during normal operation, thus improving the aesthetic appearance.

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

[0082] If the height of the test guide 42 is 50 mm, during a leak test, it is sufficient to maintain the tip of the suction probe at a distance of approximately 10 to 30 mm from the porous portion 41a of the porous plate 41. Therefore, even if the filter unit is located on a ceiling C with a high ceiling height, the possibility of the suction probe colliding with the porous plate can be reduced. Furthermore, since the test guide 42 is also provided on the cover 4 during normal operation of the cleanroom, setting its height to 50 mm or less makes it less likely to be in the line of sight of workers in the cleanroom, which is aesthetically preferable.

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

[0084] The tester can reliably test the entire surface of the porous portion 41a by scanning the trace marking M1 with the suction probe, ensuring that a marker, such as an arrow, located on the central part of the suction probe is positioned on the trace marking M1. This improves work efficiency.

[0085] (5) Test guide 42 may be provided with height markings M2 indicating the height to which the suction probe scans during the leak test.

[0086] The tester can perform the test without collision between the suction probe and the porous section 41a by scanning the tip height of the suction probe to match the height marking M2. Since collision between the suction probe and the porous section 41a may generate fine particles, the height marking M2 supports accurate leak testing. Furthermore, if the measurement distance between the suction probe and the porous section 41a becomes unnecessarily large, the suction probe may draw in surrounding fine particles. By 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 10 mm or more away from the porous portion 41a.

[0088] To perform leak testing accurately, it is preferable to set the measurement distance of the suction probe so that it is located near the porous section 41a. On the other hand, collision between the suction probe and the porous section 41a must be avoided. Therefore, by placing the height marking M2 at a distance of at least 10 mm from the porous section 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, it is also possible to configure the system by adding only the test guide 42 to the cover included in a commercially available filter unit. In that case, the test guide 42 can be considered as a frame-shaped member that surrounds the entire perimeter of the porous portion 41a and extends perpendicularly from the porous portion 41a. If the cover included in the commercially available filter unit is made of steel plate, the test guide 42 can be fixed to the cover using magnets. If the cover is made of stainless steel, for example, it can be fixed using fasteners.

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

[0091] (3) The test aid may be equipped with a mechanism to help maintain the height of the suction probe. For example, the suction probe may be equipped with a distance detection function using laser light. For example, if the height of the test guide 42 is 50 mm, the measurement distance can be set to 30 mm, and an alarm sound can be emitted if the distance deviates by 10 mm or more from 30 mm. This configuration helps to ensure that the suction probe fits securely inside the test guide 42. [Explanation of symbols]

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

Claims

1. A filter unit cover including a filter and a container for housing the filter, A perforated plate is provided to cover the opening of the aforementioned storage container, The porous plate has a porous portion formed therein, through which air supplied from the opening side of the storage container can pass, The apparatus includes a frame-shaped test guide that extends perpendicularly from the porous portion and is provided so as to surround the entire perimeter of the porous portion, The height of the aforementioned test guide is 20 mm or more and 200 mm or less. cover.

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

3. The cover according to claim 1, wherein the height of the test guide is 50 mm.

4. The cover according to claim 1, wherein the porous portion is provided with trace markings indicating the trajectory scanned by the suction probe during a leak test.

5. The cover according to claim 1 or 4, wherein the test guide is provided with height markings indicating the height to which the suction probe scans during a leak test.

6. The cover according to claim 5, wherein the height marking is provided at a position at least 10 mm away from the porous portion.

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

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

9. The test guide according to claim 7, wherein the height of the frame-shaped member is 50 mm.

10. A filter unit comprising a filter, a container for housing the filter, and a cover for the housing container, The aforementioned cover is A perforated plate is provided to cover the opening of the storage container, The porous plate has a porous portion formed therein, through which air supplied from the opening side of the storage container can pass, The device includes a frame-shaped test guide that extends perpendicularly from the porous portion and is provided to surround the entire perimeter of the porous portion, The height of the aforementioned test guide is 20 mm or more and 200 mm or less. Filter unit.

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