JP2016029324A - Clean booth - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a clean booth which does not hinder products being carried thereinto or therefrom.SOLUTION: A clean booth 20 includes an air curtain in a carry-in/out part 27. The air curtain includes an air outlet 30 which is provided along a periphery of a ceiling part 21 and blows air having high cleanliness. A suction port is not provided on a floor surface 2 facing the air outlet 30. The invention improves barrier performance from an external part with the air curtain and employs a structure which does not divide a target space from the external part like a conventional wall or curtain. Thus, the clean booth 20 does not interfere with circulation of workers and a transfer route of products and does not hinder the products being carried in/out.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a clean booth having an air curtain structure. Specifically, it is a clean booth installed in a clean room.

  Conventionally, in order to prevent dust from being mixed into industrial products and pharmaceuticals, a clean room in which dust in the air is greatly reduced is used. Specifically, a manufacturing apparatus is installed inside the clean room, and the manufacturing apparatus is operated in an environment with little dust.

  By the way, in recent years, the manufacturing apparatus installed in this clean room has become larger. Therefore, it is necessary to increase the volume of the clean room, but in this case, there is a problem that it is costly to maintain a high cleanliness of the air over the entire clean room.

  Therefore, a local cleaning method has been proposed in which the air cleanliness of the internal space of the clean room is suppressed to a certain level, and only a part of the clean room where the manufacturing apparatus is installed has a high air cleanliness (patent) Reference 1).

  Specifically, in the local clean system, a space in which a manufacturing apparatus is installed and the air cleanliness is to be increased is set as a target space, and the local air cleaner is disposed so as to cover the target space. Specifically, this local air purifying device includes a flat plate-like ceiling portion suspended from the ceiling, and a plurality of air purifying devices provided at the central portion and the peripheral portion of the ceiling portion. The air cleaning device has an air cleaning filter and a fan.

  According to this local air purifying apparatus, air with high cleanliness is blown out downward by the air purifying apparatus in the central part to increase the air cleanliness of the target space immediately below the local air purifying apparatus, and By blowing out air directly from the air purifier, the blown-out air prevents ambient air from entering the target space.

JP 2003-148777 A

  However, even if air is blown downward from the air purifier at the periphery, the airflow diffuses in the lower end of the air curtain, that is, near the floor surface. I can't get it.

  Therefore, instead of providing the air cleaning device at the peripheral portion, it is also conceivable to provide partition members such as vinyl curtains and walls that cover the side surfaces of the target space and completely partition the target space and the outside with these partition members. However, when such a partition member is provided, there is a problem that the partition member interferes with an operator's conductor or a product conveyance path, and the production efficiency of the product decreases.

  An object of this invention is to provide the clean booth which does not become an obstacle of carrying in / out.

  A clean booth according to claim 1 (for example, clean booths 20, 20A, 20B described later) is a clean booth provided with an air curtain at least in a loading / unloading section (for example, loading / unloading section 27 described later), Is provided with an air outlet (for example, air outlets 30, 30A, 30B described later) that blows out highly clean air provided on the ceiling side, and a floor surface (for example, floor surface 2 described later) that faces the air outlet. Is characterized in that no air inlet is provided.

  The clean booth according to claim 2 is characterized in that the air blowing direction is set to an angle of 5 ° or more and 20 ° or less with respect to the vertical direction from the blow-out port.

According to the present invention, air is blown out at an angle from the vertical direction, and the blown-out air flows downward while diffusing outward to prevent surrounding air from entering the target space. It becomes an air curtain. Therefore, the air cleanliness of the target space can be locally increased compared to the surroundings. A blower outlet can be provided in addition to a carrying in / out part.
Since there is no need to provide an air inlet on the floor, there are no restrictions on the location of the clean booth, and local clean locations in large spaces can be installed freely. In particular, it is not necessary to provide a partition structure on the peripheral wall, and the clean booth can be installed only with the upper structure on the ceiling side.

In addition, the air curtain improves the shielding property from the outside, and it is not configured to partition the target space from the outside like conventional walls and curtains, so it will not interfere with the worker's conductors and product conveyance path It will not be an obstacle for loading and unloading. Therefore, it can prevent that the manufacturing efficiency of a product falls.
In addition, after the air blown out from the blowout outlet reaches the vicinity of the floor surface, it is divided into an airflow toward the outside of the clean booth and an airflow toward the inside of the clean booth. In the present invention, since the angle with respect to the vertical direction is set to 5 ° or more, the air flow toward the inside of the clean booth is reduced, and the amount of dust entering the clean booth can be greatly reduced.

When the air blowing angle is less than 5 °, the air flow toward the inside increases, and the dust near the floor is caught in the air flow toward the inside and easily flows into the clean booth.
On the other hand, when the blowing angle exceeds 20 °, the distance from the blower outlet to the floor surface becomes long, so that the airflow is excessively diffused and the function as an air curtain is deteriorated.

  The clean booth according to claim 3 is characterized in that the air blowing direction is a multi-layer and the blowing direction of the inner layer is set at a small angle.

  According to this invention, after the air blown from the inner layer reaches the floor surface, it becomes an airflow urged in the direction toward the outside of the clean booth. Therefore, near the floor surface, the airflow of the outer layer is pushed by the airflow of the inner layer and goes to the outside of the clean booth, so that it is possible to more reliably prevent the shunting of the outer airflow from entering the inside. . Since the inner airflow has a shorter distance to the floor where the angle difference is separated than the outer airflow, a stronger flow than the outer airflow can be formed, and the pushing force to the outside is also increased.

  The clean booth according to claim 4 has a hanging wall (for example, a curtain 25 described later, a second curtain 26 described later, curtains 41-47, 51-57, described later) in the air outlet in the air outlet direction. 61-66, 71-77, 81-87).

  According to this invention, since air is blown out along the inner wall surface of the drooping wall, outside air is not involved in the range of the dripping wall, and the air is blown below the drooping wall while maintaining the direction and strength of the airflow. Therefore, the shielding property can be improved and the size can be reduced. Further, the air blowing direction can be restricted by the drooping wall. When the airflow is provided in multiple layers, the airflow can be divided depending on the installation direction of the drooping wall.

  The clean booth according to claim 5 is installed in a clean room (for example, a clean room 1 described later).

  According to the present invention, the air curtain improves the shielding property from the outside. Since it is not the structure which partitions the object space and the exterior like the partition space by the conventional wall, it does not interfere with a conductor's conducting wire and a product conveyance path, and does not become an obstacle of carrying in / out. Therefore, it can prevent that the manufacturing efficiency of a product falls. Further, since the angle of the hanging wall with respect to the vertical direction is set to 5 ° to 20 °, the air flow toward the inside of the clean booth is reduced, and the amount of dust entering the clean booth can be greatly reduced. Since there is no need for an air inlet on the floor, the degree of freedom of installing a clean booth is improved in a large space.

It is sectional drawing which shows the clean room to which the air curtain structure which concerns on 1st Embodiment of this invention was applied. It is a longitudinal cross-sectional view of a part of a clean booth provided in the clean room according to the embodiment. It is a figure which shows the air flow analysis result which concerns on the Example of the said embodiment. It is a figure which shows the air flow analysis result which concerns on the Example of the said embodiment. It is a longitudinal cross-sectional view of a part of a clean booth to which an air curtain structure according to a second embodiment of the present invention is applied. It is a figure which shows the air flow analysis result which concerns on the Example of the said embodiment. It is sectional drawing of the clean booth to which the air curtain structure which concerns on 3rd Embodiment of this invention was applied. It is a longitudinal cross-sectional view of the air purification apparatus of the clean booth which concerns on the said embodiment. It is a plane sectional view of the corner of the ceiling part of the clean booth according to the embodiment. It is a plane sectional view of the corner | angular part of the ceiling part of the clean booth which concerns on the 1st modification of this invention. It is a plane sectional view of the corner of the ceiling part of the clean booth concerning the 2nd modification of the present invention. It is a plane sectional view of the corner of the ceiling part of the clean booth concerning the 3rd modification of the present invention. It is sectional drawing of the air cleaning apparatus of the clean booth to which the air curtain structure which concerns on 4th Embodiment of this invention was applied. It is a figure for demonstrating the experimental method about the Example of the said embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description of the embodiments, the same constituent elements are denoted by the same reference numerals, and the description thereof is omitted or simplified.
[First Embodiment]
FIG. 1 is a cross-sectional view showing a clean room 1 in which a clean booth 20 according to a first embodiment of the present invention is installed.
The clean room 1 is a space surrounded by the floor surface 2, the wall surfaces 3A and 3B, and the roof surface 4, and has a high ceiling height and a large space with a large span.

Here, the left wall surface in FIG. 1 is a wall surface 3A, and the right wall surface in FIG. 1 is a wall surface 3B. A plurality of pillars 5A and 5B are provided on the wall surfaces 3A and 3B, respectively. Between the pillars 5A and 5B, truss beams 6 extending in the left-right direction in FIG. The surface 4 is supported by the truss beam 6.
This clean room 1 is not provided with a ceiling material, and the lower surface of the roof surface 4 is the ceiling surface of the clean room 1.
A clean booth 20 is installed in the clean room 1, and a large manufacturing apparatus 7 is installed inside the clean booth 20.

  The clean room 1 is provided with an air conditioning system 10. The air conditioning system 10 includes an air cooling device 11 provided in the truss beam 6, a cold aisle 12 provided as an air passage provided in the truss beam 6, and an air purification provided in the vicinity of the cold aisle 12. And a device 13.

The air cooling device 11 is provided on the side of the wall surfaces 3 </ b> A and 3 </ b> B, sucks and cools air from the lower surface, and blows out the cooled air to the cold aisle 12.
The cold aisle 12 extends along the truss beam 6, and air (cold air) cooled by the air cooling device 11 circulates therethrough.
The air purifier 13 purifies the air flowing through the cold aisle 12 and blows it out downward in the room.

  The manufacturing apparatus 7 is an apparatus that requires high air cleanliness. A space in which the manufacturing apparatus 7 is installed is set as a target space 8, and the clean booth 20 covers the target space 8.

  The clean booth 20 includes a rectangular flat plate-shaped ceiling portion 21 that covers the upper surface of the target space 8, a post 22 (not shown) that supports the ceiling portion 21, and an air cleaning device 23 provided near the center of the ceiling portion 21. The air purifier 24 provided at the peripheral edge of the ceiling portion 21 and the curtain 25 as a hanging wall extending obliquely downward from the outer edge of the air purifier 24 and reaching a predetermined height from the floor surface. .

The air purifiers 23 and 24 clean air by taking in air from the upper surface and blow out from the air outlet 30 on the lower surface.
This blower outlet 30 is provided in the loading / unloading part 27 where an operator goes in / out or carries in / out a product.
Moreover, although the blower outlet 30 is facing the floor surface 2, the inlet port is not provided in this floor surface 2. FIG.

FIG. 2 is a longitudinal sectional view of a part of the clean booth 20.
An air outlet 30 of the air cleaning device 24 is provided at the periphery of the ceiling portion 21.
The curtain 25 is made of vinyl chloride, and spreads outward as it goes downward, so that the angle with respect to the vertical direction is not less than 5 ° and not more than 20 °, here 15 °.
The blower outlet 30 extends along the inner wall surface of the curtain 25, and blows out highly purified air cleaned by the air purifier 24 along the inner wall surface of the curtain 25 to form an air curtain. .

  In the clean room 1 described above, the air cooling device 11, the cold aisle 12, and the air cleaning device 13 form a circulation path through which air circulates up and down in the room of the clean room 1.

That is, the air circulation path is formed as follows.
As shown in FIG. 1, the cold air blown out from the air cooling device 11 flows in the cold aisle 12 in a substantially horizontal direction, is cleaned by the air cleaning device 13, and is blown out downward. The air descends to near the floor surface of the clean room 1, then rises to near the ceiling surface above the cold aisle 12, is sucked into the air cooling device 11, cooled, and supplied to the cold aisle 12 again.

  In the clean booth 20, high-cleanness air is blown out directly below by the air cleaning device 23 to locally increase the air cleanliness of the target space 8 inside the clean booth 20, and the air cleaning device 24. By blowing out air of high cleanliness obliquely downward from the target space 8, the target space 8 is separated from the surroundings by the blown-out air, and the surrounding air is prevented from entering the target space 8.

FIG. 3 is a diagram illustrating an airflow analysis result according to an example of the present embodiment.
Air blown out from the outlet along the inner wall surface of the curtain flows downward while diffusing to form an air curtain that prevents the surrounding air from entering the target space.
Then, the air that has reached the vicinity of the floor surface is divided into an airflow toward the outside of the clean booth and an airflow toward the inside of the clean booth. As shown in FIG. 3, it can be seen that the airflow toward the inside of the clean booth is significantly reduced as compared to the airflow toward the outside of the clean booth.

FIG. 4 is a diagram illustrating the concentration analysis result according to the example of the present embodiment.
As experimental conditions, a clean booth having a length of 6 m, a width of 6 m, and a height of 3 m was assumed. Further, a curtain having a height of 1 m was provided on the outer edge of the outlet, and the outlet angle was set to 15 °.
As a result, as shown in FIG. 4, it can be seen that the cleanliness inside the clean booth is about 1/100 of the cleanliness outside the clean booth.
Further, when the experiment was conducted with the blown wind speed of 1.2 m / s, the ratio of the number of fine particles to the outside inside the clean booth was 2.0% to 2.5%.

According to this embodiment, there are the following effects.
(1) By blowing out from the outlet 30 along the inner wall surface of the curtain 25, the air is blown out at an angle from the vertical direction to the outside, and the blown air flows downward while diffusing outside, The air curtain prevents the surrounding air from entering the target space 8. Therefore, the air cleanliness of the target space 8 can be locally increased compared to the surroundings.

  Since no air inlet is provided on the floor 2, there is no restriction on the installation location of the clean booth 20, and a local clean location in a large space can be installed freely. In particular, it is not necessary to provide a partition structure on the peripheral wall, and the clean booth can be installed only with the upper structure on the ceiling side.

  In addition, the air curtain improves the shielding property from the outside, and it is not configured to partition the target space 8 from the outside like a conventional wall or curtain, so that it does not interfere with the worker's lead wire or product conveyance path. There is no hindrance to loading and unloading. Therefore, it can prevent that the manufacturing efficiency of a product falls.

  In addition, the air blown out from the outlet 30 along the inner wall surface of the curtain 25 is divided into an airflow toward the outside of the clean booth 20 and an airflow toward the inside of the clean booth 20 in the vicinity of the floor surface 2. Here, since the angle of the curtain 25 with respect to the vertical direction is set to 5 ° or more, the air flow toward the inside of the clean booth 20, that is, the target space 8, is reduced, and the amount of dust entering the target space 8 can be greatly reduced.

  (2) Since air is blown out along the inner wall surface of the curtain 25, outside air is not involved in the range of the curtain 25, and the air can be blown below the curtain 25 while maintaining the direction and strength of the airflow. Therefore, it is possible to improve the blocking performance and reduce the size. Also, the air blowing direction can be regulated by the curtain 25.

[Second Embodiment]
FIG. 5 is a cross-sectional view of a peripheral portion of a clean booth 20A to which an air curtain structure according to a second embodiment of the present invention is applied.
In this embodiment, the point which provided the 2nd curtain 26 as a hanging wall inside the curtain 25, and the shape of 30 A of blower outlets differ from 1st Embodiment.
Specifically, the second curtain 26 is made of vinyl chloride and extends downward in the vertical direction.

  Further, the air outlet 30 </ b> A extends along the inner wall surface of the curtain 25 and extends along the inner wall surface of the second curtain 26. Thereby, the air with high cleanliness cleaned by the air cleaning device 24 is blown out along the inner wall surface of the curtain 25 and the inner wall surface of the curtain 26 to form an air curtain. Therefore, the air blowing direction becomes two layers, and the blowing direction of the inner layer is set to a small angle, here substantially vertical.

FIG. 6 is a diagram illustrating an airflow analysis result according to an example of the present embodiment.
The air blown out along the inner wall surface of the second curtain inside from the air outlet flows downward in the vertical direction, reaches the floor, and flows toward the outside of the clean booth and toward the inside of the clean booth. Divided into airflow.

Since the airflow flowing along the second curtain functions as a wall, the airflow flowing along the outer curtain flows downward while diffusing outward.
Then, in the vicinity of the floor surface, the airflow flowing along the outer curtain is pushed by the airflow flowing along the inner second curtain and goes to the outside of the clean booth.

  Further, when the experiment was conducted with the blown wind speed of 1.2 m / s, the ratio of the number of fine particles to the outside inside the clean booth was 0.03% to 0.4%.

According to this embodiment, in addition to the effects (1) and (2) described above, the following effects can be obtained.
(3) After the air blown out along the second curtain 26 on the inner side reaches the floor surface 2, the air is urged in the direction toward the outside of the clean booth 20. Therefore, in the vicinity of the floor surface 2, the airflow flowing along the outer curtain 25 is pushed by the airflow flowing along the inner second curtain 26, and goes to the outside of the clean booth 20. It can prevent more reliably that a shunt flow penetrate | invades inside. Since the inner airflow has a shorter distance to the floor where the angle difference is separated than the outer airflow, a stronger flow than the outer airflow can be formed, and the pushing force to the outside is also increased.

[Third Embodiment]
FIG. 7 is a cross-sectional view of a clean booth 20B to which an air curtain structure according to a third embodiment of the present invention is applied.
In the present embodiment, the structures of the air cleaning device 24B and the curtains 41 to 47 on the periphery of the ceiling portion 21 are different from those of the first embodiment.
That is, the air purifier 24 </ b> B is provided on the four sides of the rectangular flat plate-shaped ceiling portion 21. The air cleaning device 24B is smaller than the air cleaning device 24 and can be moved up and down. That is, the height H of the air cleaning device 24B can be changed as appropriate.

FIG. 8 is a longitudinal sectional view of the air cleaning device 24B.
The air cleaning device 24B includes an FFU (fan filter unit) 28 and a screen mesh 29.
The air outlet 30B of the air cleaning device 24B is provided with a plurality of curtains 41, 42, 43, 44, 45, 46, and 47 arranged at equal intervals from the inside to the outside, here. Yes. Each of these curtains 41 to 47 expands outward as it goes downward, and the angle with respect to the vertical direction is approximately 5 °.

  The air outlet 30B of the air cleaning device 24B blows out the cleaned highly clean air along the curtains 41 to 47 to form an air curtain. That is, in this embodiment, the blower outlet 30B blows out air only in a predetermined direction.

  Here, since there are many fine particles entering the inside of the clean booth 20B from the corner of the ceiling portion 21, the curtains 41 to 47 on the adjacent surfaces are joined to each other at this corner without any breaks. Specifically, it is as follows.

FIG. 9 is a plan sectional view of a corner portion of the ceiling portion 21 of the clean booth 20B.
At the corners of the ceiling portion 21, the curtains 41 to 47 extending in a straight line on adjacent surfaces are abutted and joined.
However, the present invention is not limited to this, and as shown in FIG. 10, the curtains 41 to 47 on the adjacent surfaces may be connected to each other with curtains 51 to 57 extending linearly in plan view in the corner portion of the ceiling portion 21. . Alternatively, as shown in FIG. 11, adjacent curtains 41 to 47 are connected by linear curtains 51 to 57 extending linearly in a plan view, and curtains 61 to 66 are attached to corners of the ceiling portion 21. May be provided. Alternatively, as shown in FIG. 12, the curtains 41 to 47 on the adjacent surfaces are connected by curtains 71 to 77 extending linearly in a plan view, and the intervals between the curtains 71 to 78 are set to the distance between the curtains 41 to 47. It may be equal to the interval.

  According to the present embodiment, there are the same effects as the above (1) and (2).

[Fourth Embodiment]
FIG. 13 is a longitudinal sectional view of an air cleaning device 24C of the clean booth 20B to which the air curtain structure according to the third embodiment of the present invention is applied.
In the present embodiment, the structure of the curtains 81 to 87 is different from that of the third embodiment.
That is, a plurality of curtains 81, 82, 83, 84, 85, 86, and 87, which are arranged at a predetermined interval from the inside to the outside, are provided at the air outlet 30B of the air cleaning device 24B. ing.
Among these curtains 81 to 87, the inner curtains 81 to 83 are respectively attached substantially at regular intervals. On the other hand, the outer curtains 84 to 87 are attached at regular intervals with an angle of about 5 ° with respect to the vertical direction.

  The air outlet 30B of the air cleaning device 24B blows out the cleaned highly clean air along the curtains 81 to 87 to form an air curtain. That is, in this embodiment, the blower outlet 30B blows air in two directions.

  According to this embodiment, the same effects as the above (1) to (3) are obtained.

Next, experiments were conducted on the following two examples.
Example 1 is an example of 3rd Embodiment, and is the structure which blows off air in one direction from the blower outlet of an air purifying apparatus.
Example 2 is an example of the fourth embodiment, and is made of steel that blows air in two directions from the air outlet of the air cleaning device.
The experimental conditions are as follows. An air cleaning device was provided on only one of the four surfaces of the clean booth, and the air outlet of this air cleaning device was disposed at a height of 2 m from the floor surface. The clean booth was ventilated 10 times per hour, and the air volume at the outlet was constant (370 m ³ / h · unit).

The experimental results were as follows.
In Example 1, the wind speed at the air outlet was 0.76, and the ratio of the number of fine particles having a diameter of 0.5 μm or more inside and outside the clean booth was 0.65.
In Example 2, the wind speed at the air outlet was 0.69, and the ratio of the number of fine particles having a diameter of 0.5 μm or more inside and outside the clean booth was 0.24.

  From this experimental result, it was found that by setting the blowing direction to two directions, the fine particles inside the clean booth can be significantly reduced compared with the case where the blowing direction is set to one direction, which is effective.

Experiments were also conducted on the following two examples.
In Example 3, as shown in FIG. 14, a wind shielding plate having a width of 0.5 m was provided on the corner of the ceiling so as to protrude outward. In addition, this wind shielding board is the height from a floor surface to a blower outlet.
On the other hand, Example 4 did not provide a windshield.

  The experimental conditions are as follows. Air purifiers were installed on the four sides of the clean booth, and the clean booth was ventilated 30 times per hour. Moreover, the wind speed in parts other than the corner | angular part of a blower outlet was 0.69.

The experimental results were as follows.
In Example 3, the ratio of the number of fine particles having a diameter of 0.5 μm or more inside and outside the clean booth was 0.31 to 0.59.
In Example 4, the wind speed at the corner was 0.71, and the ratio of the number of fine particles having a diameter of 0.5 μm or more inside and outside the clean booth was 0.95 to 1.48.

  From this experimental result, it was found that the installation of a wind shield can greatly reduce the fine particles in the clean booth without performing corner blowing, and is effective. Therefore, by providing the wind shielding plate, it is not necessary to blow out corners, so that energy saving can be realized and the cost can be reduced.

  It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.

DESCRIPTION OF SYMBOLS 1 ... Clean room 2 ... Floor surface 3A, 3B ... Wall surface 4 ... Roof surface 5A, 5B ... Pillar 6 ... Truss beam 7 ... Manufacturing apparatus 8 ... Target space 10 ... Air conditioning system 11 ... Air cooling device 12 ... Cold aisle 13 ... Air purification Cleaner 20, 20A, 20B ... Clean booth 21 ... Ceiling 22 ... Prop 23, 24, 24B, 24C ... Air purifier 25 ... Curtain (hanging wall)
26 ... Second curtain (hanging wall)
27 ... Carry-in / out part 28 ... FFU
29 ... Screen mesh 30, 30A, 30B ... Air outlet 41, 42, 43, 44, 45, 46, 47 ... Curtain (hanging wall)
51, 52, 53, 54, 55, 56, 57 ... Curtain (hanging wall)
61, 62, 63, 64, 65, 66 ... Curtain (hanging wall)
71, 72, 73, 74, 75, 76, 77 ... Curtain (hanging wall)
81, 82, 83, 84, 85, 86, 87 ... Curtain (hanging wall)

Claims (5)

A clean booth equipped with an air curtain at least in the loading / unloading section,
The air curtain includes a blowout port that blows out air of high cleanliness provided on the ceiling side,
A clean booth characterized in that no air inlet is provided on the floor facing the air outlet.   The clean booth according to claim 1, wherein an air blowing direction is set to an angle of 5 ° or more and 20 ° or less with respect to a vertical direction from the outlet.   The clean booth according to claim 1 or 2, wherein the air blowing direction is a multiple layer, and the blowing direction of the inner layer is set to a small angle.   The clean booth according to any one of claims 1 to 3, wherein a drooping wall is provided at the air outlet toward the air blowing direction.   The clean booth according to claim 1, wherein the clean booth is installed in a clean room.

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