JP3832612B2 - Fire extinguishing method and apparatus in clean room - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fire extinguishing method and apparatus in a clean room, and more particularly, to a fire extinguishing method and apparatus in a clean room equipped with a production line for semiconductor manufacturing equipment and ultra-precision equipment.
[0002]
[Prior art]
As semiconductor elements are highly integrated and miniaturized, a semiconductor manufacturing apparatus is housed in a clean room. As a general configuration of a clean room, conditioned air is supplied into the ceiling chamber and blown into a clean room through a filter (HEPA filter) disposed on the ceiling surface. It is usually used in circulation.
[0003]
In clean rooms, many combustible materials such as chemicals and gases are used together with semiconductor manufacturing equipment, and various efforts have been made for disaster prevention measures.
Conventionally, as a fire extinguishing measure when a fire occurs in a clean room of a semiconductor factory, initial fire fighting measures such as installing a halogen gas fire extinguishing facility or a fire extinguishing facility such as a water sprinkling facility locally have been taken.
[0004]
[Problems to be solved by the invention]
However, extinguishing with a halogen-based fire extinguishing gas involves the generation of corrosive gases (hydrogen bromide, hydrogen fluoride, etc.), which is not only dangerous to human life but may also cause secondary disasters such as corroding the equipment. There is a drawback of becoming.
In addition, there is a fire extinguishing method by discharging carbon dioxide gas throughout the clean room, but it has the same drawbacks as in the case of halogen-based fire extinguishing gas, and is not a fundamental solution.
[0005]
In addition, in the event of a fire, the above fire extinguishing gas is released to the clean room with all the devices that air-condition the clean room stopped, so the pressure in the clean room may rise all at once. The adverse effect on the human body and equipment is also a problem.
The present invention has been made in view of such circumstances, and can quickly extinguish an initial fire, can protect human lives in a clean room, and further is an apparatus disposed in the clean room. An object of the present invention is to provide a fire extinguishing method and apparatus in a clean room that can prevent contamination such as that as much as possible.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention supplies air conditioned air into the ceiling chamber and blows it out into the clean room through a filter disposed on the ceiling surface. In a fire extinguishing method in a clean room that circulates, a fire that has occurred in the clean room is detected, the supply of conditioned air from the outside to the ceiling chamber is stopped, and air circulation between the clean room and the ceiling room is performed. The fire extinguishing gas composed of carbon dioxide gas and inert gas is discharged into the ceiling chamber while being continued, and the discharged fire extinguishing gas is circulated through the filter between the clean room and the ceiling chamber by the air circulation. On the other hand, the air in the clean chamber is diluted with the fire extinguishing gas while adjusting the pressure of the clean chamber by discharging the air in the clean chamber.
[0007]
In order to achieve the above object, the present invention supplies conditioned air into the ceiling chamber and blows it into a clean room through a filter disposed on the ceiling surface. In a fire extinguisher in a clean room that is circulated between a fire detector that detects a fire, a pressure detector that detects an increase in pressure in the clean room, and an outside of the conditioned air from the outside into the ceiling chamber An air supply stop means for stopping air supply, a fire extinguishing gas discharge means provided with a discharge port for a fire extinguishing gas comprising carbon dioxide gas and an inert gas in the ceiling chamber, and exhausting the air in the clean chamber to Pressure adjusting means for adjusting the pressure in the clean chamber, the supply stop means, the fire extinguishing gas discharge means, and the pressure adjusting means based on the detection results of the fire detector and the pressure detector And control means for controlling, in that it consists characterized.
[0008]
According to the present invention, when a fire occurs in a clean room, only air circulation between the ceiling chamber and the clean room is performed in a state where the supply of conditioned air from the outside into the ceiling chamber is stopped and the oxygen supply system is shut off. Continue. With this air circulation continued, a fire extinguishing gas composed of carbon dioxide and inert gas is released into the ceiling chamber. The fire extinguishing gas released into the ceiling chamber is blown out to the clean room through a filter disposed on the ceiling surface by air circulation. The pressure in the clean chamber by blowing out the fire extinguishing gas into the clean chamber is adjusted by exhausting the air in the clean chamber. As a result, the oxygen concentration in the clean room is rapidly reduced to about 15% or less, and the fire is quickly extinguished. Also, by blowing out the fire extinguishing gas released into the ceiling chamber to the clean room through the filter, not only can the dust accompanying the fire extinguishing gas be removed and then supplied to the clean room, but also the ventilation of the filter By using the resistance, fire extinguishing gas can be prevented from being blown out from the ceiling chamber to the clean room at a time. Therefore, since the pressure in the clean chamber does not rise at a stretch, there is no adverse effect on people and devices in the clean chamber due to a sudden pressure change.
[0009]
Furthermore, by diluting the clean room air with a fire extinguishing gas consisting of carbon dioxide and inert gas, the oxygen concentration in the clean room becomes a low oxygen state of 15% or less, and flammability is lost even with kerosene. Extinguishes fire. For those who remain in the room, the number of breathing naturally increases as the carbon dioxide concentration increases moderately, so there is no abnormality in life even in a clean room with low oxygen, and necessary fire extinguishing activities are possible. To.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a fire extinguishing method and apparatus in a clean room according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a diagram for explaining a first embodiment of the present invention, and is a configuration diagram in which the clean room extinguishing method and apparatus of the present invention are applied to a turbulent flow (conventional type) clean room.
[0011]
As shown in FIG. 1, the outside air introduced from the outside air introduction path 12 is air-conditioned by the external air conditioner 14 and is supplied into the ceiling chamber 18 through the air supply duct 16. An air supply valve 20 is provided in the air supply duct 16 and is connected to a controller 24 via a signal cable 22. As a result, the supply of conditioned air conditioned by the external air conditioner 14 into the ceiling chamber 18 can be blocked. The conditioned air supplied into the ceiling chamber 18 is filtered with dust and the like through a HEPA filter 28 disposed on the ceiling surface 26 and blown into the clean room 30 as clean conditioned air. An intake port 32 is formed below the side wall 30 </ b> A of the clean chamber 30, and the intake port 32 and the air supply duct 16 are communicated with each other by a circulation duct 34. A circulation fan 36 is provided in the circulation duct 34. The circulation fan 36 is connected to the controller 24 via a signal cable 38. Thus, when the controller 24 operates the circulation fan 36, the conditioned air blown into the clean room 30 is circulated and used between the ceiling chamber 18. Further, the amount of circulation can be adjusted by changing the rotational speed of the circulation fan 36. In the middle of the circulation duct 34, an exhaust duct 42 having an exhaust valve 40 is communicated, and the exhaust valve 40 is connected to the controller 24 via a signal cable 44. Accordingly, when the controller opens the exhaust valve 40, a part of the circulating air can be exhausted to the outside. The exhaust amount can be varied by adjusting the opening of the exhaust valve.
[0012]
A fire extinguishing gas discharge pipe 46 is provided in the ceiling chamber 18, and the discharge pipe 46 is connected to an external fire extinguishing gas supply device 48. An operation unit (not shown) of the fire extinguishing gas supply device 48 is connected to the controller 24 via a signal cable 50. Thus, when the controller 24 operates the fire extinguishing gas supply device 48, the fire extinguishing gas is released from the discharge pipe 46 into the ceiling chamber 18. The fire extinguishing gas is composed of carbon dioxide and inert gas, and the carbon dioxide concentration is preferably about 8 ± 2%. A specific configuration of the digestion gas is, for example, a composition of carbon dioxide 10% and nitrogen 90%, carbon dioxide 8%, nitrogen gas 52%, and argon gas 40%.
[0013]
A temperature detector 52 that reacts depending on temperature is provided in the clean room 30, and a smoke detector 54 that reacts by smoke is provided near the inlet 32 of the circulation duct 34. The detection results detected by the detectors 52 and 54 are input to the controller 24 by signal cables 56 and 58. Further, a pressure detector 60 is provided in the clean chamber 30, and the detection result detected by the pressure detector 60 is input to the controller 24 via the signal cable 62.
[0014]
A pressure adjustment damper 64 is provided on the side wall 30 </ b> B of the clean chamber 30, and the drive unit 64 </ b> A is connected to the controller 24 via a signal cable 66. Based on the detection result of the pressure detector 60, the controller 24 opens the pressure adjustment damper 64 when the pressure increase in the clean chamber 30 exceeds 30 mmAq, for example, and corridors 68 adjacent to the clean chamber 30 allow air to enter the clean chamber 30. To increase the pressure in the clean chamber 30.
[0015]
Next, a fire extinguishing method for a fire generated in the clean room of the clean room using the clean room fire extinguishing apparatus configured as described above will be described.
When a fire occurs, the temperature detector 52 and the smoke detector 54 detect that a fire has occurred, and the detection result is output to the controller 24. The controller 24 closes the air supply valve 20 and stops supplying new conditioned air into the ceiling chamber 18, while continuing the operation of the circulation fan 36. As a result, air circulation is performed between the ceiling chamber 18 and the clean room 30 in a state in which the new oxygen supply system is shut off. Next, the controller 24 operates the fire extinguishing gas supply device 48 with the exhaust valve 40 opened for a short time (about 15 to 30 seconds) while continuing the air circulation to extinguish the fire from the discharge pipe 46 into the ceiling chamber 18. Release gas. The discharge amount of the fire extinguishing gas is an amount that replaces approximately half of the air in the clean chamber 30, and the discharge amount is preset in the controller 24 according to the volume of the clean chamber 30.
[0016]
The fire extinguishing gas released into the ceiling chamber 18 is blown out into the clean room 30 through the HEPA filter 28 disposed on the ceiling surface by air circulation. When the fire extinguishing gas is blown into the clean chamber 30, the exhaust valve 40 is opened for a short time, so that a part of the air in the clean chamber 30 flows into the clean chamber 30 while being pushed out. Then, after the exhaust valve 40 is closed, it circulates with the residual air in the clean chamber between the ceiling chamber 18 and is uniformly mixed. The release time of the fire extinguishing gas is suitably within 5 minutes, preferably in the range of 2 to 3 minutes. This is because, in the case of a clean room in which conditioned air is circulated between the clean room 30 and the ceiling chamber 18, the number of ventilations (the number of times the air in the clean room 30 is completely circulated per hour) is 80 times / hour. Usually there are more. Therefore, since the ventilation frequency per minute is a little over 1 time, if the release time is set to 2 to 3 minutes, the ventilation frequency can be obtained at least twice during the discharge of the fire extinguishing gas. The air and the fire extinguishing gas can be sufficiently mixed.
[0017]
In this way, the oxygen concentration in the clean chamber 30 is lowered with the fire extinguishing gas while circulating between the clean chamber 30 and the ceiling chamber 18 in a state in which a new oxygen supply system to the clean chamber 30 is shut off. As a result, the oxygen concentration in the clean chamber 30 can be quickly reduced to quickly extinguish the fire. That is, by diluting the oxygen concentration in the clean chamber 30 from 21% to 15% or less, it is possible to reliably suppress the fire if it is an initial fire. Note that when the oxygen concentration is 15% or less, the gas lighter does not ignite.
[0018]
Moreover, the life in the clean room 30 can be protected by replacing about half of the air in the clean room 30 instead of completely replacing the air in the clean room 30 with the fire extinguishing gas. The reason for this is that even in a low oxygen state where the oxygen concentration in the clean room 30 is reduced, the amount of human respiration is increased by increasing the carbon dioxide concentration to an appropriate level (3-4%). This is because it becomes possible to act. Incidentally, the air composition in the clean room when the air in the clean room 30 is replaced by about half of the extinguishing gas having the composition of carbon dioxide gas 8%, nitrogen gas 52%, argon gas 40% is nitrogen gas 67-70%, Argon gas is 12 to 16%, oxygen is 12 to 14%, and carbon dioxide gas is 3 to 4%. Therefore, even if the fire extinguishing gas is released, there is no problem in human life, and the fire extinguishing gas can be released before the person evacuates from the clean room 30, so that it is possible to perform a quick fire extinguishing.
[0019]
In addition, the fire extinguishing gas released into the ceiling chamber 18 is blown into the clean room 30 through the HEPA filter 28 disposed on the ceiling surface 26, so that the dust accompanying the fire extinguishing gas is removed. The clean chamber 30 can be supplied with air and dust generated by the fire can be removed. Further, since the fire resistance gas can be prevented from being blown out from the ceiling chamber 18 into the clean room 30 at once due to the ventilation resistance of the HEPA filter 28, the pressure in the clean room 30 does not rise at a stretch. Furthermore, the controller 24 adjusts the pressure in the clean chamber 30 by opening the pressure adjustment damper 64 when the pressure rise of the pressure detector 60 provided in the clean chamber 30 becomes 30 mmAq or more. Therefore, since there is no sudden pressure change in the clean chamber 30, there is no adverse effect on the people in the clean chamber 30 and precision instruments such as semiconductor devices.
[0020]
FIG. 2 is a diagram for explaining a second embodiment of the present invention, and is a configuration diagram in which the clean room fire extinguishing method and apparatus of the present invention are applied to a vertical flow (big fan system) clean room. The same members and devices as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.
As shown in FIG. 2, in the vertical flow method, a HEPA filter 28 is disposed on the entire ceiling surface 26, and conditioned air blown from the ceiling chamber 18 through the HEPA filter 28 into the clean room 30 is supplied to the grating floor 70. A vertical flow is generated in the clean room 30 by being sucked into the underfloor chamber 72 through. Other configurations are the same as those of the first embodiment.
[0021]
Even in the case of the second embodiment configured as described above, the inside of the clean room 30 is protected by protecting the life and preventing the contamination of the apparatus by extinguishing the fire according to the procedure described in the first embodiment. The fire can be extinguished.
FIG. 3 is a diagram for explaining a third embodiment of the present invention, and is a configuration diagram in which the clean room extinguishing method and apparatus of the present invention are applied to a local return type (fan filter unit type) clean room. The same members and devices as those in the first and second embodiments are denoted by the same reference numerals and description thereof is omitted.
[0022]
As shown in FIG. 3, in the local return method, a hanging wall 74 is suspended from the ceiling surface 26 in the clean chamber 30 around a space where high cleanliness is required, such as a semiconductor manufacturing apparatus or a wafer transfer path. By surrounding, it divides into a high cleanliness area 76 in the hanging wall 74 and a low cleanliness area 78 outside the hanging wall 74. That is, a fan filter unit 80 (hereinafter referred to as “FFU”) composed of a HEPA filter and a fan is disposed on the ceiling surface 26 of the high cleanliness area 76, and the conditioned air conditioned by the external air conditioner 14 is supplied to the air supply duct. 16 is directly connected to the FFU 80. Each FFU 80 is connected to the controller 24 via a signal cable 84 and can be individually operated according to an instruction from the controller 24. An intake opening (not shown) is formed in the FFU 80, and when the FFU 80 is activated, air in the ceiling chamber 18 is taken into the FFU 80 in addition to the conditioned air from the air supply duct 16.
[0023]
On the other hand, a return opening 82 is formed in the ceiling surface 26 of the low cleanliness area 78.
The conditioned air blown from the FFU 80 to the high cleanliness area 76 is blown toward the grating floor 70. Most of the conditioned air blown out flows into the underfloor chamber 72 through the grating floor 70. This forms a vertical flow of conditioned air in the high cleanliness area 76. The conditioned air that has flowed into the underfloor chamber 72 reaches the clean room 30 again from the grating floor 70, circulates through the low cleanliness area 78 and into the ceiling chamber 18 from the return opening 82. The air circulated in the ceiling chamber 18 is sucked into the FFU 80, mixed with the conditioned air from the air supply duct 16, and blown out into the clean room 30 again. Thereby, a circulation flow is formed between the clean room 30 and the ceiling chamber 18.
[0024]
An exhaust port 83 is formed in the side wall 72 </ b> A of the underfloor chamber 72 and is connected to the exhaust duct 42 provided with the exhaust valve 40. The exhaust valve 40 is connected to the controller 24 via a signal cable 44. Thereby, when the controller 24 opens the exhaust valve 40, a part of the air circulating between the ceiling chamber 18, the clean room 30 and the underfloor chamber 72 can be exhausted. Other configurations are the same as those of the first and second embodiments.
[0025]
In the third embodiment configured as described above, when a fire occurs in the clean room 30, the temperature detector 52 and the smoke detector 54 detect that a fire has occurred, and the detection result is output to the controller 24. The The controller 24 closes the air supply valve 20 to stop the supply of new conditioned air into the ceiling chamber 18 while continuing the operation of the FFU. As a result, air circulation is performed between the ceiling chamber 18 and the clean room 30 in a state in which the new oxygen supply system is shut off. Next, the controller 24 operates the fire extinguishing gas supply device 48 with the exhaust valve 40 opened for a short time (about 15 to 30 seconds) while continuing the air circulation, and enters the ceiling chamber 18 from the discharge pipe 46. Release fire extinguishing gas. Thus, the fire extinguishing gas released into the ceiling chamber 18 is sucked into the FFU 80 and blown out into the clean room 30 to dilute the air in the clean room 30. In this case, the fire extinguishing gas can be blown out to the clean room 30 via the HEPA filter of the FFU 80 by blowing out the fire extinguishing gas into the ceiling chamber 18 in a state where the FFU 80 is operated to form a circulation flow.
[0026]
FIG. 4 shows the relationship between the fire extinguishing gas blowing time and the oxygen concentration in the clean room 30. Curve A shows the case where the fire extinguishing gas is blown into the ceiling chamber 18 with the FFU 80 operated, and the curve B shows the FFU 80. This is a case where fire extinguishing gas is blown out into the ceiling chamber 18 without operating. As apparent from FIG. 4, when the FFU 80 is operated, the time required to reduce the oxygen concentration to 15% or less is about 30 seconds, whereas it takes 80 seconds if the FFU 80 is not operated. As described above, the fire extinguishing gas released into the ceiling chamber 18 can be blown into the clean chamber 30 from the return opening 82 without operating the FFU 80. However, if the FFU 80 is not operated, the air in the clean chamber 30 is discharged. It takes a long time to dilute the oxygen concentration to 15% or less. Therefore, quick fire extinguishing can be performed by operating the FFU 80.
[0027]
Even when the fire extinguishing method of the present invention is applied to a local return type clean room as in the third embodiment, the same effects as those of the first and second embodiments can be obtained.
[0028]
【The invention's effect】
As described above, according to the fire extinguishing method and apparatus in the clean room of the present invention, it is possible to quickly extinguish a fire, protect the lives of workers in the clean room, and the apparatus disposed in the clean room. It is possible to prevent such contamination.
[Brief description of the drawings]
FIG. 1 is a configuration diagram illustrating a fire extinguishing method and apparatus in a clean room according to a first embodiment of the present invention.
FIG. 2 is a configuration diagram illustrating a fire extinguishing method and apparatus in a clean room according to a second embodiment of the present invention.
FIG. 3 is a configuration diagram illustrating a fire extinguishing method and apparatus in a clean room according to a third embodiment of the present invention.
FIG. 4 is an explanatory diagram showing the relationship between the extinguishing gas blowing time and the oxygen concentration in the clean chamber when the FFU is activated and not activated in the third embodiment.
[Explanation of symbols]
14 ... external air conditioner 16 ... air supply duct 18 ... ceiling chamber 20 ... air supply valve 24 ... controller 26 ... ceiling surface 28 ... HEPA filter 30 ... cleaning chamber 34 ... circulation duct 36 ... circulation fan 40 ... exhaust valve 46 ... discharge piping 48 ... Fire extinguishing gas supply device 52 ... Temperature detector 54 ... Smoke detector 60 ... Pressure detector 64 ... Pressure adjusting damper 70 ... Grating floor 72 ... Underfloor chamber 74 ... Dripping wall 76 ... High cleanliness area 78 ... Low cleanliness area 80 ... FFU

Claims (6)

In a fire extinguishing method in a clean room in which conditioned air is supplied into the ceiling chamber and blown into the clean room through a filter disposed on the ceiling surface, and the conditioned air blown is circulated and used between the ceiling chamber,
Detecting a fire that occurred in the clean room, stopping the supply of conditioned air from the outside to the ceiling chamber,
While continuing the air circulation between the clean room and the ceiling room, a fire extinguishing gas composed of carbon dioxide gas and inert gas is released into the ceiling chamber,
The discharged fire extinguishing gas is circulated through the filter between the clean chamber and the ceiling chamber by the air circulation, while the air in the clean chamber is adjusted while adjusting the pressure of the clean chamber by discharging the air in the clean chamber. A fire extinguishing method in a clean room, characterized by diluting with the fire extinguishing gas. 2. The fire extinguishing method in a clean room according to claim 1, wherein the fire extinguishing gas comprises a composition of nitrogen gas and carbon dioxide, and the concentration of carbon dioxide is 8 ± 2%. The fire extinguishing method in a clean room according to claim 1, wherein about half of the air in the clean room is replaced with the fire extinguishing gas by the dilution. The discharge time of the fire extinguishing gas into the ceiling chamber is in the range of 2 to 5 minutes, and the circulation amount is adjusted so that the air circulation is performed at least twice within the discharge time. The fire extinguishing method in the clean room of Claim 1. The fire extinguishing method in a clean room according to claim 1, wherein an exhaust amount of air from the clean room is adjusted so that an increase in pressure in the clean room due to the discharge of the fire extinguishing gas is 50 mmAq or less. In a fire extinguisher in a clean room in which conditioned air is supplied into the ceiling chamber and blown out into the clean room through a filter disposed on the ceiling surface. ,
A fire detector for detecting a fire;
A pressure detector for detecting an increase in pressure in the clean chamber;
An air supply stop means for stopping air supply from the outside into the ceiling chamber of the conditioned air;
Fire extinguishing gas discharge means provided with a discharge port of a fire extinguishing gas composed of carbon dioxide gas and inert gas in the ceiling chamber,
Pressure adjusting means for exhausting the air in the clean chamber to adjust the pressure in the clean chamber;
Based on the detection results of the fire detector and the pressure detector, the air supply stop means, the fire extinguishing gas discharge means, and control means for controlling the pressure adjustment means,
A fire extinguishing device in a clean room characterized by comprising:

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