JP5975738B2 - Fire extinguishing system - Google Patents

Description

  The present invention relates to a fire extinguishing system, and more particularly to a closed spray fire extinguishing system provided in a parking lot or the like.

  Conventionally, there is a so-called closed spray fire extinguishing system in which a fire extinguishing agent is directly sprayed on a fire source in a state of an aqueous extinguishing agent solution mixed with water without foaming. The closed spray fire extinguishing system collides an aqueous fire extinguishing agent solution in which a fire extinguishing agent is mixed with fire extinguishing water against a deflector of the closed head, thereby obtaining a spray pattern over a wide range in the same manner as when watering a normal sprinkler head.

  Generally, a closed spray fire extinguishing system is provided with a water flow detection device having a normally closed check valve mechanism, and a secondary side pipe provided with a closed head is connected to the secondary side of the water flow detection device. The primary side is connected to a primary pipe provided with a water tank for storing fire-extinguishing water, a fire-extinguishing chemical tank for storing a fire-extinguishing chemical, a mixer for mixing the fire-extinguishing water and the fire extinguishing chemical, and the like. The flowing water detector opens when the pressure in the primary side pipe becomes higher than the pressure in the secondary side pipe, and the fire-extinguishing chemical aqueous solution flows from the primary side pipe to the secondary side pipe. In general, a plurality of water flow detection devices are provided in a closed spray fire extinguishing system.

  By the way, the closed spray fire extinguishing system is often installed in an outdoor parking lot, and the secondary side piping is often provided exposed to the outside air. Therefore, when the temperature rises, the volume of the extinguishing agent aqueous solution filled in the secondary side pipe expands, and the pressure in the secondary side pipe increases. If the pressure in the secondary side pipe becomes too high, the closed head connected to the secondary side pipe may be damaged and opened, and the fire-extinguishing chemical aqueous solution may be sprayed. Therefore, each water flow detection device is provided with a drain valve, and when the pressure in the secondary side pipe exceeds a certain level due to temperature rise or the like, the fire extinguishing agent aqueous solution filled in the secondary side pipe Is draining. Then, when the temperature rises and the expanded fire-extinguishing agent aqueous solution in the secondary side pipe is drained to the outside, the volume of the fire-extinguishing agent aqueous solution in the secondary side pipe shrinks when the temperature is lowered, and the secondary side The pressure in the piping decreases. Then, in order to keep the pressure difference between the secondary side pipe and the primary side pipe constant, the extinguishing chemical aqueous solution flows from the primary side to the secondary side by the check valve mechanism in the flowing water detection device. (See Patent Documents 1 and 2).

JP 2002-219186 A JP 2004-135849 A

  If the temperature rises and falls repeatedly, the fire-extinguishing agent aqueous solution is drained from the secondary-side piping, and the fire-extinguishing agent aqueous solution flows repeatedly from the primary-side piping to the secondary-side piping, reducing the pressure in the primary-side piping. It will follow. If the pressure in the primary side pipe is too low, the water supply pump that pumps the fire-extinguishing water from the water tank is activated to recover the pressure in the primary side pipe, and much power is used.

  The present invention has been made in view of the above problems, and keeps the pressure in the secondary pipe constant even when the temperature changes, and prevents the pressure in the primary pipe from being reduced as much as possible. The purpose is to reduce the number of activations.

The present invention relates to a check in which an aqueous fire extinguishing agent solution flows from a primary side pipe to a secondary side pipe when the pressure-charged primary side pipe and the secondary side pipe are connected and the pressure in the secondary side pipe decreases. Equipped with a running water detection device with a valve mechanism, the primary side pipe is supplied with a water tank for supplying fire-extinguishing water, a fire-extinguishing chemical tank for supplying fire-extinguishing chemical, and a mixture that generates fire-extinguishing chemical aqueous solution by mixing fire-extinguishing water and fire-extinguishing chemical In a fire extinguishing system in which a closed head for spraying a fire-extinguishing chemical aqueous solution is connected to the secondary side pipe, the primary side pipe starts when the pressure of the primary side pipe falls below a certain value, A water supply pump and an auxiliary pump that supply fire extinguishing water from the water tank are provided, and the pressure of the primary side pipe when the auxiliary pump starts is set higher than the pressure of the primary side pipe when the water pump starts, With secondary piping In addition, when the pressure in the secondary side pipe is higher than the pressure in the primary side pipe by a certain value or more, a boost prevention valve having a check valve mechanism that releases the pressure in the secondary side pipe to the primary side pipe is connected and mixed. A drain valve is provided only on the pipe that is provided on the primary side of the vessel and branched from the branch pipe to which the auxiliary pump is connected at the tip . When the pressure in the primary side pipe exceeds a certain value, the drain is discharged from the primary side pipe. A drain valve is provided.

  According to the fire-extinguishing system of the present invention, the pressure increase prevention valve having a check valve mechanism that releases the pressure in the secondary side pipe to the primary side pipe, and the drainage that drains when the pressure in the primary side pipe exceeds a certain value. Since the valve is provided, it is possible to reduce the number of activations of the water supply pump while keeping the pressure in the secondary side pipe and the primary side pipe constant.

It is a system diagram concerning Embodiment 1 of the present invention. FIG. 6 is a system diagram in the vicinity of a pressure increase prevention valve according to a second embodiment of the present invention. It is a schematic diagram of the flowing water detection apparatus which concerns on Embodiment 3 of this invention.

Embodiment 1 FIG.
A closed spray fire extinguishing system 100 according to Embodiment 1 of the present invention will be described with reference to FIG.

  Reference numeral 1 denotes a running water detector, which has a secondary side pipe 50 connected to the secondary side and a primary side pipe 60 connected to the primary side. The secondary side pipe 50 and the primary side pipe 60 are supplied with a fire-extinguishing chemical solution or fire water. It is filled with pressure and both are kept at almost the same pressure. The flowing water detection device 1 has a check valve mechanism, and when the pressure of the secondary side pipe 50 is reduced, the check valve mechanism is opened to connect the primary side pipe 60 and the secondary side pipe 50. More specifically, when the pressure of the secondary side pipe 50 becomes lower than the pressure of the primary side pipe 60, the check valve mechanism is opened, and the primary side pipe 60 and the secondary side pipe 50 communicate with each other. The flowing water detection device 1 is provided with a pressure switch, the check valve is opened, and the flow rate of the extinguishing chemical aqueous solution from the primary side pipe 60 to the secondary side pipe 50 reaches a certain value or more. A pressure rise is detected and a flowing water detection signal is output to the fire receiver 20 described later. The flowing water detection device 1 is a check that opens when the pressure in the secondary side pipe 50 becomes lower than the pressure in the primary side pipe 60 due to a pressure drop in the secondary side pipe 50, for example. It may have a valve mechanism.

  Reference numeral 4 denotes a pressure increase prevention valve, which has a check valve mechanism, and is connected between the secondary side pipe 50 and the primary side pipe 60. The primary side of the pressure increase prevention valve 4 is connected to the secondary side pipe 50, and the secondary side of the pressure increase prevention valve 4 is connected to the primary side pipe 60. More specifically, the primary side of the pressure increase prevention valve 4 is connected to the secondary side pipe 50 between the water flow detection device 1 and the closed head 3, and the secondary side of the pressure increase prevention valve 4 is the mixer 5 and the water flow detection. Connected to the primary pipe 60 between the devices 1. Note that the secondary side of the pressure increase prevention valve 4 may be connected to the primary side of the mixer 5 of the primary side pipe 60. In addition, the primary side of the pressure increase prevention valve 4 is connected to a bypass pipe that is branched from the secondary side in the water flow detection device 1, and the secondary side of the pressure increase prevention valve 4 is connected to the primary side in the water flow detection device 1. You may connect to the bypass piping provided by making it branch. Then, when the pressure in the secondary side pipe 50 becomes higher than the pressure in the primary side pipe 60 by a certain value (for example, 0.25 MPa) or more, the pressure increase prevention valve 4 is filled with the secondary side pipe 50. The aqueous fire extinguishing agent solution is returned to the primary side pipe 60. That is, the pressure in the secondary side pipe 50 is released to the primary side pipe 60.

  Reference numeral 3 denotes a closed head, which is connected to the tip of the secondary side pipe 50. The closed head is composed of a horseshoe sprinkler head having a deflector fixed under two frames. The heat sensitive part is composed of a glass bulb and supports a valve body that stops the water outlet. When the fire extinguisher aqueous solution is radiated from the outlet, it does not foam so much (for example, less than 5 times the foaming ratio) and does not foam so much that it hits the deflector and is sprayed onto the protected area.

  Reference numeral 5 denotes a mixer having a venturi tube, which has an inflow port for the extinguishing water supplied from the water tank 11, an inflow port for the extinguishing chemical supplied from the extinguishing chemical tank 7, and an outflow port for the mixed extinguishing chemical aqueous solution. . The fire-extinguishing agent aqueous solution generated by mixing the fire-extinguishing water and the extinguishing agent is sent to the flowing water detection device 1 side.

  Branch pipes 61, 63, and 65 are connected between the water supply pump 9 that supplies fire-extinguishing water from the water tank 11 and the mixer 5.

  The branch pipe 61 is connected to the fire extinguishing chemical tank 7. When the water supply pump 9 is activated, the fire extinguishing water flows into the fire extinguishing chemical tank 7 from the branch pipe 61, and the fire extinguishing chemical is directed toward the mixer 5 by the pressure of the fire extinguishing water. Sent out. As the fire extinguishing agent, for example, water film foam extinguishing agent Megafoam F-623T (registered trademark) is used. In addition, it is not a water film foam extinguishing agent, but as a fire extinguishing agent as a foam extinguishing agent, it is possible to enhance the fire extinguishing effect by mixing it with extinguishing water or other extinguishing agents such as protein foam extinguishing agent, synthetic surfactant foam extinguishing agent, etc. Any fire extinguishing agent that can be used.

  The branch pipe 63 is connected to the primary side pipe 60 at a position closer to the water tank 11 than the branch pipe 61, and the pump activation device 12 is connected to the tip. The pump activation device 12 has a pressure switch, monitors the pressure in the primary side pipe 60, and when the pressure in the primary side pipe 60 falls below a certain value (for example, 0.6 MPa), An activation signal is transmitted to the pump control panel 22 described later.

  The branch pipe 65 is provided on the primary side of the mixer 5, and the drain valve 15 that drains water when the pressure of the primary pipe 60 reaches a certain value (for example, 1.4 MPa) or more is further branched from the branch pipe 65. A strainer is provided on the primary side of the drain valve 15. One drain valve 15 is provided in one closed spray fire extinguishing system 100 and is installed in a pump room or the like. The auxiliary pump 13 is connected to the tip of the branch pipe 65. The auxiliary pump 13 is started when the pressure of the primary side pipe 60 is slightly lowered, and the pressure of the primary side pipe 60 when the auxiliary pump 13 is started is the primary side pipe when the feed water pump 9 is started. Higher than 60 pressures. Note that the power required to start the auxiliary pump 13 is smaller than the power required to start the water supply pump 9.

  Reference numeral 20 denotes a fire receiver, which is connected to the pressure switch of the flowing water detection device 1 by a signal line. Then, when the check valve mechanism of the flowing water detection device 1 is opened and flowing water is started from the primary side pipe 60 to the secondary side pipe 50, the pressure switch transmits a flowing water signal to the fire receiver 20. The fire receiver 20 that has received the running water signal displays on the panel that running water has occurred in the running water detection device 1.

  Reference numeral 22 denotes a pump control panel, which is connected to the pressure switch of the pump activation device 12 and the water supply pump 9 by signal lines. That is, the pressure switch of the pump activation device 12 is connected to the water supply pump 9 via the pump control panel 22. When the pressure in the primary side pipe 60 becomes a certain value or less, the pressure switch of the pump activation device 12 transmits the activation signal of the water supply pump 9 to the pump control panel 22 and receives the activation signal. 22 controls to start the water supply pump 9. The pump control panel 22 is also connected to the fire receiver 20 by a signal line. The pump control panel 22 transmits a signal indicating that the water supply pump 9 has been activated to the fire receiver 20, and the fire receiver 20 that has received the signal displays on the panel that the water supply pump 9 has been activated.

  Although not shown in detail, the primary side piping 60 on the secondary side of the mixer 5 may be provided with a plurality of water flow detection devices 1 corresponding to a plurality of protection areas, for example. And the secondary side piping 50 to which the closed type head 3 grade | etc., Is connected is provided in the secondary side of each flowing water detection apparatus 1, respectively.

  Next, the operation of the closed spray fire extinguishing system 100 during a fire will be described.

  First, when a fire occurs, an ascending airflow is generated that transfers heat from the vicinity of the combustible to the ceiling, the temperature of the closed head 3 rises, and the closed head 3 near the fire source operates. From the closed type head 3, the fire extinguishing chemical aqueous solution filled in the secondary side pipe 50 is radiated and sprayed toward the fire source. And the pressure in the secondary side piping 50 falls.

  Next, when the pressure of the secondary side pipe 50 becomes lower than the pressure of the primary side pipe 60, the check valve mechanism of the flowing water detection device 1 is opened, and the primary side pipe 60 and the secondary side pipe 50 are in communication. The aqueous fire extinguishing agent solution filled in the primary side pipe 50 flows into the secondary side pipe 50. And the pressure in the primary side piping 60 falls. At this time, the pressure switch of the flowing water detection device 1 is activated to transmit a flowing water signal to the fire receiver 20, and the fire receiver 20 displays on the board surface that flowing water has occurred in the flowing water detection device 1.

  Next, when the pressure of the primary side pipe 60 decreases, the pressure switch provided in the pump starter device 12 connected to the primary side pipe detects the pressure drop of the primary side pipe 60 and the pump starter 12 An activation signal for the feed water pump 9 is output from the pressure switch to the pump control panel 22. And the water supply pump 9 starts and supplies fire extinguishing water from the water tank 11 to the primary side piping 60.

  Finally, the fire-extinguishing water supplied from the water tank 11 flows into the mixer 5 and flows into the fire-extinguishing chemical tank 7 through the branch pipe 61. When the fire extinguishing water flows into the fire extinguishing chemical tank 7, the fire extinguishing chemical is pushed out from the fire extinguishing chemical tank 7 by the pressure of the fire extinguishing water, and the fire extinguishing chemical flows into the mixer 5. And with the mixer 5, fire extinguishing water and a fire extinguishing chemical | medical agent are mixed, and it becomes about 3% of fire extinguishing chemical | medical agent aqueous solution. The generated fire-extinguishing agent aqueous solution passes through the flowing water detection device 1 and flows into the secondary pipe 50 and is sprayed from the closed head 3 toward the fire source. Since the fire-extinguishing agent aqueous solution sprayed from the closed head 3 toward the predetermined protective area hardly foams, it adheres to the surface of the combustible material with a high penetration force and quickly forms a coating on the surface of the combustible material. Bring things into suffocation.

  Next, an operation relating to pressure adjustment in the pipe when the pressure in the secondary pipe 50 changes due to a change in temperature, especially during fire monitoring will be described.

  The closed spray fire extinguishing system 100 is often installed outdoors such as a parking lot, and the secondary pipe 50, particularly the periphery of the closed head 3, is exposed to the outside air. That is, the temperature around the secondary side pipe 50 is constantly changing, and when the temperature rises, the fire-extinguishing agent aqueous solution filled in the secondary side pipe 50 expands, and the pressure in the secondary side pipe 50 increases. On the other hand, when the temperature falls, the fire-extinguishing agent aqueous solution filled in the secondary side pipe 50 contracts, and the pressure in the secondary side pipe 50 becomes low.

  When the temperature decreases and the pressure in the secondary side pipe 50 decreases, the check valve in the flowing water detection device 1 is slightly opened, and the fire extinguishing chemical aqueous solution flows into the secondary side pipe 50 from the primary side pipe 60. The pressure of the secondary side pipe 50 is increased. When the pressure of the secondary side pipe 50 increases, the check valve of the flowing water detection device 1 is closed, and the fire extinguishing chemical aqueous solution does not flow from the primary side pipe 60. When the temperature falls, the pressure of the secondary side pipe 50 is kept constant in this way (for example, 0.7 to 1.0 MPa). And since the fire extinguishing agent aqueous solution of the primary side piping 60 flowed into the secondary side piping 50, the pressure of the primary side piping 60 falls. Then, the auxiliary pump 13 is activated, extinguishing water is supplied into the primary side pipe 60, and the pressure of the primary side pipe 60 is kept constant (for example, 0.7 to 1.0 MPa).

  Here, when the pressure of the secondary side pipe 50 is lowered, the check valve in the flowing water detection device 1 is slightly opened, and the pressure of the secondary side pipe 50 is increased until it becomes equal to the primary side pipe 60. However, the same effect can be achieved by a water flow detection device provided with an auxiliary check valve that allows the extinguishing chemical aqueous solution to flow from the primary side pipe 60 to the secondary side pipe 50 in the check valve. Specifically, in the case of a small pressure drop in the secondary side pipe 50 due to a change in temperature, the auxiliary head valve 60 supplies pressure from the primary side pipe 60 to the secondary side pipe 50 to open the closed head 3. In the case of a large pressure change due to this, the check valve in the flowing water detection device 1 is fully opened.

  On the other hand, when the temperature rises and the pressure of the secondary side pipe 50 rises, when the pressure of the secondary side pipe 50 becomes higher than the pressure of the primary side pipe 60 by a certain value or more, the secondary side pipe 50 and the primary side pipe 50 The pressure increase prevention valve 4 having a check valve mechanism connected to the valve 60 is opened. And if the pressure | voltage rise prevention valve 4 opens, the fire-extinguishing agent aqueous solution in the secondary side piping 50 will flow in in the primary side piping 60, and the pressure of the secondary side piping 50 will be released to the primary side piping 60. FIG. When the pressure difference between the secondary side pipe 50 and the primary side pipe 60 becomes less than a certain value, the pressure increase prevention valve 4 is closed, and the fire-extinguishing chemical aqueous solution does not flow from the secondary side pipe 50 to the primary side pipe 60.

  Further, when the temperature rises rapidly, the fire-extinguishing agent aqueous solution in the secondary side pipe 50 rapidly expands, and a large amount of the fire-extinguishing agent aqueous solution flows from the secondary side pipe 50 to the primary side pipe 60 rapidly. The pressure in the pipe 60 may increase suddenly (above a certain value). In this case, the fire extinguishing chemical aqueous solution in the primary side pipe 60 is drained from the drain valve 15 provided in the closed spray fire extinguishing system 100, and the pressure in the primary side pipe 60 is kept constant.

  In the closed spray fire extinguishing system 100 according to the first embodiment, as described above, the pressures of the primary side pipe 60 and the secondary side pipe 50 can be kept constant even when the temperature rises and falls repeatedly. . At the same time, when the pressure in the secondary side pipe 50 increases, the fire extinguishing chemical aqueous solution is not drained from the flowing water detection device 1 but is returned to the primary side pipe 60 once. The amount of fire-extinguishing agent aqueous solution to be drained is small. That is, the amount of fire-extinguishing agent drained is reduced, and the facility can be maintained for a long time. Moreover, since the pressure of the primary side piping 60 becomes extremely low at the time of fire monitoring, thereby reducing the number of times the water supply pump 9 is started, power consumption can be suppressed.

  Further, since the drainage is performed by the single drainage valve 15 in the closed spray fire extinguishing system 100 with respect to the pressure increase in the primary side pipe 60, the amount of drainage can be understood and managed easily. Furthermore, since there is only one drain valve 15 compared with the case where a plurality of water flow detectors provided in the conventional closed spray fire extinguishing system 100 are provided, the possibility of biting of dust can be reduced. In addition, since periodic inspections are only required at one location, maintenance and management of the closed spray fire extinguishing system 100 is facilitated. In addition, by installing a sensor that detects running water on the secondary side of the drain valve 15, it is possible to monitor the leak of the drain valve 15 at any time. Can be prevented.

  Note that the open-type head 19 can be connected to the secondary pipe 50 via a heat-sensitive open joint 17 that opens the valve body by heat. In this case, a heat-sensitive open joint 17 is provided near the ceiling, and an open-type head 19 is provided at the tip of a falling pipe extending downward therefrom. For example, by providing the heat-sensitive open joint 19 at a height of 5 m or more on the floor and providing the open head 19 within 4 m from the floor below it, the closed type according to the first embodiment is also applied to a high ceiling building. A spray fire extinguishing system 100 can be introduced.

Embodiment 2. FIG.
FIG. 2 is a drawing in the vicinity of the flowing water detection device 1 according to Embodiment 2 of the present invention. In the second embodiment, differences from the first embodiment will be described in detail, and members corresponding to the first embodiment are denoted by the same reference numerals and description thereof is omitted. Furthermore, the overall configuration of the closed spray fire extinguishing system 100, the explanation of the operation at the time of fire, and the explanation of the operation at the time of fire monitoring are the same as those in the first embodiment, and will be omitted.

  Reference numeral 6 denotes a normally open maintenance valve, which is provided on the primary side (inlet side) and secondary side (outlet side) of the pressure increase prevention valve 4 one by one. More specifically, the maintenance valve 6 is connected between the primary side and the secondary side pipe 50 of the boost prevention valve 4, and another one is provided between the secondary side of the boost prevention valve 4 and the primary side pipe 60. A maintenance valve 6 is connected. The maintenance valve 6 closes the valve when the pressure rise prevention valve 4 has some trouble and the pressure rise prevention valve 4 has to be replaced.

  According to the configuration of the second embodiment, when the pressure increase prevention valve 4 is replaced, the two maintenance valves 6 are closed, so that the fire-extinguishing water and the fire-extinguishing chemical aqueous solution in the secondary side pipe 50 and the primary side pipe 60 can be obtained. The pressure increase prevention valve 4 can be replaced without leaking. The closed spray fire extinguishing system 100 according to the second embodiment can continue to monitor the fire while the pressure increase prevention valve 4 is replaced.

Embodiment 3 FIG.
FIG. 3 is a schematic diagram of the flowing water detection device 2 according to Embodiment 3 of the present invention. In the third embodiment, differences from the first embodiment will be described in detail, and members corresponding to the first embodiment are denoted by the same reference numerals and description thereof is omitted. Furthermore, the overall configuration of the closed spray fire extinguishing system 100, the explanation of the operation at the time of fire, and the explanation of the operation at the time of fire monitoring are the same as those in the first embodiment, and will be omitted.

  The flowing water detection device 2 according to the third embodiment is configured so that the fire extinguishing agent aqueous solution flows from the primary side pipe 60 to the secondary side pipe 50 when the pressure of the primary side pipe 60 is higher than the pressure of the secondary side pipe 50. When the pressure of the secondary side pipe 50 becomes higher than the pressure of the primary side pipe 60 by a certain value or more, together with the check valve mechanism that opens at the same time, the fire extinguishing agent aqueous solution flows from the secondary side pipe 50 to the primary side pipe 60. A check valve mechanism that opens as described above is provided. That is, the flowing water detection device 2 has two inlets that allow the primary side pipe 60 and the secondary side pipe 50 to communicate with each other, and a check valve mechanism is provided at each of the inlets.

  The first inlet 30 has a check valve mechanism that opens the primary side pipe 60 and the secondary side pipe 50 so as to communicate with each other when the pressure of the primary side pipe 50 becomes higher than the pressure of the secondary side pipe 50. It is formed by valve.

  The second inlet 32 is a check valve that causes the secondary side pipe 50 and the primary side pipe 60 to communicate with each other when the pressure of the secondary side pipe 50 becomes higher than the pressure of the primary side pipe 60 by a certain value or more. It is formed by opening the mechanism.

  According to the configuration of the third embodiment, by providing the water flow detection device 2 in the closed spray fire extinguishing system 100, the check valve mechanism provided in the first inlet 30 and the second inlet 32 can provide the secondary The pressure in the side pipe 50 and the primary side pipe 60 can be kept constant.

  1, 2 Flow detection device, 3 Closed head, 4 Booster prevention valve, 5 Mixer, 6 Maintenance valve, 7 Fire extinguishing chemical tank, 9 Water supply pump, 11 Water tank, 12 Pump activation device, 13 Auxiliary pump, 15 Drainage Valve, 20 Fire receiver, 22 Pump control panel, 30 First inlet, 32 Second inlet, 50 Secondary pipe, 60 Primary pipe, 61, 63, 65 Branch pipe, 100 Closed spray fire extinguishing system.

Claims (3)

A check valve in which an aqueous fire extinguishing agent solution flows from the primary side pipe to the secondary side pipe when the pressurized and charged primary side pipe and the secondary side pipe are connected and the pressure in the secondary side pipe decreases. Equipped with a running water detection device having a mechanism,
A water tank for supplying fire-extinguishing water, a fire-extinguishing chemical tank for supplying a fire-extinguishing chemical, and a mixer for mixing a fire-extinguishing water and a fire-extinguishing chemical to produce a fire-extinguishing chemical aqueous solution are connected to the primary pipe.
In the fire extinguishing system in which a closed head for spraying a fire extinguishing chemical aqueous solution is connected to the secondary side pipe,
The primary side pipe is activated when the pressure of the primary side pipe drops below a certain value, and includes a water supply pump and an auxiliary pump for supplying fire water from the water tank,
The pressure of the primary side pipe when the auxiliary pump is activated is set higher than the pressure of the primary side pipe when the feed water pump is activated,
When the pressure in the secondary side pipe is higher than the pressure in the primary side pipe by a certain value or more between the primary side pipe and the secondary side pipe, the pressure in the secondary side pipe is changed to the primary side pipe. A pressure increase prevention valve having a check valve mechanism that escapes to the side pipe is connected,
Provided on the primary side of the mixer and provided with a drain valve only on the pipe branched from the branch pipe to which the auxiliary pump is connected at the tip, the primary side when the pressure in the primary side pipe exceeds a certain value Fire extinguishing system, characterized in that a drain valve is provided for draining from the side pipe.   The primary side and the secondary side of the boost prevention valve have maintenance valves, respectively, and the primary side of the boost prevention valve is connected to the secondary pipe via the maintenance valve, and the boost prevention valve The fire extinguishing system according to claim 1, wherein the secondary side is connected to the primary side pipe via the maintenance valve.   The fire extinguishing system according to claim 1 or 2, wherein a sensor for detecting flowing water is provided on the secondary side of the drain valve to monitor leakage of the drain valve.