Negative pressure wet pre-action sprinkler system

Abstract

To elongate a time for retaining a negative pressure sufficient for preventing water leakage in a secondary side pipe when a pipe or a sprinkler head is damaged in monitoring.SOLUTION: A buffer tank 2, the negative-pressure air capacity booster, is connected to an upper side of a part close to a connecting part 108A toward a rising branch pipe 104A of a secondary side pipe 104 in a suction pipe 108. The buffer tank 2 is configured to have a larger volume than a negative-pressure air volume of a part extending from a connecting part in the suction pipe 108 to an automatic valve 112 with an orifice.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a negative pressure wet pre-action sprinkler system in which water is filled in a secondary piping and a negative pressure state is maintained except when a fire occurs. [Background technology]

[0002] Conventional fire extinguishing equipment includes a negative pressure wet pre-activation sprinkler system, which has the function of preventing water leakage in the event of an abnormality such as pipe breakage or sprinkler head breakage and of quickly discharging water in the event of a fire. The secondary piping is filled with water and kept under negative pressure except when a fire occurs.

[0003] Fig. 10 is a schematic diagram of such a negative pressure wet pre-action sprinkler system, in which 100 is a negative pressure wet pre-action sprinkler system.

[0004] Reference numeral 101 denotes a primary side pipe that rises from a fire extinguishing water tank 102 via a water supply pump 103. Reference numeral 104 denotes a secondary side pipe that is connected to the primary side pipe 101 and that is piped to a sprinkler head 105. The sprinkler head 105 is of a closed type that opens due to the heat of a fire.

[0005] Reference numeral 106 denotes a pre-activation type water flow detection device that is installed between the primary pipe 101 and the secondary pipe 104 and is kept closed except when a fire occurs. Reference numeral 107 denotes a fire detector that is installed on the ceiling and detects a fire and sends out a fire signal.

[0006] Reference numeral 108 denotes a suction pipe having one end 108A connected to the rising branch pipe 104A of the secondary side piping 104, and the other end 108B connected to an intake pipe 110 that rises from a vacuum pump 109 and is piped, and a drain pipe 111 whose lower end hangs down to the fire extinguishing water tank 102.

[0007] Reference numeral 112 denotes an automatic valve with an orifice that is installed midway through the suction pipe 108 and allows a small amount of flow during normal monitoring of the negative pressure state in the secondary piping 104 and a large amount of flow during abnormalities such as piping breakage or sprinkler head breakage, and closes when discharging water.

[0008] Reference numeral 113 denotes a vacuum switch that detects the pressure inside the secondary piping 104 and is installed at a position on the secondary piping 104 side of the automatic valve with orifice 112 in the middle of the suction pipe 108 .

[0009] Reference numeral 114 denotes a signal receiving panel which receives a fire signal from the fire detector 107 in the event of a fire and transmits the signal to a control panel which will be described later.

[0010] Reference numeral 115 receives a signal from the signal receiving panel 114, and opens the pre-action type water flow detection device 106 to communicate with the primary side pipe 101 and the secondary side pipe 104. Reference numeral 116 in the figure also denotes an air-water separator installed at the connection portion of the intake pipe 110 to the suction pipe 108, and reference numeral 117 denotes a check valve installed at the connection portion of the suction pipe 108 between the intake pipe 110 and the drain pipe 111.

[0011] When a fire is not occurring, both the primary side piping 101 and the secondary side piping 104 are filled with water, and the inside of the secondary side piping 104 is made to be in a negative pressure state by the vacuum pump 109 via the suction pipe 108 and the intake pipe 110.

[0012] When a fire occurs, the fire detector 107 detects the fire and sends a fire signal to the signal receiving panel 114, which then sends the signal to the control panel 115. The control panel 115 receives the signal and opens the pre-action water flow detection device 106. It then detects a pressure change in the piping and starts the water pump 103. This allows water to be continuously discharged from the sprinkler head 105, which is open due to the heat of the fire. At this time, the automatic valve with orifice 112 allows a small amount of water to flow through the orifice, and the operation of the vacuum pump 109 is stopped. As described above, the secondary piping 104 is always filled with water, so water can be discharged quickly when a fire occurs.

[0013] Also, when an abnormality such as pipe breakage or sprinkler head breakage occurs during monitoring other than when a fire has broken, no water leakage will occur because the pressure inside the secondary pipe 104 is negative, but the pressure will gradually rise. When the pressure rises and reaches a predetermined pressure, this is detected by the vacuum switch 113 installed in the middle of the suction pipe 108, and the automatic valve 112 with orifice is energized to open its valve body, allowing a large amount of water to flow, and the vacuum pump 109 also starts operating, so that a large amount of water can be continuously sucked in, preventing water leakage.

[0014] The configuration and operation of a conventional negative pressure wet pre-action sprinkler system are as described above. In the conventional system, the operation when an abnormality such as pipe breakage or sprinkler head breakage occurs during monitoring is as described above. However, in the operation when such an abnormality occurs, there is a slight time lag between the operation of the vacuum switch 113 and the start of operation of the vacuum pump 109 to perform sufficient continuous suction. This time lag makes it impossible to maintain the negative pressure in the secondary pipe 104, and there is a risk of water leaking, albeit slightly, from the damaged area.

[0015] That is, air is sucked in from the damaged area and flows back through the piping, and the water pushed out flows into the suction pipe 108 from the secondary piping 104. When the suction pipe 108 is filled with water due to the inflowing water, the negative pressure air in the suction pipe 108 decreases, and it becomes impossible to maintain a negative pressure sufficient to prevent water leakage in the secondary piping 104. This causes a problem of water leaking, albeit slightly, from the damaged area. Since the piping volume (negative pressure air volume) of the suction pipe 108 is limited, if the damaged area is large, such as when the sprinkler head is severely damaged, the suction pipe 108 will be filled with water within 2 to 3 seconds, and the damaged area will become atmospheric pressure, which may cause water leakage. Summary of the Invention [Problem to be solved by the invention]

[0016] The present invention has been made in consideration of the above points, Buffer tanks, bypass pipes, enlarged pipe diameter, etc. By increasing the negative pressure air volume in the suction pipe, it is possible to hold more negative pressure air in the suction pipe, and when an abnormality such as damage to the pipe or damage to the sprinkler head occurs during monitoring, particularly when the damaged part is large and the pressure in the secondary piping rises rapidly, it is possible to extend the time for which negative pressure sufficient to prevent water leakage in the secondary piping is maintained, thereby providing a negative pressure wet pre-activation sprinkler system that can efficiently prevent water leakage from the damaged part. [Means for solving the problem]

[0017] The gist of the present invention is as follows: A pre-activation water flow detection device; A secondary side pipe provided on the secondary side of the pre-activation type water flow detection device and connected to a sprinkler head; One end of the secondary piping is connected to a rising branch pipe of the secondary piping, others The suction pipe is connected to a vacuum pump at one end and has a vacuum switch and an automatic valve with an orifice at the middle part from the secondary piping side. In a negative pressure wet pre-action sprinkler system, the water filled in the secondary piping is normally maintained in a negative pressure state by sucking the inside of the secondary piping with the vacuum pump, A buffer tank connected to an upper portion of a portion between a connection portion of the suction pipe to the rising branch pipe of the secondary side piping and other devices including at least a vacuum switch and an automatic valve with an orifice arranged in the middle of the suction pipe. The negative pressure wet pre-start sprinkler system is characterized in that the negative pressure air volume in the suction pipe is increased by is located.

[0018] In the above configuration, a negative pressure wet pre-action sprinkler system having an orifice for adjusting the flow rate of water flowing into the buffer tank, the orifice being provided on the buffer tank side of a connection portion between the buffer tank and the suction pipe; The above is also within the scope of the present invention.

[0019] Also, A pre-activation water flow detection device; A secondary side pipe provided on the secondary side of the pre-activation type water flow detection device and connected to a sprinkler head; One end of the suction pipe is connected to the rising branch pipe of the secondary piping, the other end of the suction pipe is connected to a vacuum pump, and a vacuum switch and an automatic valve with an orifice are disposed in the middle of the suction pipe from the secondary piping side. In a negative pressure wet pre-action sprinkler system, the water filled in the secondary piping is normally maintained in a negative pressure state by sucking the inside of the secondary piping with the vacuum pump, A negative pressure wet pre-action sprinkler system characterized in that a negative pressure air volume in the suction pipe is increased by a bypass pipe provided in a portion between a connection portion of the suction pipe to a rising branch pipe of the secondary side piping and other devices including at least a vacuum switch and an automatic valve with an orifice disposed in the middle of the suction pipe. The above is also within the scope of the present invention.

[0020] Also, A pre-activation water flow detection device; A secondary side pipe provided on the secondary side of the pre-activation type water flow detection device and connected to a sprinkler head; One end of the suction pipe is connected to the rising branch pipe of the secondary piping, the other end of the suction pipe is connected to a vacuum pump, and a vacuum switch and an automatic valve with an orifice are disposed in the middle of the suction pipe from the secondary piping side. In a negative pressure wet pre-action sprinkler system, the water filled in the secondary piping is normally maintained in a negative pressure state by sucking the inside of the secondary piping with the vacuum pump, A negative pressure wet pre-action sprinkler system characterized in that a pipe diameter of a portion of the suction pipe between a connecting portion of the suction pipe to a rising branch pipe of the secondary side piping and other devices including at least a vacuum switch and an automatic valve with an orifice disposed in the middle of the suction pipe is made larger than that of other portions, thereby increasing the negative pressure air volume of the suction pipe portion. The above is also within the scope of the present invention. Effect of the Invention

[0021] The present invention has the above-mentioned configuration, Buffer tanks, bypass pipes, enlarged pipe diameter, etc.This increases the negative pressure air volume in the suction pipe. Therefore, it becomes possible to hold more negative pressure air in the suction pipe, and when an abnormality such as a broken pipe or a broken sprinkler head occurs during monitoring, it becomes possible to extend the time for which a negative pressure sufficient to prevent water leakage in the secondary pipe is maintained, particularly when the broken part is large and the pressure in the secondary pipe rises rapidly. In other words, it becomes possible to efficiently prevent water leakage from the broken part during the time from when the vacuum switch is activated immediately after the breakage of the pipe or sprinkler head until the vacuum pump starts operating and sufficient continuous suction is performed. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a schematic explanatory diagram of a negative pressure wet pre-activation sprinkler system according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a front view of the buffer tank in the first embodiment. [Diagram 3] FIG. 2 is an explanatory diagram of the operation of the first embodiment, showing a state during monitoring. [Figure 4] FIG. 2 is an explanatory diagram of the operation of the first embodiment, showing the state immediately after the sprinkler head is broken. [Diagram 5] FIG. 4 is an explanatory diagram of the operation of the first embodiment, showing the state immediately after the vacuum switch is activated. [Figure 6] FIG. 4 is an explanatory diagram of the operation of the first embodiment, showing a state in which water has started to enter the buffer tank. [Figure 7] FIG. 5 is a schematic explanatory diagram of a negative pressure wet pre-action sprinkler system according to a second embodiment of the present invention. [Figure 8] FIG. 11 is an explanatory diagram of a main part of a negative pressure wet pre-activation sprinkler system according to a third embodiment of the present invention. [Figure 9] 1 is a graph showing pressure changes when a sprinkler head is severely damaged. [Figure 10] FIG. 1 is a schematic diagram of a conventional negative pressure wet pre-action sprinkler system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0024] First, a first embodiment of the present invention shown in FIGS. 1 to 6 will be described.

[0025] The basic configuration is the same as that of the conventional negative pressure wet pre-action sprinkler system shown in Fig. 10. Therefore, the same members will be described with the same reference numerals.

[0026] In the drawings, 1 denotes a negative pressure wet pre-action sprinkler system according to the first embodiment of the present invention. The negative pressure wet pre-action sprinkler system 1 includes a primary side pipe 101 that rises from a fire extinguishing water tank 102 via a water supply pump 103, a secondary side pipe 104 that is connected to the primary side pipe 101 and is piped to a sprinkler head 105, a pre-action water flow detection device 106 that is installed between the primary side pipe 101 and the secondary side pipe 104 and is kept closed except when a fire occurs, a fire detector 107 that is installed on the ceiling and detects a fire and sends a fire signal, a suction pipe 108 that has one end 108A connected to a rising branch pipe 104A of the secondary side pipe 104 and has the other end 108B connected to an intake pipe 110 that rises from a vacuum pump 109 and a drain pipe 111 whose lower end hangs down to the fire extinguishing water tank 102, and a discharge pipe 111 that is connected to the discharge pipe 111 of the suction pipe 108. The system comprises an automatic valve 112 with an orifice installed in the middle of the suction pipe 108, which allows a small amount of flow during normal monitoring of the negative pressure state in the secondary piping 104 and a large amount of flow during abnormalities such as pipe breakage or sprinkler head breakage, and which closes when water is discharged; a vacuum switch 113 which detects the pressure in the secondary piping 104 and is installed in the middle of the suction pipe 108 on the secondary piping 104 side of the automatic valve 112 with an orifice; a signal receiving panel 114 which receives a fire signal from the fire detector 107 in the event of a fire and transmits the signal to a control panel described later; and a control panel 115 which receives a signal from the signal receiving panel 114, opens the pre-action water flow detection device 106 to connect the primary piping 101 and secondary piping 104, and operates the water supply pump 103. In addition, in the figure, reference numeral 116 denotes an air-water separator installed at the connection portion of the intake pipe 110 to the suction pipe 108, and reference numeral 117 denotes a check valve installed at the connection portion of the suction pipe 108 between the intake pipe 110 and the drain pipe 111.

[0027] Under normal circumstances other than when a fire occurs, both the primary side piping 101 and the secondary side piping 104 are filled with water, and the inside of the secondary side piping 104 is made to be in a negative pressure state by the vacuum pump 109 via the suction pipe 108 and the intake pipe 110.

[0028] In addition, the operation of this embodiment when a fire occurs and when an abnormality such as pipe breakage or sprinkler head breakage occurs during monitoring is the same as that of the conventional negative pressure wet pre-activation sprinkler system described above, so a description thereof will be omitted.

[0029] And so, Embodiment The features of , suck A connection portion 108A of the upright branch pipe 104A of the secondary side pipe 104 in the upright pipe 108 and other devices including at least a vacuum switch 113 and an automatic valve 112 with an orifice disposed in the middle of the suction tube 108. Part Connected to Buffer Tank 2 By The negative pressure air volume in the suction tube 108 is increased. 。

[0030] Next, the operation of the above embodiment will be described. Fig. 3 shows the state during monitoring, where a negative pressure (-0.04MPa in the figure) is maintained near the sprinkler head 105 of the secondary side piping 104 by a negative pressure (0.08MPa in the figure) created by a vacuum pump 109 via a suction pipe 108. The reason why the negative pressure value near the sprinkler head 105 of the secondary side piping 104 is lower than that of the suction pipe 108 is due to the positional head caused by the difference in height (4m in the figure) between the suction pipe 108 and the sprinkler head mounting part (highest part of the water filling) of the secondary side piping 104. In addition, P in the figure indicates the gas-liquid branch point.

[0031] When the pressure (negative pressure) in the secondary piping 104 drops to a predetermined value, the vacuum pump 109 stops, but the negative pressure in the secondary piping 104 is maintained. The inside of the buffer tank 2 connected to the upper part of the suction pipe 108 is also maintained at negative pressure. The reason for connecting the buffer tank 2 to the upper part of the suction pipe 108 is to prevent water that has flowed into the suction pipe 108 from entering the buffer tank 2, and to keep only negative pressure air inside.

[0032] FIG. 4 shows the state immediately after the sprinkler head is damaged, and because there is negative pressure inside the secondary piping 104, air A starts to flow into the secondary piping 104 from the damaged part of the sprinkler head 105. As a result, the pressure in the damaged part of the sprinkler head 105 rises to -0.02 MPa in the figure. Similarly, the pressure inside the suction pipe 108 also rises to -0.06 MPa in the figure. Then, the inflow of air A causes the water in the secondary piping 104 to Press The water is pushed into the suction pipe 108 and starts to seep into the inside of the suction pipe 108. In FIG.

[0033] 5 shows the state immediately after the vacuum switch is activated, and the inside of the suction pipe 108 is filled with negative pressure air during normal monitoring, but as described above, air A flows into the secondary piping 104 due to the damage to the sprinkler head 105, and the water in the secondary piping 104 flows into the suction pipe 108, and even when the water further fills the entire inside of the suction pipe 108 after the vacuum switch 113 is activated, the negative pressure (-0.06 MPa) is still maintained inside the suction pipe 108 because negative pressure air exists in the buffer tank 2. As a result, the negative pressure in the damaged part of the sprinkler head 105 is also maintained at the same negative pressure (-0.02 MPa), preventing water leakage.

[0034] FIG. 6 shows the state in which water has begun to seep into the buffer tank 2. The buffer tank 2 is normally filled with air at negative pressure (-0.08 MPa), but when the suction pipe 108 becomes full of water, water also begins to seep into the buffer tank 2.

[0035] As shown in FIG. 5, when water penetrates into the suction pipe 108 and the pressure in the suction pipe 108 reaches a predetermined value (-0.04 MPa in the figure), the vacuum switch 113 is activated. Then, the automatic valve 112 with an orifice is energized and the vacuum pump 109 starts to operate. When the vacuum pump 109 starts to operate in this manner, sufficient negative pressure can be maintained in the suction pipe 108 and the secondary side piping 104 due to sufficient continuous suction, and water leakage from the damaged part of the sprinkler head 105 is prevented. However, there is a time lag between the activation of the vacuum switch 113 and the start of continuous suction by the vacuum pump 109, and during this time, if the negative pressure air in the suction pipe 108 cannot be maintained until the negative pressure in the damaged part of the sprinkler head 105 becomes the same as the atmospheric pressure (0.00 MPa), water leakage cannot be prevented. It is expected that it will take a maximum of 2 to 3 seconds from the damage of the sprinkler head 105 to the maintenance of the pressure drop by restarting the vacuum pump, depending on the piping condition and the damage situation.

[0036] Therefore, by connecting a buffer tank 2 having a predetermined negative pressure air volume, the suction pipe 108 can be made to have a negative pressure air volume that can maintain a negative pressure for this period, and water leakage can be prevented. Therefore, as shown in Figure 6, even if the amount of water that has entered the buffer tank 2 gradually increases and approaches full capacity, the negative pressure in the suction pipe 108 is maintained by the negative pressure air remaining inside.

[0037] In the above embodiment, although not shown, an orifice for adjusting the flow rate of water flowing into the buffer tank 2 may be provided on the buffer tank 2 side of the connection between the buffer tank 2 and the suction pipe 108.

[0038] In this case, it becomes possible to adjust the rate at which the negative pressure air present in the buffer tank 2 decreases due to the inflow of water, thereby further improving efficiency.

[0039] Next, a second embodiment of the present invention shown in FIG. 7 will be described. The basic configuration is the same as that of the above embodiment. In this embodiment, the suction pipe 108 is connected to the rising branch pipe 104A of the secondary side pipe 104 at the connecting portion 108A. The suction pipe 108 is connected to another device including at least a vacuum switch 113 and an automatic valve 112 with an orifice, and a bypass pipe 3 is provided between the suction pipe 108 and the other device. The negative pressure air volume in the portion of the draw tube 108 is increased.

[0040] In other words, when air flows into the secondary piping 104 due to damage to the sprinkler head 105, the water in the secondary piping 104 flows into the suction pipe 108, and when this water fills the entire inside of the suction pipe 108, it also flows into the bypass pipe 3. However, since the bypass pipe 3 has a negative pressure air volume similar to that of the buffer tank 2 in the above embodiment, it acts in the same way as the buffer tank 2 and can prevent water leakage from the damaged part of the sprinkler head 105.

[0041] Next, a third embodiment of the present invention shown in FIG. 8 will be described.

[0042] The basic configuration is the same as that of the above embodiment. In this embodiment, the suction pipe 108 is connected to the rising branch pipe 104A of the secondary side pipe 104 at the connecting portion 108A. between the suction tube 108 and other devices including at least a vacuum switch 113 and an automatic valve 112 with an orifice disposed in the middle of the suction tube 108. The pipe diameter of the portion 108' is made larger than that of the other portions. By doing so , the negative pressure air volume in the suction tube 108 portion is increased.

[0043] That is, when air flows into the secondary piping 104 due to damage to the sprinkler head 105, the pushed water flows from the secondary piping 104 into the suction pipe 108. The water flows along the bottom of the portion 108' of the suction pipe 108 whose pipe diameter is enlarged. When the water fills the inside of the suction pipe 108 from the portion 108' whose pipe diameter is enlarged, the water volume in the portion 108' whose pipe diameter is enlarged begins to increase. Since the portion 108' of the suction pipe 108 whose pipe diameter is enlarged has a negative air volume similar to that of the buffer tank 2 in the above embodiment, it acts in the same way as the buffer tank 2 and can prevent water leakage from the damaged portion of the sprinkler head 105.

[0044] Next, a graph showing an example of a pressure change when the sprinkler head shown in FIG. 9 is broken will be described.

[0045] Incidentally, FIG. 9 shows the case where the vacuum pump is not connected, and since the negative pressure is not improved even when the vacuum switch is operated, the line of the graph continues to rise.

[0046] In addition, in the figure, the thin solid line and dashed line show an example of pressure change in the conventional example (without a buffer tank), the thin dotted line and double dotted line show an example of pressure change when the pipe diameter near the connection point of the suction pipe to the rising branch pipe of the secondary side piping is expanded (from 40A to 80A), and the thick solid line and dashed line show an example of pressure change when a buffer tank is connected to the suction pipe.

[0047] Additionally, "0" on the horizontal time axis indicates the point at which the sprinkler head was severely damaged. The vertical axis is the pressure axis, with the top indicating positive pressure and the bottom indicating negative pressure, with -0.08MPa being the value inside the suction pipe by the vacuum pump (the pressure value at which water will not leak even if damaged). Additionally, -0.04MPa is the value at the sprinkler head (the pressure value at which water will not leak even if damaged). Additionally, 0.00MPa is the pressure value at which water will start to leak when damaged.

[0048] The pressure in the sprinkler head is higher than the value in the suction pipe because, in this example, the sprinkler head is installed 4 m below the connection point of the suction pipe to the rising branch pipe of the secondary piping, and the positional head makes it 0.04 MPa higher than the pressure in the suction pipe.

[0049] In addition, the head pressure refers to the pressure in the sprinkler head (inside the head mounting part of the secondary piping), and the vacuum switch pressure refers to the pressure in the suction pipe.

[0050] As mentioned above, when the sprinkler head is damaged, the pressure in the secondary piping begins to rise due to being pushed by atmospheric pressure. Eventually, when the pressure in the sprinkler head reaches 0.00 MPa, water starts to leak, but this is the case when the pressure in the suction pipe 108 exceeds -0.04 MPa before that, the vacuum switch operates, the automatic valve with orifice opens, and the vacuum pump starts to operate. This allows sufficient continuous suction, and the inside of the piping is restored to a sufficient negative pressure.

[0051] However, there is a slight time lag between when the vacuum switch is activated and when the vacuum pump starts operating to achieve sufficient continuous suction. Therefore, if the pressure inside the sprinkler head connection part of the secondary piping can be prevented from reaching 0.00 MPa during this time lag, leakage can be completely prevented.

[0052] In the graph of Figure 9, which shows a case where the damage to the sprinkler head is large, in the conventional example, it takes 0.1 seconds for the pressure in the sprinkler head to reach 0.00MPa after the vacuum switch is activated (-0.04MPa). Even if the vacuum switch is activated, the limit at which water leakage begins is reached 0.1 seconds later, i.e., 0.6 seconds after the damage. This shows that if the damage is large as in this example, water may leak before sufficient negative pressure is reached in the piping. Even if the vacuum switch is activated, there is a delay due to the dynamic inertia of the vacuum pump, so it takes a short amount of time before sufficient negative pressure is reached. Therefore, it is desirable to devise a way to extend the aforementioned 0.6 seconds as long as possible.

[0053] In the case of FIG. 9, by installing the negative pressure air capacity increase device, it is shown that the time can be extended to about 3.6 seconds, and since the vacuum pump operates before the suction pipe 108 becomes full of water and sufficient negative pressure can be secured, there is no risk of water leakage even if the sprinkler head is broken. Also, when the diameter of the suction pipe is enlarged, it takes about 2.5 seconds from the breakage of the sprinkler head until the broken part reaches atmospheric pressure (0.00 MPa), and it can be seen that the time can be extended. From these, it can be seen that according to the present invention, the time that the inside of the pipe maintains negative pressure is extended, and water leakage can be effectively prevented. In addition, in the graph of FIG. 9, "40A → 80A" means that 40A = inner diameter about 40 mm, 80A = inner diameter about 80 mm, and the pipe volume is four times as large when the length is the same. [Explanation of symbols]

[0054] 1. Negative pressure wet pre-action sprinkler system 2 Buffer Tank 3. Bypass pipe 100 Negative pressure wet pre-action sprinkler system 101 Primary side piping 102 Fire Water Tank 103 Water Pump 104 Secondary piping 104A Secondary piping rise branch pipe 105 Sprinkler Head 106 Pre-activation water flow detection device 107 Fire detector 108 Suction tube 108' Enlarged diameter part of suction tube 109 Vacuum Pump 110 Intake pipe 111 Drain pipe 112 Automatic valve with orifice 113 Vacuum Switch 114 Signal receiving board 115 Control Panel 116 Steam water separator 117 Check valve

Claims

1. A pre-activation water flow detection device; A secondary side pipe provided on the secondary side of the pre-activation type water flow detection device and connected to a sprinkler head; One end of the suction pipe is connected to the rising branch pipe of the secondary piping, the other end of the suction pipe is connected to a vacuum pump, and a vacuum switch and an automatic valve with an orifice are disposed in the middle of the suction pipe from the secondary piping side. In a negative pressure wet pre-action sprinkler system, the water filled in the secondary piping is normally maintained in a negative pressure state by sucking the inside of the secondary piping with the vacuum pump, A negative pressure wet pre-action sprinkler system characterized in that the negative pressure air volume of the suction pipe is increased by a buffer tank connected to the upper part of the portion between the connection portion of the suction pipe to the rising branch pipe of the secondary side piping and other equipment including at least a vacuum switch and an automatic valve with an orifice arranged in the middle of the suction pipe.

2. A negative pressure wet pre-activation sprinkler system as described in claim 1, wherein an orifice for adjusting the flow rate of water flowing into the buffer tank is provided on the buffer tank side of the connection between the buffer tank and the suction pipe.

3. A pre-activation water flow detection device; A secondary side pipe provided on the secondary side of the pre-activation type water flow detection device and connected to a sprinkler head; One end of the suction pipe is connected to the rising branch pipe of the secondary piping, the other end of the suction pipe is connected to a vacuum pump, and a vacuum switch and an automatic valve with an orifice are disposed in the middle of the suction pipe from the secondary piping side. In a negative pressure wet pre-action sprinkler system, the water filled in the secondary piping is normally maintained in a negative pressure state by sucking the inside of the secondary piping with the vacuum pump, 1. A negative pressure wet pre-action sprinkler system comprising: a bypass pipe provided between a connection portion of the suction pipe to a rising branch pipe of the secondary piping and other equipment including at least a vacuum switch and an automatic valve with an orifice disposed midway along the suction pipe, thereby increasing the negative pressure air volume of the suction pipe.

4. A pre-activation water flow detection device; A secondary side pipe provided on the secondary side of the pre-activation type water flow detection device and connected to a sprinkler head; One end of the suction pipe is connected to the rising branch pipe of the secondary piping, the other end of the suction pipe is connected to a vacuum pump, and a vacuum switch and an automatic valve with an orifice are disposed in the middle of the suction pipe from the secondary piping side. In a negative pressure wet pre-action sprinkler system, the water filled in the secondary piping is normally maintained in a negative pressure state by sucking the inside of the secondary piping with the vacuum pump, A negative pressure wet pre-action sprinkler system characterized in that the pipe diameter of the portion of the suction pipe between the connection portion of the suction pipe to the rising branch pipe of the secondary side piping and other equipment including at least a vacuum switch and an automatic valve with an orifice arranged in the middle of the suction pipe is made larger than that of other portions, thereby increasing the negative pressure air volume of the portion of the suction pipe.

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