JP7792144B2 - Vacuum Sprinkler System - Google Patents

Description

The present invention relates to a vacuum sprinkler system, and more particularly to a vacuum sprinkler system that initiates fire extinguishing water discharge based on two signals: a fire detection signal from a fire detector and a pressure change signal from a pressure sensor in the secondary piping.

There are various types of sprinkler systems, including wet and dry sprinkler systems, depending on whether the secondary piping is normally filled with water, and vacuum and pressure sprinkler systems, depending on whether the secondary piping is normally under negative or pressurized pressure. Among these, vacuum wet sprinkler systems (see Patent Document 1) and vacuum dry sprinkler systems (see Patent Document 2) have attracted attention because they solve the problem of water damage caused by sprinkler head malfunctions.

In vacuum wet sprinkler systems and vacuum dry sprinkler systems (collectively referred to as vacuum sprinkler systems), when a fire breaks out, a fire detector detects the fire and sends a fire detection signal to the control unit. The control unit then stops the operation of the negative pressure device in the secondary piping and allows the pressure in the secondary piping to increase. The sprinkler head then melts due to heat, causing the pressure in the secondary piping to increase. The pressure sensor (switch) sends a pressure change signal to the control unit when the pressure in the secondary piping reaches a predetermined pressure. The control unit is configured to begin spraying water to extinguish the fire, for example by operating a water pump, upon receiving both the fire detection signal and the pressure change signal.

A system that uses two signals, a fire detection signal and a pressure change signal, is called a double-action system. It is possible to initiate fire-extinguishing water discharge based solely on the fire detection signal from the fire detector, but fire detectors often malfunction, making it risky to use fire-extinguishing water discharge based solely on the fire detector. It is also possible to initiate fire-extinguishing water discharge based solely on the pressure change signal in the secondary piping, but in this case, it is impossible to distinguish between a sprinkler head malfunction and an actual fire.

Until now, the pressure value at which the pressure sensor (switch) emits a pressure change signal was determined according to the initial pressure value. When the initial pressure value is low, the pressure change curve is steep, whereas when the initial pressure value is high, the pressure change curve is gentle.

In addition, when the water pump is operating and water flows from the primary piping to the secondary piping through the on-off valve for a predetermined period of time, an alarm (fire alarm) will be issued by, for example, a water flow detection device to indicate that firefighting activities are underway.

Patent No. 3264939 Patent No. 5054789

In a vacuum sprinkler system, the control unit must receive two signals to initiate fire extinguishing water discharge: a fire detection signal and a pressure change signal (double action system). The fire detection signal can be sent as soon as a fire occurs, while the pressure change signal is sent when the pressure in the secondary piping rises from an initial value to a specified pressure. This specified pressure is set to a value that is not affected by error from the initial value to prevent malfunction.

As a result, it takes a long time for the pressure in the secondary piping to reach the specified pressure value, which causes problems such as a long time before an alarm is issued that firefighting activities are underway and before water spraying can begin.

The present invention was made in consideration of the above-mentioned problems, and its purpose is to provide a vacuum sprinkler system that can immediately issue a fire alarm and start fire-fighting water discharge operations in the event of a fire, without waiting for the pressure sensor that monitors the pressure in the secondary piping to rise to a predetermined value at which it emits a pressure change signal.

In order to achieve the above object, the vacuum sprinkler system according to the present invention comprises :
A primary piping that extends vertically across each floor and receives fire water from the fire water tank;
A secondary piping that branches off from the primary piping on each floor and is routed to a sprinkler head for discharging fire water;
A fire detector is installed on each floor and detects the occurrence of a fire and transmits a fire detection signal.
a negative pressure device that normally creates a negative pressure in the secondary side piping;
a pressure sensor that detects the pressure in the secondary piping;
a control unit that receives signals from the fire detector and the pressure sensor and controls the supply of the fire extinguishing water from the primary piping to the secondary piping and the operation of the negative pressure device,
The control unit
When a fire detection signal is received from the fire detector, the operation of the negative pressure device is stopped to allow the pressure in the secondary piping to increase,
The device is characterized in that it calculates the increase (increase rate) in the pressure value in the secondary piping for each specified time based on the signal from the pressure sensor after the operation of the negative pressure device has stopped, and when the increase rate exceeds a specified value, it allows water to be sent from the primary piping to the secondary piping.

With this configuration, when the fire detector detects a fire and sends a fire detection signal to the control unit, the control unit stops operation of the negative pressure device in the secondary piping, allowing pressure in the secondary piping to increase. At this time, the fire activates the sprinkler head, i.e., the sprinkler head opens, and pressure in the secondary piping increases. After operation of the negative pressure device is stopped, the control unit calculates the increase in the pressure value per specified time, i.e., the increase rate, based on pressure value information in the secondary piping from the pressure sensor. If this increase rate exceeds a specified value, the control unit assumes that the pressure in the secondary piping will definitely rise to the specified pressure value that initiates conventional fire extinguishing water discharge, and begins fire extinguishing water discharge. It also issues a fire alarm, alerting the user that firefighting activities are underway.

As a result, it is possible to start fire extinguishing water discharge within a set short time, without waiting for the pressure in the secondary piping to rise to a predetermined pressure value. This allows firefighting efforts to start sooner, enabling more effective firefighting. It also allows for earlier notification that firefighting efforts are underway (fire alarm).

Further, the vacuum sprinkler system according to the present invention is the vacuum sprinkler system,
The predetermined time is preferably 3 to 5 seconds.

Generally, there are small changes in the pressure inside the secondary piping, and if you check it only once for a short period of time, there is a risk that changes that are not related to a fire will be detected as a fire. Therefore, by checking for 3 to 5 seconds, it is possible to eliminate changes that are not related to a fire, such as those mentioned above, thereby achieving accurate early detection of a fire and avoiding misidentification.

Further, the vacuum sprinkler system according to the present invention is the vacuum sprinkler system,
The predetermined increase rate is set by varying it depending on the initial pressure value in the secondary pipe when the operation of the negative pressure device is stopped.

In a vacuum sprinkler system, the initial pressure value when the negative pressure device stops operating varies depending on the diameter, length, and degree of curvature of the secondary piping. The pressure rise curve after the negative pressure device stops operating also differs.

Therefore, if the specified increase rate were set to a constant value regardless of the initial pressure value when the negative pressure device stopped operating, there was a risk that the timing of fire extinguishing water discharge would be delayed in vacuum sprinkler systems with high initial pressure. Therefore, by setting the specified increase rate to vary depending on the initial pressure value, it is possible to start fire extinguishing water discharge within a set short period of time, without waiting for the pressure in the secondary piping to rise to the specified pressure value, regardless of whether the vacuum sprinkler system has a low initial pressure value or a high initial pressure. This allows fire extinguishing activities to start sooner, resulting in more effective fire extinguishing.

Further, the vacuum sprinkler system according to the present invention is the vacuum sprinkler system,
The predetermined increase rate is set to be smaller as the initial pressure value is higher and larger as the initial pressure value is lower.

As a result, if the initial pressure value is low, the pressure increase in the secondary pipe is small over time after the operation of the negative pressure device is stopped, so by setting the specified increase rate to a small value, the effect of the invention described in claim 1 can be accurately achieved.

With the vacuum sprinkler system of the present invention, it is possible to start fire extinguishing water discharge within a set short time after the fire detector sends a fire detection signal to the control unit, without waiting for the pressure in the secondary piping to rise to a predetermined pressure value. This allows for a faster start of fire extinguishing activities and more effective fire extinguishing. It also allows for a faster notification that fire extinguishing activities are underway (fire alarm).

1 is a schematic diagram illustrating the main configuration of a vacuum dry sprinkler system according to one embodiment of the vacuum sprinkler system of the present invention. 2 is an explanatory diagram showing the change in pressure in the secondary piping from the time when the negative pressure device in the vacuum dry sprinkler system shown in FIG. 1 stops operating. An example of measurement data of the pressure change in FIG. 2 is shown.

The vacuum sprinkler system of the present invention will be described in detail below with reference to the drawings. Figure 1 shows the schematic configuration of a vacuum dry sprinkler system 10 according to one embodiment of the vacuum sprinkler system of the present invention. However, only the main components for one floor are shown.

In the vacuum dry sprinkler system 10, water stored in the fire water tank 44 is discharged via the water pump 35, primary piping 32, gate valve 36, secondary piping 34, and sprinkler head 33. The gate valve 36 is connected to the base end of the secondary piping 34, which branches off on each floor, and is composed of an on-off valve 36a and an alarm device (water flow detection device) 36b. Under normal circumstances (normal conditions), the on-off valve 36a is kept closed and is opened in response to a detection signal from a fire detector 40 installed on each floor. This opening operation is performed by the control unit 50. The water flow detection device 36b detects flowing water and issues an alarm when the on-off valve 36a is opened and water has been supplied for a predetermined period of time. This alarm is an important notification (fire alarm) indicating that firefighting activities are underway.

One end of the secondary piping 34 is connected to a gate valve 36, extends roughly parallel to the ceiling on each floor, and then branches off to form vertically hanging drop pipes, the ends of which are equipped with sprinkler heads 33 exposed from the ceiling of each floor. A test valve 38 is provided at the other end of the secondary piping 34 to open the secondary piping 34 after a test water flow or after a system malfunction causes water to flow into the secondary piping 34.

Under normal conditions, the secondary piping 34 is not filled with water, and the suction solenoid valve 54 is open, causing the vacuum pump 52 to suck air from the suction pipe 48 and the secondary piping 34. The suction solenoid valve 54, suction pipe 48, and vacuum pump 52 form a negative pressure device. This negative pressure device is controlled by the control unit 50. Under normal conditions, the pressure inside the secondary piping 34 is below atmospheric pressure, creating a negative pressure corresponding to the suction of the vacuum pump 52.

If the sprinkler head 33 is damaged when there is no fire, air will flow into the secondary piping 34, causing the pressure to rise. This pressure increase is detected by the pressure sensor 42 attached to the secondary piping, and the control unit 50 calculates the rate of pressure increase over a specified period of time. However, since there is no fire detection signal from the fire detector 40, a malfunction of the sprinkler head 33 is reported.

The pressure sensor 42 attached to the secondary piping 34 is configured to constantly measure the pressure inside the secondary piping 34, and the measured value is sent to the control unit 50. As explained below, if a pressure change occurs, the rate of pressure change is calculated.

In previous vacuum dry sprinkler systems, the control unit 50 started the water pump 35 when it received a fire detection signal from the fire detector 40 and a pressure change signal from the pressure sensor 42. For example, if the initial pressure value in the secondary piping 34 when the negative pressure device stopped operating was -0.08 MPa, the pressure change signal was sent to the control unit 50 when the pressure in the secondary piping 34 rose to -0.06 MPa.

Figure 2 shows the change in pressure inside the secondary piping 34 immediately after a fire breaks out and the control unit 50 stops the operation of the negative pressure device. An example is shown. The horizontal axis represents time (seconds), with zero seconds indicating when the control unit 50 stops the operation of the negative pressure device. At this time, the sprinkler head 33 has melted, so the pressure inside the secondary piping 34 will rise. The vertical axis represents pressure (MPa), with the initial pressure being -0.08 MPa.

In this state, the fire detector 40 detects a fire and sends a fire signal to the control unit 50, so the on-off valve 36a of the gate valve 36 is open. At the same time, the suction solenoid valve 54 is closed, suction of the inside of the secondary piping 34 by the vacuum pump 52 is stopped, and the pressure inside the secondary piping 34 is allowed to rise. At this point, the water pump 35 has not yet started.

Since the vacuum pump 52 is no longer suctioning the secondary piping 34, air is sucked out of the melted sprinkler head 32, and the pressure in the secondary piping 34 rises from an initial pressure of -0.08 MPa as shown by curve B.

In Figure 2, if the water pump 35 is not started, curve B continues to gradually rise beyond point P. In previous vacuum dry sprinkler systems, when the pressure in the secondary piping 34 reached approximately -0.06 MPa (point P, time T1 second), the pressure sensor 42 sent a pressure change signal to the control unit 50, which started the water pump 35 and sent water from the primary piping 32 to the secondary piping 34.

When the water pump 35 is started, the pressure in the secondary piping 34 rises sharply from point P as shown by line A in Figure 2 (point P is referred to as the operating point). Conventionally, when the pressure in the secondary piping 34 reaches point P, the pressure sensor 42 sends a pressure change signal to the control unit 50, and the control unit 50 starts the water pump 35 based on this pressure change signal and the fire detection signal it has already received (double-action system).

It takes approximately 40 seconds for the water pump 35 to start (to point P in Figure 2). This is an extremely long time, which leads to delays in firefighting activities. To avoid this, this time can be shortened by bringing the pressure value emitted by the pressure change signal closer to the initial pressure value, i.e., by bringing the operating point P closer to the origin. However, as can be seen from Figure 2, the measured pressure value oscillates and contains errors, so it is not possible to bring it too close to the initial pressure value. In other words, bringing the pressure value emitted by the pressure change signal closer to the initial value could result in a malfunction.

Figure 3 shows actual data for curve B shown in Figure 2. The first column is time (seconds), and the second column is the measured pressure (KPa). The third, fourth, and fifth columns show the increments every 1, 2, and 5 seconds, respectively. The measured value of -80.116 (KPa) at time 0 seconds is the initial value. Point P in Figure 2 corresponds to time 40 seconds in Figure 3. However, in this figure, the increments every 5 seconds represent, for example, the increment from 0 to 5 seconds at time 5 seconds, and the increment from 1 to 6 seconds at time 6 seconds. Similarly, the increments every 2 seconds represent the increment from 1 to 2 seconds at time 2 seconds, and the increment from 2 to 3 seconds at time 3 seconds.

In the vacuum dry sprinkler system of this embodiment, rather than waiting for the pressure to rise to operating point P, fire extinguishing water supply begins when the increase in pressure change over a predetermined time period (increase rate) exceeds a predetermined value. In this embodiment, the predetermined time period is 5 seconds. As shown in Figure 3, the increase (sum) from the past 0 to 5 seconds at 5 seconds is 3.428 KPa. From this, the increase rate is 0.6856 KPa/sec, which exceeds the predetermined increase rate of 0.5 KPa/sec. Therefore, the control unit 50 assumes that the pressure value in the secondary piping 34 will definitely reach -0.06 MPa, and starts the water supply pump 50 to begin fire extinguishing activities.

This configuration allows the water pump 35 to start instantly after a change in pressure occurs in the secondary piping 54, without having to wait for the pressure to rise to a predetermined value (point P) as in the past. Because the water pump 35 starts up quickly, the alarm device 36b can also quickly issue a fire alarm to notify the public that firefighting activities are underway.

Furthermore, it is important to change the above-mentioned predetermined value depending on the initial pressure value. For example, if the initial pressure value is higher, the increase in the curve of the pressure change in the secondary side pipe 34 over time is small, so the predetermined value is set small. If the initial pressure value is low, the increase in the curve is large, so the predetermined value is set large.

When the rate of pressure increase in the secondary piping 34 exceeds a predetermined value, it is assumed that the pressure in the secondary piping 34 will always rise to the operating point. This predetermined value can be changed depending on the initial pressure value of the secondary piping 34 in its normal state, making it possible to apply the present invention to vacuum sprinkler systems with different initial pressure values (pressure values when operation of the negative pressure device is stopped). In other words, the initial pressure value of the secondary piping 34 varies depending on the diameter, length, degree of bending, etc., and by changing the above predetermined value according to this initial pressure value, the present invention can be applied to a variety of sprinkler systems.

The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention. For example, although a vacuum dry sprinkler system has been described, it goes without saying that the present invention can also be applied to a vacuum wet sprinkler system.

10 Vacuum dry sprinkler system 32 Primary side piping 33 Sprinkler head 34 Secondary side piping 35 Water pump 36 Gate valve 36a Opening/closing valve 36b Alarm device (flow detection device)
38 Test valve 40 Fire detector 42 Pressure sensor 44 Fire extinguishing water tank 48 Suction pipe 50 Control unit 52 Vacuum pump 54 Suction solenoid valve

Claims (3)

A primary piping that extends vertically across each floor and receives fire water from the fire water tank;
A secondary piping that branches off from the primary piping on each floor and is routed to a sprinkler head for discharging fire water;
A fire detector is installed on each floor and detects the occurrence of a fire and transmits a fire detection signal.
a negative pressure device that normally creates a negative pressure in the secondary side piping;
a pressure sensor that detects the pressure in the secondary piping;
a control unit that receives signals from the fire detector and the pressure sensor and controls the supply of the fire extinguishing water from the primary piping to the secondary piping and the operation of the negative pressure device,
The control unit
When a fire detection signal is received from the fire detector, the operation of the negative pressure device is stopped to allow the pressure in the secondary piping to increase,
a rate of increase in the pressure value in the secondary piping for each predetermined time period based on a signal from the pressure sensor after the operation of the negative pressure device has been stopped, and when the rate of increase exceeds a predetermined value, water is allowed to be sent from the primary piping to the secondary piping;
A vacuum sprinkler system characterized in that the predetermined increase rate is set by changing it depending on the initial pressure value in the secondary side piping when the operation of the negative pressure device is stopped . The vacuum sprinkler system described in claim 1, characterized in that the predetermined time is 3 to 5 seconds. 3. The vacuum sprinkler system according to claim 1 , wherein the predetermined increase rate is set to be smaller as the initial pressure value is higher and set to be larger as the initial pressure value is lower.