JP4935576B2 - Gas shut-off device - Google Patents

Description

  The present invention relates to a gas shut-off device that improves safety in use of gas and improves convenience in gas use when gas is used after the gas shut-off device.

  Conventionally, this type of gas shut-off device is described in the prior art document as a configuration described in Patent Document 1 and Patent Document 2.

FIG. 9 shows a conventional gas cutoff device described in Patent Literature 1 and Patent Literature 2. As shown in FIG. As shown in FIG. 9, the flow rate detection means 1 that outputs a flow rate signal a corresponding to the gas flow rate that passes through the gas passage, and the flow rate b that calculates the flow rate b when the flow rate signal a of the flow rate detection means 1 is received. Comparing the calculation means 2, the monitoring value storage means 13 for storing the judgment value m for monitoring abnormalities in the use state, the flow rate b of the flow rate calculation means 2 and the judgment value m of the monitoring value storage means 13 is abnormal If so, the abnormality determining means 3 for outputting the valve closing signal c, the valve closing signal c of the abnormality determining means 3, the valve closing signal c of the earthquake determining means 7, the valve opening signal h of the automatic return means 10, or manual operation. A valve driving means 4 for outputting a valve driving signal d in response to the valve opening signal h of the return input means 8; and an opening / closing means 5 for closing or opening the gas passage when the valve driving signal d of the valve driving means 4 is received. When an earthquake is detected, an earthquake signal And the earthquake determination means for outputting the valve closing signal c and the return request signal f when the earthquake detection means 6 coincides with a previously held earthquake pattern based on the earthquake signal e of the earthquake detection means 6. 7 and when the return request signal f of the earthquake determination means 7 is received, the pressure value g from the pressure input means 9 is monitored, and if there is no predetermined pressure drop in a predetermined time, a valve opening signal h is output and a pressure higher than a predetermined pressure is output. If there is a drop, the automatic return means 10 that does not output the valve open signal h, the pressure input means 9 that monitors the pressure and outputs the pressure value g, and the valve open signal upon receiving a return instruction by manual operation from the outside. Based on the flow rate b of the manual flow rate input means 8 that outputs h and the flow rate calculation means 2, a leak in the gas passage after the gas shut-off device is determined, and if there is a leak in the gas passage, a leak warning signal i is output. Leak And means 11, and an external communication means 12 for warning leaking outside on the basis of the leakage warning signal i of the leakage determination unit 11.
Japanese Patent Application Laid-Open No. 07-239099 Japanese Patent Laid-Open No. 10-103547

  However, in the conventional configuration, based on the flow rate b calculated by the flow rate calculation unit 2, the leakage determination unit 11 determines whether or not the gas appliance is continuously used as a leak in the gas passage. Only reported to the remote monitoring center. Further, when an earthquake occurs, the automatic return means 10 confirms whether or not there is a leak in the gas passage (the gas passage is once closed after the occurrence of the earthquake) and then automatically opens.

  Therefore, the presence or absence of a leak in the gas passage was automatically detected when an earthquake occurred, but when a leak was detected by the flow rate b (for example, a leak was detected when a flow rate of 5 L / h or more was detected continuously for 30 days). However, there is a problem that it is impossible to distinguish whether there is a leak in the gas passage or whether the gas is continuously used.

The present invention solves the above-mentioned conventional problems. When a leak due to the flow rate b is detected, the gas passage is forcibly closed once, and then the presence or absence of gas leak due to the pressure drop in the gas closed state is automatically detected. It is an object of the present invention to provide a gas shut-off device that is improved in convenience without increasing the safety of the gas user and the burden of inspection work by the gas operator.

  In order to solve the above-mentioned conventional problems, in the gas shutoff device of the present invention, the leakage determination means 31 leaks into the gas passage based on the flow rate B (for example, when a flow rate of 5 L / h or more is detected continuously for 30 days. (Similar effect can be obtained by making leakage when the appliance is not identified by appliance discrimination), and the valve closing signal C and the leakage return request signal L are output, and the automatic return means 30 first opens the valve. A gas H is output by outputting a signal H and a valve closing signal C, and then a predetermined pressure drop within a predetermined time in the gas passage is determined. If there is no leakage, the gas passage is opened.

  This makes it possible to distinguish whether the gas user has continued to use the gas for 30 days or whether there is really a leak in the gas passage.

  In the gas shutoff device of the present invention, when leakage due to the flow rate is detected, the gas passage is forcibly closed once (in the case of an instrument that does not have an automatic extinguishing device even if gas filling is performed, the downstream side of the gas shutoff device is opened) In this case, since there is no gas pressure, it is determined that there is a leak.For this reason, the gas user keeps the gas passage closed and the gas cannot be used, so the gas supplier is notified that the gas cannot be used. It is possible for the gas user to understand the abnormal usage method of using gas continuously for 30 days and to provide advice to the gas user on safe gas usage and replacement of equipment). Then, by automatically determining whether there is a gas leak due to a pressure drop when the gas is closed, the safety of the gas user and the burden of inspection work by the gas operator are increased. It is possible to improve convenience and without.

According to a first aspect of the present invention, there is provided a flow rate detection means for measuring a flow rate, a flow rate calculation means for calculating a flow rate value from a detection value of the flow rate detection means, and a monitoring value storage means for storing a judgment value for monitoring an abnormal use state. An abnormality determination means for comparing the flow rate value with the determination value to determine the presence or absence of an abnormality, and a gas in the gas passage on the downstream side of the gas shut-off device based on the flow rate value of the flow rate calculation means If there is a leak in the passage, a leak judgment means for outputting a leak return request signal, a pressure input means for monitoring the pressure and outputting a pressure value, and monitoring the pressure value from the pressure input means to obtain a predetermined pressure at a predetermined time If there is no drop, the valve opening signal is output, and if there is a pressure drop above a predetermined level, the valve opening signal is not output automatically, the valve driving means for outputting the valve driving signal, and the gas passage is closed by the valve driving signal. Or opening and closing A stage, said manual reset input means for outputting the valve open signal and receiving the return instruction by manual operation from the outside, and a communication capable external communication means with the outside, into the gas passage in the leakage determination means After the gas passage is once closed when a leak is detected, the automatic return means is instructed to return the valve opening signal from the manual return input means when the pressure input means detects a pressure drop exceeding a predetermined value. The gas passage can be unplugged due to carelessness of the gas user by enabling the return instruction by the valve opening signal from the manual return input means only by the return impossible release signal from the external communication means. To prevent and improve safety.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the present invention is not limited by this embodiment, and that the present invention is also intended to be modified and applied by those skilled in the art based on the description in the specification and well-known techniques, and protection is sought. Included in the range.

(Embodiment 1)
FIG. 1 shows a functional block diagram of a gas cutoff device in an embodiment of the present invention. The gas shut-off device is composed of a processor and an operation program that constitute a microcomputer (microcomputer) and the like. Each function is realized by executing a predetermined operation program in the processor and performing a corresponding process, and is driven by a battery. Yes.

  In FIG. 1, the flow rate detection means 21 may output a signal according to the flow rate of gas passing through the gas passage (for example, each time a certain amount is measured, or connected to a path in the gas passage, which will be described later. The flow rate signal A may be output by using the ultrasonic signal to determine the propagation time difference caused by the gas flow in the gas passage and detecting the instantaneous gas flow rate.

  The flow rate calculation unit 22 calculates the flow rate B based on the flow rate signal A detected by the flow rate detection unit 21 (for example, calculates the flow rate value by averaging the instantaneous flow rate based on the detected instantaneous flow rate, The flow rate is integrated to calculate an integrated flow rate value, or a flow rate difference value for appliance discrimination, and various calculations relating to the flow rate are performed.

  The monitoring value storage means 33 stores a determination value M for monitoring abnormal use conditions.

  The abnormality determination unit 23 outputs a closing signal C when the flow rate B of the flow rate calculation unit 22 and the determination value M stored in advance in the monitoring value storage unit 33 are equal to or greater than the determination value M.

  The valve driving means 24 is a valve closing signal C from the abnormality judging means 23, a valve closing signal C from the earthquake judging means 27, a valve closing signal C from the leakage judging means 31, or a valve closing signal C from the automatic returning means 30 and a valve opening signal H. When the valve opening signal H of the manual return input means 28 is received only when there is no return disable signal K output from the automatic return means 30, the valve drive signal D is output. When the opening / closing means 25 receives the valve driving signal D from the valve driving means 24, the opening / closing means 25 closes or opens the gas passage.

  When the earthquake detection means 26 detects an earthquake, it outputs an earthquake signal E.

  The earthquake determination means 27 is based on the earthquake signal E of the earthquake detection means 26, and an earthquake pattern (for example, a seismic sensor (for example, a steel ball and a contact terminal) When the ON / OFF signal is shorted and the ON / OFF signal is output), the valve closing signal C and the return request signal F are Output.

When the automatic return means 30 receives the return request signal F of the earthquake determination means 27, the leak return request signal L of the leak determination means 31, or the remote return request signal J of the external communication means 32, the valve is only turned on when the leak return signal L is received. An opening signal H and a valve closing signal C are output (for example, the interval between the valve opening signal H and the valve closing signal C is set to 10 seconds. Thereafter, the pressure value G is set to 20 seconds so as not to be affected by adiabatic compression due to gas filling. Then, the gas is filled into the gas passage on the downstream side of the gas shut-off device. Alternatively, the closure signal C is output only when the remote return request signal J is received (the gas user contacts the gas user to stop the use of the gas appliance, but the gas shut-off device is closed by the opening / closing means 25. Otherwise, gas leaks due to pressure drop cannot be confirmed).

Thereafter, the pressure value G from the pressure input means 29 is monitored, and a predetermined pressure drop is detected at a predetermined time (for example, from the time [2] after leakage due to the flow rate B is detected at the time [1] as shown in FIG. At this time, if the predetermined gas pressure does not remain in the gas passage, it is determined that there is a leak (in the case of the remote return request signal J, the gas is used from the center monitoring the gas shut-off device) Since the gas is stopped by the person, the downstream side of the gas shut-off device is not opened, so gas filling is not necessary.) When there is a gas pressure above a predetermined value, the pressure value G [2] of [2] (Instantaneous pressure at time [2]) is stored, and if there is a drop of 10 mmH ₂ O or more from the pressure value G [2] stored at time [3] after 60 seconds have passed, there is no leakage. If valve open signal H is output and the pressure drop exceeds a predetermined level, valve open signal H And it outputs a return disabling signal K is not output.

  The pressure input means 29 monitors the pressure and outputs a pressure value G.

  The manual return input means 28 is opened by supplying a reverse current to the open / close means 25 by an external (for example, a return button that is mechanically attached to the gas shut-off device and moving the open / close means 25 to the open state or a switch input by electronic components. When a return instruction by manual operation is received from a return switch to be plugged, a valve opening signal H is output (for example, a signal every time a certain amount is measured at a predetermined time (for example, 2 minutes) after manual return). The gas passage may be closed again if there is a flow rate at a predetermined time, or the pressure value G of the pressure input means 29 may be monitored in the same way as during automatic recovery. After judging the leakage of the gas passage (it may be the same time and pressure drop amount as the automatic return or different time and pressure drop amount), the gas passage may be opened).

  The leak determination means 31 determines that there is a leak in the gas passage after the gas shut-off device based on the flow rate B of the flow rate calculation means 22 (for example, when a flow rate of 5 L / h or more is detected continuously for 30 days. If the gas passage is leaked, the valve closing signal C and the leak return request signal are determined based on the preset selection contents. L is output, or a leakage warning signal I is output instead of the valve closing signal C and the leakage return request signal L.

  The external communication means 32 issues a leak warning to the outside (for example, the center monitoring the gas shutoff device) based on the leak warning signal I of the leak determination means 31, and outputs a remote return request signal J when receiving a remote return request from the outside. .

  It should be noted that the external communication means 32 (for example, from the center that monitors the gas shut-off device, or a setting device that can be carried freely at the site where the gas shut-off device is installed in the state in which the reset impossible signal K is output. The output of the non-recoverable signal K of the automatic return means 30 may be stopped by giving a non-recoverable release signal to the same effect obtained by connecting and communicating). As a result, after the gas supplier repairs the leak in the gas passage downstream of the gas shut-off device, the gas supplier uses the manual return input means 28 at the site to release the gas passage plugged state by the gas shut-off device. It becomes possible to (open).

Opening the gas passage unintentionally by the gas user means that the gas shut-off device is usually a high-accuracy (takes time to check for gas leaks) mode and a gas shut-off device that detects leaks downstream When there is no risk of leakage on the downstream side, normal pressure (time is shorter than high-precision mode and pressure drop amount is small. For example, it is used at the time of in-home opening / closing function used instead of main plug), etc. It has a function to judge the leakage of return.

  Therefore, if there is a leak due to a pressure drop during automatic return, and there is a manual return input after the gas passage is closed due to a new factor that does not cause a leak downstream of the gas shut-off device after that, There is a possibility that the gas shut-off device performs the opening determination in the normal accuracy mode instead of the high accuracy mode. The purpose of the reset impossible signal K is to prevent this mode transition. It should be noted that the same effect can be obtained even if the above-described configuration is replaced with the appliance discrimination means 34, the second leakage judgment means 35, and the storage means 36. This will be described below. The other operations from 23 to 33 that are not particularly described are assumed to perform the operations already described.

  The appliance discriminating means 34 determines the flow rate change characteristics of the gas flow rate such as the flow rate change amount and the change time based on the stored judgment value for each appliance based on the calculated flow rate difference value (flow rate value B), and enters the gas passage. The gas appliance used when the gas is flowing is discriminated.

  The second leak determination means 35 determines whether or not a gas leak has occurred based on the flow characteristic value including the calculated gas flow value and the integrated flow value. When the second leak determining means 35 determines that there is a leak in the gas passage, the valve closing signal C and the leak return request signal L are output as in the leak determining means 31.

  The storage unit 36 includes appliance discrimination information such as a judgment value used for appliance discrimination, flow rate characteristic information used for leak judgment, instantaneous flow rate value information measured by the flow rate detection unit 21, and gas flow rate value information calculated by the flow rate calculation unit 22. Various information used in appliance discrimination such as flow rate information such as flow rate difference information, integrated flow rate value information, and flow rate difference value information, and history information of appliances used and usage status.

  The operations of the flow rate detection means 21 and the flow rate calculation means 22 will be described in detail. FIG. 3 is a block diagram showing a schematic configuration of the ultrasonic flowmeter (flow rate detection means 21).

  The ultrasonic flow meter (flow rate detection means 21) has a measurement flow path 42 having a rectangular cross section communicating with the gas passage, and on the upstream side and the downstream side of the opposite flow path walls of the measurement flow path 42, A pair of ultrasonic transceivers 43 and 44 are arranged. These ultrasonic transmitters / receivers 43 and 44 are set so that the ultrasonic propagation path obliquely crosses the gas flow flowing through the measurement flow path 42, and alternately transmits / receives ultrasonic waves, so Propagation of ultrasonic waves in the opposite direction.

  At this time, the distance between the ultrasonic transceivers 43 and 44, that is, the measurement distance is L, the angle of the ultrasonic propagation path with respect to the gas flow is φ, and the ultrasonic propagation time from the upstream to the downstream of the ultrasonic transceivers 43 and 44 is If t1, the ultrasonic propagation time from downstream to upstream is t2, and the sound velocity is C, the flow velocity V can be obtained by the following equation.

V = L / 2 cos φ ((1 / t1) − (1 / t2)) (1)
The instantaneous flow rate of the gas flow is calculated from the flow velocity V and the cross-sectional area of the measurement channel 42.

The time interval for measuring the instantaneous flow rate can be set within a range where ultrasonic waves can be transmitted and received. Since the time to change by activation and control varies depending on the gas appliance, reducing the measurement time interval is advantageous in terms of instantaneous instrument discrimination, but shortening the measurement time interval increases battery consumption. . Further, when the measurement time interval is a two-digit order interval equivalent to the membrane type used in the conventional gas meter, it becomes difficult to judge by looking at the difference in flow rate change. Therefore, in the present embodiment, the periodic instantaneous flow rate at intervals of 2 seconds is measured, and the difference value is taken to determine the activation of the gas appliance. The measurement time interval can be further shortened. For example, after starting the gas appliance, control such as shortening the measurement time interval may be performed in order to increase measurement accuracy.

  Next, the operation of the appliance discrimination means 34 will be described in detail. FIG. 4 is a characteristic diagram showing a change in gas flow rate and a difference value when using a gas appliance, and FIG. 5 is a characteristic diagram showing a change in gas flow rate and a difference value when using a plurality of gas appliances.

  In FIG. 4, the solid line indicates the instantaneous flow rate value of the gas measured by the ultrasonic flow meter (flow rate detecting means 21), and the broken line indicates the differential value at that time, that is, the difference value at each predetermined measurement time interval. . The difference value is expressed with a peak on the plus side when the gas appliance is started, and is expressed with a peak on the minus side when the gas appliance is stopped. Here, when the difference value is greater than or equal to a predetermined value (change determination value), it is determined that there is a change in the gas flow rate and the change of the appliance or the state is determined.

  As shown in FIG. 5, based on the difference value of the instantaneous flow rate value of gas, for example, even when three appliances (A, B, C) are used at the same time, starting and stopping of individual gas appliances and output are performed. Changes in gas flow rate during adjustment can be detected. The form of control in the gas flow rate adjustment at the time of starting and ending and at the time of output adjustment differs for each gas appliance, and the flow rate change characteristics of the gas flow rate are different. Therefore, it is possible to determine the type of gas appliance by determining the gas flow rate and its flow rate change characteristics.

  For example, a gas stove, a fan heater using gas combustion heat as a heat source, and a gas water heater can be identified. The gas stove has a single function for cooking and the fan heater has a single function such as for hot air heating, but the gas water heater has two functions for hot water supply and floor heating. In the floor heating, a heat medium flow path is formed on the back side of the floor, and the heat medium flowing therethrough is heated with hot water boiled by a gas water heater. And for hot water supply and floor heating, the start-up or control pattern is different, and naturally there is a difference in the change amount and change time of the difference value. Therefore, when the gas appliance is a gas water heater, it can be determined whether it is for hot water supply or floor heating, based on the number of times the difference value is continuously generated or the continuous generation time. Note that the difference value may be a negative difference at the time of stopping or ending the control as well as at the time of starting or controlling.

  Next, the operation of the second leakage determination unit 35 will be described in detail. FIG. 6 is a diagram showing an example of flow rate characteristic information used for determining gas leakage in the present embodiment. In the storage means 36, flow characteristic information including determination data as shown in FIG. 6 is set and stored. The second leak determination means 35 uses this flow rate characteristic information to determine whether there is a gas leak based on the flow rate value set for each appliance type and the flow rate change until the predetermined integrated flow rate value is reached. .

As the flow rate characteristic information, first, a flow rate determination value Qr, which is a standard flow rate value set for each appliance type, is stored as first determination data. For example, 150 L (liter) / h (time) corresponding to the fan heater, 100 L / h corresponding to the gas table, and the like are set. The flow rate determination value Qr may be set with a certain width. Then, an integrated flow rate determination value Qmax that defines the upper limit of the flow rate when the flow rate is normal is set as second determination data. here,
A plurality of integrated flow rate determination values may be set for each type of gas appliance such as Qmax (A) and Qmax (B), or one integrated flow rate determination value Qmax may be set.

The second leak determination means 35 first determines whether or not the flow rate value Qm measured by the ultrasonic flowmeter (flow rate detection means 21) and the flow rate calculation means 22 matches the flow rate determination value Qr set for each instrument type. Determine. Here, when the flow rate value Qm does not coincide with the flow rate determination value Qr that has been set and stored, and there is no corresponding device, the measured flow rate value Qm is abnormal, and thus it is determined that there is a gas leak. When the flow rate value Qm matches the flow rate determination value Qr and corresponds to the instrument flow rate, the subsequent flow rate change is monitored. In this state, the flow rate value Qm is integrated, and if there is a change in the flow rate until the integrated flow rate value Qn reaches the stored integrated flow rate determination value Qmax, the gas appliance is in a normal use state. Is detected, and it is determined that there is no gas leakage, and monitoring of the flow rate change is reset. On the other hand, if there is no change in the flow rate even when the flow rate integrated value Qn becomes equal to or greater than the integrated flow rate determination value Qmax, it is determined that there is a suspicion of gas leakage, assuming that it is different from the normal use of the gas appliance.

  The condition for starting the monitoring of the flow rate change is a case where the judgment value of the predetermined flow rate characteristic coincides with the flow rate value Qm in the steady state during the normal operation as described above. It is also possible to use flow rate characteristic values relating to various flow rates such as flow rate patterns and instantaneous flow rate values.

FIG. 7 is a diagram showing an example of a gas flow rate change characteristic, and FIG. 8 is a diagram showing an integrated flow rate judgment value for leak judgment. When the gas flow rate is a flow rate pattern as shown in FIG. 7, for example, at the timing a when the gas appliance is stably operated, the measured flow rate value Qm is compared with the flow rate determination value Qr that is set and stored, and the flow rate value Qm To determine whether it corresponds to the instrument flow rate. If the flow rate value Qm corresponds to the instrument flow rate, the flow rate change is monitored while integrating the flow rate value Qm, and is there a change in flow rate until the integrated flow rate value Qn reaches the stored integrated flow rate determination value Qmax? It is determined whether the gas flow is due to the use of a normal gas appliance or whether the gas leaks, depending on whether there is a change in flow rate.

  The above-mentioned appliance discrimination can improve the accuracy of distinguishing between gas appliances and gas passage leaks, and can reduce the judgment of gas passage leaks that took 30 days from several hours to several days.

  The operation and action of the gas shut-off device configured as described above will be described below.

  First, after the leakage determination means 31 determines the possibility that there is a leak in the gas passage based on the flow rate B (the same effect can be obtained by the second leakage determination means 35), the automatic return means 30 then presses the pressure input means 29. The pressure value G of the gas is monitored, and the presence or absence of leakage in the gas passage is reconfirmed to determine.

  Further, the movement of the automatic return means 30 can be instructed from the center through the external communication means 32, and if there is a leak in the gas passage, the gas user is prohibited from opening the gas passage by the return impossible signal K.

  As described above, in the present embodiment, it is possible to determine the possibility of leakage in the gas passage and then reconfirm and determine whether or not there is leakage in the gas passage due to a pressure drop. For example, in an environment where the gas passage cannot be forcibly closed, such as in a ramen shop, check the date when the gas can be stopped from the center that remotely monitors the gas shutoff device to the ramen shop, and leak at a predetermined date and time. It is possible to confirm the presence or absence of.

  As a result, the gas supplier only needs to be dispatched to the site when there is a leak, and it is possible to prevent unnecessary dispatch, and if there is a leak in the gas passage, it is safe by prohibiting the manual return of the gas user. And convenience can be improved.

  As described above, after detecting leakage due to the flow rate, the gas passage can be once closed and the presence or absence of leakage in the gas passage due to pressure drop can be reconfirmed and determined. It is useful for this gas cutoff device that improves.

Functional block diagram of a gas shut-off device in an embodiment of the present invention The figure which shows an example of the leak determination by the pressure drop in embodiment of this invention The block diagram which shows schematic structure of the ultrasonic flowmeter in this embodiment The characteristic view which shows the change of the gas flow rate at the time of gas appliance use in this embodiment, and the change of a difference value The characteristic view which shows the change of the gas flow rate at the time of use of several gas appliances in this embodiment, and the change of a difference value The figure which shows an example of the flow volume characteristic information used for determination of the gas leak in this embodiment The figure which shows an example of the flow volume change characteristic of the gas in this embodiment The figure which shows the integrated flow volume determination value for the leak determination in this embodiment Functional block diagram of a conventional gas shut-off device

Explanation of symbols

DESCRIPTION OF SYMBOLS 21 Flow rate detection means 22 Flow rate calculation means 23 Abnormality determination means 24 Valve drive means 25 Opening / closing means 26 Earthquake detection means 27 Earthquake determination means 28 Manual return input means 29 Pressure input means 30 Automatic return means 31 Leakage determination means 32 External communication means 33 Monitoring Value storage means 34 Instrument discrimination means 35 Second leak determination means 36 Storage means 42 Measurement flow path 43, 44 Ultrasonic transceiver

Claims (1)

Flow rate detection means for measuring the flow rate;
A flow rate calculation means for calculating a flow rate value from a detection value of the flow rate detection means;
Monitoring value storage means for storing a judgment value for monitoring abnormal use state;
An abnormality determining means for comparing the flow rate value and the determination value to determine the presence or absence of an abnormality;
Leakage determining means for determining leakage in the gas passage downstream of the gas shutoff device based on the flow rate value of the flow rate calculating means and outputting a leakage return request signal if there is leakage in the gas passage;
Pressure input means for monitoring pressure and outputting pressure values;
An automatic return means for monitoring the pressure value from the pressure input means and outputting a valve opening signal if there is no predetermined pressure drop at a predetermined time and not outputting the valve opening signal if there is a pressure drop greater than a predetermined value;
Valve driving means for outputting a valve driving signal;
Opening and closing means for closing or opening the gas passage by the valve drive signal;
The manual return input means for outputting the valve opening signal when receiving a return instruction by manual operation from outside ,
An external communication means capable of communicating with the outside ,
After the gas passage is once closed when the leak judgment means detects a leak in the gas passage, the automatic return means is configured to detect the manual return input means when the pressure input means detects a pressure drop exceeding a predetermined value. A return instruction can not be issued by the valve opening signal from the external communication means, and a return instruction can be issued by the valve opening signal from the manual return input means only by a non-recoverable release signal from the external communication means. Shut-off device.

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