JPH081410B2 - Gas leak detector - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a gas leakage detection device for detecting gas leakage from a gas flow path, and more particularly to a gas leakage detection device for detecting gas leakage when using igniting. The present invention relates to a leak detection device.

<Prior Art> In recent years, gas explosion accidents due to gas leakage from gas pipes have frequently occurred. Especially when there is a long distance from the gas storage facility to the gas use facility, such as in hospitals and schools, and there is a gas pipe buried underground between these facilities, corrosion of the buried pipe and uneven settlement of the ground may occur. , There is a risk of cracking the buried pipe and causing gas leakage.

Conventionally, in order to detect a gas leak from such a gas flow path, a pressure sensor is provided in the gas flow path, and a predetermined inspection period, for example, once a year or once every two years is set. , Close both ends of the gas flow path to be inspected and set the pressure in the gas flow path to 850 mmH ₂ O.
Gas leakage is detected by increasing the pressure to a certain degree and inspecting for the presence of pressure drop due to leakage.

There is also a method of arranging a flow rate sensor in a gas flow path and constantly monitoring the gas flow rate, thereby monitoring an abnormal gas flow rate that cannot be attained by normal gas use, and detecting gas leakage.

Gas shutoff device 1 interlocked with the pressure sensor shown in FIG.
Is an example.

The gas shutoff device 1 includes a gas flow path 3 including a shutoff valve 2.
A pressure sensor 4 for detecting the pressure of the gas flow path 3, a flow rate signal transmitter 5 for detecting the gas flow in the gas flow path 3 and transmitting a flow rate signal, and a pressure signal based on the output of the pressure sensor 4. Of the pressure signal from the pressure signal transmitter 6 and the pressure signal from the pressure signal transmitter 6 are stored, and after the pressure signal is stored, the decreasing pressure rises and the flow signal from the flow signal transmitter 5 increases. Is supplied, a shutoff signal 7 for sending a signal to close the shutoff valve 2 is provided.

Then, with this gas shutoff device 1, while using the gas appliance, LP cylinder (container) replacement, for some reason,
If the gas pressure drops and the flame disappears and you forget to close the gas appliance plug, the gas pressure rises again,
The gas flow path 3 is shut off to prevent gas leakage.

<Problems to be Solved by the Invention> However, in the method of detecting a gas leak by a regular inspection, the leak that occurs immediately after the inspection is overlooked until the next inspection, and early detection cannot be performed.

Further, in the method of constantly monitoring the gas flow rate with the flow rate sensor to detect gas leakage, the flow rate sensor does not function when leakage occurs on the upstream side of the flow rate sensor, so leakage on the downstream side of the flow rate sensor does not occur. Even if it can be found, the upstream leakage cannot be found.

Further, the conventional gas leakage detection device has no means for detecting even a slight gas leakage when using igniting.

Therefore, since a minute leak of gas during use of the igniter cannot be detected, a serious accident may occur.

<Means for Solving the Problems> The present invention has been proposed in view of the above, and a shutoff valve provided in the gas flow passage, and a gas flow passage provided downstream of the shutoff valve in the gas flow passage A flow rate sensor that detects the flow rate of flowing gas, a flow rate signal transmitter that transmits a flow rate signal when the flow rate sensor detects the flow of gas, and a gas flow path upstream of the shutoff valve A pressure sensor that detects the gas pressure, a pressure signal transmitter that sends a pressure fluctuation signal when a gas pressure fluctuation is detected based on the output of the pressure sensor, and a pressure signal transmitter that is only using the fire of a gas appliance. The pressure fluctuation storage means for storing the pressure fluctuation pattern of the pressure fluctuation signal transmitted by the pressure fluctuation signal and the pressure fluctuation signal supplied in the state where the flow rate signal is not supplied, gas leakage has occurred on the upstream side of the flow rate sensor. Judge that the gas When only the igniting of the device is used and a pressure fluctuation signal other than the pressure fluctuation pattern stored in the pressure fluctuation storage means is supplied while the flow signal is being supplied, gas leakage will occur at least at the downstream side of the flow sensor. It is characterized in that it comprises an arithmetic means for judging that it is occurring.

<Operation> The flow rate sensor monitors the gas flow rate in the gas flow path, and when the flow rate sensor detects the flow of gas, the flow rate signal transmitter transmits a flow rate signal.

The pressure sensor monitors the gas pressure in the gas flow path, and when a change in gas pressure is detected, the pressure signal transmitter transmits a pressure change signal.

The pressure fluctuation storage means stores the pressure fluctuation signal when only igniting is used as a pressure fluctuation pattern.

The calculation means determines that gas leakage has occurred on the upstream side of the flow rate sensor when the pressure fluctuation signal is supplied even when the gas appliance is not used, that is, when the flow rate signal is not supplied. To do.

The pressure fluctuation pattern of the pressure fluctuation signal stored in the pressure fluctuation storage means and the pressure fluctuation pattern of the measured pressure fluctuation signal are stored in the state where the igniting of the gas appliance is continuously used and the flow rate signal is supplied. If the two do not match, it is determined that gas leakage has occurred at least on the downstream side of the flow rate sensor.

<Example> The present invention will be described below based on an example shown in the drawings.

FIG. 1 is a schematic block diagram of an embodiment according to the present invention.

This gas leakage detection device 8 is provided with a shutoff valve 10 in the middle of the gas passage 9, and a pressure sensor 11 for detecting the gas pressure of the gas passage 9 is provided upstream of the shutoff valve 10 and downstream of the shutoff valve 10. Further, a gas meter 12, which is a flow rate sensor for detecting the flow rate of the gas flowing through the gas flow path 9, is provided. Then, in the microcomputer 13 which is the calculating means, the pressure sensor 11 is provided through the pressure signal transmitter 14 and the gas meter is provided through the flow rate signal transmitter 15.
12 is electrically connected, and the pressure fluctuation pattern storage unit 16 that is the pressure fluctuation storage means is also electrically connected. Further, the microcomputer 13 is electrically connected to a display unit 17 for displaying an abnormality and the shutoff valve 10 and is supplied with drive power from a battery 18. The shutoff valve 10 includes
A return safety device 19 is connected to restore the.

Further, on the upstream side of the gas flow passage 9, a pressure adjuster 20 for adjusting the pressure of the gas flowing into the gas flow passage 9 constant is provided.

The pressure signal transmitter 14 described above amplifies the signal from the pressure sensor 11, takes out only the effective signal component by the filter, shapes the waveform with the waveform shaper, and outputs a pulse signal when the fluctuation of the gas pressure is detected. Sends a pressure fluctuation signal.

In addition, the flow rate signal transmitter 15 changes mechanical movement of the gas meter 12 into an electric signal every time the gas meter 12 makes one revolution. Explaining the case where the flow rate signal transmitter 15 is provided in a membrane gas meter, the flow rate signal transmitter 15 includes a membrane driven by the flow of gas, a magnet rotating in conjunction with the movement of the membrane, and It consists of a reed switch that detects the movement of the magnet and repeats on and off. Then, when the magnet rotates in response to the flow of gas, the magnet approaches or moves away from the reed switch, the reed switch is turned on and off, and the membrane makes one reciprocation, that is, the magnet moves once.
Each time it rotates, it emits a one-pulse flow rate signal.

The pressure adjuster 20 is a device for adjusting the gas pressure flowing into the gas flow passage 9 to a constant value. For example, in the case of LP gas, the pressure inside the cylinder is limited to 0.7 to 15.6 kg / cm ² , and in order to burn the gas normally with a gas appliance, the gas pressure is reduced to 200 to 330 mmH ₂ O. It is necessary to adjust and supply. Therefore, attach a pressure regulator 20 to the cylinder outlet,
The pressure of the gas flowing into the gas passage 9 is adjusted.

 FIG. 3 shows an example of the pressure regulator 20.

The pressure regulator 20 is a single-stage pressure regulator, and the inside of the main body 21 is divided into upper and lower parts by a diaphragm 22, and an upper part is an air chamber 23 and a lower part is a decompression chamber 24. A nozzle 26 is provided on the gas inlet 25 side of the decompression chamber 24, and a valve rod 29 having a closing valve 28 faces the injection port 27 of the nozzle 26.
Is connected to the operator 31 attached to the diaphragm 22 via the lever 30. Further, the diaphragm 22 is pushed down toward the decompression chamber 24 by a spring 32 provided inside the air chamber 23.

Therefore, when the high pressure gas flows in through the gas inlet 25, the gas passes through the nozzle 26 and enters the decompression chamber 24. Here, if the gas continues to flow in, the pressure in the decompression chamber 24 rises,
The diaphragm 22 resists the bias of the spring 32 and
It is pushed up to the 23 side. Therefore, the operator 31 attached to the diaphragm 22 also rises, and the lever connected to the operator 31
30 rotates about the fulcrum 33, the valve rod 29 moves to the gas inlet 25 side, and the closing valve 28 restricts the injection amount of gas from the nozzle 26, or the injection port 27 when the pressure is high. To close. On the other hand, when the gas in the decompression chamber 24 flows out from the gas outlet 34, the pressure in the decompression chamber 24 drops, and the diaphragm 22 is urged by the spring 32 to descend to the decompression chamber 24 side. Therefore, the lever 30 connected to the operator 31 rotates about the fulcrum 33 as an axis, the valve rod 29 moves to the gas outlet 34 side, the closing valve 28 separates from the injection port 27 of the nozzle 26, and the high pressure gas is discharged. Inflow increases again.

In this way, the diaphragm 22 moves up and down as the pressure in the decompression chamber 24 rises and falls, and the gas inflow amount from the nozzle 26 is adjusted to keep the gas pressure flowing into the gas flow passage 9 substantially constant.
In this case, the gas pressure flowing into the gas passage 9 pulsates.

In addition, in this embodiment, the mechanism of the pressure adjustment is explained by the single-stage pressure adjuster, but the same applies when this is changed to another pressure adjuster, for example, an automatic switching type pressure adjuster. .

As described above, when the gas pressure flowing into the gas flow path 9 is adjusted using the pressure adjuster 20, the gas pressure changes periodically.

The pressure fluctuation pattern when a slight gas leakage occurs is shown in FIGS. 4 and 5. FIG. 4 is a variation pattern when a single-stage pressure regulator is used, and four patterns are shown. Further, FIG. 5 shows a variation pattern when an automatic switching type pressure regulator is used. The time interval at which this pressure fluctuation pattern occurs is not constant, but differs depending on the amount of leakage. The pressure fluctuation pattern also differs depending on the components of the flow path system, but if the leak amount does not change when the flow path system is specified, it shows a substantially constant pressure fluctuation pattern.

Therefore, the pressure fluctuation pattern storage unit 16 stores the pressure fluctuation pattern when the igniting of the gas appliance is continuously used,
The stored pressure fluctuation pattern and the measured pressure fluctuation pattern are compared and calculated by the microcomputer 13, and if there is a difference between the two, it is determined that the gas is leaking.

The gas leak determination process by the gas leak detection device 8 described above will be described below.

 FIG. 6 shows the criteria for judging gas leakage.

To determine the gas leakage, the presence or absence of a flow rate signal and the presence or absence of a pressure fluctuation signal are compared, and the pressure fluctuation pattern stored in the pressure fluctuation pattern storage unit 16 is compared with the measured pressure fluctuation pattern.

That is, when the pressure fluctuation signal is detected and the flow rate signal is detected, it is determined that gas leakage has occurred at least on the downstream side of the gas meter 12.

When the pressure fluctuation signal is detected and the flow rate signal is not detected, it is determined that gas leakage has occurred on the upstream side of the gas meter 12.

If the flow rate signal is detected without the pressure fluctuation signal being detected, it is determined that the pressure sensor 11 is abnormal.

When the pressure fluctuation signal is not detected and the flow rate signal is not detected, it is determined that there is no gas leakage, that is, normal.

Further, during use of igniting, the pressure fluctuation pattern stored in the pressure fluctuation pattern storage unit 16 is compared with the measured pressure fluctuation pattern, and if both match, it is determined that there is no gas leakage, and both do not match. In this case, it is determined that gas leakage has occurred on the upstream side of the gas meter 12.

Gas leak determination processing will be described with reference to the time chart of FIG. 7 and the flowchart of FIG.

In this embodiment, the determination process is automatically performed, and the use of igniting is also determined, and when a gas leak occurs at least on the downstream side of the gas meter 12, it is displayed that the gas is leaking, or automatically. Specifically, the shutoff valve 10 is operated.

In the microcomputer 13, a predetermined constant signal reception start time, for example, 30 minutes, when the gas appliance is not used and the flow signal from the flow signal transmitter 15 is not detected, the pressure fluctuation from the pressure signal transmitter 14 Start accepting signals. When a pressure fluctuation signal is detected, a timer is started and a predetermined fixed signal interval time, for example,
If the pressure fluctuation signal is continuously detected within 30 minutes, the counting is continued, and when the signal interval time is reached, a leak signal is transmitted. On the other hand, when the pressure fluctuation signal is not detected within the signal interval time, the count is cleared,
The timer is reset and the above processing is repeated. When the gas appliance is restarted within the signal interval time and the flow signal from the flow signal transmitter 15 is detected, the previous count value is cleared, the count is stopped, and the initial stage of the process is started. Return to.

The above-mentioned signal interval time is set in order to prevent a leak signal from being generated due to pressure fluctuations not based on gas leakage, for example, pressure fluctuations due to expansion of the gas pipe due to sunlight or temperature changes. Such pressure fluctuations that are not based on gas leakage occur in a longer cycle than pressure fluctuations that occur due to gas leakage. Therefore, by setting a certain signal interval time, it is assumed that pressure fluctuations that occur continuously within the signal interval time are due to gas leakage, and pressure fluctuations that occur beyond the signal interval time period are caused by factors other than gas leakage. It is judged that it is a pressure fluctuation caused by.

Note that both the signal reception start time and the signal interval time can be appropriately changed and implemented.

When the determination process is started and the flow rate signal Q is not detected, the presence or absence of the pressure fluctuation signal P is determined.

Here, when the pressure fluctuation signal P is not detected, since gas leakage has not occurred, the display unit 17 displays that the signal is normal, and then returns to the determination of the presence or absence of the flow rate signal Q. on the other hand,
When the pressure fluctuation signal P is detected, since gas leakage has occurred on the upstream side of the gas meter 12, the display unit 17 displays that gas leakage has occurred on the upstream side, and the process ends.

Next, when the flow rate signal Q is detected, the presence or absence of the pressure fluctuation signal P is determined.

Here, if the pressure fluctuation signal P is not detected, it means that the pressure sensor 11 is abnormal.
A message indicating that an abnormality has occurred is displayed and the processing ends.

On the other hand, when the pressure fluctuation signal P is detected, it is determined whether the flow rate signal Q is less than 21 liter / h.

When the flow rate signal Q is 21 liter / h or more, the above process is repeated.

Here, it is determined whether or not the flow rate signal Q is less than 21 liters / h, when the gas appliance is using a igniter, the gas flow passage 9 normally has a gas flow rate of 21 liters / h or less. This is to distinguish the gas flow due to the use of igniting from the gas flow due to the gas leakage. In addition, 21 liters / h is the case where gas appliances for general households are used, and when using gas appliances for business use, the standard value is 60 liters / h.
And

Then, the presence / absence of gas leakage during use of igniting is determined by comparing the pressure fluctuation pattern stored in advance in the pressure fluctuation pattern storage unit 16 with the measured pressure fluctuation pattern. This pressure fluctuation pattern is automatically stored when the gas leak detection device 8 is newly installed. For example, the flow rate is measured for 14 days after the gas leak detection device 8 is installed, the minimum flow rate value that satisfies the registered fire flow rate range is registered as the fire flow rate, and the pressure change pattern at this fire flow rate value is stored in the pressure change pattern memory. It is stored in the section 16. The ignition registration range in the micro leak detection area is shown in FIG. In this case, since the ignition flow rate is constant, it is assumed that there is no gas leakage within ± 5% of the pressure fluctuation pattern in consideration of the pressure fluctuation error.

If the flow rate signal Q is less than 21 liters / h, it is determined whether or not the igniter is registered.

Here, when the igniting is registered, the pressure fluctuation pattern stored in the pressure fluctuation pattern storage unit 16 is compared with the measured pressure fluctuation pattern. If the two match, it is assumed that there is no minute leak of gas, and the display unit
Shows 17 as normal. If they do not match, at least the gas leak has occurred at the downstream side of the gas meter 12, so the shutoff valve 10 is operated to close the gas flow path 9 and at least the gas meter is displayed on the display unit 17.
The process ends after displaying that a gas leak has occurred on the downstream side of 12.

Comparison of pressure fluctuation patterns will be described with reference to FIG.

The relationship between the flow rate pulse and the pressure signal pulse when there is no gas leakage is as shown in FIG. 10 (A). Then, when there is a gas leak on the upstream side of the gas meter 12, since there is a gas flow rate based on the gas leak in addition to the flow rate of the gas that is normally used, the interval of the pressure signal pulse is more than that in the normal time. Although it becomes shorter, there is no change in the flow rate pulse interval (Fig. 10 (B)). If there is no change in the flow rate pulse interval, and if the difference between the pressure signal pulse intervals is ± 5% or more of the normal interval, it is determined that gas leakage has occurred on the upstream side of the gas meter 12. . If the pressure signal pulse interval changes and the flow rate pulse interval changes, it is determined that gas leakage has occurred on the downstream side of the gas meter 12.

On the other hand, if the igniter is not registered, it is determined that the micro leak has occurred at least on the downstream side of the gas meter 12, and the display unit 17 indicates that the micro leak has occurred at least on the downstream side. At the same time, the shutoff valve 10 is shut off to stop the gas flow.

The present invention is not limited to the case of using LP gas,
It can also be applied when using city gas or simple gas that supplies gas using a device with a pressure adjustment function.

In addition, when the gas leakage occurs at least on the downstream side of the gas meter 12, the shut-off valve 10 is operated to close the gas passage 9, but the shut-off valve 10 closes or does not close the gas passage 9. Regardless of what, the display unit 17 may display that gas leakage has occurred at least on the downstream side of the gas meter 12 and terminate the process.

<Effects of the Invention> As described above, according to the present invention, the flow sensor is provided in the gas flow passage downstream of the shutoff valve, the pressure sensor is provided in the gas flow passage upstream of the shutoff valve, and the output of the flow sensor is provided. The flow rate signal transmitted by the flow rate signal transmitter as an input, the pressure fluctuation signal transmitted by the pressure signal transmitter by using the output of the pressure sensor as an input, and the pressure fluctuation pattern stored in the pressure fluctuation storage means when using only the caliber. Since the gas leak is detected by the calculation means based on the above, even if the gas appliance is not used, that is, if the pressure fluctuation signal is supplied in the state where the flow signal is not supplied, the upstream of the flow sensor is detected. It is possible to detect that a gas leak has occurred on the side, and the pressure fluctuation storage means stores it while only the igniting of the gas appliance is used and the flow rate signal is supplied. When a pressure fluctuation signal other than the pressure fluctuation pattern is supplied, it is possible to detect that gas leakage has occurred at least on the downstream side of the flow rate sensor.

Therefore, in facilities such as hospitals and schools, the distance from the gas storage facility to the gas use facility is long, and the gap is connected by a gas pipe buried underground, and the flow rate sensor is built in the gas meter of the gas use facility or Even if it is fixed on the wall of the facility being used, upstream of the flow sensor,
For example, a gas leak in the buried pipe can be reliably detected.

Further, since the gas leakage can be easily determined, it is possible to detect the gas leakage at an early stage and prevent a serious accident from occurring.

Also, since one set of pressure sensor and one set of flow rate sensor may be provided upstream and downstream of the shutoff valve, the intended purpose can be achieved with a simple and inexpensive configuration.

Further, it is possible to detect a gas leak while using the spark.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a schematic block diagram showing a gas leakage detection device of the present invention, FIG. 2 is a schematic block diagram showing a conventional gas shutoff device, and FIG. 3 is a pressure diagram. Side views showing the internal structure of the regulator, FIG. 4 and FIG. 5 are graphs showing pressure fluctuation patterns at the time of slight leakage, and FIG. 4 is a pressure fluctuation pattern when a single-stage pressure regulator is used, FIG. 5 is a pressure fluctuation pattern when an automatic switching type pressure regulator is used, FIG. 6 is an explanatory diagram of gas leak determination criteria, FIG. 7 is a time chart of determination processing, and FIG. 8 is determination processing. A flow chart, FIG. 9 is a graph showing a minute leak detection area and a fire registration area, and FIG. 10 is a graph showing a flow rate pulse and a pressure signal pulse when using fire. In the figure, 8 ... Gas leak detection device, 9 ... Gas flow path, 10 ... Shut-off valve, 11 ... Pressure sensor, 12 ... Gas meter, 13 ... Microcomputer, 14 ... Pressure signal transmitter, 15 ... Flow signal transmitter, 16 ... Pressure fluctuation pattern storage unit.

Claims (1)

[Claims] 1. A cutoff valve provided in a gas flow path, a flow rate sensor provided in a gas flow path downstream of the cutoff valve for detecting a flow rate of gas flowing in the gas flow path, and the flow rate sensor Flow rate signal transmitter that sends a flow rate signal when a gas flow is detected, a pressure sensor installed in the gas flow path upstream of the shutoff valve to detect the gas pressure in the gas flow path, and a gas sensor based on the output of the pressure sensor. A pressure signal transmitter that transmits a pressure fluctuation signal when a pressure fluctuation is detected, and a pressure fluctuation storage means that stores the pressure fluctuation pattern of the pressure fluctuation signal transmitted by the pressure signal transmitter when only the igniting gas appliance is used. If a pressure fluctuation signal is supplied when the flow rate signal is not supplied, it is determined that a gas leak has occurred on the upstream side of the flow rate sensor, and only the igniting gas appliance is used and the flow rate signal is supplied. Status When a pressure fluctuation signal other than the pressure fluctuation pattern stored in the pressure fluctuation storage means is supplied, the calculating means determines that gas leakage has occurred at least on the downstream side of the flow rate sensor. Gas leak detection device.