JPH0464574B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for monitoring gas piping. This invention relates to a gas pipe monitoring method that detects gas leaks based on fluctuations in gas pressure when the gas pipes are closed.

``Conventional technology'' Conventionally, this type of monitoring method uses gas by placing a solenoid valve upstream of the gas pipe and a pressure switch downstream thereof that is turned on and off according to gas pressure fluctuations. When the use start switch is turned on, the solenoid valve is opened, and when the gas is finished using, the use end switch is used to close the solenoid valve. When the use start switch is turned on, the solenoid valve is temporarily closed. After the downstream side of the solenoid valve is opened and the supply gas pressure is reached, it is closed, and a piping inspection is performed before gas use for a certain period of time (for example, 1 minute), and the gas downstream of the solenoid valve is If the closed gas leaks in the pipe and the pressure switch is activated, an abnormality is detected, and only if no abnormality is detected within this time, the solenoid valve is held open to make the gas usable. In addition, after the solenoid valve is closed by turning on the end-of-use switch, the piping is inspected after it has been used for a certain period of time, and if the closing gas in the gas supply path downstream of the solenoid valve leaks within this set time and the pressure switch is activated. A gas piping monitoring method has been proposed in which a solenoid valve does not open unless an abnormality is detected and a predetermined reset operation is performed thereafter.

``Problem to be Solved by the Invention'' However, the conventional gas piping monitoring method described above monitors gas leaks by monitoring changes in the closing gas pressure of the gas that is closed downstream of the solenoid valve before and after the gas is used. Therefore, gas users have to turn on the start switch.
If you leave it ON and do not operate the stop switch even after the gas has finished using it, the gas will always be considered to be in use and no gas leakage inspection will be performed, and depending on how it is used, the monitoring function may not work at all. There was a problem that they would not be able to accomplish.

``Purpose'' The gas supply monitoring device of the present invention was developed to solve the above problems, and in addition to performing the conventional piping inspection before gas use and piping inspection after gas use,
It also detects whether gas is in use or not, and when it detects that gas use has stopped, the end-of-use switch is automatically operated, and piping inspection is performed after gas use, achieving higher reliability. The purpose is to provide a gas piping monitoring method.

"Means for Solving the Problems" In accordance with the above object, the configuration of the present invention, which is summarized in the claims described above, includes a solenoid valve 2 in the upstream part of the gas pipe 1, in order to solve the above problems. A pressure sensor 3 is disposed downstream of the solenoid valve 2 and reads the gas pressure in the pipe as an electrical value, and when the start switch 4a is operated on the control panel P, the solenoid valve 2 is temporarily opened. After setting the downstream side of the electromagnetic valve 2 to the supplied gas pressure, the solenoid valve 2 is closed, the gas pressure value inputted from the pressure sensor 3 is stored, and this stored gas pressure value is compared with the gas pressure value after a set time. If the pressure drop rate is above a predetermined value, an abnormality is detected, and if this pressure drop rate is within a predetermined value, the solenoid valve 2 is held open to make the gas usable. Piping inspection is performed before gas use. Furthermore, when the end-of-use switch 4b is operated on the control panel P, after the solenoid valve 2 is closed, the stored gas pressure value is compared with the gas pressure value after a certain period of time, and if the pressure decrease rate is above a predetermined value, In a gas piping monitoring method that performs a piping inspection after gas use to detect an abnormality if any, after the above-mentioned piping inspection before gas use is performed and the solenoid valve 2 is held in the open state, the gas that is sequentially input from the pressure sensor 3 is The pressure values are compared at regular time intervals and the gas pressure fluctuation rate at that point is repeatedly determined, and this pressure fluctuation rate is less than the gas pressure pulsation rate that occurs when the gas in use passes through the gas meter. This technical means is characterized in that when the gas continues for a certain period of time, it is determined to stop using the gas, and the end-of-use switch 4b is automatically operated.

``Operation'' Therefore, in the gas pipe monitoring method of the present invention, when the gas is not to be used, the use start switch 4a is turned on. Then, the piping is inspected before using the gas, and if no piping defect is detected, the solenoid valve 2 is opened and the gas can be used.

Furthermore, when the use of the gas is finished, the electromagnetic valve 2 is closed by operating the end-of-use switch, and then the piping is inspected after using the gas, as in the conventional case.

By the way, since the gas piping monitoring method of the present invention monitors the detected value of the pressure sensor 3 even when gas is being used, it is also possible to detect whether or not gas is actually being used.

Normally, the gas being used in the gas supply system pulsates to some extent due to the configuration of the gas meter (measuring cell). Therefore, by detecting this pulsation, if pulsation is detected, it can be determined that gas is being used, and if pulsation is no longer detected, it can be determined that gas usage has ended.

Therefore, even if you forget to operate the end-of-use switch, the present invention compares the gas pressure values sequentially input from the pressure sensor 3 at regular time intervals to repeatedly determine the gas pressure fluctuation rate at that point. When the pressure fluctuation rate continues to be less than the gas pressure pulsation rate caused by the gas being used passing through the gas meter for a certain period of time, it is determined that gas use has ended.
The end-of-use switch 4b is automatically operated, the solenoid valve 2 is closed, and the piping is inspected after using the gas.

"Embodiments" Next, embodiments of the present invention will be described below with reference to the accompanying drawings.

In the figure, 1 is a gas pipe, and this gas pipe 1 has one end connected to a gas supply source (not shown), that is, an outdoor pipe or a gas cylinder via a gas meter.
The other end is branched as necessary and connected to a gas valve 7, and each gas valve 7, 7, 7... is connected to a desired gas appliance G such as a stove, a stove, a bath burner, etc.
1, G2, G3... are connected to form a gas supply system. In short, the gas supply system including this gas pipe 1 is conventionally known, and there is no problem in using the existing gas supply system as is.

A solenoid valve 2 is disposed upstream of the gas pipe 1, preferably near an outlet of a gas meter (not shown), and a pressure sensor 3 for converting and reading gas pressure into an electrical signal is disposed downstream thereof.

A conventionally known solenoid valve 2 is used as the solenoid valve 2, and detailed illustrations are omitted, but when the solenoid is energized, the valve body is attracted by electromagnetic force and pulled up to open the valve.
When the power to the solenoid is cut off, the valve body is demagnetized and pulled up, and then the valve body is lowered by the biasing force of a spring to close the valve. The valve body is attracted and held by the attraction force of a permanent magnet, and the valve remains open even when the electricity is cut off. To close this valve body, an electromagnetic force is applied to the above or another solenoid in a direction that cancels the attraction force of the permanent magnet. It is also possible to use a so-called latch type solenoid valve that conducts a current to generate the .

Further, since the pressure sensor 3 is also a conventionally known one, a detailed illustration thereof will be omitted, but in this embodiment, one side faces the gas pipe 1 and the other side is airtight from the gas pipe 1. Using a strain gauge that faces the atmosphere while maintaining
Gas pressure is detected as a voltage value using a Wheatstone bridge 3a shown in the figure. It goes without saying that this pressure sensor 3 may be of any other structure, such as a differential transformer, as long as it converts changes in gas pressure within the gas pipe 1 into electrical signals such as voltage. be.

The solenoid valve 2 and the pressure sensor 3 are connected to a control panel P, and the solenoid valve 2 is controlled to open and close by combining and organizing the detection signal of the pressure sensor 3 and other input signals on the control panel P. When the use start switch 4a is operated on the control panel P, the solenoid valve 2 is temporarily opened and the downstream side of the solenoid valve 2 is set to the supply gas pressure, and then closed, and the gas pressure input from the pressure sensor 3 is closed. The value is memorized and this memorized gas pressure value is compared with the gas pressure value after a set time. If the pressure drop is more than a predetermined value, an abnormality is detected, and if the pressure drop is within a predetermined value, the solenoid valve 2 is opened. The piping is inspected before using the gas to ensure that the gas is in a usable state, and when the end of use switch 4b is operated on the control panel P, the solenoid valve 2 is closed and the gas pressure value is memorized and the gas is stored after a certain period of time. As in the past, piping inspection is performed after gas use to detect an abnormality if the pressure drop exceeds a predetermined value by comparing the gas pressure value, but the present invention is capable of performing the above-mentioned piping inspection before gas use. After the solenoid valve 2 is held open, the gas pressure values sequentially input from the pressure sensor 3 are compared at regular time intervals to repeatedly determine the gas pressure fluctuation rate at that point. When the pressure fluctuation rate continues to be less than the gas pressure pulsation rate caused by the gas in use passing through the gas meter for a certain period of time, it is determined that gas use is to be stopped, and the end of use switch 4b is automatically operated. It is arranged so that it is in the same state as before.

As most clearly shown in FIG. 2, the control panel P includes a power supply circuit 11, a pressure signal input terminal 14, a pressure signal amplifier 14a, an A/D converter 15, an oscillator 16, a use start switch 4a, and a use end switch 4b. , reset switch 5, external signal input terminal 1
7, Solenoid valve power supply circuit 18, Solenoid valve power output terminal 1
3. Abnormality warning light 19 (hereinafter simply referred to as red lamp 19), buzzer 20, energization and inspection indicator light 21
(hereinafter simply referred to as blue lamp 21) and a microcomputer CPU (hereinafter simply referred to as CPU) to which these lamps are connected. That is,
The oscillator 16 is connected to the clock signal input terminal X1 of the CPU,
X2, and the pressure signal input terminal 14 is connected to the pressure signal amplifier 14a and the A/D converter 15.
It is connected to the pressure signal input terminals DB0 to DB7 of the CPU. In addition, the external signal input terminal 17 is connected to the external abnormal signal input terminal P22 of the CPU, and the reset switch 5
The start switch 4a and the end switch 4b are connected to the reset signal input terminal P21 of the CPU.
It is connected to the use open/end close signal input terminal P20 of the CPU via an I/O port, respectively. In this embodiment, the above-mentioned use start switch 4a and use end switch 4b are the same, and when pressed for the first time, the use start switch 4a is used, and when pressed for the second time, it is used as the use end switch 4b. They are designed to function alternately. Furthermore, the applicable
A red lamp 19 is installed at the abnormality notification signal output terminal P13 of the CPU, a blue lamp 21 is installed at the energization and inspection display signal output terminal P12, a buzzer 20 is installed at the abnormality notification signal output terminal P11, and a solenoid valve open signal output terminal P10 is installed. Solenoid valve power supply circuits 18 are connected to each other via I/O ports. The solenoid valve power supply terminal 13 of the solenoid valve power supply circuit 18 is connected to the solenoid valve 2, and the external signal input terminal 17 is connected to an abnormality sensor 30 such as a gas leak alarm.
The signal output terminal of the pressure sensor 3 is connected to the pressure signal input terminal 14 . It should be noted that the power supply circuit 11 is a conventionally known one, and supplies the necessary power to each of the above-mentioned parts.

The CPU operates according to the programs shown in FIGS. 3 to 7 to realize the gas piping monitoring method of the present invention. In other words, this CPU program consists of the recovery inspection flowchart section shown in Figure 3 (inspecting piping before gas use), the normal operation confirmation flowchart section shown in Figure 4, and the gas leak detection flowchart section shown in Figure 5. It consists of an inspection flowchart section (inspects piping after gas use), an abnormality processing flowchart section shown in Fig. 6, and an external signal processing flowchart section shown in Fig. 7. Explain the program.

<Return inspection flowchart section> First, in this program, the CPU inputs pressure signal input terminals DB0 to DB7, external abnormality signal input terminal P22, reset signal input terminal P21, and use open/end close signal input terminal P20. The input signal is read at predetermined time intervals.

When the program of this CPU is started by energization, an energization signal is output to the energization and inspection display signal output terminal P12, the blue lamp 21 is lit, and the use start switch 4a is turned on by the use start switch operation judgment section F1. Wait until.

When using gas, the use start switch 4a is operated. When the use start switch 4a is turned on, a use start signal is input to the use start signal input terminal P20, and the next return inspection judgment section F2 checks the state before use. Determine whether reinstatement testing is necessary.

When using gas, it goes without saying that it is useful to check for leaks before use to prevent accidents. However, this inspection requires time (usually 3 to 5 minutes to detect small gas leaks in domestic pipes).
(5 to 15 minutes for commercial use with large piping capacity),
This means that the use of gas will have to wait until the end of the inspection. Therefore, in the present invention, this gas leakage test is performed both before and after using the gas, but if it is determined that there is an abnormality in the return test before the previous gas use, the test during the use of the gas, and the test after the use of the gas, Otherwise, this return check is omitted. That is, in this restoration inspection judgment section F2, if an abnormality signal is sent to the abnormality processing flowchart section to be described later, a flag is set to store that an abnormality has been detected. Lower the flag and proceed to the next return first valve operating section F3, and if there is no flag, the program will jump to the part where the return inspection has been completed and there is no abnormality (after the return judgment section F6, which will be described later). It's getting old.

If the return inspection determination section F2 determines that a return inspection before use is necessary, the return first valve operation section F2
3, a solenoid valve open signal is outputted from the solenoid valve open signal output end P10, and this solenoid valve open signal is continuously outputted at the next time elapse determination section F4 until a certain period of time (5 seconds in the example) has elapsed. However, after this certain period of time has elapsed, the return second valve operating section F5 turns off the output of the solenoid valve open signal from the solenoid valve open signal output end P10 and closes the solenoid valve 2. Note that when this solenoid valve open signal is first input to the I/O port, the I/O port will continue to output the solenoid valve open signal, and after a certain period of time has elapsed, the solenoid valve open signal will be input to this I/O port. Of course, when the signal is input again, the I/O port may cut off the output of the electromagnetic valve opening signal.

The reason why the solenoid valve 2 is opened only for a certain period of time and then closed is because if the gas pressure in the gas pipe 1 is "0" or has dropped extremely low, Since it is impossible to judge whether there is a gas leak based on changes in gas pressure, first open the solenoid valve 2, apply sufficient supply gas pressure to the gas pipe 1, and then close the solenoid valve 2. This is to conduct an inspection. Note that if the piping capacity on the downstream side of the solenoid valve 2 is large, the supply gas pressure may not be reached in the gas piping 11 when the solenoid valve is opened for 5 seconds in this embodiment. It is only necessary to extend the time, and in practice, it is preferable to make it possible to set the time for opening the solenoid valve 2 variably using a dip switch or the like.

In addition, the first return valve operating section F3 outputs an intermittent energization signal to the energization and inspection display signal output terminal P12 to blink the blue lamp 21 to indicate that the return test is in progress, and the second return valve Valve operation part F5
Then, after a certain period of time (2 seconds in the example) after the solenoid valve 2 closes, the pressure signal input terminals DB0 to DB7 are
Stores the gas pressure value input.

Here, to explain the variables used in this program, the latest gas pressure value V1 is detected by the pressure sensor 3 and sent from the pressure signal input terminals DB0 to DB0 at regular intervals via the A/D converter 15.
Value input to DB7.

Second gas pressure value V2 A value detected by the pressure sensor 3 and read alternately via the A/D converter 15 separately from the latest gas pressure value V1. Alternatively, the latest gas pressure value V1 is temporarily stored and updated with this latest gas pressure value V1 after a certain time delay (in the example, a 2 second delay).

Memory gas pressure value V0 Latest gas pressure value V1 (second gas pressure value V2 may also be used)
A memory value stored at a specified time.

Therefore, in the return second valve operation part F5, the pressure signal input terminal DB is activated after a certain period of time after the solenoid valve 2 is closed.
The latest gas pressure value V1 inputted from 0 to DB7 is stored as the memory gas pressure value V0. In addition,
The reason why the latest gas pressure value V1 is stored as the memory gas pressure value V0 after a certain period of time after the solenoid valve 2 is closed by the second return valve operation part F5 is because the instantaneous fluctuation in the gas pressure in the pipe due to the closing operation of the solenoid valve 2 is This is to avoid any influence on the pressure sensor 3.

After the solenoid valve 2 is closed by the second return valve operation section F5, the presence or absence of gas leakage is inspected by the return judgment section F6. There are two ways to test whether there is a gas leak in the return judgment section F6. The first method is to close the solenoid valve 2 using the second return valve operation section F5 and store the memorized gas pressure value V0. , then for a certain period of time (e.g. 3 minutes)
When the time has elapsed, the stored gas pressure value V0 is compared with the latest gas pressure value V1 or the second gas pressure value V2, and if the difference is above a certain level, an abnormality is detected as gas leaking. , the second method compares the latest gas pressure value V1 with the second gas pressure value V2 or the stored gas pressure value V0 every time the latest gas pressure value V1 is input,
If the difference is above a certain level, an abnormality is detected as gas leaking. In both of these tests, the first method requires a relatively long waiting time but can detect fewer leaks, and the second method requires a relatively long waiting time but has poor leak detection accuracy. However, recently, the accuracy of the pressure sensor 3 has improved, so in this embodiment, the second method described above is adopted (of course, the first method may also be adopted), and the return judgment section F6 uses the latest gas pressure value. Store V1 gas pressure value V0
, and determine whether the fluctuation of a certain percentage or more (±3% or more as an example) continues for a certain period of time (2 seconds as an example) for a certain period of time (10 seconds as an example)
This is monitored, and if there is any variation, it is determined to be abnormal. In other words, if this variation occurs, proceed to the abnormality processing flowchart shown in Figure 6.
If there is no fluctuation, it is determined to be normal and the process proceeds to the next valve opening operation section F7.

Here, to explain in more detail the reason why the second method was adopted in this embodiment, the reason why a continuous gas pressure fluctuation of ±3% or more is considered abnormal is usually due to a piping failure in the household gas supply system. If not, it is because actual measurements have confirmed that there is no further pressure fluctuation even considering the atmospheric temperature change conditions, and it is also because it can eliminate misidentification due to noise input to the CPU, but there is an even more important point. is caused by the characteristics of the pressure sensor 3 made of a strain gauge used in this embodiment. That is, the strain gauge itself is susceptible to temperature changes, and an accurate comparison cannot be made by comparing the measured value with the measured value several minutes later, when temperature conditions may change and measurement errors may occur. To solve this problem, it would be possible to add a temperature correction circuit, but since multiple temperature correction circuits are expensive, in this example, the measured values are compared within an extremely short period of time when temperature changes can be ignored. The aim was to detect pressure fluctuations by accumulating the comparison results.

Then, the valve open operating section F7 outputs an electrode valve open signal to the solenoid valve open signal output end P10, so that the solenoid valve 2 is kept in the open state from now on, and the energization and inspection display signal output end P12 An energizing signal is output to turn on the blue lamp 21 to indicate that preparation is complete.

<Normal Usage Confirmation Flowchart Section> When this program completes the above-mentioned restoration inspection flowchart section, it proceeds to the normal usage confirmation flowchart section shown in FIG. This normal use confirmation flowchart part is separated from Figure 3 for illustration purposes, but it is a program that continues with Figure 3 (hereinafter, the program continues up to Figure 6), including overcurrent inspection and discontinuation of use. Inspections are carried out.

(Excess flow test) First, in the return test flowchart section, when the process of the used valve opening operation section F7 is completed, the over flow detection judgment section F8
Proceed to. This excessive flow detection/judgment section F8 monitors whether or not a rubber hose or the like comes off while gas is in use, causing more gas to flow than expected.The latest gas pressure value V1
Or, if the second gas pressure value V2 decreases by more than a certain level (40% or more as an example) than the stored gas pressure value V0, it is determined that there is an overflow. If this decrease occurs, the process jumps to the abnormality processing flowchart section, and if there is no such decrease, the process jumps to the abnormality processing flowchart section. is determined to be normal and proceeds to the next usage confirmation determination section F9.

(Use discontinuation inspection) This use confirmation judgment section F9 monitors whether or not the use of gas has been discontinued, and changes in gas pressure (second gas pressure value) at fixed time intervals (1 second intervals in the example) V2 - Latest gas pressure value V1 = M) is ignored when there is an extremely small change, and when it is more than that, M = 1, and this state of M = 0, that is, a state with no gas pressure change, is constant. When it is determined that M=0 has continued for a certain period of time (20 minutes as an example), it is determined that gas use is to be stopped and the process proceeds to the next automatic closing operation section F10. A loop is formed in which it is determined that the gas is in use, and the process returns to the overflow detection/judgment section F8 to again perform the use confirmation determination, and the overflow inspection and discontinuation inspection are repeated.

In other words, in this example, we decided to stop using Kazu when the gas pressure did not change above a certain level for 20 minutes.In a normal gas supply system, the pressure inside the pipes pulsates when gas is used. This is accompanied by pressure pulsations due to the intermittent delivery of gas (in actual measurements, pulsations of approximately 3 mm/H ₂ O were observed, although this varies somewhat depending on the capacity of the gas pipe 11). If there is no pulsation detected by the second gas pressure value V2 minus the latest gas pressure value V1, it can be determined that the gas is not flowing and that gas use has been stopped. However, if you immediately judge that the gas has finished using it, you will have to stop the gas for a short time and operate the start switch 4a each time you use it again. (However, it is desirable to make it variable) The system waits for the gas to continue until it is determined that the gas usage has ended.

If the use confirmation judgment unit F9 determines that the use is finished, the automatic shut-off valve operation unit F10 turns off the solenoid valve open signal at the solenoid valve open signal output end P10, closes the solenoid valve 2, and closes the solenoid valve 2. The latest gas pressure value V1 after a certain period of time after closing is re-stored as a stored gas pressure value V0 that will not change until the next update.

Further, when the process in the automatic closing operation section F10 is completed, in this embodiment, the process proceeds to the end-of-use reconfirmation judgment section F11, and this end-of-use reconfirmation judgment section F11
Then, after the solenoid valve 2 closes, check whether there is a gas pressure drop of more than a predetermined value (a gas pressure drop of 3% or more as an example) within a certain period of time (20 seconds in an example). The judgment is made by comparing the value V1 with the second gas pressure value V2 or the stored gas pressure value V0. If there is no drop in gas pressure, it is assumed that the discontinuation of use has been confirmed and the next step is taken. If there is a drop in gas pressure, a malfunction occurs. A loop is formed so as to return after the above-mentioned return judgment section F6, that is, to the part where the return inspection is completed and it is judged that there is no abnormality.

If you close the solenoid valve 2 even though you are using gas appliances G1, G2, G3..., open the solenoid valve 2 immediately (while gas remains in the gas pipe 11). It is possible to continue to maintain the gas appliance in a combustion state without causing the gas to go out, but if it takes time to open the solenoid valve 2 again at this time, there is a risk that the gas will go out and the raw gas will flow out. Yes. Therefore, this latest gas pressure value
The comparison between V1 and the second gas pressure value V2 or the stored gas pressure value V0 is not performed after a set period of time after closing the solenoid valve 2, but rather by inputting the latest gas pressure value V1 that is input at extremely short intervals. If a drop in gas pressure is found after each test, the system immediately returns to the return judgment section F6 and opens the solenoid valve 2.

"Gas Leak Inspection Flowchart Section" Further, when the discontinuation of use is confirmed in the discontinuation reconfirmation determination section F9, the program proceeds to the gas leakage inspection flowchart section shown in FIG.

In this gas leak test flowchart section, first, the gas leak test determination section F12 tests for the presence or absence of a gas leak. There are two possible methods for this gas leakage test, similar to the gas leakage test in the return judgment section F6 described above, and either of these methods may be adopted, but in this embodiment, the return judgment section F6 Similarly, each time the latest gas pressure value V1 is input, the latest gas pressure value V1 is compared with the second gas pressure value V2 or the stored gas pressure value V0, and the gas pressure is determined to be above a certain level (5% or more as an example). We monitor whether the pressure drop occurs continuously for a certain period of time (3 seconds as an example) (10 minutes as an example), and if this pressure drop occurs, it is determined that there is an abnormality and the process jumps to the abnormality processing flowchart section. If this does not occur, it is assumed to be normal and the process proceeds to the next step.

There is a high probability that gas usage will end in the evening before going to bed, when the nighttime temperature tends to drop.
In addition, it can be assumed that gas heating will be turned off and gas usage will be terminated in cold regions. In such a case, solenoid valve 2
The gas pressure closed in the downstream gas pipe 1 is naturally affected by the ambient temperature, and it is necessary to identify whether the pressure drop is due to a temperature change or a leak. Considering this point, when you finish using the gas, close the solenoid valve 2 and store the memorized gas pressure value.
After memorizing V0 and after a set time, this memorized gas pressure value V0
and the latest gas pressure value V1, the unstable factor of how much the temperature has fallen within this set time will affect the test results. Therefore, it is advantageous to detect a leak by determining whether or not there is a drop in the pressure inside the pipe within a short period of time when the influence of this temperature change or temperature change is small.As a result, this example Now, the latest gas pressure value V1
The latest gas pressure value V1 is set as the second gas pressure value each time
This method employs a method of comparing with V2 or the stored gas pressure value V0.

Even if the gas leakage inspection determination unit F12 determines that the gas leakage is normal, this is within the monitoring time, and the cause of the gas leakage may occur thereafter. Therefore, even after the gas leakage inspection judgment unit F12 determines that the gas leakage inspection judgment unit F12 is normal, the gas leakage inspection judgment unit F12
You are given an opportunity to reconsider.

That is, if the gas leakage test determination section F12 determines that the gas is normal, the second determination section F13 after use
After use, the second judgment unit F13 waits until the latest gas pressure value V1 has decreased by a certain amount or more (40% or more as an example) with respect to the stored gas pressure value V0. After proceeding to the one-valve operation section F14 and outputting a solenoid valve open signal to the solenoid valve open signal output end P12 to open the solenoid valve 2, the time elapse determination section F15 determines whether a predetermined period of time (5 seconds in the example) is reached. Wait for the elapse of time, and when the predetermined time has elapsed, proceed to the second valve operation section F16 after use, and turn the solenoid valve open signal output end P.
After use, the second valve operating section F16 stores the latest gas pressure value V1 as the memory gas pressure value V0, and performs a gas leak test. A loop is formed that returns to the region determined to be normal by the determining section F12.

<Abnormality processing flowchart section> In the abnormality processing flowchart section shown in FIG. 6, when proceeding to this abnormality processing flowchart section from the above-mentioned parts, first, the abnormality processing section F17 opens the valve of the solenoid valve open signal output end P10. Turn off the signal and close solenoid valve 2,
A flag is set to the above-mentioned recovery inspection judgment section F2 to remember that an abnormal signal has been input, and an energization signal is output to the abnormality notification signal output terminals P11 and P13, the red lamp 19 is turned on or flashed, and the buzzer 20 is activated. ring.

When the processing in the abnormality processing section F17 is completed, the reset switch 5 is turned on in the release switch operation judgment section F18, and the reset signal input terminal P2 is turned on.
1 until a reset signal is input. That is, by waiting in the release switch operation determining section F18, this program progresses until a reset signal is input to the reset signal input terminal P21, and the solenoid valve open signal is output to the solenoid valve open signal output terminal P10, and the solenoid valve is closed. 2 is locked to prevent it from being opened.

Then, when the reset switch 5 is turned on and a reset signal is input to the reset signal input terminal P21, the abnormality release processing section F19 resets the abnormality notification signal output terminal P.
11, the energizing signal of P13 is turned off, the red lamp 19 is turned off, and the buzzer 20 is stopped.
It is designed to return immediately after the start of the return inspection flowchart shown in the figure.

<External signal processing flowchart section> The external signal processing flowchart section shown in FIG. In this embodiment, it is determined whether or not the abnormality signal continues for a certain period of time set by the time elapse determination section F20, and the process proceeds to the abnormality processing flowchart section in FIG.

The above is the program shown in the illustrated flowchart. When the gas usage end switch 4b is operated during the progress of this program, the release switch operation determination section F1 of the abnormality processing flowchart section is activated.
This program is designed to return to the start section in FIG. 3 except during standby at step 8.

"Effects of the Invention" The method for monitoring gas piping according to the present invention is as described above. After the piping is inspected before gas use and the solenoid valve 2 is held in the open state, the gas pressure is sequentially input from the pressure sensor 3. The values are compared at regular time intervals to repeatedly determine the gas pressure fluctuation rate at that point, and the value is determined as a constant if this pressure fluctuation rate is less than the gas pressure pulsation rate caused by the gas in use passing through the gas meter. When the time continues, it is determined to stop using the gas, and the end of use switch 4b is automatically operated, so even if you forget to operate the end of use switch 4b after using the gas, the system will automatically stop using the gas. Since the end of gas use is detected, the electromagnetic valve 2 is closed, and the pipe inspection is started after the gas is used, a highly reliable gas pipe monitoring method can be provided.

[Brief explanation of the drawing]

FIG. 1 is a front view of an example of a device showing an embodiment of the gas piping monitoring method of the present invention, FIG. 2 is a wiring diagram of the control panel,
3 to 7 are flowcharts of programs used in the present invention. 1 - gas piping, 2 - solenoid valve, 3 - pressure sensor,
4a - use start switch, 4b - use end switch, P - control panel.

Claims (1)

[Scope of Claims] 1. A solenoid valve 2 is disposed upstream of the gas pipe 1, and a pressure sensor 3 located downstream of the solenoid valve 2 reads the gas pressure in the pipe as an electrical value. When the use start switch 4a is operated on the panel P, the solenoid valve 2 is temporarily opened, the downstream side of the solenoid valve 2 is set to the supply gas pressure, and then closed, and the gas pressure value input from the pressure sensor 3 is memorized. This stored gas pressure value is compared with the gas pressure value after a set time, and if the pressure drop rate is above a predetermined value, an abnormality is detected. If this pressure drop rate is within a predetermined value, the solenoid valve 2 is opened. In addition, when the end-of-use switch 4b is operated on the control panel P, the solenoid valve 2 is closed, and the gas pressure value is memorized. In a gas piping monitoring method that performs a piping inspection after gas use, which compares the gas pressure value after a certain period of time and detects an abnormality if the pressure drop rate exceeds a predetermined value, the solenoid valve is 2 is held in the open state, the gas pressure values sequentially input from the pressure sensor 3 are compared at fixed time intervals to repeatedly determine the gas pressure fluctuation rate at that point. When the gas pressure pulsation rate generated by the gas inside the gas meter continues to be lower than the gas pressure pulsation rate for a certain period of time, it is determined that the gas use is to be stopped, and the use end switch 4b is automatically operated. Characteristic gas piping monitoring method.