JPH09119882A - Method and system for monitoring of very small gas leak - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely detect a very small gas leak from a buried pipe and to prevent an accident by a method wherein, when a gas flow rate inside a gas supply pipe is reduced, a gas flow is bypassed automatically and its flow rate is detected. SOLUTION: A bypass 6 which connects the primary side 3 to the secondary side 4 of a gas supply pipe 1 is installed at the gas supply pipe, and a pressure subregulator 5 whose valve blocking pressure is set to be high as compared with that of a pressure main regulator 2 is installed at the bypass. Then, a gas usage amount is reduced at midnight, a flow rate inside a regulator 2 is reduced, and a gas is not used finally. Then, the regulator 2 closes a valve automatically, and the gas flows preferentially into the regulator 5 which is set at a high pressure. At this time, when a gas in a very small flow rate due to a very small gas leak exists, the gas flows exclusively to the supply pipe 1 through a very-small-flow-rate gas meter A, and a flow rate at this time is detected by the meter A so as to be recorded by a self-recording flowmeter 7. That is to say, a very small gas leak amount is detected by the bypass as a gas inflow amount to a leak place.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas micro-leakage monitoring method and a gas micro-leakage monitoring system for carrying out the method, which are capable of detecting micro-gas leaks in a buried gas feed pipe.

[0002]

2. Description of the Related Art In many cases, gas leakage accidents in domestic gas pipes are caused particularly by corrosion of underground pipes. Therefore, conventionally, as one of the preventive measures, a security officer of a gas company observes that the gas consumption decreases at midnight, and the gas supply source gas meter 2 shown in FIG.
By checking 0, it was determined whether or not there was a gas leak downstream of the original gas meter 20. In the figure, 16 is an LP gas cylinder, 17 is an automatic switching regulator,
2 is a pressure regulator, 21 is a gas appliance.

As another method, a method has been adopted in which underground boring near the buried pipe 19 is carried out at a rate of about once every two years, and a check is made with a gas leak detector.

[0004]

However, the former checking method is labor-intensive and does not have sufficient accuracy to determine the minute flow rate sufficient for the original gas meter to monitor the minute leak of gas. However, even if there is a small gas leak, the minute flow rate due to the leak cannot be grasped as the gas inflow amount to the leak location, and there is a disadvantage that the leak judgment is lacking in certainty. In addition, the supply of gas must be stopped during the operation, which inconveniences the user.

Therefore, in view of the above-mentioned point, the present invention grasps a minute flow rate due to a minute gas leak as a gas inflow amount to a leak location without manpower, and surely finds a minute gas leak from a buried pipe. Therefore, it is an object of the present invention to provide a gas micro leak monitoring method and a system for implementing the method, which prevent accidents.

[0006]

In order to achieve the above object, a method for monitoring gas leakage according to the present invention is a gas feed pipe when the gas flow rate to the gas feed pipe is reduced because the gas is no longer used. The valve means provided in the valve means is automatically closed so that all of the gas flowing through the gas supply pipe is passed through a bypass provided so as to connect the primary side and the secondary side of the valve means, and the flow rate of the bypass is adjusted. It is characterized by detecting and monitoring minute gas leaks.

According to the above method, when the flow rate of the gas flowing through the gas supply pipe decreases due to the exhaustion of the gas, the valve means provided in the gas supply pipe is automatically closed to flow the gas flowing through the gas supply pipe. All of the gas flow to a bypass provided to connect the primary side and the secondary side of the valve means, and the flow rate of the bypass is detected to monitor the minute gas leakage. It can be detected in the bypass as the amount of gas flowing into the.

The gas micro-leakage monitoring system according to the present invention for achieving the above object is provided automatically when the gas flow rate of the gas feed pipe is decreased because the gas is no longer used and the gas feed pipe is provided in the middle of the gas feed pipe. The valve means for closing the valve, the bypass connecting the primary side and the secondary side of the valve means, and the flow rate detecting means provided in the bypass for detecting the flow rate of the bypass, and depending on the flow rate detected by the flow rate detecting means. It is characterized by monitoring minute gas leaks.

According to the above system, the valve means provided in the middle of the gas feed pipe closes when the gas flow rate in the gas feed pipe decreases due to the exhaustion of gas, and the valve means is connected to the primary side of the valve means. The gas leakage is monitored by the flow rate of the bypass detected by the flow rate detection means provided in the bypass connecting the secondary side. All of the flowing gas is allowed to flow to the bypass, and the minute gas leakage can be monitored by the flow rate detection by the flow rate detection means, and the minute gas leakage amount can be detected in the bypass as the gas inflow amount to the leakage location.

In order to achieve the above-mentioned object, the gas micro leak monitoring system according to the present invention has a main pressure provided in a gas feed pipe for adjusting and supplying a high pressure gas from an LP gas cylinder to a supply pressure. A regulator, a bypass connecting the primary side and the secondary side of the main pressure regulator, a sub-pressure regulator provided in the bypass and having a valve closing pressure set higher than that of the main pressure regulator, and a bypass provided in the bypass. A flow rate detecting means for detecting the flow rate of the bypass is provided, and the minute gas leakage is monitored by the flow rate detected by the flow rate detecting means.

According to the above system, the main pressure regulator provided in the gas supply pipe is connected to the primary side and the secondary side of the main pressure regulator in the gas supply pipe in order to supply the high-pressure gas from the LP gas cylinder to the supply pressure. A sub-pressure regulator with a valve closing pressure set higher than the pressure regulator and a flow rate detection means are provided, and gas leakage is monitored by the flow rate of the bypass detected by this flow rate detection means, eliminating gas usage. When the flow rate of gas flowing through the gas supply pipe decreases, all of the gas flowing through the gas supply pipe begins to flow to the bypass. The amount can be detected in the bypass as the amount of gas flowing into the leak location.

[0012]

1 shows an embodiment of a gas micro leak monitoring system according to the present invention for carrying out a gas micro leak monitoring method according to the present invention. In the figure, a primary side 3 and a secondary side of a gas feed pipe 1 provided with a main pressure regulator 2 for adjusting a supply pressure to supply a high pressure gas from an LP gas cylinder serving as valve means. A bypass 6 connecting 4 is provided, and a small auxiliary pressure adjuster 5 having a valve closing pressure set to about 30 mmH ₂ O higher than that of the main pressure adjuster 2 is provided for the bypass 6, and the auxiliary pressure adjuster 5 is provided. Is provided with a minute flow rate gas meter A as a flow rate detecting means for detecting a minute flow rate, and an automatic flow meter 7 is connected to the minute flow rate gas meter A.

The self-recording flow meter 7 has a disk-shaped recording paper 8 shown in FIG. 2 set therein. The recording paper 8 has a time scale 9 in the circumferential direction and a flow scale 10 in the radial direction. It is noted.

As described above, since the valve closing pressure of the sub-pressure regulator 5 is set higher than that of the main pressure regulator 2, when the gas flows through the main pressure regulator 2, the sub-pressure regulator 5
The gas always flows to the bypass through the passage, and the flow rate of this gas is detected by the minute flow gas meter A,
Will be recorded. Therefore, while the gas is being used, the gas meter A detects the gas flow rate, and when the gas is no longer used, the gas pressure in the gas delivery pipe 1 gradually rises, and the gas pressure is the main pressure. When the pressure becomes higher than the set pressure of the regulator 2, the main pressure regulator 2 serving as the valve means does not flow the gas and becomes the valve closed state. On the other hand, the auxiliary pressure regulator 5
Since the valve closing pressure is set to be about 30 mmH ₂ O higher than the main pressure regulator 2, the gas continues to flow even if the gas stops flowing to the main pressure regulator 2, and the gas pressure of the gas supply pipe 1 becomes When the pressure becomes higher than the valve closing pressure, the gas stops flowing, and the gas flow rate of the bypass 6 also becomes zero.

Therefore, when the amount of gas used decreases at midnight and the flow rate in the main pressure regulator 2 decreases, and finally when the gas is no longer used, the main pressure regulator 2 automatically closes the valve to release the gas. Since it preferentially flows into the auxiliary pressure regulator 5 set to a high pressure, when there is a minute flow rate of gas due to minute gas leakage, the gas mainly passes through the minute flow rate gas meter A to the gas feed pipe 1. The flow rate at this time is detected by the minute flow rate gas meter A, and the result is recorded on the recording paper 8 by the self-recording flow meter 7. That is, the minute gas leak amount can be detected in the bypass as the gas inflow amount to the leak location.

FIG. 3 shows another embodiment of the gas micro-leakage monitoring system of the present invention. In the figure, a float valve 11 is provided for the gas supply pipe 1 and the float valve 11 is provided.
For the bypass 14 connecting the primary side 12 and the secondary side 13 of
A minute flow rate gas meter A similar to that of the above embodiment is provided, and a small float valve 15 is provided on the secondary side of the gas meter A. To the above-mentioned minute flow rate gas meter A, the same note flow meter 7 as in the above embodiment is connected.

Then, the gas supply pipe 1 with reduced gas usage
When the flow rate in the inside decreases, the float valve 11 closes, and the gas flows to the gas feed pipe 1 through the minute flow rate gas meter A provided in the bypass 14, but at that time, the small float valve 15
Prevents backflow.

The monitoring system shown in FIG. 3 is preferably provided in the secondary side feeding pipe 18 of the pressure regulator 2 shown in the conventional example.

The amount of gas flowing out at midnight can be quantitatively grasped by the flow rate diagram drawn on the recording paper 8,
When the recorded flow rate is zero, it can be confirmed that there is no leakage from the pipe (buried pipe 19). When the minute flow rate is recorded quantitatively every day, the presence of gas leakage is checked together with the investigation of gas usage. Can be determined.

[0020]

As described above, according to the present invention, when gas is used out at midnight and the gas flow rate in the gas supply pipe decreases, the gas flow is automatically bypassed to detect the gas flow rate. Since the minute leakage is monitored, when the gas is no longer used and the flow rate of the gas flowing to the gas supply pipe decreases, all the gas flowing to the gas supply pipe will flow to the bypass, and the amount of gas minute leakage will be reduced. It is possible to obtain a method capable of detecting an amount of gas flowing into a leakage location in a bypass and reliably detecting a minute gas leakage from a buried pipe without manpower to prevent an accident.

Also, since the gas leakage of the bypassed gas is detected and the minute gas leakage is monitored, when the gas is no longer used and the flow rate in the gas supply pipe becomes very small, the gas flowing through the gas supply pipe is reduced. Everything starts to flow to the bypass,
A system that can detect a small amount of gas leakage as an amount of gas flowing into a leak location in a bypass and detect a small amount of gas leakage from a buried pipe without human intervention to prevent an accident before it is obtained. .

In particular, the main pressure regulator is connected to a bypass connecting the primary side and the secondary side of the main pressure regulator provided in the gas supply pipe in order to supply the high-pressure gas from the LP gas cylinder at a supply pressure. A sub pressure regulator with a high valve closing pressure and a flow rate detecting means are provided, and the gas leak is monitored by the flow rate detected by the flow rate detecting means. By functioning as a valve means, just by adding a bypass equipped with a sub-pressure regulator and flow rate detection means, it is possible to discover minute gas leaks from buried pipes without human intervention and to prevent accidents. A system is obtained that can be prevented.

Therefore, the amount of gas leakage from the buried pipe or the like can be detected early and reliably by detecting the amount of gas leakage from the buried pipe or the like by detecting the amount of gas leakage as a gas inflow into the leakage location at the bypass, and without any manual operation. In addition to preventing accidents due to gas leaks, there is no need for late-night patrols, so the burden on security personnel is reduced, and burial pipes can be inspected without stopping gas supply. The effect of disappearing is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a gas micro-leakage monitoring system according to the present invention that implements the method of the present invention.

FIG. 2 is a front view showing a recording sheet used in the present invention.

FIG. 3 is a diagram showing another embodiment of the present invention.

FIG. 4 is a diagram showing a conventional gas pipe.

[Explanation of symbols]

 1 Gas Supply Pipe 2 Main Pressure Regulator (Valve Means) 11 Float Valve (Valve Means) 3,12 Primary Side 4,13 Secondary Side 5 Sub Pressure Regulator 6,14 Bypass A Micro Flow Gas Meter (Flow Rate Detection Means)

Claims (3)

[Claims] 1. When all the gas flowing through the gas supply pipe is closed by automatically closing the valve means provided in the gas supply pipe when the flow rate of the gas flowing through the gas supply pipe decreases due to the exhaustion of gas. A method for monitoring a minute gas leak, characterized in that the gas is allowed to flow through a bypass provided so as to connect the primary side and the secondary side of the valve means, and the minute flow rate of the bypass is detected to monitor the minute gas leak. 2. Valve means for automatically closing the valve when the gas flow rate of the gas feed pipe is reduced, which is provided in the middle of the gas feed pipe when the gas is no longer used, and primary and secondary sides of the valve means. A gas micro-leakage monitoring system, comprising: a bypass connecting the two; and a flow rate detection unit provided in the bypass for detecting the flow rate of the bypass, and monitoring the gas micro-leakage by the flow rate detected by the flow rate detection unit. 3. A main pressure regulator provided in a gas feed pipe for adjusting the supply pressure of high-pressure gas from an LP gas cylinder to supply the main pressure regulator, and connecting the primary side and the secondary side of the main pressure regulator. A bypass, a sub pressure regulator provided in the bypass and having a valve closing pressure set higher than that of the main pressure regulator, and a flow rate detection unit provided in the bypass for detecting a flow rate of the bypass are provided. A gas micro-leakage monitoring system characterized by monitoring gas micro-leakage based on the detected flow rate.