JP3103249B2 - Gas leak detection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to detect a gas leak in a so-called service pipe from a gas supply book / branch to a gas meter through a land occupied or owned by a customer and to a gas meter. About the method.

[0002]

2. Description of the Related Art FIG. 4 shows a method of supplying city gas. 1 is a main pipe, 2 is a site boundary, 3 is a service pipe connecting the main pipe 1 and the gas meter 4, 5 is an indoor pipe connecting the indoor gas tap 6 and the gas meter 4, and 7 is a gas leak alarm installed indoors. It is. In the conventional supply system, if a gas leak occurs downstream of the gas meter 4, a gas leak detection circuit incorporated in the gas meter 4 operates to stop the gas or issue an alarm. Is performed, and when such a circuit is not added, gas leak is monitored by means of the gas leak alarm 7 issuing an alarm, which is safe. However, even if a gas leak occurs in the service pipe 3 between the main pipe 1 and the gas meter 4, there is no means for detecting this at present, and it is a conventional example. At regular security patrols every three years, patrolers will check for odors. b. The meter reader notices the odor when reading the meter. c. Consumers notice by odor. It is only discovered by such methods.

[0003]

As a result, the discovery of gas leaks may be delayed or may not be noticed if the amount is small.

An object of the present invention is to monitor a gas leak from a service pipe on a daily basis, and to propose a gas leak detecting method capable of immediately detecting a gas leak if it occurs. is there.

[0005]

The gas leak detecting method according to the present invention is as follows.

[0006] A backflow prevention mechanism is incorporated in the upstream portion of the service pipe, and a pressure detection mechanism and a backflow detection mechanism are incorporated in the gas meter. It is determined that there is no use of gas equipment downstream of the gas meter. Is determined that there is no gas leakage when the pressure rise is detected and at the same time the reverse flow is detected from the reverse flow detection mechanism, while when the pressure rise is not detected and the reverse flow is detected A gas leak detection method for determining that there is gas leak.

The gas pressure detecting mechanism and the reverse flow detecting mechanism are
If the gas meter has this function, use it as it is; if not, attach it separately.

[0008]

[Function] In the supply of city gas, when the gas from the main pipe to the gas stopper at the end of the indoor pipe via the service pipe is seen, the service pipe section buried underground and the indoor pipe (gas meter section) ), The rise in temperature and the room temperature in the room affect the thermal expansion of the gas in the gas pipe. For this reason, for example, when all the gas appliances are not used, and a backflow prevention mechanism such as a check valve is attached to the upstream portion of the service pipe, when the pressure increases, the pressure decreases from the indoor piping side where the pressure increases. A minute backflow phenomenon occurs on the service pipe side, and eventually equilibrates under high pressure.

In the present invention, monitoring is continued by paying attention to this state, and when a slight backflow is detected but the pressure decreases, it is determined that a gas leak has occurred in a part of the service pipe. can do. The gas leak detection circuit makes this determination (determination) based on the following criteria.

If no gas equipment is used and the pressure in the pipe is uniform, no gas flow occurs. If the gas in the indoor piping is warmed in this state, the gas pressure rises and a pressure imbalance occurs. As a result, a small flow is generated in the opposite direction to that during normal use of the device in order to maintain balance. Although the gas in the service pipe is pushed back, it does not flow further by the backflow prevention mechanism, and the gas between the backflow prevention mechanism and the gas stopper is equilibrated at a higher pressure than the initial state. If there is a leak in the pipe, the reverse flow is observed but the pressure does not rise because it is not sealed.

[0011] "No gas equipment is used"
Even if it is not possible to determine whether there is no gas leak obtained under certain conditions such as "gas pressure of indoor piping is higher than supply pressure", there is a gas leak in the piping for safety confirmation even if it is not obtained for a certain period. May be provided.

[0012]

FIG. 1 shows an embodiment of the present invention. 1 is the main pipe, 2
Is the site boundary, 3 is the service pipe connecting the main pipe 1 and the gas meter 4,
Reference numeral 5 denotes an indoor pipe connecting the indoor gas tap 6 and the gas meter 4.

Reference numeral 10 denotes a backflow prevention mechanism attached to the upstream portion of the service pipe 3, and reference numeral 11 denotes a gas leak detection circuit. The detection circuit 11 makes the following determination.

When it is detected by the gas meter 4 that all the gas appliances (gas taps 6) are not used, the gas pressure is detected by the gas pressure detecting mechanism 12 incorporated in the gas meter 4 and at the same time, the backflow detecting mechanism 13 is used. When a small gas flow flowing backward from the indoor pipe 5 to the serving pipe 3 is detected, the gas pressure becomes higher than the gas pressure when the gas stopper 6 was used, and when the gas reverse flow is detected, It is determined that there is no gas leakage. On the other hand, when the backflow of the gas is detected but the rise in the pressure is not detected, it is determined that there is a gas leak from the service pipe 3 and, for example, an alarm device (not shown) is driven.

FIG. 2 is a flow when it is determined that there is no gas leakage, and FIG. 3 is a flow when it is determined that there is gas leakage.

[0016]

As described above, the present invention can detect gas leakage from the service pipe, and thus has the following effects.

A. When all the gas taps are not used, a check for gas leakage from the service pipe is automatically performed each time, so that the detection is quick in case of emergency.

B. A gas leakage detection circuit can be configured simply by installing a backflow prevention mechanism upstream of the service pipe and using a gas meter with a known gas pressure detection mechanism and a backflow detection mechanism. Cost is low.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of the present invention.

FIG. 2 is an explanatory diagram of a determination flow of no gas leakage.

FIG. 3 is an explanatory diagram of a determination flow of gas leakage.

FIG. 4 is an explanatory diagram of a conventional city gas supply system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main pipe 2 Site boundary 3 Service pipe 4 Gas meter 5 Indoor piping 6 Gas plug 10 Backflow prevention mechanism 11 Gas leak detection circuit 12 Gas pressure detection mechanism 13 Reverse flow rate detection mechanism

Claims (2)

(57) [Claims] 1. A backflow prevention mechanism is incorporated in an upstream portion of a service pipe, and a pressure detection mechanism and a backflow detection mechanism are incorporated in a gas meter. It is determined that no gas appliance is used downstream of the gas meter. When a rise in pressure is detected in the mechanism and a reverse flow is detected from the reverse flow detection mechanism at the same time, it is determined that there is no gas leakage, while a rise in pressure is not detected and a reverse flow is detected A gas leak detection method for determining that there is a gas leak. 2. The gas leak detecting method according to claim 1, wherein the pressure detecting mechanism and the backflow detecting mechanism are separately mounted near the upstream side of the gas meter.