JPH0727659A - Gas leak detection method - Google Patents

Abstract

(57) [Abstract] [Purpose] To obtain a gas leak detection method capable of detecting a minute amount of gas leak and not malfunctioning. [Structure] A pressure measuring device 2, a flow rate measuring device 3, and a supply gas pressure fluctuation device 10 are incorporated in a gas meter 1, a pressure fluctuation is applied to a supply gas, fluctuations of gas pressure and flow rate at this time are measured, and an average value And the average value before the fluctuation are compared, and if the fluctuation range is large, it is determined that there is a gas leak.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is mainly applied to a method for detecting a gas leak occurring in a city gas indoor piping and a gas appliance.

[0002]

2. Description of the Related Art In the case of a consumer of city gas, a gas meter is attached to the end of a lead-in pipe (serving pipe) drawn from a main pipe, and the gas meter and an indoor gas tap are connected by an indoor pipe. There is. In such a situation, the following two methods are generally practiced as means for detecting gas leakage from indoor piping and gas appliances.

A. When the flow rate of the gas passing through the gas meter is abnormally high, that is, when the gas meter detects a certain flow rate or more, it is determined that there is a gas leak and the gas is shut off.

B. The continuous use safety time of the gas appliance connected to the gas tap is set in advance, and the gas is shut off when the continuous use safety time is exceeded.

Incidentally, Table 1 shows an example of criteria for judging that there is a gas leak (gas ejection accident) when detecting the abnormal gas flow rate described in the above a, and Table 2 shows the continuation described in the above b. It shows an example of a standard for determining a gas leak by monitoring a usage safety time.

[0006]

[Table 1]

[0007]

[Table 2]

[0008]

However, the known examples described above have the following drawbacks.

With respect to a, when a very small amount is flowing, it cannot be detected as a gas leak, so that the gas may continue to flow without interruption, leading to a gas accident. On the contrary, when a gas appliance using a high calorie gas amount is used for a long time, it may be judged as a gas leak and shut off.

Regarding b, it is possible to make a decision to prevent a gas leak accident by changing the continuous use safety time according to the amount of gas used, but a device with a larger amount of gas used has a shorter use time. This is not the case, so it is highly possible that a malfunction occurs.

An object of the present invention is to propose a gas leak detection method capable of reliably detecting even a small amount of gas leak and not shutting off gas when the gas appliance is normally used. is there.

[0012]

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

A gas appliance is attached to the terminal of the gas leak inspection section, and the gas appliance is in a used state,
A supply gas pressure fluctuation device is attached to the upstream part of the gas leak inspection section, and a gas pressure measurement device and a flow rate measurement device are installed in the gas leakage inspection section, and the supply gas pressure is actively changed by the supply gas pressure fluctuation device, The pressure fluctuation and flow rate fluctuation in the gas leak inspection section that occurs at this time are measured by the gas pressure measuring device and the gas flow measuring device respectively to obtain the respective measured values, and this average value is compared with the average value before the fluctuation. If the difference between the average values is within a certain range, it is determined that there is a gas leak, and if the difference is below, it is determined that there is no gas leak.

[0014]

[Function] In addition to the gas flow rate, a gas meter with a mechanism for detecting changes in the gas supply pressure corrects changes in the gas flow rate due to changes in the gas supply pressure on the instrument side when the gas supply pressure is actively changed. Without such a mechanism, the fluctuation of the gas supply pressure causes the fluctuation of the gas flow rate as it is. This is the case when there is a gas leak. Therefore, when a gas leak occurs, there is a correlation between the gas supply pressure and the gas flow rate.

On the other hand, a gas water heater, a bath kettle, etc. have a built-in gas governor in the equipment, and the gas governor absorbs the fluctuation of the gas supply pressure. It does not appear. Therefore, there is no correlation between the gas supply pressure and the gas flow rate. The present invention detects gas leakage by focusing on the correlation between gas supply pressure and gas flow rate.

This will be described with reference to FIGS. 3 to 8. FIG. 3 shows that the supply gas pressure fluctuates when the bath kettle with a governor is used, the supply pressure is constant, and the gas flow rate is stable. When the pressure fluctuations are applied stepwise by the device, the pressure measuring device can detect the pressure fluctuations corresponding to the applied pressure fluctuations. This pressure fluctuation is shown in FIG. There is almost no difference with 4.
Further, the flow rate fluctuation at this time is the same as in the case where there is no leakage in FIG.
There is almost no visual difference even if there is a noise. However, in order to remove the noise in FIGS. 5 and 6 and to quantitatively determine that the step has occurred, the fluctuation of By averaging 100 pieces of data before and after, data can be converted into the case of no leak in FIG. 7 and the case of leak in FIG. As is clear from FIG. 7, when there is no gas leak, the fluctuation of the flow rate follows the fluctuation of the pressure within ± 4, but when there is a gas leak, it is clear from FIG. To
The followability of flow rate fluctuations to pressure fluctuations is very different. Gas leaks can be detected from this data.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is for explaining an embodiment of the present invention. 1 is a gas meter (microcomputer meter),
In the gas meter 1, a gas pressure measuring device 2 and a gas flow measuring device 3, a supply gas pressure changing device (eg, governor, valve) 10 capable of actively changing pressure, a gas shutoff valve 4, a pressure / flow rate calculating circuit 5 are provided. -1, gas leak determination circuit 5-
2 is incorporated. 6 is a supply pipe, 7 is an indoor pipe that connects the header 8 and the gas appliance 9 with a governor, and the supply gas that has entered the gas meter 1 from the supply pipe 6 is measured by the gas meter 1 and then the header 8 → indoors Flows from pipe 7 to gas appliance 9.

In the above embodiment, when any one of the gas appliances 9 is used and the supply gas pressure changing device 10 is changed stepwise, the pressure / flow rate calculating circuit 5-1 is operated by the pressure measuring device. 2 and the fluctuating pressure value and the flow rate value input from the flow rate measuring device 3, an average value is obtained, and this average value is compared with the average value before the fluctuation, and when this difference is a certain value or more, the gas leakage determination circuit 5- Send a signal to 2. Upon receiving this signal, the gas leakage determination circuit 5-1 drives the alarm device and at the same time closes the gas cutoff valve 4. Figure 2 shows the pressure
It is a determination flow of the flow rate calculation circuit 5-1.

[0019]

As described above, the present invention actively applies pressure fluctuations to the supply gas during use of the gas appliance, measures the fluctuations in pressure and flow rate at this time, and determines the direction of fluctuations in pressure and flow rate ( Increase
Decrease) and the fluctuation range to determine the presence or absence of gas leakage, so this determination can be performed arbitrarily during use of the gas appliance.
Therefore, it is possible to strengthen the monitoring posture for gas leakage, and to perform gas leakage inspection that is not affected by the size and size of gas appliances and how they are used.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram of a determination flow.

FIG. 3 is an explanatory diagram of a gas pressure fluctuation in an inspection section.

FIG. 4 is an explanatory diagram of gas pressure fluctuations in an inspection section when there is a gas leak.

FIG. 5 is an explanatory diagram of a gas flow rate variation in the inspection section.

FIG. 6 is an explanatory diagram of gas flow rate fluctuation in the inspection section when there is a gas leak.

FIG. 7 is an explanatory diagram of organized data when there is no gas leakage.

FIG. 8 is an explanatory diagram of organized data when there is a gas leak.

[Explanation of symbols]

 1 Gas Meter 2 Gas Pressure Measuring Device 3 Gas Flow Measuring Device 4 Gas Cutoff Valve 5-1 Pressure / Flow Rate Calculation Circuit 5-2 Gas Leakage Judgment Circuit 6 Service Pipe 7 Indoor Pipe 8 Header 9 Gas Appliance with Governor 10 Active Supply Gas pressure fluctuation device

Claims (1)

[Claims] 1. A gas appliance is attached to a terminal of the gas leak inspection section, the gas appliance is in a use state, a supply gas pressure fluctuation device is attached to an upstream portion of the gas leak inspection section, and the gas leak inspection section is provided. A gas pressure measuring device and a flow rate measuring device are installed inside, and the supply gas pressure fluctuation device actively fluctuates the supply gas pressure. Measure each with the measuring device and the gas flow measuring device to obtain each measured value and compare this average value with the average value before fluctuation.If the difference between the average values is within a certain range, it is judged that there is a gas leak. Then
A gas leak detection method that determines that there is none in the following cases.