JPH085502A - Gas leak detection device and gas meter with it - Google Patents

Abstract

PURPOSE:To provide a gas leak detection device which detects gas leak of a gas facility in a relatively short period. CONSTITUTION:Provided between a supply side gas piping 18 and a demand side gas piping 19, detects gas leak at a demand side gas facility. A gas usage expectation means 21 expecting low possibility of using the gas facility by a consumer, a shut off valve 13 with automatic open/close function which shuts off gas, and a gas pressure detection means 11 detecting the pressure on the demand side of the shut off valve 13 are provided. When a signal telling that gas usage expectation is low is inputted from the gas usage expectation means 21, the shut of valve 13 is closed, then, detection gas pressure of the gas pressure detection means 11 is monitored for a specified period. When the gas pressure drop is detected by more than certain degree, existence of gas leak is determined.

Description

Detailed Description of the Invention

The present invention relates to a gas leak detection device for gas equipment in a gas consumer such as a general household and a gas meter having the same.

[0002]

2. Description of the Related Art A conventional technique will be described by taking a gas leak detection of a gas facility in a general home as an example. Some of the city gas meters currently in use have a microcomputer function (brand name My Safe). In such a gas meter, when "the situation where the gas has not been used for 1 hour or more cannot be detected for 30 days ", the gas meter is located downstream (gas equipment such as household gas consuming equipment and piping).
It is judged that there is a slight leak of gas, and the gas supply valve is shut off by closing the gas shutoff valve provided in the gas meter.

[0003]

In other words, the condition in "" described above is "when the gas is not used for at least one hour but for 30 days, not for one day". . In other words, it is judged that there is a gas leak for the first time when the situation is reached in which "the days when gas is used almost for a month has continued". Therefore, there has been a demand for a gas leak detection device that can detect a gas leak in a shorter period. Further, in the case of My Safe described above, once the gas was cut off, the gas could not be used unless the user turned on the return switch.

An object of the present invention is to provide a gas leak detection device and a gas meter having the gas leak detection device which can detect a gas leak in a gas facility in a relatively short period of time.

[0005]

In order to solve the above-mentioned problems, a gas leakage detection device of the present invention is provided between a supply side gas pipe and a demand side gas pipe to prevent gas leakage in a demand side gas facility. A gas leak detecting device for detecting; a detecting means for detecting a gas flow rate, a gas availability determining means for determining that a customer is unlikely to use the gas facility, and an automatic opening / closing for shutting off the gas. Possible shutoff valve, gas pressure detection means for detecting the pressure on the demand side of this shutoff valve, and the shutoff when a signal indicating that gas availability is low is input from the gas availability determination means. Close the valve, and then monitor the gas pressure detected by the gas pressure detection means for a predetermined time.If it is detected that the gas pressure has dropped to some extent during this time, it is judged that there is a gas leak and a gas leak signal is issued, Low pressure detected And control means for the shut-off valve open if you did, characterized by comprising an alarm command means for issuing an alarm to the customer entered the gas leakage signal from the control means.

[0006]

The basic mechanism of gas leak detection of the gas leak detection device of the present invention is to first close the shutoff valve to isolate the gas equipment (gas consuming equipment and piping) on the demand side, and to isolate the gas pressure in the isolated gas equipment. When the gas pressure falls below a certain level within a predetermined time, it is determined that there is a gas leak in the gas equipment on the demand side.

For that purpose, it is necessary to close the shutoff valve, but it is important to find the chance. It is inconvenient for customers to close the shut-off valve when they want to use gas. Therefore, detection must be started (shut-off valve closed) in anticipation of when the customer is unlikely to use gas. That is the role of the gas availability determination means.

As a specific mode of the gas availability determining means, a flow rate signal of the gas pipe on the supply side is input from a gas meter or the like, and this signal is stored in association with a day time zone. It is possible to select a time zone in which the gas facility is least likely to be used, and to judge that the gas availability is low when the time zone is entered.

For example, no gas was used between 2 and 5 o'clock in the middle of the night (the gas flow rate was almost 0, or
If you don't want to switch on each gas equipment), if 5 days continue, the time from 2 am to 5 pm in the middle of the night is set as "the time when gas equipment is unlikely to be used". is there. Then, the gas leak detection described above is performed in consideration of this time period. By doing so, it is possible to perform accurate gas leak detection without inconvenience to consumers.

In the gas leakage detection device of the present invention, it is preferable that the gas pressure detecting means is a pressure switch that turns on or off upon detecting a predetermined pressure drop. With a high-grade gas pressure detecting means such as quantitatively detecting a pressure value and monitoring the value with a CPU or the like, the gas leak detection device is expensive, whereas such a gas switch type pressure detection device is expensive. Things are cheap.

In this pressure switch, the gas pressure detecting means is
It is preferable that the pressure immediately before the shutoff valve is detected, the pressure be set as a reference pressure, and the pressure is turned on or off when a predetermined pressure drop from the reference pressure occurs. The supply pressure of city gas differs depending on the time and the area where the customer is present (for example, the pressure range is 100 to 250 mmAq). Therefore, rather than a pressure switch that operates when a certain absolute pressure is reached, a pressure switch that turns on and off when there is a predetermined pressure drop from the reference pressure as described above, that is, a relative operation pressure switch. However, it is preferable because the pressure drop caused by the gas leakage can be grasped sharply.

In the gas leakage detecting device of the present invention, the gas pressure detecting means includes a cylinder for receiving a pressure medium,
A piston that divides the inside of the cylinder in a pressure-tight manner. Two pistons that are slidable inside the cylinder and two ends that sandwich the piston of the cylinder and that can independently take in and discharge the pressure medium are provided. A port and a piston support member that elastically supports the piston with respect to the cylinder;
And a piston displacement detecting means for detecting displacement of the piston in the cylinder.

With such a pressure switch, it is possible to detect the gas pressure difference between the demand side and the supply side, and to grasp the decrease in the gas pressure on the demand side due to gas leakage.

The gas meter of the present invention is a gas meter provided between a supply side gas pipe and a demand side gas pipe and having a gas leakage detection function for detecting gas leakage in a demand side gas facility; gas flow rate detection Means, an automatically openable shutoff valve for shutting off gas, a gas pressure detection means for detecting the pressure on the demand side of the shutoff valve, and a gas flow rate signal from the gas flow rate detection means, and this signal is input for one day. It is stored in association with the time zone of, and the gas availability is determined by selecting the time zone with the least gas facility availability during the day and determining that the gas availability is low when the time zone is entered. Means and the gas availability determination means input a signal that the gas availability is low, and when the gas is not used, the shutoff valve is closed and then the gas pressure is detected for a predetermined time. The gas pressure detected at the stage is monitored, and if it is detected that the gas pressure has dropped to some extent during this period, it is judged that there is a gas leak, and a gas leak signal is issued, and if no drop in gas pressure is detected, it is shut off. It is characterized by comprising a control means for opening the valve and an alarm command means for receiving a gas leak signal from the control means and issuing an alarm to a customer.

Gas meters often include a gas flow meter, a shutoff valve, and a control CPU. That is, many of the elements required for the gas leak detection device of the present invention are already provided in the gas meter. Therefore, when the function of the gas leak detection device of the present invention is incorporated into a gas meter, the system becomes simple and economical and easy to install.

[0016]

Embodiments of the present invention will be described below. Figure 1
It is a figure which shows the structure of the gas meter which concerns on one Example of this invention. (A) is a conceptual diagram showing an overall configuration, and (B) is a block diagram of a control system.

The gas meter 1 of FIG. 1 is provided between a supply-side gas pipe 18 for supplying city gas and a demand-side gas pipe 19. The supply-side gas pipe 18 is connected to a city gas source pipe (not shown). The demand-side gas pipe is connected to a gas consuming device (a stove, etc., not shown) via a domestic gas pipe. In the gas meter 1, an electric shutoff valve 13 for shutting off the pipe, a pressure difference detector 11 for detecting a gas pressure difference before and after the shutoff valve 13, a flow meter for measuring the flow rate of gas flowing through the pipe, a control unit 17, etc. Are arranged.

As shown in FIG. 1B, the flow rate signal indicating the flow rate of the gas captured by the flow meter 15 is input to the gas availability determining means 21 in the control unit 17. The gas availability determination means 21 stores the time signal from the clock 22 incorporated therein and the flow rate signal in association with each other in the memory 23. Specifically, the cumulative gas flow rate for each hour of the day is accumulated in time series in the storage unit assigned to that time. Then, a time zone in which the accumulated gas flow rate for the past 5 days is 0 is selected to be a time zone suitable for the gas leak inspection. Then, when the current time is in that time zone, a low gas availability signal is sent to the control means 25.

The control means 25 receives the low gas availability signal and performs the control shown in FIG. 2 and the following. FIG. 2 is a flow chart showing the control operation of the control means 25 arranged in the gas meter of FIG. First, in step 001, it is determined whether or not the gas facility availability is low, that is, whether or not a low gas availability signal is input from the gas availability determination means. If it is determined that the gas facility is not available, the gas cutoff valve is closed (step 0).
02).

Next, the pressure signal from the pressure difference detector 11 is checked to determine whether or not the pressure drop after the interruption is equal to or more than a predetermined value (step 003). The reference value of this pressure drop is stored in the memory 27 in the control means 25. When the pressure drop is a predetermined value or more, the alarm command means 31
(Fig. 1 (B)) issues a command to issue an alarm. If the pressure drop is less than the predetermined value, the process proceeds to the next step 004.

In step 004, the elapsed time after closing the shutoff valve is checked. This time is controlled by the clock 26 in the control means 25 (FIG. 1 (B)). When the predetermined time has elapsed, the process proceeds to the next step 005, and the shutoff valve is opened so that the customer can use the gas facility. If the predetermined time has not elapsed, the process returns to step 003 (gas pressure drop check), and the step is repeated again.

[0022]

As is apparent from the above description, the present invention exhibits the following effects. Since the pressure drop in the demand side gas pipe is directly detected to judge the gas leak, the period required for gas leak detection is short. It can be detected in a few hours.

Since gas leak detection is performed by selecting a time when gas availability is low, it does not cause much trouble to customers. By combining with the gas meter or incorporating it into the gas meter, the gas leak detection can be performed using the components inside the gas meter, so the gas leak detection device becomes inexpensive.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a gas meter according to an embodiment of the present invention. (A) is a conceptual diagram showing the overall configuration, (B)
Is a block diagram of a control system.

FIG. 2 is a control means 25 arranged in the gas meter of FIG.
3 is a flowchart showing the control operation of FIG.

[Explanation of symbols]

1 Gas Meter 3 Gas Leak Detector 11 Pressure Difference Detector 13 Gas Circuit Breaker 15 Flow Meter 17 Control Unit 18 Supply Side Gas Pipe 19 Demand Side Gas Pipe

Claims (6)

[Claims] 1. A gas leak detection device which is provided between a supply side gas pipe and a demand side gas pipe and detects a gas leak in a demand side gas facility; a detection means for detecting a gas flow rate; Gas availability determination means for determining that the customer is unlikely to use the gas facility, a shutoff valve that can automatically open and close the gas, and gas pressure detection that detects the pressure on the demand side of this shutoff valve Means and the gas availability determination means, when a signal that the gas availability is low, the shutoff valve is closed,
After that, monitor the detected gas pressure of the gas pressure detection means for a predetermined time,
In the meantime, when it is detected that the gas pressure has dropped to a certain extent or more, a gas leak signal is generated by determining that there is a gas leak, and a control means that opens the shut-off valve when no gas pressure drop is detected, A gas leak detection device, comprising: an alarm command unit that inputs a gas leak signal from the control unit and issues an alarm to a consumer. 2. The gas availability determining means inputs a flow rate signal of the supply side gas pipe from a gas meter or the like,
This signal is stored in association with the time zone of the day, the time zone in which the gas facility is least likely to be used in the time zone of the day is selected, and it is determined that the gas availability is low when the time zone is entered. The gas leak detection device according to claim 1. 3. The gas leakage detection device according to claim 1, wherein the gas pressure detection means is a pressure switch that turns on or off upon detection of a predetermined pressure drop. 4. The gas pressure detecting means detects the pressure immediately before the shutoff valve is closed, sets the pressure as a reference pressure, and turns on or off when a predetermined pressure drop occurs from the reference pressure.
The gas leak detection device according to claim 1, which is a pressure switch for F. 5. A gas meter, which is provided between a supply-side gas pipe and a demand-side gas pipe and has a gas leakage detection function for detecting a gas leak in a demand-side gas facility; A shutoff valve that can be opened and closed automatically, a gas pressure detection unit that detects the pressure on the demand side of this shutoff valve, and a gas flow rate signal from the above gas flow rate detection unit are input, and this signal is used as the time of day. A gas operability determination means that stores the data in association with each other, selects a time zone in which the gas facility is least likely to be used during the day, and determines that the gas availability is low when the time zone is entered, When a signal that the gas availability is low is input from the gas availability determination means and the gas is not used, the shutoff valve is closed and then the gas pressure detected by the gas pressure detection means for a predetermined time. To When a decrease in gas pressure is detected for some time during this period, it is judged that there is a gas leak and a gas leak signal is issued.If no decrease in gas pressure is detected, the shutoff valve is opened. A gas meter, comprising: a means and an alarm command means for issuing a warning to a customer when a gas leak signal from the control means is input. 6. The gas pressure detecting means is a cylinder that receives a pressure medium, and a piston that divides the inside of the cylinder in a pressure-tight manner. The piston is provided slidably in the cylinder and the piston of the cylinder. Two ports provided at both ends capable of independently taking in and discharging the pressure medium, a piston support member for elastically supporting the piston with respect to the cylinder, and a piston displacement detection means for detecting displacement of the piston in the cylinder. 1 to 1.
5. The gas leak detection device or gas meter according to any one of 5 above.