JP2000111040A - Gas shutting-off apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shut off gas even at the time of a fault caused by a damage of piping without limiting to a fire by eliminating a complicated wiring work and improving reliability. SOLUTION: Piping 23 for connecting an outdoor gas meter 23 to an indoor combustor 31 and a housing of the meter 23 are constituted of a conductive material. A driving circuit 33 having a resistance detector is contained in the meter 23, one end of the detector is grounded with a wiring 45, and piping 27 near the combustor 31 is grounded via a wiring 47. The detector detects an electric resistance of the piping 27. If this detected value has a difference of a predetermined value or more from that at the time of a normal state, a resistance discriminator contained in the circuit 33 discriminates a fault such as a rise of the electric resistance value caused by a fire or change of the electric resistance value caused by a damage of the piping 27, shuts off a gas shut-off mechanism 23c in the meter 23 to stop supplying the gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas shut-off device for shutting off gas supply to a combustor installed indoors when an abnormality such as a fire occurs.

[0002]

2. Description of the Related Art FIG. 3 is a diagram showing the general construction of a conventional gas shut-off device. A gas inlet 5a of a gas meter 5 is connected to a gas cylinder 1 through a pressure regulator 3 via a pipe 7 in a gas cylinder 1 containing propane gas.
The gas outlet 5b is connected to a combustor 13 in a house 11 via a pipe 9.

A fire alarm 15 is installed in the house 11, and the fire alarm 15 and a drive circuit 5 c built in the gas meter 5 are connected by a wiring 17.
In the vicinity of the gas inlet 5a of the gas meter 5, a gas shutoff mechanism 5d for shutting off the inflow of gas is incorporated.
d is operated by the drive circuit 5c.

[0004] In the above gas shut-off device, the house 11
When a fire occurs, the fire alarm 15 detects the fire, and this detection signal is transmitted via the wiring 17 to the drive circuit 5c.
It is taken in. Upon receiving the detection signal, the drive circuit 5c operates the gas cutoff mechanism 5d to cut off the flow of gas from the gas cylinder 1 into the gas meter 5, and stops the supply of gas to the combustor 13.

[0005]

However, such a conventional gas shut-off device has the following problems.

(1) The drive circuit 5c in the gas meter 5 installed outdoors and the fire alarm 15 installed indoors need to be connected by the wiring 17, and the connection work is complicated and the connection cost is high. It will be enormous.

(2) Even if the fire alarm 15 malfunctions, the gas shut-off mechanism 5d is shut off and the gas supply is stopped, resulting in a decrease in reliability.

(3) Only in case of fire, the piping 9
No consideration is given to its own anomalies.

SUMMARY OF THE INVENTION It is an object of the present invention to eliminate the need for complicated connection work, to improve reliability, and to shut off gas even in the event of an abnormality due to a damaged pipe.

[0010]

In order to achieve the above object, the invention of claim 1 is directed to a gas supply system which supplies gas to a combustor to which gas is supplied through a gas supply pipe made of a conductive material. A gas shutoff mechanism for shutting off the supply, a resistance detection circuit for detecting the electric resistance of the gas supply pipe between the gas supply facility side and the gas combustor side, and an electric resistance value detected by the resistance detection circuit A control circuit is provided for comparing the set electrical resistance value of the gas supply pipe with the normal value to determine an abnormality, and executing a gas shut-off by the gas shut-off mechanism in the event of an abnormality.

According to the gas shut-off device having such a configuration,
When the resistance detection circuit detects the electric resistance of the gas supply pipe, the control circuit compares the detected electric resistance value with a preset normal electric resistance value to determine whether or not the electric resistance is abnormal. In the event of an abnormality, a signal is output to the gas shutoff mechanism to shut off the gas supply, assuming that the change in resistance is caused by a rise in the temperature of the gas supply pipe due to a fire or a change in resistance due to breakage of the gas supply pipe.

According to a second aspect of the present invention, in the configuration of the first aspect, the end of the gas supply pipe whose electric resistance is to be measured is connected to ground at the end of the combustor, and the end of the gas supply facility is connected to the ground. It was connected to ground via a resistance detection circuit.

According to the above configuration, the electric resistance between both ends of the grounded gas supply pipe is detected, and abnormality is determined based on the detected electric resistance value.

According to a third aspect of the present invention, in the configuration of the first or second aspect, the gas shut-off mechanism is incorporated in a gas meter for measuring a flow rate of gas supplied from the gas supply equipment to the combustor side. Inside, a resistance detection circuit and a control circuit were provided.

According to the above configuration, the electric resistance of the gas supply pipe connecting the gas meter and the combustor is detected by the resistance detecting circuit built in the gas meter, and the electric resistance is built in the gas meter based on the detected electric resistance value. The control circuit determines the abnormality. In the event of an abnormality, the gas shutoff mechanism in the gas meter operates to shut off the gas supply.

According to a fourth aspect of the present invention, in the configuration of the third aspect, the gas meter housing is made of a conductive material and is electrically connected to a gas supply pipe also made of the conductive material. Was connected to the housing of the gas meter.

According to the above configuration, by connecting the resistance detection circuit to the housing of the gas meter, the end of the gas supply pipe on the gas supply facility side is grounded via the resistance detection circuit.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an overall configuration diagram of a gas shut-off device showing one embodiment of the present invention. A gas inlet 23a of a gas meter 23 is connected to a gas cylinder 19 containing propane gas via a pressure regulator 21 via a pipe 25, and a gas outlet 23b is connected to a gas outlet 23b via a pipe 27 constituting a gas supply pipe. The combustor 31 in the house 29 is connected. Housing and piping 27 of the gas meter 23
Are made of a conductive material, and both are in an electrically conductive state. Further, the gas cylinder 19, the pressure regulator 21, and the gas meter 23 constitute a gas supply facility.

In the vicinity of the gas inlet 23a of the gas meter 23, a gas shut-off mechanism 23c composed of a shut-off valve for shutting off gas inflow is built in. The gas cut-off mechanism 23c is driven by a drive circuit 33 built in the gas meter 23. Operate.

As shown in FIG. 2, the drive circuit 33 includes a resistance detection circuit 35 for detecting the electric resistance of the pipe 27 between the gas meter 23 and the combustor 31, and a specified electric resistance value of the pipe 27 in a normal state. And a control circuit for comparing the electric resistance value detected by the resistance detection circuit 35 with the specified electric resistance value stored in the storage means 37 to determine whether or not there is an abnormality. Resistance determination circuit 3
9, a switching circuit 41 that is turned on when the resistance discriminating circuit 39 determines that there is an abnormality, and a switching circuit 41.
And a shutoff valve output circuit 43 for performing a gas shutoff operation by the gas shutoff mechanism 23c in response to the output signal.

The resistance detection circuit 35 has one terminal connected to the wiring 4
5 and the other terminal is connected to the housing of the gas meter 23, whereby the resistance detection circuit 35 is connected to the pipe 27 through the housing of the gas meter 23.
Is electrically connected to the terminal.

The indoor pipe 27 near the combustor 31 is grounded by a wiring 47. Thereby, the resistance detection circuit 35 can detect the electric resistance of the conductive portion from the housing of the gas meter 23 to the pipe 27 at the portion where the wiring 47 is connected.

Next, the operation will be described. First, the electrical resistance of the pipe 27 in a normal state is detected by the resistance detection circuit 35, and the detected specified electrical resistance value is stored in the storage circuit 37. Here, when a fire occurs in the house 29, the temperature around the pipe 27 rises, and the temperature of the pipe 27 itself also rises. As a result, the electric resistance value of the pipe 27 increases, and the increased electric resistance value is compared with the normal specified electric resistance value stored in the storage means 37 by the resistance determination circuit 39. Here, when the detected electric resistance value is larger than the specified electric resistance value by a predetermined value or more, it is assumed that the temperature of the pipe 27 has risen due to the fire, and the resistance discrimination circuit 39 determines that there is an abnormality.

The resistance determining circuit 39 which has determined that an abnormality has occurred,
The switching circuit 41 is turned on to shut off the gas shutoff mechanism 23c by the shutoff valve output circuit 43, and the flow of gas into the gas meter 23 is stopped. This allows
The supply of gas to the combustor 31 in the event of a fire is stopped, and a secondary disaster due to gas leakage is avoided beforehand.

Thus, when a fire occurs, the gas shutoff mechanism 2
When the gas supply is stopped by operating 3c, in the above embodiment, the resistance detection circuit 35 built in the gas meter 23 and the pipe 27 near the combustor 31 are
The wirings 45 and 47 may be connected to the ground, respectively. This eliminates the need for the complicated work of connecting the indoor fire alarm and the outdoor gas meter by wiring as in the conventional case shown in FIG. Can be suppressed.

Further, since the occurrence of a fire is determined based on the change in the electric resistance value of the pipe 27, a reduction in reliability is avoided irrespective of erroneous determination of the fire alarm.

Even when the pipe 27 is broken as another abnormal condition after the occurrence of a fire, the electric resistance value of the pipe 27 changes from the normal value. The changed electric resistance value is compared with the specified electric resistance value stored in the storage means 37 by the resistance discriminating circuit 39. If the specified electric resistance value has changed by a predetermined value or more, the abnormal electric resistance value is determined. Then, the gas supply mechanism 25c is operated to stop the gas supply in the same manner as in the case of the fire described above.

[0029]

As described above, according to the first aspect of the present invention, an abnormality such as the occurrence of a fire is determined based on a change in electric resistance of a gas supply pipe from a gas supply facility to a combustor. This eliminates the need for complicated wiring work between the fire alarm installed indoors and the gas meter installed outdoors as in the past, thus reducing the cost of wiring and causing malfunctions in the fire alarm. Even so, the detection of the electric resistance value is not affected, and the reliability is improved. In addition, when the gas supply pipe is damaged in addition to a fire, the electric resistance of the gas supply pipe changes, so it is possible to judge that the gas supply pipe is broken and to stop the gas supply. it can.

According to the second aspect of the present invention, the connection operation includes the steps of: connecting the end of the gas supply pipe on the combustor side and the resistance detection circuit to
Since each of them may be connected to the ground, it is easy, and the connection cost can be extremely reduced.

According to the third aspect of the present invention, the electric resistance value of the gas supply pipe is detected and the abnormality is determined by the resistance detection circuit and the control circuit built in the gas meter. To stop the gas supply.

According to the fourth aspect of the present invention, by connecting the resistance detection circuit to the housing of the gas meter, electrical connection between the end of the gas supply pipe on the gas supply facility side and the resistance detection circuit can be performed.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a gas shut-off device showing one embodiment of the present invention.

FIG. 2 is a control block diagram of the gas shut-off device of FIG.

FIG. 3 is an overall configuration diagram of a gas shut-off device showing a conventional example.

[Explanation of symbols]

 Reference Signs List 19 gas cylinder (gas supply equipment) 21 pressure regulator (gas supply equipment) 23 gas meter (gas supply equipment) 23c gas shutoff mechanism 27 pipe (gas supply pipe) 31 combustor 35 resistance detection circuit 39 resistance discrimination circuit (control circuit)

Claims (4)

[Claims] 1. A gas shut-off mechanism for shutting off gas supply from a gas supply facility to a combustor to which gas is supplied via a gas supply pipe made of a conductive material, and a gas supply facility side and a gas combustor side And a resistance detection circuit for detecting the electrical resistance of the gas supply pipe between the, the electrical resistance value detected by the resistance detection circuit and the normal state of the electrical resistance value of the gas supply pipe to determine an abnormality A control circuit for causing the gas shut-off mechanism to shut off gas when an abnormality occurs. 2. A gas supply pipe whose electric resistance is to be measured,
2. The gas shut-off device according to claim 1, wherein the end on the combustor side is grounded, and the end on the gas supply facility side is grounded via a resistance detection circuit. 3. The gas shut-off mechanism is incorporated in a gas meter for measuring a flow rate of a gas supplied from a gas supply facility to a combustor side, and a resistance detection circuit and a control circuit are provided in the gas meter. The gas shut-off device according to claim 1 or 2, wherein 4. The gas meter housing is made of a conductive material and is electrically connected to a gas supply pipe also made of a conductive material, and a resistance detection circuit is connected to the gas meter housing. Item 3. The gas shut-off device according to Item 3.