JPH0222668Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a differential pressure sensor that detects gas leakage due to an open downstream shutoff valve or damage to gas piping.

If the gas supply is cut off in the event of an emergency such as an earthquake, gas leak, or fire, or if the gas supply is cut off at the service pipe of a building to ensure safe gas use, it is necessary to prevent raw gas from escaping when restarting the gas supply. Check whether downstream shut-off valves are closed to prevent
It is necessary to check whether the gas piping is damaged.

(Prior art) As an example of a method for automatically detecting gas leakage at the time of recovery when the building is large and the downstream volume of the gas piping is relatively large, it is disclosed in Japanese Patent Publication No. 51-42781 and shown in Fig. 2. There is a method of detecting the differential pressure between the balance tank and the downstream piping, as illustrated in .

In this method, when returning, the return button on the control panel is pressed to first open the shutoff valve 12 of the gas pipe 1, and after a certain period of time, the valve 6 inserted into the flow path 5 connecting the gas pipe 12 and the balance tank 15 is closed. , monitor whether a difference in gas pressure occurs between the balance tank 15 and the downstream side of the gas pipe due to this closed circuit,
If a difference occurs, the differential pressure sensor 13 sends a signal to the control panel to notify it of the abnormality and to lock the shutoff valve 12 from opening.

The basic principle of the differential pressure sensor 13 used in this method is that pressure on the upstream side, that is, the high pressure side, of the gas pipe 12 is applied to the compartment 3 on one side of the thin film diaphragm 2, while the pressure on the upstream side, that is, the high pressure side, is applied to the compartment 3 on the other side of the diaphragm 2. Pressure on the downstream side, that is, the low pressure side, of the gas pipe 12 is applied to 4, and the movement or deformation of the diaphragm 2 due to the differential pressure between the internal pressures of the two compartments 3 and 4 is converted into an electric signal and detected.

(Problem to be solved by the invention) However, with this type of operation, when detecting a differential pressure of several mm of water column, the diameter of the diaphragm 2 becomes relatively large, and the movement of the diaphragm 2 causes the differential pressure sensor to A volumetric expansion occurs in the high pressure side compartment 3 of. Therefore, a pressure drop corresponding to the volume expansion occurs in the balance tank 15 communicating with the high pressure side compartment 3.

In order to keep the pressure drop in the balance tank 15 below the allowable accuracy of the differential pressure for detecting it, it is necessary to set the volume of the balance tank 15 to be considerably large. According to Boyleschallard's law, for example, 5mm
Detects the differential pressure in the water column and reduces the pressure drop on the high pressure side by 0.5mm
If a water column is desired, the required volume of the balance tank will be 2x10 ⁴ of the expansion volume. Therefore,
An increase in the size of the entire device is unavoidable.

Therefore, the purpose of the present invention is to move the diaphragm of the differential pressure sensor body so that the high pressure side compartment expands in volume.
can prevent a pressure drop from occurring in the compartment;
It is an object of the present invention to provide a differential pressure sensor for detecting gas leakage, which allows the entire device to be miniaturized.

(Means for Solving the Problems) The following will be explained using reference numerals in the attached drawings. The gist of the differential pressure sensor for detecting gas leakage of the present invention is that
diaphragm 2 due to the differential pressure between the pressure on the high pressure side of the gas pipe 1 applied to the gas pipe 1 and the pressure on the low pressure side of the gas pipe 1 applied to the compartment 4 on the other side of the diaphragm 2.
In the differential pressure type sensor device for detecting movement or deformation of the gas pipe, an internal pressure stabilizer is provided in which a flow path 5 connecting the high pressure side compartment 3 to the gas pipe 1 includes a valve 6 for opening and closing the flow path 5, and a driven diaphragm 8. 7 is inserted, and the compartment 9 on one side of the driven diaphragm 8 is communicated with the high pressure side compartment 3, and the driven diaphragm 8 is inserted into the internal pressure stabilizer 7 in accordance with the internal pressure of the compartment 9. An adjustment spring 11 is provided to hold the cylinder body 10 at an intermediate position.

(Function) When a detection signal of an abnormal situation is sent from a detector such as a seismic sensor, gas leak alarm, or fire alarm to a controller (not shown), the controller closes the shutoff valve 12 of the gas pipe 1. Close the circuit immediately. After the abnormal situation ends, the return button on the control panel is pressed to open the shutoff valve 12 of the gas pipe 1 and the valve 6 of the flow path 5, and after a certain period of time, both valves are closed again. As a result, the gas pressure in the compartment 9 of the internal pressure stabilizer 7 and the compartment 3 of the differential pressure sensor body 13 becomes the same as the gas pressure in the gas pipe 1.

Here, the gas pressure on the low pressure side of the gas pipe introduced into the other compartment 4 of the differential pressure sensor main body 13 and the gas pressure in the compartment 3 are compared. When the gas pressure in the compartment 4 is low, the diaphragm 2 is moved and deformed to the right in the drawing, and the electrical signal conversion means 1
An abnormality detection signal is sent to the controller via 4,
A buzzer or the like on the monitoring panel notifies you that there is damage to the downstream gas piping or that the downstream shutoff valve remains open.

If there is no differential pressure between the gas pressures in the compartments 4 and 3 of the differential pressure sensor body 13, or after confirming safety by closing the shut-off valve you forgot to close or repairing any damaged parts, the controller shuts off. The valve 12 is opened, thereby restarting the gas supply.

As described above, the compartment 4 of the differential pressure sensor main body 13
When there is a pressure difference between the gas pressure in the compartment 3 and the gas pressure in the compartment 3, the diaphragm 2 moves toward the compartment 4, but at this time, the compartment 9 of the internal pressure stabilizer 7 communicates with the compartment 4. Therefore, the driven diaphragm 8 of the internal pressure stabilizer 7 is pushed by the adjustment spring 11 and moves in the same direction.

Therefore, the combined volume of both the compartment 3 of the differential pressure sensor main body 13 and the compartment 9 of the internal pressure stabilizer 7 does not increase or decrease, and the pressure in the compartment 3 due to movement of the diaphragm 2 is prevented from decreasing.

(Example) In the example shown in FIG. 1, a pressure switch was used as the main body of the differential pressure sensor, but the type and structure of the differential pressure sensor are not particularly limited to this.
Any known material can be selected and used as appropriate. In addition, the shutoff valve 12 of the gas pipe 1 and the valve 6 of the flow path 5 are constituted by electromagnetic valves.

The diameter of the diaphragm 2 of the differential pressure sensor body and the diameter of the driven diaphragm 8 of the internal pressure stabilizer 7 are the same or almost the same.

(Effect of the invention) As described above, in the differential pressure sensor for gas leak detection of the present invention, the high pressure side compartment 3 of the differential pressure sensor main body 13
A valve 6 for opening and closing the flow path 5 and an internal pressure stabilizer 7 having a built-in driven diaphragm 8 are inserted into the flow path 5 connecting the flow path 5 to the gas pipe 1, and the compartment 9 on one side of the driven diaphragm 8 is inserted into the flow path 5 connected to the gas pipe 1. A driven diaphragm 8 is connected to the internal pressure stabilizer 7 in communication with the high pressure side compartment 3, and the driven diaphragm 8 is connected to the compartment 9.
Since the adjustment spring 11 is equipped to hold the inner cylinder main body 10 at an intermediate position corresponding to the internal pressure of The volumetric expansion of the high-pressure side compartment 3 does not cause a pressure drop in the compartment 3.

That is, by adding the internal pressure stabilizer 7, the volumetric expansion of the compartment 3 is compensated for by the volume reduction of the compartment 9.
It is possible to perform highly accurate differential pressure detection, and
Since the diameter of the driven diaphragm 8 of the internal pressure stabilizer 7 is approximately the same as the diameter of the diaphragm 2 of the differential pressure sensor body 13, the entire device can be made smaller compared to conventional devices that require a large volume balance tank. Yes, the installation space can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a differential pressure sensor for gas leak detection according to an embodiment of the present invention, and Fig. 2 is a schematic diagram of a differential pressure sensor for gas leak detection using a conventional balance tank. . 1... Gas piping, 2... Diaphragm, 3, 4
...Differential pressure sensor body compartment, 5...Flow path, 6...
... Valve, 7 ... Internal pressure stabilizer, 8 ... Driven diaphragm, 9 ... Compartment of internal pressure stabilizer, 10 ... Inner cylinder main body, 11 ... Adjustment spring, 12 ... Gas piping cutoff valve, 13 ... ...Differential pressure sensor body.

Claims (1)

[Scope of utility model registration request] The pressure on the high pressure side of the gas pipe 1 is applied to the compartment 3 on one side of the diaphragm 2 of the differential pressure sensor main body 13, the pressure on the low pressure side of the gas pipe 1 is applied to the compartment 4 on the other side of the diaphragm 2, In a differential pressure sensor for detecting gas leakage that detects movement or deformation of a diaphragm 2 due to the differential pressure between compartments 3 and 4, a channel 5 connecting the high pressure side compartment 3 to the gas pipe 1 is opened and closed. A valve 6 and an internal pressure stabilizer 7 having a built-in driven diaphragm 8 are inserted, and the compartment 9 on one side of the driven diaphragm 8 is communicated with the high pressure side compartment 3. A differential pressure sensor for detecting gas leakage, characterized in that it is equipped with an adjustment spring 11 that holds the diaphragm 8 at an intermediate position of the inner cylinder body 10 in accordance with the internal pressure of the compartment 9.