JPH04297993A - Gas leakage detector - Google Patents

Abstract

PURPOSE:To detect the leakage of gas from a gas flow passage on the upstream side of a gas meter in the early stage by a simple means. CONSTITUTION:The flow rate of gas is monitored by a gas meter 5, and a flow rate signal transmitter 8 transmits a flow rate signal. A leakage tone of gas is monitored by a leakage tone detecting sensor 4, and a leakage signal transmitter 6 transmits a leakage signal. In a microcomputer 7, the leakage of gas is monitored with a leakage discriminating means 15. When 'absence' of the flow rate signal is discriminated by a flow rate signal discriminating means 13 and the leakage signal from the leakage signal transmitter 6 is inputted, a reference leakage signal stored in a reference leakage signal storage means 14 and the received leakage signal are compared with each other to not only estimate the extent of leakage but also transmit a leakage occurrence signal.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas leak detection device for detecting gas leak from a gas flow path upstream of a gas meter.

0002

BACKGROUND OF THE INVENTION In recent years, gas explosion accidents caused by gas leaks from gas pipes have been occurring frequently. In particular, the distance between gas storage facilities and gas usage facilities is long, such as hospitals and schools.
If these areas are connected via gas pipes buried underground, there is a risk that cracks may occur in the buried pipes due to corrosion or uneven ground subsidence, resulting in gas leakage. Conventionally, in order to detect gas leakage from such a gas flow path, a pressure sensor is placed inside the gas flow path, and inspection is carried out at a predetermined period, for example, once a year or once every two years. , Close both ends of the gas flow path to be inspected and reduce the pressure inside the gas flow path to 850 mmH2.
Gas leaks are detected by raising the pressure to around 0.0 O and inspecting for the presence or absence of a pressure drop due to a leak. There is also a method of detecting gas leakage by disposing a flow rate sensor in the gas flow path and constantly monitoring the gas flow rate to monitor for abnormalities in the gas flow rate that would not occur during normal gas use.

0003

[Problems to be Solved by the Invention] However, in the method of detecting gas leaks through periodic inspections, leaks that occur immediately after inspections are overlooked until the next inspection, and early detection is not possible. In other words, there is no leakage during regular inspections, or
If the leak is not discovered because it is a very small amount of leakage, the accumulated gas may reach a dangerous amount due to leakage over a long period of time, or the buried pipes will corrode and the amount of leakage will increase over time, creating a risk of a gas explosion. arise. In addition, with the method of detecting gas leaks by constantly monitoring the gas flow rate with a flow sensor, if a leak occurs upstream of the flow sensor, the flow sensor will not function, so leaks downstream of the flow sensor will be detected. Even if possible, leaks on the upstream side cannot be detected. As explained above, in facilities such as hospitals and schools, the distance from the gas storage facility to the gas usage facility is long, and the distance between them is often communicated by gas pipes buried underground. In such cases, the flow rate sensor is usually built into a gas meter of the gas-using facility or fixed to the wall of the gas-using facility. Therefore, even if a leak occurs in the buried pipe, the flow rate sensor does not function and the gas leak cannot be detected.

0004

[Means for Solving the Problems] The present invention has been proposed in view of the above, and is intended to detect gas leakage from the gas flow path on the upstream side of a gas meter by a simple means and at an early stage. a flow rate sensor that detects the flow rate of gas flowing through the gas flow path; a flow rate signal transmitter that transmits the gas flow detected by the flow rate sensor as a flow rate signal; and a leakage sound detection sensor that detects the sound of gas leaking from the gas flow path. A gas leak detection device comprising a leak signal transmitter that transmits leak sound detected by a leak sound detection sensor as a leak signal, and a calculation means electrically connected to the flow rate signal transmitter and the leak signal transmitter, The calculation means includes a flow rate signal determining means for determining the presence or absence of a flow rate signal from a flow signal transmitter, a reference leak signal storing means for storing a leak signal pattern based on a leakage amount determined in advance through an experiment, and a flow rate signal determining means When the flow rate signal is determined to be "absent" by the means, the presence or absence of a leakage signal from the leakage signal transmitter is determined, and when a leakage signal is received, the leakage signal and the reference leakage signal are stored in the reference leakage signal storage means. The present invention is characterized by comprising a leakage determining means that compares the pattern of the leakage signal to estimate the amount of leakage and transmits a leakage occurrence signal.

[0005]

[Operation] The flow rate sensor monitors the gas flow rate in the gas flow path, and when the flow rate sensor detects the gas flow, the flow rate signal transmitter emits a flow rate signal. The leakage sound detection sensor monitors the leakage sound generated when gas leaks from the gas flow path, and when the leakage sound detection sensor detects the leakage sound, the leakage signal transmitter transmits a leakage signal. The reference leakage signal storage means of the calculation means stores leakage signal patterns based on several types of leakage amounts determined in advance through experiments. and,
When the leakage determination means receives a leakage signal when the flow rate signal is determined to be "absent" by the flow rate signal determination means, the leakage signal is compared with the leakage signal pattern stored in the reference leakage signal storage means, It estimates the amount of leakage and sends a leakage signal.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below based on embodiments shown in the drawings. FIG. 1 is a schematic block diagram of an embodiment of a gas leak detection device according to the present invention. This gas leak detection device 1 is provided with a cutoff valve 3 in the middle of a gas flow path 2, and provided with a leakage sound detection sensor 4 upstream of the cutoff valve 3 to detect the sound of gas leaking from the gas flow path 2. A gas meter 5 that is a flow rate sensor that detects the flow rate of gas flowing into the gas flow path 2 is provided downstream of the cutoff valve 3 . Then, the leakage sound detection sensor 4 is electrically connected to a microcomputer 7 which is a calculation means via a leakage signal transmitter 6, and the gas meter 5 is electrically connected to the microcomputer 7 via a flow rate signal transmitter 8. do. In addition, a display section 9 for displaying an abnormality, etc., and a cutoff valve 3 for cutting off the gas flow path 2 are electrically connected to the microcomputer 7.
Drive power is supplied from a battery 10. A return safety device 11 for returning the cutoff valve 3 is connected to the cutoff valve 3 . Further, on the upstream side of the gas flow path 2, a pressure regulator 12 is provided for adjusting the gas pressure flowing into the gas flow path 2 to a constant value.

The above-mentioned microcomputer 7 is shown in FIG.
As shown in FIG. 2, a flow rate signal determining means 13 determines the presence or absence of a flow rate signal from the flow rate signal transmitter 8, a reference leak signal storage means 14 stores a leak signal pattern based on a leakage amount determined in advance through experiments, When the flow rate signal determining means 13 determines that the flow rate signal is "absent", it is determined whether or not there is a leak signal from the leak signal transmitter 6, and when a leak signal is received, the leak signal and the reference leak signal are determined. Leak determination means 15 which compares the leakage signal pattern stored in storage means 14 to estimate the amount of leakage and transmits a leakage signal, and storage means which stores leakage signals etc. from leakage signal transmitter 6. 16, a first timer 17, a second timer 18, etc., which generate timing for determining leakage.

The leakage sound detection sensor 4 described above is composed of, for example, an ultrasonic microphone, and detects the leakage sound from the gas flow path 2 and converts it into an electrical signal. Further, the flow rate signal transmitter 8 converts the mechanical movement of the gas meter 5 into an electrical signal every time the gas meter 5 rotates once. To explain the case where this flow rate signal transmitter 8 is installed in a membrane type gas meter, the flow rate signal transmitter 8 consists of a membrane driven by the flow of gas, a magnet that rotates in conjunction with the movement of this membrane, and a magnet that rotates in conjunction with the movement of this membrane. It consists of a reed switch that detects movement and turns on and off repeatedly. When the magnet rotates in response to the gas flow, the magnet approaches or moves away from the reed switch, turning the reed switch on and off. Sends a pulsed flow signal.

The pressure regulator 12 is a device for adjusting the gas pressure flowing into the gas flow path 2 to a constant level. For example, L
In the case of P gas, the cylinder pressure is 0.7 to 15.6
Kg/cm2, and in order to properly burn the combustion equipment, the gas pressure must be 200 to 330mmH2.
It is necessary to adjust the pressure to O before supplying it. Therefore, a pressure regulator 12 is attached to the cylinder outlet to adjust the gas pressure flowing into the gas flow path 2.

Ultrasonic waves are generated when gas leaks due to minute holes in the gas pipe or when gas leaks from a threaded portion of a connection. This ultrasonic wave has a different waveform because the sound pressure and frequency differ depending on the diameter of the leakage hole and the amount of leakage. Further, ultrasonic waves caused by leakage from a threaded portion of a gas piping connection exhibit a different waveform than when leaking from a hole. Even when using normal gas without gas leakage, ultrasonic waves are generated from the pressure regulator 12, etc., but this ultrasonic wave also has a different waveform from the ultrasonic waves generated due to leakage, so it is not normal. It is possible to distinguish between usage and leakage.

That is, in normal use, ultrasonic waves are generated from the gas discharge nozzle of the gas appliance and the pressure regulator 12, and the ultrasonic waves are input from both ends of the leakage sound detection sensor 4. Since the ultrasonic waves generated from the leak source upstream of the gas meter 5 and the ultrasonic waves generated from the pressure regulator 12 are input only from one end of the leak sound detection sensor 4, even if they have the same composite waveform, the leak sound detection sensor 4 detects different waveforms. This also applies when a starter is used, so by memorizing the ultrasonic waveform when the device is used normally or when the device's starter is used, and comparing it with the waveform at the time of leakage, it is possible to check for normal use and leakage. can be distinguished from occurrence. Also,
Directional leakage sound detection sensor 4 on the upstream side of gas meter 5
If you use , the ultrasonic waveform will be from only the pressure regulator 12 during normal use, and if there is a leak upstream of the gas meter 5, the ultrasonic waveform will be a combination of the pressure regulator 12 and the leak source, so it will be normal. This is effective because the difference in waveforms during leakage and leakage becomes clearer.

Therefore, through experiments, we have determined the relationship between the waveform caused by normal instrument use and the diameter of the hole created in gas piping, and the waveform of the generated ultrasonic wave, and the relationship between the waveform of the ultrasonic wave generated from the threaded part of the gas piping connection. By determining the waveform etc. in advance and comparing it with the waveform of the ultrasonic wave generated when a gas leak actually occurs in the gas piping, it is possible to determine normal use and estimate the shape and amount of leakage. The leakage signal pattern based on the determination of normal use and the amount of leakage determined in advance through experiments is stored in the reference leakage signal storage means 14 of the microcomputer. Further, waveforms of normal equipment use without leakage can be automatically stored in the reference leakage signal storage means 14 in order to correspond to individual equipment.

The procedure for determining leakage will be explained based on the flowchart of FIG. The leakage determining means 15 monitors the determination of the presence or absence of a flow rate signal by the flow rate signal determining means 13. When the state in which the flow rate signal is determined to be "absent" by the flow rate signal determining means 13 continues for a predetermined period of time predetermined by the first timer 17, for example, 30 minutes, the second timer 18 determines that the flow rate signal is "absent" for a predetermined period of time, for example, 30 minutes. For example, the leakage sound detection sensor 4 is turned on for two minutes. Here, when the leakage sound detection sensor 4 detects a leakage sound and a leakage signal from the leakage signal transmitter 6 is input, the leakage signal and the reference leakage signal storage means 1
4, the amount of leakage is estimated, and a leakage signal is transmitted. In response, the display unit 9 displays that a gas leak has occurred to warn the user.

It should be noted that the flow rate signal determination means 13 determines that the flow rate signal is "
The time period during which the leakage sound detection sensor 4 is turned on after it is determined that the leakage sound detection sensor 4 is "no" is not limited to the above-mentioned time, but can be changed as appropriate, or the leakage sound detection sensor 4 may be turned on at all times. In addition, instead of immediately transmitting a leakage signal when the leakage sound detection sensor 4 detects a leakage sound, in order to eliminate measurement errors, monitoring is continued for a certain period of time, for example, about 7 days, and the measurement results are stored in the storage means 16. In addition to storing the information, a leak occurrence signal may be transmitted when leak sound is detected for seven consecutive days. In this case, if the estimated leakage amount is equal to or greater than a predetermined value, the leakage signal may be transmitted earlier than after 7 days. In addition, even if the flow rate signal is "present," the ultrasonic waveform caused by normal use or sparks can be stored as a signal pattern and compared with the detected signal pattern.
It is also possible to determine whether normal use or leakage has occurred.

[0015]

[Effects of the Invention] As explained above, the present invention provides a leakage sound detection sensor in the gas flow path, and when the leakage determination means of the calculation means determines that the flow rate signal is "absent" by the flow rate signal determination means. When the leakage sound detection sensor detects leakage sound,
The amount of leakage is estimated by comparing the leakage sound with the reference leakage sound stored in the reference leakage sound storage means, and a leakage occurrence signal is transmitted. Therefore, it is possible to reliably discover gas leaks not only downstream of the flow sensor but also upstream of the flow sensor, for example in a buried pipe. Furthermore, since there is no need to measure gas pressure or the like, gas leakage can be easily determined, gas leakage can be detected early, and serious accidents can be prevented from occurring.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram showing the configuration of the present invention.

FIG. 2 is a schematic block diagram showing the configuration of a microcomputer that is a calculation means.

FIG. 3 is a flowchart showing a procedure for determining leakage.

[Explanation of symbols]

1 Gas leak detection device 2 Gas flow path 4 Leakage sound detection sensor 5 Gas meter 6 Leakage signal transmitter 7. Microcomputer 8 Flow signal transmitter 13 Flow rate signal judgment means 14 Standard leakage signal storage means 15 Leakage judgment means

Claims (1)

[Claims] Claim 1: A flow rate sensor that detects the flow rate of gas flowing in a gas flow path, a flow rate signal transmitter that transmits the gas flow detected by the flow rate sensor as a flow rate signal, and a flow rate signal transmitter that transmits the gas leakage sound from the gas flow path. It consists of a leakage sound detection sensor that detects a leakage sound, a leakage signal transmitter that transmits the leakage sound detected by the leakage sound detection sensor as a leakage signal, and a calculation means that is electrically connected to the flow rate signal transmitter and the leakage signal transmitter. In the gas leak detection device, the calculation means includes a flow rate signal determination means for determining the presence or absence of a flow rate signal from a flow rate signal transmitter, and a reference leakage determination means for storing a leakage signal pattern based on a leakage amount determined in advance through an experiment. When the flow rate signal is determined to be "absent" by the signal storage means and the flow rate signal determination means, it is determined whether or not there is a leak signal from the leak signal transmitter, and when a leak signal is received, it is determined that the flow signal is "absent". 1. A gas leak detection device comprising: leak determination means for estimating a leak amount by comparing the pattern with a leak signal pattern stored in a reference leak signal storage means, and transmitting a leak occurrence signal.