JPH0862002A - Leakage inspection method and apparatus using fluidic gas meter with flow sensor - Google Patents

Abstract

PURPOSE: To eliminate erroneous judgment in a leakage inspection employing a fluidic gas meter with a flow sensor. CONSTITUTION: Output signals outputted from a flow sensor in a predetermined time are averaged by an average value operating circuit 14. When the averaged value is lower than a set value, a leakage decision circuit 15 makes a decision that the gas is not leaked. When a decision of the leakless state is not made at all within a predetermined period, a decision is made that the gas has leaked and rt is notified on a leak display circuit 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leakage inspection method and apparatus using a fluidic gas meter with a flow sensor.

[0002]

2. Description of the Related Art A fluidic gas meter with a flow sensor is provided with a function for monitoring gas leakage. This concept is as shown in FIG. The integration circuit 101 outputs 1 pulse when the integration circuit 101 integrates a fixed amount (for example, 1.5 liters), and this pulse is input to the determination circuit 102. Whether or not there is a pulse input every time) is monitored, and if the state of the pulse continues for a certain period (for example, one month), it is determined that there is a leak and the leak display circuit 103 displays a leak.

[0003]

However, the above-mentioned conventional leakage determination method has the following drawbacks. In the case of a fluidic gas meter that measures a low flow rate with a flow sensor, if there is a slight fluctuation in the flow velocity due to pressure fluctuation or the like, this may be integrated. For example, if the variation (standard deviation) of the minute signal is σ, the variation of the integrated value of n times is √nσ, so that the probability of exceeding a certain value (for example, 1.5 liters) increases as the number of integration increases. Become. FIG. 4 is a specific example of this, and when there is a minute change in the flow velocity as shown in (1), since it is integrated by the integrating circuit 101 as described above, for example, 1.5 liters in (b). When the integrated value of is obtained, one pulse signal is output as shown in (c). Therefore, even if there is no gas leakage in reality, the flow rate is measured from the flow rate based on the minute fluctuation of the pressure, and the flow rate signal is output based on this, and the determination circuit 103 outputs a gas leak. I will erroneously judge that. It is an object of the present invention to propose a leak inspection method and its apparatus, which are performed by using a fluidic gas meter with a flow sensor without the risk of making an erroneous determination.

[0004]

The leak inspection method and apparatus using the fluidic gas meter with a flow sensor according to the present invention are as follows.

1. If the signals output from the flow sensor are averaged within a certain period of time, and if the averaged value is less than or equal to the set value, it is determined that there is no leakage, and if this state without leakage is not determined even once within a certain period of time. Is a leak inspection method that uses a fluidic gas meter with a flow sensor that determines that there is a leak.

2. An average value calculation circuit for averaging the signals output from the flow sensor, and if the value output from the average value calculation circuit is smaller than a preset value, it is determined that there is no leakage, If the state is not judged even once within a certain period, there is a leak judgment circuit that judges that there is a leak, and a leak display circuit that displays a leak when the leak judgment circuit judges that there is a leak. Leak inspection device using a Dick gas meter.

[0007]

[Function] In the case of a fluidic gas meter with a flow sensor, a gas leak inspection is automatically performed by selecting a time period when no nighttime gas is considered to be used. Since gas leakage is usually minute, the flow rate at the time of leakage inspection is measured by the output from the flow sensor. In the case of the present invention, the signals output from the flow sensor are averaged by the average value calculation circuit within a fixed time, and the leakage determination circuit determines that there is no leakage when the averaged value is less than or equal to the set value. If the state of none is not determined even once within a certain period, it is determined that there is leakage, and the leakage display circuit displays this.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a fluidic gas meter with a flow sensor embodying the present invention, in which 1 is a meter body, 2 is a gas inlet, 3 is an outlet, 4 is a fluidic element, 5 is a nozzle, and 6 is a nozzle. Is a flow sensor, 7 is a gas flow path, 8
Is a valve seat, 9 is a solenoid valve, 10 is a shutoff valve, 11 is a reset button, and 12 is an electronic integrating circuit. In addition to a flow rate measuring function, there is a gas leakage inspection circuit for implementing the present invention. It has been incorporated.

FIG. 2 is a block diagram of the gas leakage inspection circuit. The flow rate signal detected by the flow sensor 6 is input to the integration circuit 13 and integrated. Flow sensor 6 at the same time
The flow rate signal detected at is input to the average value calculation circuit 14, and the average value is obtained here. The average value is input to the leakage determination circuit 15. When the value averaged by the average value calculation circuit 14 is less than or equal to the set value, the leakage determination circuit 15 determines that there is no leakage, and this leakage-free state occurs once within a certain period (one month in the embodiment). If no is determined, it is determined that there is a leak, and a signal is sent to the leak display circuit 16 to display a leak. In the figure, 17 is an average value time (number of times) setting circuit,
This sets the number of times of averaging the measured values output from the flow sensor 6. Reference numeral 18 is a leakage determination flow rate setting circuit, and 19 is a determination period setting circuit.

[0010]

The present invention has the following effects because the leak determination is performed by the method and apparatus as described above. Even if there is a slight change in the gas flow velocity, the leak determination will not be erroneous. For example, if the variation (standard deviation) of a minute signal is σ, the average value of n times is σ / √n, and the higher the number of times, the higher the accuracy of flow rate measurement, and therefore the determination error is almost eliminated.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a fluidic gas meter with a flow sensor embodying the present invention.

FIG. 2 is a block diagram of an electronic circuit (device) for implementing the present invention.

FIG. 3 is an explanatory diagram of a conventional leak inspection method.

FIG. 4 is an explanatory diagram of a reason for making an erroneous determination in a conventional leak inspection.

[Explanation of symbols]

 1 Meter Main Body 4 Fluidic Element 6 Flow Sensor 13 Integration Circuit 14 Average Value Calculation Circuit 15 Leakage Judgment Circuit 16 Leakage Display Circuit 17 Average Time Setting Circuit 18 Leakage Judgment Flow Rate Setting Circuit 19 Judgment Period Setting Circuit

Claims (2)

[Claims] 1. A signal output from a flow sensor is averaged within a fixed time, and when the averaged value is less than or equal to a set value, it is determined that there is no leakage, and the state without leakage is 1 within a certain period. A leak inspection method that uses a fluidic gas meter with a flow sensor that determines that there is a leak if the number of times is not determined. 2. An average value calculation circuit for averaging the signals output from the flow sensor, and when the value output from the average value calculation circuit is smaller than a preset value, it is determined that there is no leakage. , If there is no leakage within the fixed period of time, the leakage judgment circuit judges that there is a leakage, and if the leakage judgment circuit judges that there is a leakage, the leakage display circuit displays the leakage. Leak inspection device using a fluidic gas meter with a flow sensor.