JP3433447B2 - LP gas meter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LP gas metering device for metering a gas usage amount, and more particularly, to an abnormal flow rate detected by monitoring a gas flow rate supplied from an LP gas container through a gas pressure regulator. , This abnormality detection or test cutoff closes the gas cutoff valve to cut off the gas supply through the gas supply, opens the closed gas cutoff valve while confirming the safety, and returns to the LP gas container. The present invention relates to an LP gas measuring device adapted to detect and manage the remaining amount of gas.

[0002]

2. Description of the Related Art Generally, an LP gas supply system is constructed as shown in FIG. In the figure, two LPs
Gas container 1 _1, 1 ₂ are connected to a gas pressure regulator 2 with automatic switching function, the gas pressure regulator 2 gas from one container 1 ₁ or 1 ₂ through is derived. The gas derived from the gas container is supplied to the gas meter 4 through the gas pipe 3 on the primary side (upstream side), and from there, through the gas pipe 5 on the secondary side (downstream side), the end of the gas bath pot, the stove, or the like. Is supplied to the gas combustor 6. Note that 3a and 5a are gas plugs provided in the gas pipes 3 and 5, respectively.

The [0003] above, the gas discharged from the gas pressure regulator 2 of one container selected by the switching function 1 ₁ or 1 ₂ is supplied to the gas meter 4 through the gas pipe 3, further gas combustion through the gas pipe 5 Is supplied to the burner 6 and consumed by the gas combustor.

Then, by the switching function of the gas pressure regulator 2,
One selected container, eg 1₁ (Supply side
Gas consumption of the container) progresses and the remaining amount of gas decreases,
Container 1 ₁ The internal pressure of is low and is necessary in the gas combustor 6.
It becomes impossible to supply a gas at a proper pressure. Therefore,
In the gas pressure regulator 2 with automatic switching function, the automatic switching
Depending on the function, the other container 1₂ (Replenishment side container) is connected
Open the inlet to automatically introduce gas and run out of gas.
Can reliably supply the gas at the required pressure without causing
It is like this.

Further, the automatic switching function with the gas pressure regulator 2, to perform a display indicating that it has started the supply in accordance with the automatic switching of the container, the container 1 ₁ of the gas remaining in the supply side There are some that are designed to let you know when it is almost gone. This allows the user who viewed this display to contact by telephone to that effect to the shipper, delivery company container 1 ₂ of the supplying-side with replacing the container 1 ₁ and a new container switched manually supply by a new container 1 ₁ is to be connected to the supplying-side.

Further, in the LP gas supply system as shown in the figure, generally, a flow rate sensor (not shown) which generates a flow rate signal each time a constant flow rate of gas is supplied into the gas meter 4, and the gas supply based on the flow rate signal. An abnormality detecting means for detecting an abnormality of the gas flow flowing in the passage, a gas shutoff valve for shutting off the gas supply passage in response to the abnormality detection, and an integrating means (not shown) for integrating the gas usage amount based on the flow rate signal are provided. Then, the transmission device 7 notifies the information center 9 of the integrated value of the integrating means at a predetermined date and time through the telephone line 8 or the like.

Further, the gas meter 4 has a valve closing operation switch 4a (the dotted line indicates that the operating portion is not exposed outside the meter case) for shutting off the gas cutoff valve for a test, and the valve is closed. A valve opening operation switch 4b for opening the gas shutoff valve is provided. However, the former switch has a safety problem that anyone can perform the shutoff operation due to its nature, so the shutoff operation is performed unnecessarily. As it cannot be done, it is composed of a reed switch that turns on when an operation magnet is brought close to a predetermined position of the meter case from the outside, and the latter switch is turned on by pressing an operation button from the outside of the meter case. Composed of switches.

However, the display, which was trying to connect to that effect to the shipper user know that the container 1 ₁ of the gas remaining in the supply side is almost exhausted,
If you fail to see the display, or if you miss the contact after seeing the display, you may fail to replace the container and, in the worst case, may run out of gas.

Therefore, a gas pressure regulator 2 with an automatic switching function, which has a transmission function, is adopted, and an information sensor is used in the gas meter 4 when the remaining gas amount in the container is controlled to reach a warning level. There is also a system in which a LP gas residual amount management function is provided so that the container is replaced and the container is not damaged.

To the gas pressure regulator 2 having the transmitting function, the gas remaining amount in the supply side container 1 ₁ becomes so small that the gas of the required pressure cannot be supplied and the supply side container 1 ₂ is supplied. Turns on when gas supply to the container starts 1 ₁
Switch for sending 2 which is turned off when the container is replaced with a new container and the container 1 ₂ on the replenishment side is manually switched to the supply side.
1 is provided.

By connecting the transmission switch 2a to the LP gas remaining amount management device in the gas meter 4, the LP gas remaining amount management device causes the transmission device 7 to make a call in response to the input of the ON signal, and the information is transmitted. Although a notification process is performed to the center 9 via the telephone line 8, when an off signal of the transmission switch 21 (not shown) is input by the switching operation of the gas pressure regulator 2 with a switching function after the container replacement work. ,
The call is not made and the information center 9 is not notified.

By the way, in the LP gas residual quantity management device, generally, the residual quantity management counter is counted by the flow rate signal from the flow rate sensor in the gas meter for integrating the flow rate of the gas supplied from the LP gas container by the flow rate integrating section. Let it up. The count value of the remaining amount management counter is compared with the remaining amount warning level set by the warning level setting unit in the comparison processing unit, and when the count value ≧ the warning level,
The comparison processing unit causes the call processing unit to perform the call processing of the remaining amount warning.

The remaining amount management counter is a container replacement switch 4c which is operated subsequent to the switching operation after the container replacement work.
The predetermined value is set according to the operation of (the dotted line indicates that the operation part is not exposed outside the meter case.), And the replacement is performed according to the count value of the remaining amount management counter after container replacement. The remaining container remaining amount is managed, and when the container remaining amount exceeds the warning level, the fact is notified to the information center,
This notification serves as a guide for the next container replacement period.

By the way, the container exchanging switch 4c, which should be operated after the switching operation after the container exchanging work, clears the count value of the remaining amount supervision counter until then and sets a predetermined value. If it is operated unnecessarily due to mischief or the like, it becomes impossible to accurately manage the remaining amount of the gas container thereafter. Therefore, in general, the operation button is not exposed in the meter case of the gas meter 4,
It is configured by a reed switch or the like which is turned on by bringing a predetermined operating magnet close to a predetermined position of the meter case.

[0015]

As described above, in the conventional LP gas metering device, the shut-off operation switch 4a is used.
There are three switches, a valve opening operation switch 4b and a container replacement switch 4c. All of these switches are operated from the front of the meter case. It required a space for operating and arranging the gas meter, which made the gas meter large, and the number of parts was large and the cost was high.

As the above-mentioned gas meter, a film type gas meter which generally involves mechanical operation in metering operation is generally used. However, in the film type gas meter, the structure becomes large and the mechanical operation part is worn out. There was also a problem from the viewpoint of durability. Therefore, the gas flow rate is measured by using, for example, ultrasonic waves, the gas flow rate is obtained by the product of this gas flow rate and the cross-sectional area of the gas supply path, and this gas flow rate is integrated to measure the gas usage amount. However, a gas meter that is completely electronic and has a long life and a small size has been studied.

In the case of the above-mentioned completely electronic gas meter, the size of the gas meter can be reduced to reduce the front space. However, if the space for the three switches is secured in the front, the size reduction is restricted.

Therefore, in developing a new electronic type LP gas metering device for metering the amount of gas used based on the measurement of the gas flow velocity, three switches, which have been conventionally required, are reduced to reduce the size and cost. Is required.

Therefore, in view of the above-mentioned conventional problems, it is an object of the present invention to provide an LP gas metering device in which the number of operation switches is reduced and the size and cost can be reduced.

Further, in view of the above-mentioned conventional problems, the present invention is an electronic type for measuring the gas usage based on the measurement of the gas flow velocity, and the number of operation switches is reduced to reduce the size and the cost. It is an object of the present invention to provide an LP gas metering device that can handle the above.

[0021]

In order to solve the above-mentioned problems, the present invention according to claim 1 supplies a gas from a pressure-controlled LP gas container as shown in the basic configuration diagram of FIG. Gas metering means 15a11 for integrating the flow rate of gas flowing through the gas supply path to measure the amount of gas used, and a gas cutoff valve provided in the middle of the gas supply path to shut off the gas supply through the gas supply path by closing the valve. 11 and an abnormality detecting means 15a12 for detecting an abnormality in the flow rate by monitoring the gas flow rate and generating an abnormality detection signal in accordance with the abnormality detection.
And a magnet for operation from the outside to a predetermined position of the case
Consists of a reed switch that turns on when
And a first operating means 15j for generating a valve closing signal for closing the gas cutoff valve by an on operation performed by bringing an operating magnet close thereto, and opening the gas cutoff valve by an operation. A second operation means 15k for generating a valve opening signal to cause the abnormality detection signal generated by the abnormality detection means when the gas cutoff valve is opened or a valve closing signal generated by the first operation means. The gas cutoff valve is closed based on the above, and when the gas cutoff valve is closed, the second
Valve control means 15a13 for controlling the valve opening of the gas cutoff valve based on the valve opening signal generated by the operating means, and counting means 15a31 for counting each time the gas metering means measures a predetermined gas usage amount. An alarm means 15a14 for generating an alarm signal for alarming that the remaining amount of the LP gas container is low when the count value of the counting means reset when the LP gas container is replaced reaches a predetermined value. In the LP gas metering device including : a resetting means 15 for resetting the counting means in response to a single ON operation without a next ON operation within a fixed time of the first operating means.
a15 is further provided, and the valve control means sets the next ON operation within a predetermined time from the ON operation of the first operation means.
A test shutoff control means 15a131 for generating a valve closing signal for closing the gas shutoff valve in response to a plurality of ON operations, and for closing the gas shutoff valve in response to the valve close signal. It exists in the LP gas metering device.

In the LP gas metering device according to the first aspect, the gas metering means 15a11 measures the gas consumption by integrating the flow rate of the gas flowing through the gas supply path for supplying the gas from the LP gas container whose pressure is adjusted. To do. A gas cutoff valve 11 provided in the middle of the gas supply path closes the valve to shut off the gas supply through the gas supply path. The abnormality detecting means 15a12 detects a flow rate abnormality by monitoring the gas flow rate,
An abnormality detection signal is generated according to this abnormality detection. The first operating means 15j generates a valve closing signal for closing the gas cutoff valve by its operation. The second operating means 15k generates a valve opening signal for opening the gas cutoff valve by its operation.

The valve control means 15a13 is based on the abnormality detection signal generated by the abnormality detection means or the valve closing signal generated by the first operation means when the gas cutoff valve is opened.
Controls the gas cutoff valve to open, and when the gas cutoff valve is closed, control is performed to open the gas cutoff valve based on the valve opening signal generated by the second operating means 15k.

The counting means 15a31 counts each time the gas measuring means measures a predetermined amount of gas used. When the count value of the counting means that is reset when the LP gas container is replaced reaches a predetermined value, the warning means 15a14 warns that the remaining amount of the LP gas container has decreased.

Further, it is constant from the ON operation of the first operation means.
The reset means 15a15 resets the counting means in response to a single ON operation without the next ON operation within the time . The test cutoff control means 15a131 included in the valve control means is
Within the predetermined time from the ON operation of the first operation means , the next
A valve closing signal for closing the gas cutoff valve is generated in response to a plurality of on- operations in which the gas cutoff valve is closed, and the gas cutoff valve is closed according to the valve close signal.

As described above, since the counting means is reset by the reset means 15a15 in response to a single operation of the first operating means, the first operating means is required when the LP gas container is replaced. LP by operating
The counting means for managing the remaining amount of the gas container can be reset when the container is replaced. Further, the test shutoff control means 15a131 generates a valve closing signal for closing the gas shutoff valve in response to a plurality of operations of the first operating means, and the gas shutoff valve closes accordingly. Can be used both for resetting the counting means and for generating the valve closing signal.

Claim 2 which is made in order to solve the above-mentioned topic
According to the invention described in claim 1, in the LP gas metering device according to claim 1, the test shutoff control means opens the gas shutoff valve after closing the gas shutoff valve according to the valve close signal. The LP gas metering device according to claim 1, wherein

In the LP gas metering device according to the second aspect of the invention, the test shutoff control means generates a valve open signal for opening the gas shutoff valve after the gas shutoff valve is closed according to the valve close signal. Not only can the first operating means be used both for resetting the counting means and for generating its original valve closing signal, it is no longer necessary to perform a return operation for opening the valve after a test cutoff. ing.

Claim 3 which was made in order to solve the above-mentioned topic
According to the invention described in claim 2, in the LP gas measuring device according to claim 2, the gas measuring means measures a flow speed of a gas flowing through a gas supply passage for supplying gas from a pressure-adjusted LP gas container. And calculating a gas flow rate based on the flow rate measured by the flow rate measuring means, integrating the calculated gas flow rate to measure the gas usage amount, and the valve control means generating the test cutoff control means. After the gas cutoff valve opens in response to the valve opening signal, the flow speed measured by the flow speed measuring means of the gas metering means is monitored, and when the monitored flow speed is not 0, the gas cutoff valve is closed. The LP gas metering device further comprises a return safety confirmation means 15a132 for generating a valve closing signal to close the gas cutoff valve.

In the LP gas measuring apparatus according to the third aspect, the gas measuring means 15a11 is the flow velocity measuring means 14 thereof.
Measures the flow velocity of the gas flowing through the gas supply passage for supplying the gas from the LP gas container whose pressure is adjusted, and the gas metering means 15a11 calculates the gas flow rate based on the measured flow velocity, and integrates the calculated gas flow rate. Then, the amount of gas used is measured and the return safety confirmation means 15a13 included in the valve control means is provided.
No. 2 monitors the flow velocity measured by the flow velocity measuring device of the gas measuring device after the gas shutoff valve opens in response to the valve opening signal generated by the test shutoff control device, and when the monitored flow velocity is not 0, the gas is discharged. Since the gas shutoff valve is closed by generating a valve closing signal for closing the shutoff valve, the test shutoff control means 1
Even if 5a131 opens the gas cutoff valve by the automatic generation of the valve opening signal after the test cutoff, the valve closing signal is immediately generated when the flow speed is not 0 by the short-time monitoring of the flow speed after the valve opening. The gas shutoff valve can be closed.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. The electronic gas meter that is the LP gas metering device in this embodiment is configured to be applied to the LP gas supply system described above with reference to FIG. 7.

The electronic gas meter 4, as shown in FIG.
A gas cutoff valve 11 provided in a gas passage (not shown) connected to a pipe of a gas supply passage (not shown) to shut off the gas supply by closing the valve, a seismoscope 12 for detecting a seismic intensity of a predetermined value or more, a pressure in the gas passage Pressure sensor 13, an ultrasonic type flow velocity sensor (hereinafter, simply referred to as flow velocity sensor) 14 that generates a flow velocity signal that changes according to the flow velocity of the gas flow flowing through the gas passage, and a controller 15 as a control unit. Built in.

The controller 15 is a microcomputer (μCO) which operates according to a predetermined program.
M) 15a. The μCOM 15a is, as is well known, a central processing unit (CPU) 15a1 that performs various processes and controls according to a predetermined program, a CPU
A ROM 15a2, which is a read-only memory that stores programs and the like, and a RAM 15a3, which is a readable / writable memory that stores various data and has an area required for processing operations of the CPU, are incorporated.

The controller 15 also includes a gas shutoff valve 1
1. A connector 15b to which the seismic sensor 12, the pressure sensor 13, and the flow velocity sensor 14 are connected, and a drive signal for driving the gas cutoff valve 11 in response to the valve close / valve open signal output from the μCOM 15a. Through the shut-off valve drive circuit 15c for outputting via the interface circuit 15d and the interface circuit 15d for inputting the signal from the seismoscope 12 and the pressure sensor 13 input through the connector 15b to the μCOM 15a, the interface circuit 15d and the connector 15b, respectively. Connected to the μCOM 15a and the flow velocity sensor 14
A sensor circuit 15e that transmits a drive signal for driving the flow velocity sensor 14 under the control of the CPU 15a1 of 15a and receives a signal generated by the flow velocity sensor 14 by this drive.

The controller 15 is further a terminal block 15 to which various external devices outside the electronic gas meter 4 are connected.
f and an interface circuit 15g for exchanging signals between the μCOM 15a and an external device via the terminal block 15f. Specifically, the controller 15 is provided with, for example, an in-home display panel 21 for providing various displays related to the gas meter, which is provided in the house, and an in-home operation for performing various remote operations on the gas meter, via the terminal block 15f. Device 22, a gas alarm device 23 that detects a gas having a concentration equal to or higher than the alarm level and issues an alarm in the house, and has a function similar to that of the gas alarm device 23 and that detects a CO gas that is an alarm level or higher and issues an alarm 2 gas alarms and CO alarms 2
4. Automatic switching regulator that automatically switches between a plurality of LP gas containers, which outputs a signal according to the switching operation of the pressure regulator 25, and the management center of the gas distributor via a public line such as a telephone line. A network control unit (NCU) 26 for controlling the communication of the above is connected.

The controller 15 is also provided with μCOM.
A liquid crystal display (LCD) 15h connected to 15a for displaying various information such as an integrated value of gas usage and an alarm, and a lithium battery 15i for supplying operating power to each unit in the controller 15 and an interface circuit 15
A shut-off valve closing / container as a first operating means which is turned on when the opened gas shut-off valve 11 connected to the μCOM 15a via d is closed and when the LP gas container is replaced. Exchange switch 15j and closed gas shutoff valve 11
Shutoff valve open switch 15k as second operation means that is turned on when opening the battery, and monitors the voltage of battery 15i,
It is detected that the voltage of the battery has dropped below a certain value that does not hinder the operation of the controller 15 and the like.
Battery voltage detection circuit 15m for detecting that the voltage of 6 is returned to the voltage required for the operation of the controller 15 and the like, and electrically non-volatile storage means capable of holding the stored contents without a backup power source. E ² PROM 15n which is

The CPU 15a1 of the μCOM 15a performs processing according to a predetermined program, and constitutes the gas metering display means together with the ultrasonic type flow velocity sensor 14, the sensor circuit 15e and the LCD 15h. μCOM15a C
In addition to the above functions, the PU 15a1 performs processing according to a predetermined program to cut off the total flow rate, increase the flow rate, shut down the operating time, shut off the leak while confirming the return safety, shut off the gas leak alarm, and shut down the seismic sensor. Acts as a functional means to execute a number of functions such as flow rate type minute leak warning, pressure type minute leak warning, adjustment pressure abnormality warning, blockage pressure abnormality warning, pressure drop cutoff, fire registration, test cutoff, automatic meter reading, residual quantity management, etc. However, various setting data for executing these functions are stored in a predetermined area in the RAM 15a3.

First, the gas metering display means will be described. Specifically, as shown in FIG. 3, for example, the flow velocity sensor 14 is a pair of gas flow sensors 16 arranged in the gas passage 16 in the gas meter 4 so as to be separated from each other in the flow direction. Oscillators 14a and 14b. The sensor circuit 15e, under the control of the μCOM 15a, transmits a signal that drives one of the transducers 14a and 14b to generate an ultrasonic wave and a transmitting circuit 15e1 that receives the ultrasonic wave generated by one transducer and the other. The signal generated by the oscillator of FIG. 2 is received via the high-pass filter (HPF) 15e4, and the received signal is amplified, for example, and the μCOM15
a receiving circuit 15e2 for sending to a, and μCOM15
Under the control of a, it has a switching circuit 15e3 that alternately switches the oscillator that supplies the signal from the transmission circuit 15e1 and the oscillator that supplies the signal to the reception circuit 15e2.

The principle of gas metering by the gas metering display means having the above-mentioned structure will be described below. Now, the switching circuit 15e3 is under the control of the CPU of the μCOM 15a, and the transmission circuit 15e
It is assumed that the output signal No. 1 is supplied to the oscillator 14a and the signal generated by the oscillator 14b is supplied to the receiving circuit 15e2. In such a state, μCOM15a
CPU outputs a trigger signal and sends it to the transmitting circuit 15e.
Apply to 1. The transmission circuit 15e1 to which the trigger signal is applied generates a burst signal and transmits the burst signal to the vibrator 14a.
To generate an ultrasonic signal in the vibrator 14a. The ultrasonic signal generated by the vibrator 14a propagates in the gas flow and is received by the vibrator 14b. The transducer 14b having received the ultrasonic signal generates a signal corresponding to the received ultrasonic signal, and transmits the signal via the receiving circuit 15e2 to the μCOM 15a.
Supply to the CPU. The CPU of the μCOM 15a measures the time from the output of the trigger signal to the reception of the signal from the reception circuit 15e2, and the flow velocity of the gas flow is obtained from the measured time as follows.

Now, assuming that the sound propagation velocity in the stationary gas is c and the gas flow velocity is v, the forward ultrasonic wave propagation velocity of the gas flow is (c + v). Assuming that the distance between the oscillators 14a and 14b is L, the time T for the ultrasonic waves emitted by the oscillator 14a to reach the oscillator 14b is T = L / (c + v) (1) = L / T-c (2), and when L is known, the flow velocity v can be obtained by measuring T.

When the flow velocity v is obtained, the flow rate Q is Q = KSv (3), where S is the cross-sectional area of the gas passage 16 and K is the correction coefficient, and the instantaneous flow rate is obtained.

Therefore, every time the flow rate Q is obtained, the integrated gas supply amount, that is, the gas usage amount can be obtained by multiplying the value obtained by multiplying the flow rate Q by the elapsed time from the previously obtained time. The required gas usage is RA
It is stored in a predetermined area in M15a3. In order to obtain the gas usage amount more accurately, the flow rate Q may be obtained by measuring the flow velocity in a short cycle when the flow rate Q is large and in a long cycle when the flow rate Q is small.

The above equation (2) for obtaining the flow velocity v includes the sound propagation velocity c as a constant. However, since the sound propagation velocity c changes with temperature, this value at room temperature is used. If a fixed value is used, an error will occur in the measurement of the flow velocity when the gas temperature is different from room temperature, so it is necessary to separately measure the temperature factor and correct the correction coefficient K. In this regard, in the configuration of FIG. 3, the switching circuit 15e3 has the μCOM15
By switching under the control of a CPU (not shown) in a, the output signal of the transmission circuit 15e1 is supplied to the oscillator 14b, and the signal generated by the oscillator 14a is received.
e2 is supplied. Therefore, in such a state, the arrival time of the ultrasonic wave in the direction opposite to the gas flow can be measured.

Assuming that the arrival time in the forward direction, that is, the ultrasonic signal propagation time is T1, and the arrival time in the reverse direction, that is, the ultrasonic signal propagation time is T2, T1 = L / (c + v) (4) T2 = L / (Cv) (5), and from equations (4) and (5), v = L / 2 (1 / T1-1 / T2) (6). When L is known, T1 and T2 are The flow velocity v can be obtained by measuring. In addition,
Since c = L / 2 (1 / T1 + 1 / T2) is obtained from the equations (4) and (5), the temperature is obtained from this c, and the equation of the flow rate, Q = of the coefficient K depending on the temperature in KSv The value can be corrected by the temperature, and the coefficient K corrected by this temperature is the RAM 15a3.
It is stored in a predetermined area inside and is updated when the temperature of the gas changes.

Further, in the above-mentioned embodiment, the information is inputted by using the pair of transducers for transmitting and receiving the ultrasonic signal, but the ultrasonic signal propagation between the pair of transducers 14a, 14b is performed. To measure the flow velocity based on the velocity and to correct the temperature of the coefficient K when calculating the flow rate based on the measured flow velocity, use a vibrator that is connected to the gas supply passage but is provided in a place where there is no gas flow. Can also This oscillator is
It is arranged toward a wall surface that is a certain distance away, and the time when the ultrasonic waves emitted toward the wall are reflected and returned by the wall surface is measured, and the relationship table between the time and the temperature stored in the RAM 15a3 is referred to. The temperature is determined, and the determined temperature is used to determine the coefficient K by referring to a relationship table between the temperature and the coefficient K prepared in advance in a predetermined area in the RAM 15a3.

As described above, the CP in the controller 15
The U15a1 constitutes a gas metering display means together with the ultrasonic flow sensor 14, LCD 15h, etc., and causes the information center to periodically report the gas usage measured by this gas metering display means through a telephone line or the like every month by an automatic meter reading function. . Further, the CPU 15a1 constantly monitors the gas flow rate required for metering by the gas metering display means by the total flow rate cutoff function, the increased flow rate cutoff function, and the usage time cutoff function, and when the gas flow rate is abnormal. A valve closing signal for closing the gas shutoff valve 11 is generated. Further, the CPU 15a1 opens the valve-closed gas cutoff valve 11 by directly operating the cutoff valve open switch 15k from the outside of the meter case to generate a valve open signal. At this time, in the CPU 15a1, the leakage cutoff function during the return safety confirmation is activated, and the flow velocity after the gas cutoff valve 11 is opened is monitored. If the flow velocity is not 0, the valve closing signal is given because there is a leak from the gas equipment or the like. It is generated and the gas shutoff valve 11 is closed.

Further, since the CPU 15a1 executes the remaining amount management function of the LP gas container, the CPU 15a1 functions as a counting unit formed in a predetermined area in the RAM 15a3 every time the gas measurement display unit measures a predetermined gas usage amount. The remaining amount management counter is incremented. The remaining amount management counter in the RAM 15a3 is turned on by the operating magnet (not shown) being brought close to the shutoff valve closing / container replacement switch 15j in the meter case from outside the meter case a single time. The count value is reset and a predetermined value, such as 0, is set. Further, when the count value of the remaining amount management counter in the RAM 15a3 becomes a value corresponding to a plurality of predetermined remaining amount alarm levels, the CPU 15a1 has a small remaining amount in the LP gas container and how much the level is. The information center is informed through a telephone line or the like.

It should be noted that the gas meter needs to be tested and shut off periodically after its installation. In such a case, an operation magnet (not shown) is brought closer to the shutoff valve closing / container exchange switch 15j as the first operation means in the meter case from the outside of the meter case a plurality of times within a fixed time of, for example, 1 to 2 seconds. And you will have to turn it on multiple times.
By turning on the shutoff valve closing / container replacement switch 15j a plurality of times within a predetermined time, the CPU 15a1 determines that a test shutoff operation has been performed and generates a valve closing signal.
This closes the gas cutoff valve 11. When the gas cutoff valve 11 is closed, a valve open signal is automatically generated after a certain period of time to open the gas cutoff valve 11. After automatically opening the gas shutoff valve 11, the leak shutoff function works during the confirmation of the return safety, and the flow velocity after the gas shutoff valve 11 is opened is monitored. Is detected, a valve closing signal is generated to close the gas cutoff valve 11.

Further, the gas meter is put into a nap state so that the battery power is not wastefully consumed when the gas meter is shipped from the factory or the installed gas meter is not used for a long time. The nap state is a state in which the CPU that performs various controls is in the sleep mode and the display device, the sensor, and the like are not driven. In such a mode, an operation magnet (not shown) is brought closer to the shutoff valve closing / container exchange switch 15j from the outside of the meter case once more within a certain time after the test shutoff, and the ON operation is performed three times in total. Set by. This mode is released by bringing an operation magnet (not shown) close to the shutoff valve closing / container exchange switch 15j from the outside of the meter case, and then turning off the shutoff valve open switch 15k as the second operating means within a fixed time. The valve opening signal is generated by directly operating from the outside to open the gas shutoff valve 11 in the valve closed state.

CPU of μCOM 15a outlined above
Details of the operation of 15a1 will be described below with reference to the flowcharts of FIGS. 4 and 5 showing the processing performed by the CPU 15a1. The CPU 15a1 starts its operation when the power is turned on, and first performs an initialization process (step S1). In this initialization processing, the flags F1 to F4 formed in the work area in the RAM 15a3 are set to 0, and the remaining amount management counter C is set to an initial value.

Next, the shutoff valve closing / container exchange switch 15
It is determined whether or not j has been turned on (step S2),
When the ON operation has not been performed and the determination in step S2 is NO, it is next determined whether or not the flag F2 is 1 (step S3). If the flag F2 is 0 and the determination in step S3 is also NO. Sometimes, it is then determined whether or not the flag F3 is 1 (step S3a), and if the determination in step S3a is NO, then the flag F1 is subsequently determined.
Is determined to be 1 (step S4).

When the determination in step S4 is YES, it is determined that the CPU 15a1 is in the sleep mode, the process returns to step S2, and the shutoff valve closing / container replacement switch 15 is executed.
Steps S2 to S4 are repeated until j is turned on. If the determination in step S3a is YES, the process proceeds to step S3b to determine whether or not a timer T2, which will be described later, has timed out. If the determination is NO, immediately, and if YES, set flag F3 to 0 in step S3c. Then proceed to step S31,
Gas meter processing such as gas flow rate detection and gas metering described later is performed. When the determination in step S4 is NO,
That is, when all of the flags F2, F3, and F1 are 0, the process proceeds to step S31 to perform gas meter processing such as gas flow rate detection and gas metering described later.

On the other hand, the shutoff valve closing / container replacement switch 15j
Is turned on and the determination in step S2 is YES, it is next determined whether or not the flag F1 is 1 (step S5). When the flag F1 is 1 and the CPU 15a1 is determined to be in the sleep mode, it will be described later. The process proceeds to the step for canceling the sleep mode, but if the determination in step S5 is NO, then the flag F2 is set to 1
If the flag F2 is 0 and the determination in step S6 is NO, then it is determined whether the flag F3 is 1 (step S6).
7). If the flag F3 is 1 and the determination in step S7 is Y
When ES, the processes of steps S16 and S17, which will be described later, are performed, and when the flag F3 is 0 and the determination in step S7 is NO, then the flag F2 is set to 1 (step S8) and then a timer T1 of, for example, 2 seconds is started. (Step S9).

Thereafter, it is determined whether or not the timer T1 formed in a predetermined work area in the RAM 15a3 has timed out (step S10), and when the timer T1 has not timed out and the determination in step S10 is NO. Gas meter processing such as gas flow rate detection and gas metering described later is performed. When the timer T1 has timed out and the determination in step S10 is YES, the flag F2 is set to 0.
Is set (step S11), the count value of the remaining amount management counter C formed in a predetermined work area in the RAM 15a3 is cleared (step S12), and then step S3.
In step 1, gas meter processing such as gas flow rate detection and gas metering described later is performed.

Until the timer T1 is started in step S9 and the time is judged to be over in step S10, the shutoff valve closing / container replacement switch 15j is not turned on, and the judgment in step S2 is NO. The determination in step S3 is performed, but since the flag F2 is set to 1 in step S8, the determination in step S3 is YES. Step S3
If the determination is YES, the process proceeds to step S10 described above to determine whether or not the timer T1 has timed out, and thereafter, step S2 is determined until the determination in step S2 is YES or the determination in step S10 is YES. ,
The processing that necessarily passes through S3 and step S10 is repeatedly executed.

If the shutoff valve closing / container exchange switch 15j is turned on before the 2-second timer T1 times out, that is, the shutoff valve closing / container exchange switch 15j is turned on within a fixed time of 2 seconds. If the switch is turned on twice, the flag F2 has already been set to 1 in step S8, and therefore the determination in step S6 is YES.
Therefore, instead of proceeding to step S7, step S13
Proceed to. In step S13, the flag F2 is set to 0 and the flag F3 is set to 1 (step S1).
3) Do. As described above, before the 2-second timer T1 times out, that is, when the shut-off valve closing / container replacement switch 15j is turned on twice within 2 seconds, it is determined that the test shut-off operation has been performed. A valve closing signal for closing the valve 11 is generated (step S14) to close the gas cutoff valve 11. After the valve closing signal is generated in step S14, the timer T2 for a fixed time of, for example, 2 minutes is started (step S15).

The flag F3 is set to 1 in step S13, and the timer T2 is started in step S15, so that the determination in step S2 is YES.
Or the determination in step S3b becomes YES, the steps S2, S3, S3a and step S2 are performed via a gas meter process such as gas flow rate detection and gas metering described later.
The processing passing through 4 is repeatedly executed. Step S14
The gas flow velocity is monitored until the timer T2 times out after the valve close signal is generated and the gas shutoff valve 11 is closed, and the shutoff function of the gas shutoff valve 11 is determined by the presence or absence of the flow velocity.

Until the timer T2 is started in step S15 and the time is judged to be over in step S3b, the shutoff valve closing / container replacement switch 15j is operated.
When the ON operation is not performed and the determination in step S2 is NO, the determination in step S3a described above is performed, but since the flag F3 is set to 1 in step S13, the determination in step S3a becomes YES. When the determination in step S3a is YES, the above-described step S3
3b, it is determined whether or not the timer T2 has timed out, and thereafter, steps S2, S3, S3a and step S3b are always passed until the determination at step S2 becomes YES or the determination at step S3b becomes YES. Repeat the process. When the timer T2 has timed out and the determination in step S3b is YES, the process proceeds to step S3c and the flag F3 is set to 0 as described above, but at the same time, the determination result of the shutoff function of the gas shutoff valve 11 is When it is determined whether it is normal, and when the determination result is normal, a valve opening signal for opening the shut off gas shutoff valve 11 is generated to automatically open the gas shutoff valve 11 and then the gas described later. Flow rate detection and gas metering will be performed. Immediately after opening the gas cutoff valve 11,
The leakage cutoff function during the return safety confirmation described above operates, and the flow velocity after the gas cutoff valve 11 is opened is monitored. If the flow velocity is not 0, a valve close signal is generated because there is a leak from the gas equipment or the like. The gas shutoff valve 11 will be closed.
When the flow velocity is 0, the gas shutoff valve 11 is left in the opened state because it is safely restored.

If the shut-off valve closing / container exchange switch 15j is turned on before the 2-minute timer T2 times out, that is, the shut-off valve is closed within a fixed time of 2 minutes from the second turn-on operation. When the combined container exchange switch 15j is turned on for the third time, the flag F3 has already been set to 1 in step S13 at this time.
When the determination in step S7 is YES, the process proceeds to step S16 instead of step S8. In step S16, the flag F1 is set to 1, and the next step S17
After the valve closing signal is generated in step S2, the process returns to step S2.

As described above, before the 2-minute timer T2 times out, that is, within 2 minutes after the valve closing signal is generated and the gas shutoff valve 11 is closed, the shutoff valve closing / container exchange switch 15j. When is turned on, the flag F1 is set to 1 because there is a sleep mode setting operation for setting the gas meter to the sleep mode. Therefore, when the shutoff valve closing / container replacement switch 15j is not turned on thereafter, steps S2, S3, S3a, S4 and S4a are performed.
The process is repeated, and the process proceeds to step S31, and the process for consuming the battery power such as the gas meter process such as the gas flow rate detection and the gas metering described later is not performed.

When the gas meter is in sleep mode,
That is, when the flag F1 is set to 1 and the gas shutoff valve 11 is closed, but the shutoff valve closing / container replacement switch 15j is turned on, the determination in step S2 is YES. However, in such a case, the flag F4 is set to 1 (step S20), and then the timer T3 for 3 minutes is started (step S21). Thereafter, it is determined whether or not the started timer T3 times out (step S22), and it is determined whether or not the shutoff valve opening operation switch 15k is turned on before the timer T3 times out (step S23). ). After the flag F4 is set to 1 in step S20, the determination in step S4a becomes YES, and it is determined whether or not the timer T3 has timed out in step S22 even in the sleep mode.

When the determination in step S23 is YES, that is, when the shutoff valve open switch 15k is turned on before the timer T3 times out, the flags F1 and F4 currently set to 1 are set. 0 is set (step S24), the count value of the remaining amount management counter C is cleared (step S25), and then the above step S
Return to 2. When the shutoff valve open switch 15k is turned on, the sleep mode is released, a valve open signal is generated, and the gas shutoff valve 11 is opened. Then, in response to the opening of the gas shutoff valve 11 that was closed, the leak shutoff function during the return safety confirmation is activated, and the flow velocity after the gas shutoff valve 11 is opened is monitored. Assuming that there is a leak from a valve or the like, a valve closing signal is generated to close the gas cutoff valve 11. When the flow velocity is 0, the gas shutoff valve 11 is left in the opened state because it is safely restored. When the shutoff valve open switch 15k is not turned on and the determination in step S23 is NO, the above-described step S23 is performed.
Return to 2. Further, when the timer T3 has timed out and the determination in step S22 is YES, the flag F4 is set to 0 and the process returns to step S2. That is, the sleep mode is not released and the sleep mode is left.

In step S31, the RAM 15a
It is determined whether or not the ΔT timer formed in the predetermined area 3 has timed out, and if this determination is YES,
The flow proceeds to the next step S32 to perform the flow rate detection process.

In this flow rate detection processing, the CPU 15a1 transmits a signal for generating an ultrasonic wave to the transmission circuit 15e1,
Prior to this, the switching circuit 15e3 is switched to switch the oscillator 1
One of 4a and 14b is driven by a signal from the transmission circuit 15e1 to act as a vibrator that generates ultrasonic waves,
The other receives the ultrasonic wave generated by one of the vibrators, generates a signal, and operates as a vibrator which supplies the signal to the reception circuit 15e2, and this is alternately performed. And the CPU 15a
In No. 1, the time from the output of a signal for generating an ultrasonic wave to a vibrator to the reception of an ultrasonic wave is measured in both directions, the flow velocity is measured from this time, and the gas flow rate Q is obtained based on the measured flow velocity.

Next, the process proceeds to step S33 and step S
It is determined whether the gas flow rate Q obtained in 32 is 0 or more and less than Q ₁ , and when the determination in step S33 is NO, the process proceeds to step S34 and the gas flow rate Q is Q ₁ or more and Q or more.
It is determined whether or not it is less than ₂ , and when the determination in step S34 is NO, the same determinations are sequentially performed, and finally, in step S35, it is determined whether or not it is greater than or _equal to Q _{n-1 and} less than Q _n. If NO in step S35, the process proceeds to step S36 to start the ΔT timer.

When the determination in step S33 is YES, the process proceeds to step S33a, where ΔT timer time is Δ
After setting T ₁ , the process proceeds to step S36 to start the ΔT timer. Further, the determination in step S34 is YE.
If S, the process proceeds to step S34a, where ΔT ₂ is set as the ΔT timer time, and then the process proceeds to step S36 where ΔT ₂ is set.
Start the T timer. Further, when the determination in step S35 is YES, the process proceeds to step S35a to set ΔT _n as the ΔT timer time, and then the process proceeds to step S36 to start the ΔT timer.

The above steps S33, S33a, S34,
S34a, S35, and S35a are for shortening the cycle of measuring the flow velocity according to the magnitude of the flow rate, and the relationship between the flow rate and the cycle is as shown in FIG.

After the ΔT timer is started in step S36, the process proceeds to step S37 and the above step S37 is performed.
Gas metering processing for metering the amount of gas used is performed based on the gas flow rate detected in 32. After that, the process proceeds to step S38, and the remaining amount management process of the gas in the LP gas container is performed. In the remaining amount management process, the gas remaining amount management counter C is incremented each time a predetermined amount of gas used in the gas metering process is measured, and the incremented gas remaining amount management counter C is set to a predetermined remaining amount. It is determined whether or not it is equal to or higher than the alarm level by comparing with the quantity alarm level, and as a result of the determination, alarm data for generating a notification for an alarm is generated, and the notification of the subsequent step S39. In the processing, it is notified to the management center. Then, the process proceeds to step S40 and the above step S
In 32, it is judged whether or not there is an abnormality in the gas flow rate based on the flow rate detected in the flow rate detection processing, and if there is an abnormal flow rate, a valve closing signal for closing the gas shutoff valve 11 is generated to shut off the gas supply path. After performing the blocking process, the process returns to step S2 described above.

As described above, the CPU 1 of the controller 4
By performing the procedure shown in FIG. 4 by 5a1, the gas meter at the time of shipping before being installed in the gas supply path is in the sleep mode in which the consumption of the battery power source is suppressed as much as possible, and 1 is set in the flag F1. However, if the shutoff valve closing / container replacement switch 15j is turned on after the gas meter is installed, the determination in step S2 is YES and step S2 is performed.
5, the determination in step S5 is also YES, the process proceeds to step S20, 1 is set in the flag F4, and the timer T3 is started in the next step S21. For example, if the shut-off valve open switch 15k is turned on before the 3-minute timer T3 times out, the determination in step S23 becomes YES and the process proceeds to step S24 to set the flags F1 and F4 to 0 and at the next step S25. The gas residual amount management counter C is reset. Therefore, after that, the gas meter will perform step S2,
When the determinations in step S3, step S3a, and step S4 are NO, the process proceeds to step S31, and processing for consuming battery power such as gas flow rate detection and gas meter processing such as gas metering is performed. That is, the sleep mode is released.

Gas meter Shut-off valve closed / container replacement switch 1 in a state where the meter is installed in the gas supply path and is normally operating.
When 5j is turned on, the determination in step S2 becomes YES and the process proceeds to step S5. However, since 0 is set in all of the flags F1 to F3, the process proceeds to step S8 and 1 is set in flag 2 and In step S9, the timer T1 is started. For example, if the shutoff valve closing / container replacement switch 15j is turned on again before the 2-second timer T1 times out, the determination in step S6 becomes YES and the process proceeds to step S13. When the switch 15j is turned on only once, the determination in step S10 becomes YES, the process proceeds to step S11 to set the flag F2 to 0, and the process proceeds to step S12 to reset the gas remaining amount management counter C. .

On the other hand, as described above, the shutoff valve closing / container exchange switch 15j is set before the timer T1 times out.
When the switch is turned on again, the flow advances to step S13 to set 0 to the flag F2 and 1 to the flag F3, and then to step S14 to generate a valve closing signal. The valve will be closed. Further, the process proceeds to step S15, and the timer T2 is started. However, before the timer T3, for example, 2 minutes, times out, the timer T2 is restarted again, that is, the shut-off valve closing / container exchange switch 15j for the third time in total. When the ON operation is performed, the determination in step S7 is YES and the process proceeds to step S16, in which the flag F1 is set to 1, so that the sleep mode is set. In addition, such a sleep mode after the gas meter is installed is set when the gas consumer moves or is away for a long time.

As described above, in the embodiment of the present invention, the gas remaining amount management counter C is reset by one ON operation of the shutoff valve closing / container replacement switch 15j, and the gas remaining management counter C is turned ON twice. Since the valve closing signal for closing the shutoff valve 11 is generated, it is not necessary to separately provide the shutoff valve close switch and the container replacement switch. In particular, since the valve closing signal is generated by the second ON operation, the sleep mode can be set by the third ON operation.

As is clear from the processing operation of the CPU performed with respect to the flowcharts of FIGS. 4 and 5, the C
The PU 15a1 is a gas metering unit 15a11 that measures the amount of gas used by integrating the flow rate of the gas flowing through the gas supply path that supplies the gas from the pressure-controlled LP gas container.
And an abnormality detecting means 15a1 for detecting an abnormality in the flow rate by monitoring the gas flow rate and generating an abnormality detection signal in accordance with the abnormality detection.
2, and when the gas cutoff valve 11 is opened, the gas cutoff valve 11 is closed based on the abnormality detection signal or the valve close signal,
Valve control means 1 for performing control to open the gas cutoff valve 11 based on the valve opening signal when the gas cutoff valve 11 is closed.
5a13, and an alarm means 15a14 for generating an alarm signal for alarming that the remaining amount of the LP gas container is low when the count value of the counting means that is reset when the LP gas container is replaced reaches a predetermined value. Reset means 15 for resetting the counting means in response to a single operation of the first operating means
a15 and a valve control means valve closing signal for closing the gas shutoff valve 11 in response to a plurality of operations of the first operating means,
The gas cutoff valve 11 is closed according to the valve close signal, and the gas cutoff valve 11 is closed according to the valve close signal.
The test cutoff control means 15a131 of the valve control means for generating a valve open signal for opening the valve, and the flow rate of the gas metering means after the gas cutoff valve 11 is opened according to the valve open signal generated by the test cutoff control means. The flow velocity measured by the measuring means is monitored, and when the monitored flow velocity is not 0, the gas shutoff valve 1
1 operates as a return safety confirmation means 15a132 of a valve control means for generating a valve closing signal for closing 1 to close the gas cutoff valve 11.

[0074]

As described above, according to the first aspect of the present invention, the counting operation for managing the remaining amount of the LP gas container by operating the first operating means once when replacing the LP gas container. The means can be reset when the container is replaced, and a valve closing signal for closing the gas cutoff valve is generated in response to a plurality of operations within a predetermined time, and the gas cutoff valve is closed in response to the signal, so that the first operation Since the means can be used both for resetting the counting means and for generating the valve closing signal, it is possible to provide an LP gas metering device in which the number of operation switches can be reduced and the size and cost can be reduced. You can

According to the invention described in claim 2, the first
Can be used not only for resetting the counting means and for generating its original valve closing signal, but also for eliminating the need for performing a return operation for opening the valve after the test interruption. Therefore, the operability is also improved.

Further, according to the third aspect of the present invention, even if the gas cutoff valve is opened by the automatic generation of the valve opening signal after the test shutoff in a short time by monitoring the flow velocity by opening the valve, the valve is opened. After a short time monitoring of the flow velocity,
If it is not, the gas shut-off valve can be generated to immediately close the gas shut-off valve.Therefore, in the electronic type, the number of operating switches can be reduced to reduce the size and cost, and the test shut-off can be accelerated. It has been designed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of an LP gas measuring device according to the present invention.

FIG. 2 is a circuit configuration diagram showing an embodiment of an LP gas measuring device according to the present invention. It shows the gas supply equipment to which is applied.

FIG. 3 is a diagram showing a specific configuration example of an ultrasonic flow velocity sensor in FIG.

FIG. 4 is a flowchart showing a part of a process performed by a CPU in μCOM of FIG.

5 is a flowchart showing another portion of the processing performed by the CPU in μCOM of FIG.

FIG. 6 is an explanatory diagram showing how the flow velocity measurement cycle is changed according to the flow rate.

FIG. 7 is a diagram showing general gas supply equipment to which an LP gas measuring device is applied.

[Explanation of symbols]

11 Gas Cutoff Valve 14 Flow Rate Measuring Means (Ultrasonic Flow Rate Sensor) 15a11 Gas Measuring Means (CPU) 15a111 Flow Rate Measuring Means (CPU, Transducer) 15a12 Abnormality Detection Means (CPU) 15a13 Valve Control Means (CPU) 15a131 Test Shutoff Control means (CPU) 15a132 Return safety confirmation means (CPU) 15a14 Warning means (CPU) 15a15 Reset means (CPU) 15a31 Counting means (RAM) 15j First operating means (shutoff valve closing / container exchange switch) 15k Second Operating means (shutoff valve open switch)

Claims (3)

(57) [Claims] 1. A gas measuring means for integrating a flow rate of a gas flowing through a gas supply path for supplying a gas from a pressure-controlled LP gas container to measure a gas usage amount, and a gas measuring means provided in the middle of the gas supply path. A gas cutoff valve that shuts off gas supply through the gas supply path by closing the valve, an abnormality detection unit that detects an abnormality in the flow rate by monitoring the gas flow rate, and generates an abnormality detection signal in response to the abnormality detection ; Predetermined place
Turns on when the operation magnet is approached from the outside
Magnet for operation composed of reed switch
First operation means for generating a valve closing signal for closing the gas cutoff valve by an ON operation performed by bringing the gas close valve close to each other, and a second operation for generating a valve open signal for opening the gas cutoff valve by an operation. Means for closing the gas cutoff valve based on an abnormality detection signal generated by the abnormality detection means when the gas cutoff valve is opened or a valve closing signal generated by the first operation means, When the gas cutoff valve is closed, a valve control means for controlling to open the gas cutoff valve based on a valve opening signal generated by the second operation means, and the gas metering means use a predetermined gas. Counting means for counting each time the quantity is measured, and when the count value of the counting means that is reset when the LP gas container is replaced reaches a predetermined value, the remaining amount of the LP gas container has decreased. Alarm signal to warn LP and a warning means for generating
In the gas metering device, the on operation is performed within a certain time after the on operation of the first operation means.
Further comprising reset means for resetting the counting means in response to a single ON operation without any trouble , wherein the valve control means makes the ON operation of the first operation means
A test shutoff control in which a valve closing signal for closing the gas shutoff valve is generated in response to a plurality of ON operations that are performed within a predetermined time from, and the gas shutoff valve is closed in response to the valve close signal. An LP gas metering device comprising means. 2. The test cutoff control means generates a valve open signal for opening the gas cutoff valve after closing the gas cutoff valve according to the valve close signal. The described LP gas measuring device. 3. The gas metering means is pressure-adjusted L
The gas flow rate measuring means for measuring the flow rate of the gas flowing through the gas supply path for supplying the gas from the P gas container is provided, the gas flow rate is obtained based on the flow rate measured by the flow rate measuring means, and the obtained gas flow rate is integrated. And measure the amount of gas used, and the valve control means, after the gas cutoff valve is opened in response to the valve opening signal generated by the test cutoff control means, the flow rate measurement means included in the gas measurement means. And further comprising return safety confirmation means for closing the gas cutoff valve by generating a valve closing signal for closing the gas cutoff valve when the monitored flow speed is not zero. The LP gas measuring device according to claim 2.