JP5140464B2 - Ultrasonic gas meter - Google Patents

Description

  The present invention relates to an ultrasonic gas meter that measures the flow rate of a gas by using ultrasonic waves, and blocks or alarms the gas.

  Conventionally, a pair of ultrasonic transducers are provided at a certain distance on the upstream side and downstream side of the flow path, and the ultrasonic signal is transmitted and received between them repeatedly. 2. Description of the Related Art An ultrasonic gas meter that obtains a gas flow rate based on a difference between a propagation integration time of a sound wave signal and a propagation integration time from a downstream side to an upstream side is known. At that time, the ultrasonic gas meter performs gas shutoff and alarm operation based on an abnormality such as flow rate data. However, such an ultrasonic gas meter closes the shut-off valve and stops the gas supply even when it is not necessary to stop the gas supply due to a transient abnormality. There is a problem that it is necessary to transmit a release command from a monitoring center or an installation device, and unnecessary work is required.

  Patent Document 1 describes a gas meter that can avoid the occurrence of unnecessary gas interruption due to a transient abnormality. This gas meter is counted by a flow rate sensor for measuring a gas flow rate, a flow rate data abnormality detecting means for detecting an abnormality in the flow rate data acquired from the flow rate sensor, a counting means for counting the number of abnormalities in the flow rate data, and a counting means. And a flow sensor abnormal state determination means for determining a flow sensor abnormal state when the number of continuous or cumulative number of abnormalities in the flow rate data reaches a predetermined number.

According to such a gas meter, since it is determined that the flow rate sensor is abnormal only when the flow rate abnormality is continuously detected a predetermined number of times or more, unnecessary gas interruption due to a transient abnormality can be avoided. In addition, the gas meter determines that the flow rate sensor is abnormal when it accumulates abnormalities in the flow rate data and detects a predetermined number of times or more. Also, the abnormal state can be accurately determined.
JP 2004-205420 A

  However, when the gas meter as described above is used, the following problems can be considered. For example, consider a case where a conventional gas meter is installed and gas is used, and then the gas meter is removed in a situation where the shut-off valve is closed in order to stop the gas use in a state where the gas meter flow path is filled with gas. In this case, the gas in the flow channel diffuses into the air from one outlet of the gas meter flow channel, but since the shut-off valve is closed at the other inlet, the gas meter flow channel is not released to the outside. Remains in. A gas meter in which the gas in the gas meter channel is in a mixed state of gas and air can be in an inclined state based on the installed state and transportation after removal, so the interface between the gas and air moves inside the gas meter channel. , Correct ultrasonic transmission / reception is not performed and a measurement error occurs. In addition, since the ultrasonic gas meter is optimized so that it can be measured correctly when it is in a horizontal state, if an equipment abnormality determination is made when the ultrasonic gas meter is not in a horizontal state, it is erroneously determined that an equipment abnormality has occurred in the ultrasonic gas meter. Is done.

  In particular, the gas meter described in Patent Document 1 determines that the flow sensor is in an abnormal state when the number of continuous or cumulative flow data abnormalities reaches a predetermined number as described above. In such a case, the flow sensor is erroneously determined to be in an abnormal state, and there is a problem that an interruption or an alarm occurs.

  Further, the gas meter described in Patent Document 1 describes that when an abnormality in flow rate data is detected, the flow rate value immediately before detecting the abnormality is integrated as the flow rate value acquired this time. Therefore, when it is determined that the flow rate data is abnormal after the removal of such a gas meter, there is a possibility that the previously acquired flow rate value may be integrated, and correct flow rate measurement is not performed.

  The present invention solves the above-mentioned problems of the prior art. When the gas meter is removed, the abnormality determination and the flow rate accumulation for the flow sensor are stopped, and the erroneous determination of the abnormality of the flow sensor is prevented and the accurate flow measurement is performed. It is an object to provide an ultrasonic gas meter to be used.

In order to solve the above problems, an ultrasonic gas meter according to the present invention is an ultrasonic gas meter having a flow sensor for measuring a flow rate of a gas flowing in a flow path, and detects an abnormality in flow data measured by the flow sensor. A flow rate data abnormality detection unit, a removal determination unit that determines whether or not the ultrasonic gas meter is removed from the pipe, and the flow rate data abnormality according to the determination result determined by the removal determination unit A counting unit that counts the number of abnormalities in the flow rate data detected by the detecting unit; a flow rate sensor abnormality determining unit that determines an abnormality in the flow rate sensor based on the number of abnormalities in the flow rate data counted by the counting unit; and the ultrasonic gas meter detection and tilt detection unit that detects the inclination, a pressure detection unit for detecting the pressure of the flow channel, the blocking state of the gas flowing in the flow path And the removal determining unit is configured such that the output of the block detecting unit is in a blocked state, the output of the tilt detecting unit is in a tilted state, and the output of the pressure detecting unit is in a pressure drop state. The ultrasonic gas meter is determined to be in a removed state, and the counting unit stops counting the number of abnormal flow data while the ultrasonic gas meter is determined to be in a removed state. The flow rate sensor abnormality determining unit determines that the flow rate sensor is abnormal when the number of flow data abnormality counted by the counting unit is equal to or greater than a predetermined value.

  According to the present invention, when the gas meter is removed, the abnormality determination for the flow sensor can be stopped, and erroneous determination of abnormality of the flow sensor can be prevented.

  Embodiments of an ultrasonic gas meter according to the present invention will be described below in detail with reference to the drawings.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of Embodiment 1 of the present invention, and FIG. 2 is a diagram showing details of the control unit 20 of the ultrasonic gas meter shown in FIG.

  First, the configuration of the present embodiment will be described. As shown in FIG. 1, the ultrasonic gas meter according to the present embodiment includes a gas inlet 10a, a gas flow path 10c, a gas outlet 10b, and an ultrasonic transducer 11a. 11b, a shutoff valve 13, a display unit 14, a tilt sensor 15, a pressure sensor 16, a shutoff sensor 17, and a control unit 20, and a flow rate sensor for measuring the flow rate of gas flowing in the gas flow path 10c (super It has acoustic wave oscillators 11a and 11b, and a propagation time measuring unit 22, a flow rate measuring unit 24, and a voltage measuring unit 25) inside the control unit 20 described later.

  The ultrasonic transducer 11a and the ultrasonic transducer 11b correspond to the flow rate sensor of the present invention, and are installed at a certain distance from the upstream side and the downstream side of the gas flow path 10c through which the gas to be measured flows. ing. Between the ultrasonic transducer 11a and the ultrasonic transducer 11b, an operation of transmitting and receiving ultrasonic waves to and from each other in the forward direction and the reverse direction of the fluid flow is repeatedly performed, and the difference in ultrasonic propagation integration time in each direction is performed. Based on the above, the flow rate of the gas flowing in the gas flow path 10c is calculated.

  The tilt sensor 15 corresponds to the tilt detection unit of the present invention, and is connected to the control unit 20. The tilt sensor 15 detects the tilt of the ultrasonic gas meter and outputs the tilt data to the control unit 20. The tilt sensor 15 may be any type as long as it can detect that the ultrasonic gas meter is tilted. As an example, a ball is contained in a mortar and is normally off. There is a mechanical sensor that turns on when tilted more than the angle of the mortar and chatters (pulse: repeated on / off) during vibration.

  The pressure sensor 16 corresponds to the pressure detection unit of the present invention, is connected to the control unit 20, detects the pressure of the gas in the gas flow path 10c, and outputs it as pressure data to the control unit 20. The pressure sensor 16 may be any type, but one example is a piezo-type pressure sensor using a piezoelectric element.

  The shutoff sensor 17 corresponds to the shutoff detection unit of the present invention, is connected to the control unit 20, detects the shutoff state of the gas flowing in the gas flow path 10c, and outputs it to the control unit 20 as shutoff data. Specifically, the shutoff sensor 17 determines whether or not the gas is shut off by the shutoff valve 13. Therefore, even if the ultrasonic gas meter does not physically have the “shut-off sensor 17”, if the control unit 20 can obtain information about the open / closed state of the shut-off valve 13, the ultrasonic It can be said that the gas meter includes a “shut-off detection unit”.

  The control unit 20 measures the flow rate based on the propagation time obtained based on the ultrasonic signals transmitted and received from the ultrasonic transducers 11a and 11b. Further, the control unit 20 monitors the measured flow rate data, and when it is determined that an abnormality has occurred based on the flow rate data, the control unit 20 sends a control signal to the shut-off valve 13 to close the shut-off valve 13 and the gas flow path 10c. Shut off the gas flowing in

  The display unit 14 is an LED, an LCD, or the like, and normally displays an integrated gas use value in accordance with a control signal output from the control unit 20, and when an abnormality such as gas leakage occurs, this is indicated. Displays a warning message.

  Next, the internal configuration of the control unit 20 will be described. As shown in FIG. 2, the control unit 20 includes a propagation time measurement unit 22, a flow rate measurement unit 24, a voltage measurement unit 25, an abnormality detection unit 26, a warning unit 27, a removal determination unit 28, a counting unit 29, and an abnormality determination unit 30. And a stop unit 31.

  The propagation time measuring unit 22 corresponds to a part of the flow rate sensor of the present invention, is connected to the ultrasonic transducers 11a and 11b, and the flow rate measuring unit 24, and is transmitted and received between the ultrasonic transducers 11a and 11b. The propagation time of the ultrasonic signal is measured.

  The flow measurement unit 24 corresponds to a part of the flow sensor of the present invention, and is connected to the propagation time measurement unit 22, the abnormality detection unit 26, the removal determination unit 28, and the display unit 14. Based on the measured propagation time, the flow rate of the gas that is the fluid to be measured is measured. In addition, the flow rate measurement unit 24 stops measuring the gas flow rate during the period in which the removal determination unit 28 determines that the ultrasonic gas meter has been removed from the pipe.

  The voltage measurement unit 25 corresponds to a part of the flow sensor of the present invention, is connected to the ultrasonic transducers 11a and 11b, and the abnormality detection unit 26, and measures the voltage level of the reception signal of the ultrasonic signal.

  The abnormality detection unit 26 corresponds to the flow rate data abnormality detection unit of the present invention, and is connected to the flow measurement unit 24, the voltage measurement unit 25, and the counting unit 29, and is measured by the flow measurement unit 24 or the voltage measurement unit 25. Detects abnormal flow data.

  The warning unit 27 may be connected to the abnormality determination unit 30 and the display unit 14, and may output warning display data to the display unit 14 as necessary and issue a warning.

  The removal determination unit 28 is connected to external sensors (inclination sensor 15, pressure sensor 16, cutoff sensor 17), and determines whether or not the ultrasonic gas meter has been removed from the pipe. Specifically, the removal determination unit 28 is at least one of the inclination of the ultrasonic gas meter detected by the inclination sensor 15, the pressure detected by the pressure sensor 16, and the cutoff state detected by the cutoff sensor 17. Based on this, it is determined whether or not the ultrasonic gas meter is removed from the pipe.

  In the present embodiment, the removal determination unit 28 determines that the ultrasonic gas meter is inclined at a predetermined angle or more, the pressure in the gas flow path 10c is lower than a predetermined value, and the shutoff valve 13 is closed. Only when it is in the gas cutoff state, it is determined that the ultrasonic gas meter has been removed from the pipe.

  The counting unit 29 counts the number of flow data abnormality detected by the abnormality detection unit 26 according to the determination result determined by the removal determination unit 28. Specifically, when the removal determination unit 28 determines that the ultrasonic gas meter has been removed from the pipe, the counting unit 29 clears the number of abnormal flow data counted in the past to zero. Therefore, when the ultrasonic gas meter is first removed from the pipe, the counting unit 29 clears the number of abnormal flow data to zero, and then counts the number of abnormal flow data until the ultrasonic gas meter is connected to the pipe again. do not do.

  The counting unit 29 may stop counting the number of abnormal flow data during the period in which the removal determining unit 28 determines that the ultrasonic gas meter has been removed from the pipe. In this case, even when the ultrasonic gas meter is first removed from the pipe, the counting unit 29 does not clear the flow data abnormality count to zero, but simply stops counting the flow data abnormality count, and thereafter When the ultrasonic gas meter is connected to the pipe again, the previous number of abnormal flow data is counted continuously.

  The abnormality determination unit 30 determines the abnormality of the flow rate sensor based on the number of flow rate data abnormalities counted by the counting unit 29. For example, the abnormality determination unit 30 determines that the flow sensor is abnormal when the number of continuous or cumulative flow data abnormality counted by the counting unit 29 reaches a predetermined value or more.

  The stop unit 31 is connected to the abnormality determination unit 30 and the shutoff valve 13 and outputs a shutoff valve opening / closing signal for opening and closing the shutoff valve as necessary.

  FIG. 3 is a flowchart showing the operation of the ultrasonic gas meter according to the present embodiment. The operation of the ultrasonic gas meter according to the first embodiment will be described with reference to FIG.

  First, the ultrasonic gas meter starts ultrasonic measurement in both the forward direction and the reverse direction. As described above, the propagation time measuring unit 22 measures the propagation time of the ultrasonic signal transmitted and received between the ultrasonic transducers 11a and 11b. The flow rate measurement unit 24 measures and integrates the flow rate of the gas that is the fluid to be measured based on the propagation time measured by the propagation time measurement unit 22. Now, if the velocity of sound is c, the flow velocity of the fluid to be measured is v, and the distance from the ultrasonic transducer 11a to the ultrasonic transducer 11b is L, the propagation time of the forward ultrasonic signal is L / (c + v), The propagation time of the ultrasonic signal in the reverse direction is L / (cv). If the value of L is known, the sound speed and flow velocity can be obtained based on these propagation times. Therefore, the flow rate measuring unit 24 can obtain the instantaneous flow rate by multiplying the flow velocity of the gas that is the measured fluid by the cross-sectional area of the gas flow path 10c.

  The propagation time measurement unit 22 measures the propagation time every predetermined time and outputs the measurement result to the flow rate measurement unit 24. The flow rate measuring unit 24 is based on the instantaneous flow rate of the gas, which is the fluid to be measured, obtained based on the propagation time measured every predetermined time, and the time between the time measured this time and the time measured this time, While calculating | requiring the flow volume which flowed from the time of the last measurement to this measurement time, the flow volume calculated | required this time is further integrated | accumulated to the integrated flow volume value until the last time, and the flow volume with respect to all the time is measured. Thereafter, the flow rate measuring unit 24 outputs the measured flow rate for the entire time to the display unit 14. In addition, the flow rate measurement unit 24 outputs the instantaneous flow rate value or the integrated flow rate value to the abnormality detection unit 26 as flow rate data.

  The voltage measurement unit 25 measures the voltage level of the reception signal of the ultrasonic signal in the ultrasonic transducer 11 a or the ultrasonic transducer 11 b and outputs the measurement result to the abnormality detection unit 26.

  The abnormality determination unit 26 determines whether or not an abnormality of the ultrasonic sensor has occurred (step S101). Specifically, the abnormality detection unit 26 determines whether or not there is an abnormality in the gas flow rate data measured by the flow rate measurement unit 24. For example, the abnormality detection unit 26 determines that there is an abnormality when the instantaneous gas flow value indicates a value outside a predetermined range. In addition, the abnormality detection unit 26 detects an abnormality in the flow rate data based on the measurement result of the voltage level output as the flow rate data by the voltage measurement unit 25 (for example, the voltage level is equal to or lower than a predetermined value, or the ultrasonic wave has not reached, etc. ) Is detected.

  If no abnormality (measurement error) in the flow rate data is detected by the abnormality detection unit 26 (step S103), the counting unit 29 clears the number of flow rate data abnormalities counted in the past to zero (step S105).

  In step S <b> 103, when an abnormality (measurement error) is detected in the flow rate data by the abnormality detection unit 26, the counting unit 29 is detected by the abnormality detection unit 26 according to the determination result determined by the removal determination unit 28. Count the number of flow rate data abnormalities.

  Specifically, the removal determination unit 28 determines whether the ultrasonic gas meter is based on whether the outputs from the inclination sensor 15 (or the seismoscope), the pressure sensor 16, and the shutoff sensor 17 satisfy a predetermined condition. It is determined whether or not is in a state removed from the pipe (step S107).

  First, the removal determination unit 28 determines whether the inclination of the ultrasonic gas meter detected by the inclination sensor 15 is equal to or greater than a predetermined angle. Even in a state where the ultrasonic gas meter is not removed, there is a possibility that the shutoff valve 13 is closed and the pressure in the gas flow path 10c decreases. Therefore, if the removal determination is performed without taking into account the inclination of the ultrasonic gas meter, the removal determination unit 28 erroneously determines that the ultrasonic gas meter has been removed even though it has not been removed from the pipe, and the flow sensor Anomalies may be missed. Therefore, it is considered that the removal determination unit 28 should perform the removal determination in consideration of the inclination of the ultrasonic gas meter.

  Here, the tilt sensor 15 may be a seismic sensor. Further, in order to detect the occurrence of intermittent inclination due to transportation or the like, the removal determination unit 28 monitors the output from the inclination sensor 15 for a predetermined period, and when an ON state (with inclination) occurs for a certain ratio or more. It may be determined that it is tilted.

  Further, the removal determination unit 28 determines whether or not the pressure in the gas flow path 10c detected by the pressure sensor 16 is less than a predetermined value. When the pressure in the gas flow path 10c is not lowered, there is a high possibility that the ultrasonic gas meter is not removed from the pipe. If the removal determination is performed based only on the outputs of the inclination sensor 15 and the shutoff sensor 17, the removal determination unit 28 erroneously determines that it was removed even when tilted due to an earthquake or the like, and overlooks the flow sensor abnormality. there is a possibility. Therefore, it is considered that the removal determination unit 28 should perform the removal determination in consideration of the pressure in the gas flow path 10c.

  Further, the removal determination unit 28 determines the gas cutoff state (open / close state of the cutoff valve 13) detected by the cutoff sensor 17. When the shut-off valve 13 is open, even if the ultrasonic gas meter is removed from the pipe, the gas in the gas flow path 10c escapes and the gas and air are not mixed. The sonic gas meter is less likely to cause a problem of erroneously determining that an abnormal state of the flow sensor has occurred and a problem such as an alarm sound accompanying it.

  Although not shown, the inclination sensor 15 and the pressure sensor 16 may be connected to the abnormality detection unit 26 and used for abnormality detection of the ultrasonic gas meter. In this case, when the ultrasonic gas meter is removed from the pipe, the stop unit 31 can control the shutoff valve 13 to generate a seismic cutoff due to the inclination of the ultrasonic gas meter or a pressure drop cutoff due to a supply pressure drop. There is sex. The stop unit 31 often performs a shut-off operation immediately before removing the ultrasonic gas meter.

  In the present embodiment, the removal determination unit 28 determines that the ultrasonic gas meter is inclined at a predetermined angle or more based on the output of each sensor, and the pressure in the gas flow path 10c is lower than a predetermined value. Only when it is determined that the shutoff valve 13 is closed and the gas is shut off, it is determined that the ultrasonic gas meter is removed from the pipe. Since the flow rate data abnormality that occurred in this state is not an abnormality of the original meaning, but is considered to be caused by the inclination of the ultrasonic gas meter being removed, the counting unit 29 counted in the past. The number of flow rate data abnormalities is cleared to zero (step S109). Therefore, the abnormality determination unit 30 does not determine that the flow sensor is abnormal during the period in which the removal determination unit 28 determines that the ultrasonic gas meter is removed from the pipe.

  Further, as described above, the counting unit 29 may stop counting the number of abnormal flow data during the period in which the removal determining unit 28 determines that the ultrasonic gas meter is removed from the pipe.

  In addition, the flow rate measurement unit 24 stops measuring the gas flow rate during the period in which the removal determination unit 28 determines that the ultrasonic gas meter has been removed from the pipe. Specifically, the flow rate measurement unit 24 integrates the instantaneous flow rate value measured this time as zero. Thus, when the ultrasonic gas meter of the present embodiment detects an abnormality in the flow rate data as in the gas meter described in Patent Document 1, the flow rate value immediately before detecting the abnormality is integrated as the flow rate value acquired this time. However, since the measurement of the gas flow rate is stopped after the removal, correct flow rate measurement can be performed.

  The removal determination unit 28 can freely set conditions for determining whether or not the ultrasonic gas meter has been removed from the pipe, and does not necessarily use all three types of sensors, and can be freely combined. It is.

  When the ultrasonic gas meter does not satisfy any of the conditions of the angle of the ultrasonic gas meter, the pressure in the gas flow path 10c, and the cutoff state of the cutoff valve 13, the removal determination unit 28 is in a state where the ultrasonic gas meter is removed from the pipe. When the determination is not made, it is considered that the generated flow rate data abnormality actually indicates an abnormality. Therefore, the counting unit 29 counts the number of flow rate data abnormality detected by the abnormality detection unit 26 (measurement error detection frequency). (Step S111).

  The number of flow rate data abnormalities counted by the counting unit 29 is the number of occurrences of flow rate data that seems to be abnormal, excluding the influence of the flow rate data abnormality that occurs when the ultrasonic gas meter is removed. Therefore, the abnormality determination unit 30 determines the abnormality of the flow sensor based on the number of flow data abnormality counted by the counting unit 29. Here, the abnormality determination unit 30 determines whether or not the number of flow rate data abnormalities (measurement error detection count) counted by the counting unit 29 has reached a predetermined value n (step S113). If it is determined that the flow sensor is abnormal (ultrasonic sensor abnormality is established), it is determined (step S115).

  When the abnormality determination unit 30 determines that the flow sensor is abnormal, the stop unit 31 outputs a cutoff valve opening / closing signal for closing the cutoff valve 13 and closes the cutoff valve 13, and gas that is a fluid to be measured Stop inflow and outflow.

  The warning unit 27 outputs warning display data to the display unit 14 when the abnormality determination unit 30 determines that the flow sensor is abnormal. The warning unit 27 may be configured to issue a warning (warning or the like) using sound or light. Further, warnings may be given in stages according to the degree of abnormality. For example, a message may be displayed on the display unit 14 if the degree of abnormality is mild, an alarm is sounded if the level is moderate, and the shutoff valve 13 is closed via the stop unit 31 only when it is severe.

  As described above, according to the ultrasonic gas meter according to the first embodiment of the present invention, when the ultrasonic gas meter is removed from the pipe, the abnormality determination for the flow sensor is stopped, and the erroneous determination of the flow sensor abnormality is performed. Can be prevented.

  Moreover, since the inclination sensor 15 for detecting the inclination is provided, the installation state of the ultrasonic gas meter can be detected based on the detected inclination data. When the ultrasonic gas meter is not in a horizontal state, it can be determined that it may have been removed from the pipe.

  Moreover, since the pressure sensor 16 for detecting the pressure is provided, the installation state of the ultrasonic gas meter can be detected based on the detected pressure data. When the detected pressure is equal to or lower than a predetermined value or substantially equal to the atmospheric pressure, it can be determined that the ultrasonic gas meter may have been removed from the pipe.

  Further, since the shutoff sensor 17 for detecting shutoff is provided, the open / closed state of the shutoff valve 13 of the ultrasonic gas meter can be detected based on the detected shutoff data.

  Furthermore, based on the combination of the output results from these sensors (tilt sensor 15, pressure sensor 16, and shutoff sensor 17), the removal determination unit 28 reliably removes the ultrasonic gas meter from the pipe without making an erroneous determination. It can be determined whether or not it has been. Therefore, the counting unit 29 counts the number of occurrences of the flow rate data abnormality only when the ultrasonic gas meter is surely connected to the pipe based on the determination result by the removal determining unit 28. For this reason, the abnormality determination unit 30 can reliably determine the abnormality of the flow sensor without causing an erroneous determination, and can prevent the occurrence of an alarm based on the erroneous determination.

  In addition, the flow rate measurement unit 24 stops measuring the gas flow rate during the period when the removal determination unit 28 determines that the ultrasonic gas meter has been removed from the pipe, so that the correct flow rate measurement can be performed. it can.

  The ultrasonic gas meter according to the present invention is applicable to an ultrasonic gas meter that measures the flow rate of a fluid such as a gas using ultrasonic waves and issues a gas cutoff or alarm in response to a measurement error.

It is a block diagram of the ultrasonic gas meter of the form of Example 1 of the present invention. It is a block diagram which shows the internal structure of the control part of the ultrasonic gas meter of the form of Example 1 of this invention. It is a flowchart figure which shows operation | movement of the ultrasonic gas meter of the form of Example 1 of this invention.

Explanation of symbols

10a Gas inlet 10b Gas outlet 10c Gas flow path 11a, 11b Ultrasonic vibrator 13 Shut-off valve 14 Display unit 15 Inclination sensor 16 Pressure sensor 17 Shut-off sensor 20 Control unit 22 Propagation time measurement unit 24 Flow rate measurement unit 25 Voltage measurement unit 26 Abnormality detection unit 27 Warning unit 28 Removal determination unit 29 Counting unit 30 Abnormality determination unit 31 Stopping unit

Claims (3)

In the ultrasonic gas meter having a flow sensor for measuring the flow rate of the gas flowing in the flow path,
A flow rate data abnormality detection unit for detecting an abnormality of the flow rate data measured by the flow rate sensor;
A removal determination unit for determining whether or not the ultrasonic gas meter is in a state of being removed from the pipe;
A counting unit for counting the number of flow rate data abnormalities detected by the flow rate data abnormality detection unit according to the determination result determined by the removal determination unit;
A flow rate sensor abnormality determination unit that determines abnormality of the flow rate sensor based on the number of flow rate data abnormalities counted by the counting unit;
An inclination detector for detecting the inclination of the ultrasonic gas meter;
A pressure detector for detecting the pressure in the flow path;
A shut-off detection unit for detecting the shut-off state of the gas flowing in the flow path;
With
The ultrasonic wave meter is removed when the output of the shutoff detector is in a shutoff state, the output of the tilt detector is in a tilted state, and the output of the pressure detector is in a pressure drop state. It is determined that
The counting unit stops counting the number of flow rate data abnormalities while it is determined that the ultrasonic gas meter is in a removed state,
The ultrasonic gas meter according to claim 1, wherein the flow sensor abnormality determination unit determines that the flow sensor is abnormal when the number of flow data abnormality counted by the counting unit is equal to or greater than a predetermined value.   2. The counter according to claim 1, wherein when the removal determination unit determines that the ultrasonic gas meter is in a state of being removed from the pipe, the count of flow data abnormality counted in the past is cleared to zero. The ultrasonic gas meter as described.   The said flow sensor stops the measurement of a gas flow rate during the period when it is determined with the said removal determination part being the state from which the said ultrasonic gas meter was removed from piping. The ultrasonic gas meter as described.

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