KR20040030352A - Gas shutoff device - Google Patents

Abstract

In this gas shutoff device, the flow rate detector detects the flow rate of the medium. The blocking portion blocks the flow path of the medium. The flow rate correction value setting section sets the flow rate correction value. The flow rate calculating section calculates the flow rate from the flow rate and corrects it with the flow rate correction value. The zero point setting section sets the flow range. The zero point determination section determines whether the corrected flow rate is out of the flow rate range. The abnormality judging section outputs a cutoff signal that cuts off the flow path when the corrected flow rate is in an abnormal state. When the flow path is blocked, if the zero determination unit determines that the corrected flow rate is out of the flow range, the state determination unit outputs a cutoff signal and the flow path is blocked. At this time, the flow rate calculation unit calculates a new flow rate correction value, and the flow rate correction value setting unit stores the flow rate correction value.

Description

Gas shut-off device {GAS SHUTOFF DEVICE}

The present invention detects the flow rate of various media flowing in the pipe using ultrasonic waves, such as various city gases or liquefied petroleum gas (LP gas), and accurately measures the amount of the media used, It relates to a gas shutoff device for monitoring whether the state of use is safe.

A conventional gas shutoff device of this kind is shown, for example, in Japanese Patent Laid-Open No. 1997-21667. 7 shows a block diagram of a conventional gas shutoff device. Hereinafter, an example of a conventional gas shutoff device will be described with reference to FIG. 7.

The first vibrator 2 is provided upstream of the fluid conduit 1. The second vibrator 3 is attached to the downstream side of the fluid passage 1 opposite the first vibrator 2. The transmitting circuit 4 transmits an ultrasonic signal to the first vibrator 2, and the amplifying circuit 5 amplifies the signal received by the second vibrator 3. The comparison circuit 6 compares the amplified signal with the reference signal. The clock unit 7 measures the time from the transmission of the ultrasonic wave to the reception with a timer counter. The measurement circuit 8 includes the transmission circuit 4 to the timepiece 7. Here, the arrow A indicates the direction in which the fluid flows.

The flow rate calculating section 9 calculates the flow rate value in consideration of the size of the pipe and the state of the flow in accordance with the ultrasonic propagation time obtained in the time display section 7. The period variable part 10 changes the measurement period corresponding to the value of the flow rate calculation part 9. The measurement start part 11 adjusts the signal transmission timing to the transmission circuit 4 according to the value of the period variable part 10. The measurement end part 12 detects the calculation end of the flow rate calculation part 9. The voltage control unit 13 reduces the voltage of the measurement circuit 8 in synchronization with the calculation end detection of the measurement end unit 12, and synchronizes with the measurement start by the measurement start unit 11 ( Return the voltage of 8).

In the conventional configuration described above, after the gas shutoff device is installed, an error occurs in the measurement of the gas flow rate due to the change over time of the measurement circuit 8, the first vibrator 2, or the second vibrator 3. It may occur.

An object of the present invention is to provide a gas shutoff apparatus that accurately measures the flow rate of a gas medium in a gas fluid line when no gas appliance is used, and monitors the amount of gas medium used and whether the use state thereof is safe. That is, the gas shutoff device accurately measures the flow rate of the gas medium in the gas fluid line when the gas appliance does not use city gas or liquefied petroleum gas (LP gas) after it is installed.

The gas shutoff device of the present invention operates as follows.

(a) The flow rate detection unit detects the flow rate of the medium.

(b) The blocking section blocks the flow path of the medium.

(c) The flow rate correction value setting section sets the flow rate correction value.

(d) The flow rate calculating unit calculates the flow rate by the flow rate detected by the flow rate detecting unit, and corrects the flow rate required by the flow rate with the flow rate correction value.

(e) The zero point setting section sets the flow range.

(g) The zero point determination unit determines whether the flow rate corrected by the flow rate calculation unit is out of the flow rate range.

(h) The abnormality judging unit judges whether or not the corrected flow rate is in an abnormal state, and when it is determined that the abnormality is abnormal, outputs a first blocking signal for blocking the flow path to the blocking unit;

(i) When the state determining unit determines that the corrected flow rate is out of the flow rate range without the blocking unit blocking the flow path of the medium, the state determining unit outputs a second blocking signal for blocking the flow path to the blocking unit.

Here, the flow rate calculating unit calculates a new flow rate correction value in accordance with the flow rate detected by the flow rate detecting unit in a state in which the blocking unit blocks the flow path by the second blocking signal, and the flow rate correction value setting unit stores the new flow rate correction value.

1 is a block diagram of a gas shutoff device of Embodiment 1 of the present invention;

2 is a block diagram of a gas shutoff device of a second embodiment of the present invention;

3 is a block diagram of a gas shutoff device of a third embodiment of the present invention;

4 is a block diagram of a gas shutoff device of a fourth embodiment of the present invention;

5 is a block diagram of a gas shutoff device of a fifth embodiment of the present invention;

6 is a block diagram of a gas shutoff device of a sixth embodiment of the present invention;

7 is a block diagram of a conventional gas shutoff device.

Explanation of symbols for the main parts of the drawings

14: flow rate detection unit 20: flow rate calculation unit

21: abnormality determination unit 22: blocking unit

23: zero setting unit 24: zero determination unit

25: state determination unit 26: flow rate correction value setting unit

28: return unit 29: return prohibition unit

30: communication control unit 32: flow rate integration unit

33: display unit 34: communication unit

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 6.

(Example 1)

1 is a block diagram of a gas shutoff device of a first embodiment of the present invention.

The first vibrator 2 is provided upstream of the flow path 1. The second vibrator 3 is attached to the downstream side of the flow path 1 so as to face the first vibrator 2. Here, the arrow A indicates the direction in which the fluid flows. The fluid is specifically a gas medium such as city gas or liquefied petroleum gas (LP gas).

The flow rate detection part 14 transmits an ultrasonic wave signal from one of the upstream vibrator 2 and the downstream vibrator 3, receives it to the other side, and detects the flow velocity of a use gas from the propagation time of the ultrasonic signal.

The flow rate detecting unit 14 includes a switching unit 15, a transmitting unit 16, a receiving unit 17, a repeating unit 18, and a propagation time measuring unit 19.

The transmitter 16 and the receiver 17 are connected to the switching unit 15. The switching unit 15 first connects the transmitter 16 to the upstream vibrator 2, the receiver 17 to the downstream oscillator 3, and then connects the transmitter 16 to the downstream oscillator 3. In order to connect the receiver 17 to the upstream vibrator 2, the connection destinations of the transmitter 16 and the receiver 17 are alternately switched.

The repeater 18 repeatedly transmits and receives an ultrasonic signal while the receiver 17 is connected to the upstream vibrator 2 and the transmitter 16 is connected to the downstream vibrator 3. The propagation time measuring unit 19 repeatedly measures the propagation time of the ultrasonic signal. In addition, the propagation time measuring unit 19 accumulates repeatedly the measured propagation time. Next, the switching section 15 connects the receiving section 17 to the downstream vibrator 3 and the transmitting section 16 to the upstream vibrator 2 to repeat the above-described operations.

The propagation time measuring unit 19 propagates the propagation time (or accumulated propagation time) of the ultrasonic signal first received and obtained, and the propagation time (or accumulated propagation time of the ultrasonic signal measured after the next switching by the switching unit 15). The propagation time difference of their ultrasonic signals.

The propagation time measuring unit 19 calculates the flow rate of gas using the propagation time (or accumulated propagation time) or propagation time difference (or accumulated propagation time difference) of the ultrasonic signal.

The flow rate calculator 20 calculates the medium flow rate, that is, the gas flow rate, used from the requested flow rate value.

The abnormality determination unit 21 determines whether or not the gas appliance use state is abnormal from the gas flow rate obtained by the flow rate calculation unit 20.

In addition, the abnormality determination part 21 stores the numerical value used as the reference | standard as follows, for example.

1) Maximum flow rate cut-off value for monitoring the large flow rate of abnormal condition that occurs when the hose supplying gas to the use device such as stove is pulled out for some reason

2) The use time cutoff table that defines the time limit for the use time corresponding to the case where the apparatus is used much longer than the normal use time.

The abnormality judging unit 21 monitors whether there is no abnormality corresponding to exceeding the reference value thereof.

The shutoff part 22 cuts off the gas flow path 1 by the cutoff signal output when the abnormality determination part 21 determines that it is abnormal.

Flow rate range FR (e.g., ± 1.5 L / h, for example, ± 1.5 L / h, etc.), which is the tolerance range of the gas flow rate (hereinafter referred to as detection flow rate) output from the flow rate detection unit 14 to the zero point setting unit 23, h is the abbreviation of liters, h Remember to set the abbreviation of time). The zero point determination unit 24 monitors whether the detected flow rate is within the flow rate range FR.

The state judging section 25 receives a signal from the zero point judging section 24 notifying whether the detected flow rate in the gas appliance stop state is within the flow rate range FR, and from the abnormality judging section 21 indicating whether or not the abnormal state is present. Determine the signal. And the state determination part 25 determines whether a flow volume correction value is measured. In addition, the state in which the detected flow volume in the gas mechanism stop state is out of the flow range FR is called "zero shift".

When the zero determination unit 24 detects a zero shift in a state where normal gas can be used, the state determination unit 25 closes the breaker 22 to measure a new flow rate correction value. In this case, the flow rate correction value setting unit 26 stores the flow rate value obtained by the flow rate calculation unit 20 as the flow rate correction value when the flow rate is 0 while the flow path 1 is closed by the breaker 22.

The notification unit 27 judges that the abnormal state of the use state of the gas is abnormal, and the driving unit 23 drives the blocking unit 23 to display the blocking state or the blocking content on the liquid crystal display device and to monitor the safety of the gas. Notify the center you are doing by telephone line.

Next, the operation of the above configuration will be described.

Usually, there is no zero shift when installing a gas shutoff device. In other words, the value of the detected flow rate when there is no use of the gas mechanism is approximately 0 or within a predetermined range.

This is for the following reason.

In advance, the state determination unit 25 measures the flow rate correction value so that the detected flow rate is within the flow rate range FR, and stores the correction value in the flow rate correction value setting unit 26. Thereafter, the flow rate calculation unit 20 corrects the flow rate value determined by the flow rate with the flow rate correction value, and outputs the corrected flow rate as the detected flow rate.

When the gas is not used, the flow rate calculation unit 20 registers the use flow rate when the gas appliance is used, but determines that there is no use of the appliance when it is completely unregistered.

However, as a result of long-term use, the value of the detected flow rate when the instrument is not used may be out of the flow rate range FR due to various environmental conditions, temperature and humidity. That is, the flow rate correction value calculated | required in advance may shift.

The abnormality determination part 21 monitors the detected flow volume output from the flow volume calculating part 20, and determines whether or not abnormality was used at the time of using a mechanism.

For example, when the abnormality determination unit 21 detects a flow rate such that a large flow rate of live gas such as a hose is released, the abnormality determination unit 21 outputs a first blocking signal to drive the blocking unit 22. do. The shut-off part 22 cuts off the flow path 1 and stops gas supply. The notification unit 27 notifies the gas consumer or the gas company of the blocked abnormality.

On the other hand, when the zero point determination unit 24 detects the zero shift in the state where the gas mechanism is stopped, the state determination unit 25 determines whether or not the zero point correction may be performed. That is, the state determination unit 25 receives that the zero determination unit 24 detects the zero shift, and performs the zero correction processing only in the normal gas use state in which the abnormality determination unit 21 has no abnormality determination of the use of the gas appliance. .

For example, when a gas hose is pulled out by an accident, the abnormality determination part 21 outputs the 1st interruption | signal signal which is a signal which informs an abnormality, and the interruption | blocking part 22 cuts off the flow path 1. In this case, the end of the flow path 1 is in an open state, and there is a possibility that the air flows backward and is mixed with city gas or LP gas in the pipe. After the flow path 1 is abnormally judged by the abnormality determination unit 21 in the situation of such an abnormal state, when the state determination unit 25 performs zero correction measurement, the flow velocity of the abnormal state is detected and set as the flow rate correction value. Therefore, when the signal determined abnormally from the abnormality determination part 21 is input into the state determination part 25, even if it determines with the zero determination part 24 being a zero deviation state, the process of measuring a flow volume correction value is delayed.

That is, the abnormality determination part 21 does not perform a zero correction measurement process immediately after returning from an abnormal interruption | blocking state or an abnormal interruption | blocking state. After the abnormal state is released and the normal gas is usable, the zero point determination measurement start signal, which is the second blocking signal, is output from the state determining unit 25.

When the zero correction measurement start signal is output from the state determination unit 25 to the breaker 22, the breaker 22 closes the flow path 1 so that no gas flows.

At that time, the state determination unit 25 measures the new flow rate correction value, that is, zero calibration measurement. In a state where the flow path 1 is blocked by the breaker 22, the flow rate detection unit 14 measures the flow rate, and the flow rate calculation unit 20 converts the flow rate into a flow rate. The flow rate value correction setting unit 26 stores the converted flow rate as a flow rate correction value and stores it. In the zero calibration measurement state, the flow path 1 is closed by the blocking unit 22.

Therefore, the flow rate correction value is measured while the mechanism is not used, that is, the gas does not flow completely.

Thereafter, the shutoff portion 26 is driven to open the flow path 1, and the gas mechanism can be used as usual. Therefore, the flow rate calculation unit 20 converts the flow rate detected by the flow rate detection unit 14 into a flow rate, and corrects the converted flow rate to the flow rate correction value stored in the flow rate correction value setting unit 26 (the sign of the correction value is ±, Addition correction or subtraction correction) and output as a detection flow rate. As a result, the value of the detected flow volume at the time of stop of the instrument is within the flow rate 0 or the predetermined flow rate range FR, and the flow rate can be accurately measured even when the instrument is used.

As described above, the flow rate correction value is updated as a zero correction value (zero offset value) at the flow rate 0, and is adjusted so that the value of the detected flow rate is always 0 in a state where no gas is used. Accordingly, the integration accuracy of the gas usage is improved, and the flow rate measurement accuracy is extremely improved without safety warning that the gas is leaking, thereby improving safety and usability.

In addition, in the monitoring of the gas appliance use state, it is mistakenly judged as a large flow rate in an abnormal state and is not judged to be the maximum flow rate interruption. In addition, when determining the time limit of the use time interruption, the measurement of the gas flow rate is carried out incorrectly and no other time limit is set. Therefore, the abnormality determination part 21 can monitor the use state of gas correctly.

(Example 2)

2 is a block diagram of a gas shutoff device of a second embodiment of the present invention.

In FIG. 2, the same code | symbol is attached | subjected to the component which has the function similar to FIG. 1, and description is abbreviate | omitted.

As shown in Fig. 2, the gas shutoff device of the present embodiment includes a return portion 28 and a return inhibiting portion 29 in addition to each element of the first embodiment.

When the flow path 1 is closed by the breaker 22, when the return unit 28 is operated, a return signal for the breaker 22 to open the flow path 1 is output.

Normally, when the return signal is output from the return unit 28, the return prohibition unit 29 outputs to the breaker 22, and the breaker 22 releases the blocked state of the flow path 1 by the return signal. .

However, when the zero determination measurement start signal, which is the second blocking signal, is input by the state determining unit 25, the return prohibiting unit 29 prohibits the reception of the return signal from the return unit 27, and the blocking unit 22 stops. Does not output the return signal. Specifically, in order to obtain the flow rate value at the time of stopping the mechanism, the flow rate unit 14 is closed, the flow path 1 is closed, the flow rate detection unit 14 detects the flow rate, and the flow rate conversion unit 20 calculates the flow rate value. As a result, the return prohibition state is maintained during the process of setting the memory.

As is apparent from the above description, even when the flow rate correction value is measured, even when the return unit 28 is operated inadvertently, the flow path 1 is kept open, and thus the flow rate correction value can be measured normally.

(Example 3)

3 is a block diagram of a gas shutoff device of a third embodiment of the present invention.

In FIG. 3, the same code | symbol is attached | subjected to the component which has the same function as FIG. 1, FIG. 2, and description is abbreviate | omitted.

As shown in FIG. 3, the gas shutoff device of this embodiment includes a communication control unit 30 in addition to each element of the first embodiment.

The communication control unit 30 externally displays the amount of gas used, the instantaneous flow rate, or the contents of the shut-off unit 22 operated by the abnormality determination unit 21 in response to a request from the center of the external device or the gas company (communication message). Return to the center of the device or gas company. In addition, the communication control unit 30 outputs a zero correction control signal to the state determination unit 25 when receiving a zero correction request (zero correction instruction full text) from an external device or a gas operator's center.

The state determination unit 25 normally checks whether or not zero deviation occurs at the zero determination unit 24 periodically, and outputs a zero correction measurement start signal that is a second cutoff signal at regular timing. When the communication control unit 30 outputs the zero correction control signal, the state determination unit 25 confirms the determination result of the abnormality determination unit 21. And when the abnormality determination part 21 does not determine that it is an abnormal state, the state determination part 25 outputs the interruption | blocking signal to the interruption | blocking part 22, cuts off the flow path 1, and outputs a zero correction measurement start signal. do. And zero correction measurement is performed like a 1st Example.

According to this embodiment, in addition to regular zero correction measurement by the zero determination part 24, zero correction measurement at arbitrary timing can be performed through the communication control part 30 externally. As a result, the following request can be responded to. Accurate flow measurement is essential as a countermeasure for leakage, and regular maintenance inspection of the gas supply facility including the gas shutoff device is necessary. In addition, when the gas shutoff device is damaged by flooding or the like due to flooding or the like, a calibration check is necessary, and the zero point correction value must be able to be checked at any time, that is, at an arbitrary timing.

In addition, the gas shutoff device of this embodiment may be provided with the same return part 28 and the return prohibition part 29 as 2nd Embodiment.

(Example 4)

4 is a block diagram of a gas shutoff device of a fourth embodiment of the present invention.

In FIG. 4, the same code | symbol is attached | subjected to the component which has the same function as FIGS. 1-3, and description is abbreviate | omitted.

In FIG. 4, the notification unit 31 determines that the abnormality of the gas appliance is abnormal by the abnormality determination unit 21, and displays a warning when the cutoff unit 22 is operated. On the other hand, when the zero determination measurement start signal which is a 2nd cutoff signal is output by the state determination part 25, the display which is carrying out zero correction will be performed, and the gas consumer or gas company will be notified of the content of the correction | amendment of a flow volume correction value. That is, since the zero point correction is performed when the instrument is stopped, it is prevented that the gas instrument can be misused during the calibration. After the zero calibration measurement, the display during zero calibration is turned off, and the normal gas mechanism is in use.

In addition, the notification unit 31 notifies the gas consumer, the gas company, and the security center that the zero point is being corrected. However, the abnormality of blocking the passage 1 like the notification unit 27 in the third embodiment is also a gas consumer. B Notify gas operators and security centers.

The operator or the security center can use the reported information as management information such as the number of times of calibration of the installed gas shutoff device and notification of the shutoff device itself.

(Example 5)

5 is a block diagram of a gas shutoff device of a fifth embodiment of the present invention.

In FIG. 5, the same code | symbol is attached | subjected to the component which has the same function as FIGS. 1-4, and description is abbreviate | omitted.

In FIG. 5, the flow rate integrating unit 32 calculates the gas consumption by integrating the detected flow rate output by the flow rate detecting unit 14. The display part 33a is comprised from the integration display part 33a which displays the gas usage calculated | required by the flow volume integration part 32, and the state display part 33b. When the abnormality determination part 21 judges the abnormal use of the gas mechanism, and operates the cut-off part 22, the state display part 33b displays a warning of the abnormality. In addition, the state display part 33b, when the zero determination measurement start signal which is a 2nd interruption signal is output by the state determination part 25, it displays that it is carrying out zero correction. The integration display unit 33a is configured with a numeric display element such as a method of displaying one digit in seven segments for notifying the gas demander or gas company of the gas usage. By numerical display, it is used for regular meter reading of gas company.

In addition, the communication unit 34 communicates the abnormality displayed on the display unit 33b to the gas consumer or the gas company.

When the abnormal state is released and the normal gas available state is output, when the zero correction measurement start signal is output from the state determination unit 25, the display unit 33 starts display during the zero correction measurement. In this way, the display unit 33 notifies the gas demand value or the gas company that the gas appliance is in an unusable state and that the flow rate correction value is being calibrated.

In the case of maintaining the gas shutoff device, the trend of the zero point correction value is an important factor, and the flow rate correction value should be read or displayed from the outside by a setter or a communication specialist.

When the communication unit 34 receives the flow rate correction value request, the flow rate correction value stored in the flow rate correction value setting unit 26 is displayed on the integration display unit 33a instead of the integrated value. The displayed flow corrections allow the gas operator to monitor the flow measurement performance of the installed gas shutoff device. When the change of the value is recorded and monitored, it is possible to grasp and monitor the change of the characteristic over time. In addition, the integration display request is transmitted from the outside to the communication unit 34, and when received, the integration display returns to the normal integration display.

As is apparent from the above description, the communication unit 34 can instruct the display unit 33 to perform the zero point correction value display. Therefore, a gas company can monitor the correction content of the flow measurement performance of a gas shutoff device, and its time-change state. This is useful for notification management and also for analysis at abnormal flow rate detection. Moreover, abnormality of a mechanism or a facility, abnormality of the measurement part of a gas shutoff apparatus, etc. can be discriminated by this. In this way, since the usability is improved and maintained, the reliability is improved.

(Example 6)

6 is a gas shutoff device of a sixth embodiment of the present invention.

In FIG. 6, the same code | symbol is attached | subjected to the component which has the same function as FIGS. 1-5, and description is abbreviate | omitted.

When the return unit 28 is operated in FIG. 6, the abnormality determination unit 21 detects an abnormality and sends a release signal to the blocking unit 22 which blocks the flow path 1, thereby releasing the blockage of the flow path 1. . The display switching unit 35 measures the time during which the return unit 28 has been operated. And when the return part 28 is operated for a predetermined time, the display switching part 35 controls to display switch of the display of the integration display part 33a from a flow volume integration value to a flow volume correction value.

For example, when the return unit 28 is operated after an abnormality such as hose detachment is solved, a return signal is output to the breaker unit 22, and the flow path 1 opens to become a gas supply state.

After the abnormal state is released and the normal gas available state is set, when the zero correction measurement start signal is output from the state determination unit 25, the display unit 33b starts the display during the zero correction measurement. In this way, the display part 33b notifies the gas consumer or gas company that the gas appliance is in an unusable state and that the flow rate correction value is being calibrated.

That is, the zero point correction is performed at the time of stopping the mechanism, but at this time, the zero point measurement is displayed using the display unit 33b to prevent the misjudgment that the gas mechanism can be used. After the zero calibration measurement, the display during zero calibration is turned off, and the normal gas mechanism is in use. In addition, since the gas supplier can be notified of the zero point correction through the telephone line or the like, the operator can easily manage the number of times the calibration of the installed gas shutoff device and the like can be utilized as maintenance information of the device itself.

In the case of holding the gas shutoff device, the change of the zero correction amount is an important factor, and the flow rate correction value is read or displayed by the return unit 28 without using a setter or a communication message. Gas operators may forget to take setters, portable communication units, etc. to the site, so the flow rate correction should be displayed in a simple way. When the return unit 28 is operated in a state where the breaker 22 does not operate and detects that the display switching unit 35 has been operated for a predetermined time, the integrated value display is switched to the integrated display unit 33a of the display unit 33. Display the flow rate correction value. From this actual flow rate correction value, a gas company can monitor the flow measurement performance of the installed gas shutoff device. When the change of the value is recorded and monitored, it is possible to grasp and monitor the change of the characteristic over time. In addition, when the display switching part 35 detects the no operation state to the predetermined time return part 28, it will return to normal integration display.

Since the zero point correction value can be displayed on the display unit 33 when the predetermined operation is performed by the return unit 28, the gas operator can monitor the correction contents of the flow measurement performance of the gas shutoff device and the state of the time change. It is also useful for the analysis at the time of abnormal flow rate detection, and it is possible to discriminate an abnormality of a mechanism or a facility, an abnormality of a measurement part of a gas shutoff device, etc., thereby improving usability, maintainability and reliability.

According to the present invention, since the correction value at the flow rate 0 is not obtained in the gas pressure drop state or the abnormal state in which the gas appliance leak is cut off, the measurement accuracy of the gas flow rate is high, and the use state of the gas appliance can be monitored by accurate flow rate measurement. There is an effect of improving the reliability and stability.

Claims (6)

In the gas shutoff device, (a) a flow rate detector for detecting a flow rate of the medium, (b) a blocking portion for blocking the flow path of the medium; (c) a flow rate correction value setting section for setting a flow rate correction value, (d) a flow rate calculating section, comprising: a flow rate calculating section for obtaining a flow rate from the flow rate detected by the flow rate detecting section and correcting the flow rate obtained from the flow rate with the flow rate correction value; (e) a zero point setting section for setting the flow rate range, (g) a zero point determination unit that determines whether or not the flow rate corrected by the flow rate calculation unit is outside the flow rate range; (h) an abnormality judging unit, which determines whether or not the corrected flow rate is abnormal, and when determining that the abnormality is abnormal, outputs a first blocking signal for blocking the flow path to the blocking unit; (i) when the zero determination unit determines that the corrected flow rate is out of the flow rate range without the blocking unit blocking the medium flow path, outputting a second blocking signal for blocking the flow path to the blocking unit. Including a state judgment unit, The flow rate calculating unit obtains a new flow rate correction value in accordance with the flow rate detected by the flow rate detecting unit in a state where the blocking unit blocks the flow path by the second cutoff signal, and the flow rate correction value setting unit stores the new flow rate correction value. Gas shutoff device. The method of claim 1, (j) a return unit for outputting a return signal for releasing the blocking state of the flow path; (k) further including a return prohibition section for prohibiting outputting the return signal to the cutoff portion until the flow rate correction portion memorizes the new flow rate correction value after the flow path is blocked by the second cutoff signal. Gas shutoff device. The method of claim 1, (j) further includes a communication control unit for outputting a zero correction control signal when a full zero calibration measurement instruction is received from the outside, The state determining unit outputs the second blocking signal when the communication control unit outputs the zero correction control signal. Gas shutoff device. The method of claim 1, (j) The flow rate calculation unit obtains the new flow rate correction value from the flow rate detected by the flow rate detection unit in a state in which the blocking unit operates by the second cutoff signal, and the flow path is blocked. And further including a notification unit for performing an indication indicating that the correction is in progress until the correction value is stored. Gas shutoff device. The method of claim 1, (j) a flow rate integration unit for accumulating the flow rate corrected by the flow rate calculation unit; (k) a display unit for displaying the flow rate correction value stored in the flow rate integration value requested by the flow rate integration section or the flow rate correction value setting section; (l) a communication unit for switching the display of the display unit from the flow rate integrated value to the corrected flow rate value stored in the flow rate correction value setting unit when receiving the zero point correction display full text from the outside; Gas shutoff device. The method of claim 1, (j) a flow rate integration part for integrating the flow rate values obtained by the flow rate calculation part; (k) a return unit for canceling the operation of the blocking unit and outputting a return signal for opening the flow path; (l) a display unit for displaying the flow rate integration value obtained by the flow rate integration unit or the flow rate correction value stored in the flow rate correction value setting unit; (m) and a display switching section for switching the display of the display section from a flow rate integration value to a display section flow rate correction value for displaying a flow rate correction value stored in the flow rate correction value setting section when the return section has been operated for a predetermined time. Gas shutoff device.