JPH11190518A - Gas cut-off device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To discriminate the kind of gas automatically and permit setting of various kinds of cut-off values for monitoring safety, by a method wherein physical amount of using gas medium is measured to compare data with the data of physical amount of various kinds of gas mediums, and specify the kind of gas while various kinds of cut-off values corresponding to the kind of gas are set. SOLUTION: A physical amount of medium detecting means 9 is installed in the measuring flow passage of town gas, LPG or the like to detect the physical amount of a using gas medium. In this case, the physical amount is decided by measuring an acoustic speed in the using gas employing an ultrasonic signal or the like or by detecting the frequency of vibration of the fluid. A medium deciding means 13 decides the kind of gas of the using medium through the output signal of the physical amount of medium detecting means 9. The physical amount of LPG gas and various town gases, for examples, under respective constituting conditions are stored as the data while the kind of the gas is specified by the physical amount detected by the physical amount of medium detecting means 9. When the kind of using gas is specified in the medium deciding means 13, a cut-off value corresponding to the kind of gas is set in an abnormality deciding means 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention discriminates the type of medium, such as various city gas or LPG gas, flowing in a pipe by using, for example, ultrasonic waves, and determines whether the medium usage and the usage state are safe. The present invention relates to a gas shut-off device for monitoring whether or not a gas is shut off.

[0002]

2. Description of the Related Art A conventional flow meter of this type has a configuration shown in FIG. 4 as disclosed in, for example, Japanese Patent Application Laid-Open No. 4-328423. FIG. 4 shows a block diagram of a conventional gas shut-off device.

In FIG. 4, reference numeral 1 denotes a pipe, and 2 denotes a first ultrasonic probe, which is installed on the upstream side of the pipe 1. 3 is the second
The ultrasonic probe is mounted opposite to the downstream side of the pipe 1.

[0004] Reference numeral 4 denotes a receiving circuit, and 5 denotes a transmitting circuit. Reference numeral 6 denotes a switch for connecting the receiving circuit 4 and the transmitting circuit 5 to the first or second circuit.
First connected to either one of the ultrasonic probes 2 and 3 for measuring the propagation time. After completion of the time measurement, the connection destinations of the reception circuit 4, the transmission circuit 5, and the first or second ultrasonic probe 2, 3 are connected to the ultrasonic probe opposite to the first, and the propagation time at the time of reverse connection is measured. . 7 is a propagation time measurement circuit, and 8 is a flow rate calculation circuit.

Next, the operation of the conventional configuration will be described. LP
A transmission circuit 5 is connected to the first ultrasonic probe 2 and a reception circuit 4 connected to the second ultrasonic probe 3 which are first opposed by the switch 6 in the pipe 1 in which gas such as gas or city gas flows. A signal is emitted from the first ultrasonic probe 2 to the second ultrasonic probe 3, and a first propagation time of the signal is measured. Next, the ultrasonic probe connected to the receiving circuit 4 and the transmitting circuit 5 is reversed by the switch 6. Similarly, a signal is emitted from the second ultrasonic probe 3 to the first ultrasonic probe 2, the second propagation time of the signal is measured, and the first and second propagation times are input to the propagation time measuring circuit 4. Then, a propagation time difference is obtained. Next, the flow rate Q at the time of measurement is obtained from the propagation time difference obtained by the flow rate calculation circuit 8.

[0006]

However, in the above-mentioned conventional configuration, there is disclosed a method of determining what kind of gas is to be used in order to measure a usage amount or to monitor whether or not an abnormal use state occurs when the gas shut-off device is installed. Absent.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems. When a gas shut-off device is installed, a customer who uses the gas automatically determines what kind of gas to use and sets various cut-off values for safety monitoring. The purpose of the present invention is to provide a gas shut-off device that performs the following.

[0008]

In order to solve this problem, the present invention first measures a physical quantity of a used gas medium and determines physical quantity data for each gas medium in order to determine a gas type when a gas shut-off device is installed. And a gas type is specified by comparing and judging. Further, when the gas type can be determined, various cutoff values corresponding to the gas type for various safety monitoring are set in the abnormality determination means.

As a result, the type of gas to be used, such as when a gas shut-off device is installed, is investigated, and the number of gas appliances possessed by the customer who uses the gas is investigated to set the cut-off value, and the cut-off value is erroneously determined. An erroneous operation for setting can be prevented, and anyone can quickly install the gas shut-off device.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to achieve the above object, the present invention provides a medium physical quantity detecting means for detecting a physical quantity generated corresponding to a flow velocity of a medium, and converts the physical quantity detected by the medium physical quantity detecting means into a flow rate. Flow rate calculating means, an abnormality determining means for determining whether or not the flow rate value obtained by the flow rate calculating means is an abnormal usage amount; a shutoff means for shutting off a medium flow path when the abnormality determining means determines that an abnormality has occurred; It comprises a medium determining means for determining the type of medium to be used based on the physical quantity detected by the medium physical quantity detecting means, and a cutoff value setting means for setting various cutoff values corresponding to the medium type obtained by the medium determining means.

Therefore, according to the present invention, the type of the medium to be used is automatically determined by the medium determining means, and an optimum cutoff value (for example, the maximum use flow rate or the use time) is selected according to the type of the medium to determine the abnormality. Since it is set as a means, it is possible to prevent a large or small cutoff value from being set by mistake, and to improve safety and usability.

[0012] Further, the present invention provides
Medium physical quantity detecting means for detecting a physical quantity generated in accordance with the flow velocity of the medium, flow rate calculating means for converting a physical quantity detected by the medium physical quantity detecting means into a flow rate, and a flow rate value obtained by the flow rate calculating means is abnormally used. Abnormality determining means for determining whether or not the amount is an amount, a blocking means for blocking a medium flow path when the abnormality determining means determines that the medium is abnormal, and detecting a used medium type by determining from a physical quantity detected by the medium physical quantity detecting means. Medium determination means, cut-off value setting means for setting various cut-off values corresponding to the medium type obtained by the medium determination means, and instruct the gas type determination means by communication of medium type determination and cut-off value setting by a message signal or the like. Setting means.

Therefore, according to the present invention, a control instruction for automatically determining the type of medium to be used can be given by the setting means at an arbitrary timing such as when the gas shut-off device is set or relocated. Since an optimal cutoff value is set according to the type, a medium such as gas can be used in a safe state, and usability is improved.

Further, the present invention has been made in order to achieve the above object.
The medium physical quantity detecting means includes a sound velocity measuring means for measuring a sound velocity at which a signal propagates in the medium.

Therefore, according to the present invention, the propagation time is measured using an ultrasonic wave or the like, the sound speed is obtained, and the type of medium to be used is accurately determined based on the sound speed. No safety is improved.

[0016]

FIG. 1, FIG. 2 and FIG. 3 show an embodiment of the present invention.
This will be described with reference to FIG.

(Embodiment 1) FIG. 1 shows a gas shut-off device according to Embodiment 1 of the present invention. Reference numeral 9 denotes medium physical quantity detecting means, which is installed in a measurement flow path of city gas or LPG and detects the physical quantity of a used gas medium. I do. In this case, the physical quantity measures the sound velocity in the used gas medium using an ultrasonic signal or the like, or detects the vibration frequency of the fluid using a fluidic element or the like. 10
Is a flow rate calculating means for converting the used medium quantity, that is, the gas flow rate, from the physical quantity measured by the medium physical quantity detecting means 9 and obtaining it. Reference numeral 11 denotes an abnormality determination unit which determines whether the gas usage amount obtained by the flow rate calculation unit 10 is in an abnormal usage state. For example, the total flow cutoff value for monitoring the large flow generated when the hose that supplies gas to the equipment used such as a stove is disconnected, or when the equipment has been used for a much longer time than the maximum usage time for normal use In addition, a use time cut-off table or the like which defines a use time limit is stored, and whether there is an abnormal state corresponding to the use time cut-off table is monitored. Reference numeral 12 denotes a shut-off means, which outputs a shut-off signal when the abnormality judgment means 11 judges that the gas flow path is abnormal, and shuts off the gas flow path.

Reference numeral 13 denotes a medium determining means for determining the gas type of the medium to be used based on the output signal of the medium physical quantity detecting means 9. For example, a physical quantity (for example, a sound velocity or a signal propagation velocity, etc.) of each component state of various city gases such as LPG gas or 6C and 13A is stored as data and detected by the medium physical quantity detecting means 9. Specify the applicable gas type from the physical quantity. The sound velocity value in the flow path is stored using, for example, an ultrasonic wave as the physical quantity, and the gas type in the medium can be specified from the measured physical quantity, for example, from the sound velocity. Reference numeral 14 denotes a cutoff value setting unit. When the type of gas used is specified by the medium determination unit 13, a cutoff value corresponding to the gas type is set in the abnormality determination unit 11.

Thereafter, the abnormality judging means 11 becomes the cutoff value setting means 1
4 and the flow rate signal value set by the flow rate calculating means 10 are compared and, if the flow rate signal value exceeds the cutoff determination value, it is determined that there is an abnormal use and the shutoff means 12 is driven to cut off the gas flow path. Reference numeral 15 denotes a notification unit that notifies the user of the gas or the gas sales company via a telephone line or the like when the interruption is performed by the abnormal unit 11.

Next, the operation of the above configuration will be described. When the gas shut-off device is installed, various shut-off values are set as initial values for flow measurement and safety monitoring. For example, even with the same city gas, if the components are different, the amount of combustion of the equipment and the like also changes. Therefore, when the gas type is confirmed and determined at the time of setting, if the initial value is a cutoff value of a gas type that does not conform, various cutoff values corresponding to the detected gas type are set next. The following is performed as follows.

A medium physical quantity detecting means 9 is provided in the used gas pipe, and detects a physical quantity of the used gas medium, for example, a physical quantity such as a sound speed or a propagation speed, periodically or continuously for a predetermined period. For example, the speed of sound at a predetermined temperature is 13
450 m / s for A and 280 m / s for LPG gas. When the physical quantity is detected by the physical quantity detecting means 9, the flow rate calculating means 10 converts the physical quantity such as the sound speed to obtain the flow rate.

At the time of installation, a physical quantity such as a sound speed of a used medium is obtained. The physical quantity obtained from the medium physical quantity detecting means 9 is input to the medium determining means 22. The medium determination unit 13 searches for a gas type indicating a physical quantity closest to the measured physical quantity. As a result, the determined gas type is output to the cutoff value setting means 14. The cutoff value setting means 14 determines the various cutoff values of the corresponding gas type, the total flow rate cutoff or the increased flow rate cutoff value, and the time limit of the use time cutoff from the cutoff value storage means 23 based on the obtained gas type. 11 is set as a judgment value. When the setting is made in the abnormality determination means 11, the cutoff value setting state is released, and the monitoring state at the time of using the gas is set (the general user can use the monitoring state).

Thus, when the gas shut-off device is installed, the type of gas used can be automatically determined and the corresponding shut-off value can be set. Thereafter, the flow rate measurement of the used gas amount and various safety monitoring are performed. The flow rate value converted by the flow rate calculation means 10 is compared with the cutoff value set in the abnormality determination means 11, and in the case of an abnormality, the cutoff means 12 is driven to stop gas supply.

In this manner, when the gas shut-off device is installed, the gas type can be automatically determined and the cut-off value can be set, so that a human can erroneously set the cut-off value corresponding to the gas type and abnormally monitor the gas use condition. No more. For example, LPG is large in comparison with the calorific value of 13A of city gas. Therefore, if the cutoff value such as the maximum use flow rate is set too large by mistake, it is dangerous when the gas medium leaks due to disconnection of the hose of the appliance, etc. The safety is improved due to automatic discrimination.

(Embodiment 2) FIG. 2 shows a gas shut-off device according to Embodiment 2 of the present invention. 2, components having the same functions as those in FIGS. 1 and 4 are denoted by the same reference numerals.

In FIG. 2, reference numeral 16 denotes a setting means. When the gas shut-off device is replaced or installed in an area where another gas type is used, the gas type is discriminated again, and a cut-off value suitable for the gas used is re-determined. An instruction for setting is output to the medium determining means 13 by a communication means such as a telegram.

Next, the operation of the above configuration will be described. At the time of replacement installation or relocation of the gas shut-off device, various cut-off values for the flow measurement and safety monitoring are set at the last time at the installation site. For example, even in the same city gas, the components are different between 6C and 13A, the combustion amount of the appliance and the like, and the level of monitoring to be interrupted needs to be changed.

When a gas company installs a gas shut-off device,
The operator gives an instruction for medium determination setting by the setting means 16. For example, when an instruction is input by a message, the setting unit 16 transmits the instruction to the medium determination unit 13. When the medium determining means 13 receives the electronic signal from the setting means 16, the gas shut-off device is in the state of determining the medium such as the gas type and setting the cut-off value, and enters the setting mode instead of the abnormality monitoring mode. The following is performed as follows.

A medium physical quantity detecting means 9 is provided in the used gas pipe, and detects a physical quantity of the used gas medium, for example, a physical quantity such as a sound speed or a propagation velocity, periodically or continuously for a predetermined period. For example, the speed of sound at a predetermined temperature is 13
450 m / s for A and 280 m / s for LPG gas. When the physical quantity is detected by the physical quantity detecting means 9, the flow rate calculating means 10 converts the physical quantity such as the sound speed to obtain the flow rate.

At the time of installation, a physical quantity such as a sound speed of a used medium is obtained. The physical quantity obtained from the medium physical quantity detecting means 9 is input to the medium determining means 22. The medium determination unit 13 searches for a gas type indicating a physical quantity closest to the measured physical quantity. As a result, the determined gas type is output to the cutoff value setting means 14. The cutoff value setting means 14 determines the various cutoff values of the corresponding gas type, the total flow rate cutoff or the increased flow rate cutoff value, and the time limit of the use time cutoff from the cutoff value storage means 23 based on the obtained gas type. 11 is set as a judgment value. When the setting is made in the abnormality determination means 11, the cutoff value setting state is released, and the monitoring state at the time of using the gas is set (the general user can use the monitoring state).

Thus, when the gas shut-off device is installed, the type of gas used can be automatically determined and a corresponding shut-off value can be set. Thereafter, the flow rate measurement of the used gas amount and various safety monitoring are performed. The flow rate value converted by the flow rate calculation means 10 is compared with the cutoff value set in the abnormality determination means 11, and in the case of an abnormality, the cutoff means 12 is driven to stop gas supply.

In this way, when the gas shut-off device is installed, the gas type can be automatically determined and the cut-off value can be set, so that a human can mistakenly set the cut-off value corresponding to the gas type and abnormally monitor the gas use condition. No more. There are various gas types in the market, and when installing a gas shut-off device as a gas company, it is necessary to accurately grasp the gas type and set a cut-off value. After the start of use, even if a gas type having a small combustion amount is used, there is no erroneous operation of erroneously setting a gas cutoff determination value that is too large, thereby improving safety.

(Embodiment 3) FIG. 3 shows a gas shut-off device according to Embodiment 3 of the present invention. 3, FIG. 2, FIG.
The components having the same functions as those described above are denoted by the same reference numerals.

In FIG. 3, reference numeral 17 denotes a sound velocity measuring means, which measures the sound velocity at which a signal propagates in the medium by a method of the medium physical quantity detecting means 9. The sonic velocity measuring means 17 includes an upstream vibrator 2 provided on the upstream side of the pipe 1, a downstream vibrator 3 provided on the downstream side of the pipe 1, a switching means 18, a transmitting means 19, and a receiving means 20. , And propagation time measuring means 21. The sound velocity measuring means 9 is constituted by an element capable of outputting or receiving an ultrasonic signal. The transmitting means 19 and the receiving means 20 are connected to the switching means 18, and the switching means 18 alternately connects the transmitting means 19 and the receiving means 20 to the upstream vibrator 2 or the downstream vibrator 3. The propagation time measuring means 21 connects the receiving means 20 to the upstream transducer 2 by the switching means 18 (connects the transmitting means 19 to the downstream transducer 3), and receives the signal propagation time;
Next, the receiving means 20 is connected to the downstream vibrator 2 by the switching means 18.
(The transmitting means 19 is connected to the upstream-side vibrator 2), and a signal propagation time difference is obtained from the received signal propagation time.

Numeral 22 is a propagation time storage means for storing the propagation times of ultrasonic signals in various gas media. For example, L
Propagation time data in the component state of various city gases such as PG gas or 6C, 13A is stored. Reference numeral 23 denotes cut-off value storage means, which stores various cut-off value data corresponding to each gas type, for example, as table data. For example, a total flow rate cutoff value for detecting a large flow rate such as a hose disconnection and judging an abnormality, a use time cutoff table which defines a use time limit time based on the maximum use time of the appliance, and the like are stored.

Next, the operation of the above configuration will be described. When the gas shut-off device is installed, various shut-off values are set as initial values for flow measurement and safety monitoring. For example, even with the same city gas, if the components are different, the amount of combustion of the equipment and the like also changes. Therefore, when the gas type is confirmed and determined at the time of setting, if the initial value is a cutoff value of a gas type that does not conform, various cutoff values corresponding to the detected gas type are set next. The following is performed as follows.

In the pipe 1, the sound speed measuring means 17 is attached so that the upstream oscillator 2 and the downstream oscillator 3 face each other. First, the receiving unit 20 connected to the upstream-side vibrator 2 by the switching unit 18 is connected to the transmitting unit 19 via the downstream-side vibrator 3.
Receive the emitted ultrasonic signal. The propagation time of the signal from the start of transmission to the reception is determined by the propagation time measuring means 21. Next, the switching means 23 receives the ultrasonic signal emitted from the transmitting means 19 via the upstream transducer 2 by the receiving means 20 connected to the downstream transducer 3. Similarly, the propagation time of the signal from the start of transmission to the reception is determined by the propagation time measuring means 15. Upon receiving ultrasonic signals from the opposing transducers 2 and 3, the propagation time measuring means 21 calculates a transmission time difference and outputs the calculated transmission time to the medium determination means 13. The medium determination unit 13 determines the gas type by comparing the input propagation time with the propagation times of various media, that is, the gas types, stored in the propagation time storage unit 22. When specified, the medium determination unit 13 outputs the gas type to the cutoff value setting unit 14. The cutoff value setting means 14 controls the cutoff value storage means 23 based on the obtained gas type.
Are set as the judgment values in the abnormality judgment means.

When the setting is made in the abnormality determining means 11, the setting mode is canceled and the monitoring state is reached when the gas is used (a state in which ordinary consumers can use the gas). Usually, for example, 13A
Such a city gas has a sound speed of 450 m / s, while an LPG gas has a sound speed of 280 m / s, and the city gas has a higher sound speed and a shorter propagation time.

In this way, a gas shut-off device is installed, the type of gas used is automatically determined, and a corresponding shut-off value is set. Then, the flow rate measurement of the used gas amount and various safety monitoring are performed. The sound speed is measured by the sound speed measuring means 17 (in this case, the propagation time is measured to determine the sound speed), the flow rate is converted from the calculated propagation time, and the calculated flow rate value and the interruption set in the abnormality determination means 17 are determined. The value is compared with the value, and if abnormal, the shut-off means 19 is driven to stop the gas supply.

The sound speed measuring means 17 of the embodiment is different from the switching means 1
In this case, the transmission time is measured by alternately switching the transmission means 19 and the reception means 20 which are connected to the upstream oscillator 2 and the downstream oscillator 3 by using the upstream oscillator 2 and the upstream oscillator 2 and the downstream oscillator. 3 has a transmission means 19 and a reception means 20 respectively, and there is also a method of connection. That is, when one is a transmitting unit, the other is connected to a receiving unit, and when the measurement is completed, the receiving unit 20 and the transmitting unit 19 connected to the upstream oscillator 2 and the downstream oscillator 3 are switched to detect the flow rate. The present invention is also the same (the sound velocity measuring means is not shown).

In this way, the type of gas used can be automatically determined, such as when a gas shut-off device is installed, and a corresponding shut-off value can be set. Thereafter, the flow rate measurement of the amount of gas used and various safety monitoring can be performed safely. However, it does not happen that the gas type is erroneously set and an abnormal cutoff value is set.

There are various gas types in the market, and when installing a gas shut-off device as a gas company, it is necessary to accurately grasp the gas type and set a cut-off value. After the start of use, even if a gas type having a small combustion amount is used, there is no erroneous operation of erroneously setting a gas cutoff determination value that is too large, thereby improving safety.

[0043]

As is apparent from the above description, according to the first aspect of the present invention, the medium physical quantity detecting means for detecting the physical quantity generated corresponding to the flow velocity of the medium and the medium physical quantity detecting means detect the physical quantity. A flow rate calculating means for converting a physical quantity into a flow rate; an abnormality determining means for determining whether or not the flow rate value obtained by the flow rate calculating means is an abnormal usage amount; and a medium flow path when the abnormality determining means determines that the flow rate is abnormal. Interrupting means, medium determining means for determining the type of medium to be used based on the physical quantity detected by the medium physical quantity detecting means, and interrupting value setting means for setting various interrupting values corresponding to the medium type obtained by the medium determining means The physical quantity such as sound velocity is measured from the gas medium used for monitoring and monitoring by the medium physical quantity detecting means at the time of installation, etc., the medium type is compared and determined by the medium determining means, and the gas used by the consumer is determined. The investigated, enter the gas type signal specific to cutoff value setting means, blocking value setting means by setting the abnormality determining means various cutoff value corresponding to the gas type,
Gas distributors do not mistakenly set the cutoff value,
It is possible to set the optimal gas cutoff value for the gas type used by the consumer, and the setting operation of extremely gas type selection, various cutoff values, etc., so that general users who use the equipment can use the gas safely. It has the effect of improving safety and safety.

According to a second aspect of the present invention, there is provided a medium physical quantity detecting means for detecting a physical quantity generated in accordance with a flow velocity of a medium, a flow rate calculating means for converting a physical quantity detected by the medium physical quantity detecting means into a flow rate, Abnormality determining means for determining whether or not the flow rate value obtained by the flow rate calculating means is an abnormal usage amount; interrupting means for interrupting the medium flow path when the abnormality determining means determines that there is an abnormality; and detecting by the medium physical quantity detecting means. Medium determination means for determining the type of medium to be used based on the determined physical quantity, cutoff value setting means for setting various cutoff values corresponding to the medium type obtained by the medium determination means, medium type determination and cutoff value based on a message signal or the like. The setting means for instructing the gas type determination means by communication to the gas type determination means. The disconnection device is in the set state, and the physical quantity such as the sound velocity is measured from the gas medium used for monitoring and monitoring by the medium physical quantity detecting means at the time of installation, etc., and the medium type is compared and determined by the medium determining means and specified. Check the gas type to be performed, input the specified gas type signal to the cut-off value setting means, and set the various cut-off values corresponding to the gas type to the abnormality determination means. It is possible to set the optimal gas cutoff value for the gas type used by the customer without erroneously setting the cutoff value, and that the general user using the appliance can use the gas safely.
It is extremely effective in selecting gas types, setting operability such as various cutoff values, and improving safety.

According to a third aspect of the present invention, the medium physical quantity detecting means comprises a sound velocity measuring means for measuring a sound velocity at which a signal propagates in the medium. The propagation time of the ultrasonic signal is measured from the medium, the medium type is compared and determined by the medium determination means from the propagation time, the gas type used by the customer is checked, and the specified gas type signal is input to the cutoff value setting means. However, the cut-off value setting means sets various cut-off values corresponding to the gas type in the abnormality determination means, so that a gas distributor or the like does not erroneously set the cut-off value and is optimal for the gas type used by the customer. It is possible to set various gas cutoff values, and general users who use the equipment can use the gas safely.It is extremely effective in selecting gas types, setting operability such as various cutoff values, and improving safety. is there.

[Brief description of the drawings]

FIG. 1 is a control block diagram of a gas shutoff device according to a first embodiment of the present invention.

FIG. 2 is a control block diagram of a gas cutoff device according to a second embodiment of the present invention.

FIG. 3 is a control block diagram of a gas shutoff device according to a third embodiment of the present invention.

FIG. 4 is a block diagram of a conventional gas shut-off device.

[Explanation of symbols]

 Reference Signs List 9 medium physical quantity detecting means 10 flow rate calculating means 11 abnormality judging means 12 shutoff means 13 medium judging means 14 shutoff value setting means 16 setting means 17 sound velocity measuring means

Claims (3)

[Claims] 1. A medium physical quantity detecting means for detecting a physical quantity generated corresponding to a flow velocity of a medium, a flow rate calculating means for converting a physical quantity detected by the medium physical quantity detecting means into a flow rate,
An abnormality determining unit that determines whether the flow rate value obtained by the flow rate calculating unit is an abnormal usage amount, a blocking unit that blocks a medium flow path when the abnormality determining unit determines that the amount is abnormal, and a medium physical amount detecting unit. A gas shut-off device comprising: a medium judging unit that judges a used medium type by judging from a detected physical quantity; and a cut-off value setting unit that sets various cut-off values corresponding to the medium type obtained by the medium judging unit. 2. The gas shut-off device according to claim 1, further comprising setting means for instructing the medium determining means to determine the medium type by communication. 3. The gas shut-off device according to claim 1, wherein the medium physical quantity detecting means is a sound speed measuring means for measuring a sound speed at which a signal propagates in the medium.