JP2017142274A - Contact combustion type gas sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a contact combustion type gas sensor capable of quickly identifying a kind of gas with a simple configuration.SOLUTION: A contact combustion type gas sensor X having a detection element 10 sensitive to detected gas and a compensation element 20 includes: gas kind identification means 30 for identifying a kind of detected gas by a resistance value varying when the compensation element 20 comes in contact with the detected gas; and concentration computing means 40 for calculating concentration of the detected gas by multiplying output of the detection element 10 by a factor according to the gas kind determined by the gas kind identification means 30.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a catalytic combustion type gas sensor having a detection element and a compensation element that are sensitive to a gas to be detected.

  The catalytic combustion type gas sensor is a sensor with a structure in which alumina with a noble metal catalyst supported on a platinum wire coil that doubles as a heater and thermometer is sintered in a spherical shape. It detects the temperature change of the element due to contact combustion of combustible gas. The gas sensor detects the concentration of the gas to be detected. In general, a bridge connection with a compensation element made by sintering only alumina without a catalyst is also used to stabilize the concentration of combustible gas up to the explosion limit (LEL) with less influence of environmental temperature and humidity. Can be detected.

  Conventionally, when identifying the gas type of the gas to be detected, a ratio of a plurality of sensor outputs having different characteristics may be calculated. For example, by using two output ratios of a catalytic combustion type gas sensor that does not react with methane but reacts with other hydrocarbon gases and a catalytic combustion type gas sensor that reacts with hydrocarbon gases including methane, naturally generated methane, A gas detector with an identification function for identifying one of city gas, LPG, and propane gas has been put into practical use.

  An apparatus is also known in which gas components are separated by a column, and the concentration of each component is detected based on the difference in passage time of the column to identify the type of gas.

  In addition, since the above-mentioned contact combustion type gas sensor used as the prior art in the present invention is a general technique, prior art documents such as patent documents are not shown.

When calculating the ratio of the output of a plurality of sensors having different characteristics to identify the gas type of the gas to be detected, a plurality of catalytic combustion gas sensors having different characteristics are required.
Further, when a gas type is identified using a column, since it is detected by a time difference, a certain amount of time is required until a gas type identification result is obtained, and the gas type cannot be quickly identified.

  Accordingly, an object of the present invention is to provide a catalytic combustion type gas sensor capable of quickly identifying a gas type with a simple configuration.

  In order to achieve the above object, a catalytic combustion type gas sensor according to the present invention is a catalytic combustion type gas sensor having a detection element and a compensation element that are sensitive to a gas to be detected. Gas type identifying means for identifying the type of the gas to be detected based on a resistance value that changes by contact with the detection gas, and a coefficient corresponding to the gas type determined by the gas type identification means for the output of the detection element And a concentration calculation means for calculating the concentration of the gas to be detected by multiplying by.

The compensation element has a characteristic that its resistance value changes due to heat being deprived according to the concentration of the gas to be detected. By taking out the resistance value change of the compensation element, an output showing a behavior equivalent to that of a gas heat conduction sensor that detects a temperature change of the minute heating element due to a difference in heat conductivity inherent to the gas can be obtained. This is an output that varies depending on the type of gas to be detected. The gas type identification means can identify the gas type by detecting the resistance value changing in this way and comparing it with a change in the resistance value unique to the gas.

  Further, the detection element generates heat by energization, whereby the catalyst is heated and reacts with the gas to be detected, and the resistance value changes according to the reaction heat (depending on the concentration of the gas to be detected). The concentration calculation means calculates the concentration of the gas to be detected by multiplying the output value obtained by detecting the resistance value thus changing by a coefficient corresponding to the gas type determined by the gas type identification means. be able to.

  As described above, according to this configuration, since two output values (compensation element and detection element) having different characteristics can be obtained simultaneously with only one catalytic combustion type gas sensor, it is not necessary to use a plurality of catalytic combustion type gas sensors. Gas species can be quickly identified with a simple configuration.

It is a figure which shows the outline | summary of the contact combustion type gas sensor of this invention. It is a figure which shows a bridge circuit. It is a graph of output Vd1 for density detection. It is a graph of gas type identification output Vd2. It is the graph which normalized output Vd1 for density detection. It is the graph which normalized the output Vd2 for gas kind identification. It is the graph which showed the ratio of normalized Vd1 and Vd2.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the catalytic combustion type gas sensor X of the present invention includes a detection element 10 and a compensation element 20.
The contact combustion type gas sensor X includes a gas type identifying means 30 for identifying the type of the gas to be detected based on a resistance value that changes when the compensation element 20 comes into contact with the gas to be detected, and a gas corresponding to the output of the detection element 10. Concentration calculating means 40 for calculating the concentration of the gas to be detected by multiplying the coefficient according to the gas type determined by the species identifying means 30.

  The detection element 10 is made of alumina or the like on which the surface of a coil of a metal wire containing platinum or tungsten having a high temperature coefficient with respect to electric resistance carries a catalyst made of a noble metal such as platinum or palladium that is active against the gas to be detected. It is formed by covering with a carrier. When the detection element 10 is placed in the gas to be detected, it generates heat by energization, whereby the catalyst provided in itself is heated and reacts with the gas to be detected, and the concentration of the gas to be detected depends on the reaction heat. The resistance value changes.

The compensation element 20 is an element for performing temperature compensation of the detection element by being placed in the gas to be detected and energized in the same manner as the detection element, and has a resistance value corresponding to the combustion heat generated by the catalyst of the detection element. It is used to extract only the amount of change.
The compensation element 20 is formed, for example, by coating the surface of a coil equivalent to the detection element 10 with a carrier such as alumina. Since the compensation element 20 does not have a catalyst, combustion of the gas to be detected due to a catalytic reaction does not occur, so that the compensation element 20 is inactive to the gas to be detected. The compensation element 20 generates heat when energized and heats a carrier such as alumina covering the periphery thereof, and its own resistance value changes due to heat.

Usually, the contact combustion type gas sensor X includes a detection element 10 that has become a high temperature due to heat generated by a combustion reaction that occurs when the gas to be detected contacts the catalyst of the detection element 10, and a detection element in which the combustion reaction by the gas to be detected does not occur. By utilizing the fact that a difference in electrical resistance value occurs between the compensation element 20 and a temperature lower than 10, it is possible to detect the concentration of the gas to be detected by offsetting the change in the electrical resistance value due to the ambient temperature.

In the catalytic combustion type gas sensor X of the present invention, the gas type identifying means 30 identifies the type of gas to be detected based on the resistance value that changes when the compensation element 20 absorbs heat according to the concentration of the gas to be detected. . The change in the resistance value of the compensation element 20 results in an output that differs depending on the type of gas to be detected, so that the gas type can be identified. In particular, city gas such as methane and 13A and gas such as LPG, propane, isobutane, and 6A can be easily identified because the polarity of the sensor output is reversed due to the difference in thermal conductivity with respect to air.
The gas type identification means 30 detects the resistance value that changes in this way, and compares it with the change in the resistance value specific to the gas, so that any type of gas can be used as long as it is configured with a microcomputer or the like that identifies the type of gas to be detected. Such a mode may be sufficient.

The concentration calculation means 40 multiplies the output obtained by the detection element 10 and the compensation element 20 by a coefficient corresponding to the gas type determined by the gas type identification means 30 to calculate the concentration of the gas to be detected.
The detection element 10 generates heat when energized, whereby the catalyst is heated and reacts with the gas to be detected, and the resistance value changes according to the reaction heat (depending on the concentration of the gas to be detected). The concentration calculating means 40 calculates the concentration of the detected gas by multiplying the output value obtained by detecting the resistance value changing in this way by a coefficient corresponding to the gas type determined by the gas type identifying means 30. Any form may be used as long as it is constituted by a microcomputer or the like.
The coefficient is preferably a numerical value in which a specific value corresponding to the gas type is determined in advance.

  In the catalytic combustion type gas sensor X of the present invention, as shown in FIG. 2, the detection element 10 and the compensation element 20 form a bridge circuit A with the load resistances RL1 and RL2 and the opposite resistances R1 and R2. That is, in the bridge circuit A, the branch side where the detection element 10 and the load resistor RL1 are connected in series, the branch side where the compensation element 20 and the load resistor RL2 are connected in series, and the opposite side resistors R1 and R2 are connected in series. The branches are connected in parallel, and a predetermined voltage is applied based on the voltage supplied from the power supply E.

In such a bridge circuit A, when the gas type identification of methane and isobutane is performed, the voltage between the connection point a of the detection element 10 and the load resistance RL1 and the connection point b of the compensation element 20 and the load resistance RL2 is detected. Thus, the density detection output Vd1 is obtained (FIG. 3). The concentration detection output Vd1 includes a voltage between a connection point a between the detection element 10 and the load resistor RL1 and a connection point c between the opposite resistances R1 and R2, and a connection point b between the compensation element 20 and the load resistance RL2 and the opposite resistance. This is equivalent to the difference from the voltage at the connection point c of R1 and R2, and the influence of ambient temperature and humidity fluctuations is eliminated by the compensation element 20.

  Further, by detecting the voltage between the connection point c of the opposite resistances R1, R2 and the connection point b of the compensation element 20 and the load resistance RL2, a gas type identification output Vd2 is obtained (FIG. 4).

An example of gas type identification in the gas type identification unit 30 will be described below.
First, the concentration detection output Vd1 and the gas type identification output Vd2 are each normalized by the 100% LEL output of methane. Next, the ratio of normalized Vd1 and Vd2 (standardized Vd2 ÷ normalized Vd1) is calculated, and the result differs depending on the thermal conductivity specific to the gas.

  The concentration calculation means 40 multiplies the output obtained by the detection element 10 and the compensation element 20 by a coefficient determined in advance according to the gas type predicted by the gas type identification means 30 to thereby determine the concentration of the gas to be detected. Is calculated.

Examples of the present invention will be described.
The operation of the contact combustion type gas sensor with identification function X according to the present invention will be described.
First, after the warm-up process, zero point correction is performed on the AD conversion results of Vd1 and Vd2, and a span coefficient for conversion to a concentration value calibrated with the actual gas concentration of methane is multiplied. Thereby, it becomes the value normalized by the 100% LEL output of methane. Thereafter, gas type identification processing, concentration display processing, and alarm processing are performed.

(Gas type identification process)
When identifying methane and isobutane, the output of the gas type identification output Vd2 is easy to identify because the polarity differs between methane and isobutane with respect to the gas concentration as shown in FIG.
The concentration detection output Vd1 and the gas type identification output Vd2 were normalized with 100% LEL of methane, respectively, and the ratio of normalized Vd1 and Vd2 (standardized Vd2 ÷ normalized Vd1) was calculated (FIGS. 5 to 7). .

As a result, as shown in FIG. 7, the ratio of Vd1 and Vd2 of methane was about 1.0, whereas the ratio of Vd1 and Vd2 of isobutane was about -1.3 to about -2.0.

As an example of the contact combustion type gas sensor X with an identification function having a gas alarm value of 1/4 LEL (25% LEL), the lower limit of identification is 10% LEL, the threshold value for identifying isobutane is −0.5, and methane 100 If the concentration value normalized by% LEL is 10% or more and the standardized Vd2 ÷ standardized Vd1 is −0.5 or more in the negative direction, it is determined to be isobutane, and other than that, it is determined to be methane and the two gas types are determined. Identified.
The identification result of the gas type was displayed on the display unit (not shown) by LCD display or LED display as necessary.

(Density display processing)
If the identification result is not isobutane, further linearization processing is performed on the value Vd1 for concentration detection normalized to 100% LEL of methane, and the result is displayed as a concentration value of methane on the concentration display portion by a display portion (not shown). displayed.

  When the identification result is isobutane, the concentration detection output Vd1 is normalized by 100% LEL of methane, multiplied by a coefficient for converting the concentration of isobutane to approximately twice the concentration, and then linearized with isobutane. The result was displayed as a concentration value of isobutane on the concentration display section. A coefficient for conversion to the isobutane concentration may be included in the linearization treatment of isobutane at this time.

(Alarm processing)
When the concentration value after linearization processing reaches or exceeds the alarm set value, a gas concentration alarm is issued by the alarm unit (not shown).

  In general, gas detectors used for the purpose of preventing explosion accidents in city gas and sewage works are used in methane calibration. As shown in FIG. 3, since isobutane and propane output about 1/2 that of methane, an ordinary catalytic combustion type gas sensor does not report unless the concentration is about twice that of methane. For example, in city gas construction, there are sites where a city gas supply area and an LPG use area are mixed adjacent to each other. With regard to LPG leakage at such a site, the contact combustion type gas sensor X of the present invention is used. The danger of explosion can be detected safely.

  INDUSTRIAL APPLICABILITY The present invention can be used for a catalytic combustion type gas sensor having a detection element and a compensation element that are sensitive to the gas to be detected.

X catalytic combustion type gas sensor 10 detection element 20 compensation element 30 gas type identification means 40 concentration calculation means

  The present invention relates to a catalytic combustion type gas sensor having a detection element and a compensation element that are sensitive to a gas to be detected.

  The catalytic combustion type gas sensor is a sensor with a structure in which alumina with a noble metal catalyst supported on a platinum wire coil that doubles as a heater and thermometer is sintered in a spherical shape. It detects the temperature change of the element due to contact combustion of combustible gas. The gas sensor detects the concentration of the gas to be detected. In general, a bridge connection with a compensation element made by sintering only alumina without a catalyst is also used to stabilize the concentration of combustible gas up to the explosion limit (LEL) with less influence of environmental temperature and humidity. Can be detected.

  Conventionally, when identifying the gas type of the gas to be detected, a ratio of a plurality of sensor outputs having different characteristics may be calculated. For example, by using two output ratios of a catalytic combustion type gas sensor that does not react with methane but reacts with other hydrocarbon gases and a catalytic combustion type gas sensor that reacts with hydrocarbon gases including methane, naturally generated methane, A gas detector with an identification function for identifying one of city gas, LPG, and propane gas has been put into practical use.

  An apparatus is also known in which gas components are separated by a column, and the concentration of each component is detected based on the difference in passage time of the column to identify the type of gas.

  In addition, since the above-mentioned contact combustion type gas sensor used as the prior art in the present invention is a general technique, prior art documents such as patent documents are not shown.

When calculating the ratio of the output of a plurality of sensors having different characteristics to identify the gas type of the gas to be detected, a plurality of catalytic combustion gas sensors having different characteristics are required.
Further, when a gas type is identified using a column, since it is detected by a time difference, a certain amount of time is required until a gas type identification result is obtained, and the gas type cannot be quickly identified.

  Accordingly, an object of the present invention is to provide a catalytic combustion type gas sensor capable of quickly identifying a gas type with a simple configuration.

In order to achieve the above object, a catalytic combustion type gas sensor according to the present invention is a catalytic combustion type gas sensor having a detection element and a compensation element that are sensitive to a gas to be detected. It lies in having a gas type identification manually stage for identifying the type of the gas to be detected by the resistance value that changes by contact with the gas to be detected.

  The compensation element has a characteristic that its resistance value changes due to heat being deprived according to the concentration of the gas to be detected. By taking out the resistance value change of the compensation element, an output showing a behavior equivalent to that of a gas heat conduction sensor that detects a temperature change of the minute heating element due to a difference in heat conductivity inherent to the gas can be obtained. This is an output that varies depending on the type of gas to be detected. The gas type identification means can identify the gas type by detecting the resistance value changing in this way and comparing it with a change in the resistance value unique to the gas.

According to the present configuration, it is possible to quickly identify the gas species in simple and convenient construction.

It is a figure which shows the outline | summary of the contact combustion type gas sensor of this invention. It is a figure which shows a bridge circuit. It is a graph of output Vd1 for density detection. It is a graph of gas type identification output Vd2. It is the graph which normalized output Vd1 for density detection. It is the graph which normalized the output Vd2 for gas kind identification. It is the graph which showed the ratio of normalized Vd1 and Vd2.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the catalytic combustion type gas sensor X of the present invention includes a detection element 10 and a compensation element 20.
The catalytic combustion type gas sensor X includes a gas type identification means 3 0 identifying the type of the gas to be detected compensating element 20 by the resistance value that varies by contact with the gas to be detected.
Further, the catalytic combustion type gas sensor X includes a concentration calculation means 40 that calculates the concentration of the gas to be detected by multiplying the output of the detection element 10 by a coefficient corresponding to the gas type determined by the gas type identification means 30. May be.

  The detection element 10 is a carrier made of alumina or the like on which the surface of a coil of a metal wire containing platinum or tungsten having a high temperature coefficient with respect to electric resistance carries a catalyst made of a noble metal such as platinum or palladium that is active against the gas to be detected. It is formed by coating with. When the detection element 10 is placed in the gas to be detected, it generates heat by energization, whereby the catalyst provided in itself is heated and reacts with the gas to be detected, and the concentration of the gas to be detected depends on the reaction heat. The resistance value changes.

The compensation element 20 is an element for performing temperature compensation of the detection element by being placed in the gas to be detected and energized in the same manner as the detection element, and has a resistance value corresponding to the combustion heat generated by the catalyst of the detection element. It is used to extract only the amount of change.
The compensation element 20 is formed, for example, by coating the surface of a coil equivalent to the detection element 10 with a carrier such as alumina. Since the compensation element 20 does not have a catalyst, combustion of the gas to be detected due to a catalytic reaction does not occur, so that the compensation element 20 is inactive to the gas to be detected. The compensation element 20 generates heat when energized and heats a carrier such as alumina covering the periphery thereof, and its resistance value changes due to heat.

  Usually, the contact combustion type gas sensor X includes a detection element 10 that has become a high temperature due to heat generated by a combustion reaction that occurs when the gas to be detected contacts the catalyst of the detection element 10, and a detection element in which the combustion reaction by the gas to be detected does not occur. By utilizing the fact that a difference in electrical resistance value occurs between the compensation element 20 and a temperature lower than 10, it is possible to detect the concentration of the gas to be detected by offsetting the change in the electrical resistance value due to the ambient temperature.

In the catalytic combustion type gas sensor X of the present invention, the gas type identifying means 30 identifies the type of gas to be detected based on the resistance value that changes when the compensation element 20 absorbs heat according to the concentration of the gas to be detected. . The change in the resistance value of the compensation element 20 results in an output that differs depending on the type of gas to be detected, so that the gas type can be identified. In particular, city gas such as methane and 13A and gas such as LPG, propane, isobutane, and 6A can be easily identified because the polarity of the sensor output is reversed due to the difference in thermal conductivity with respect to air.
The gas type identification means 30 detects the resistance value that changes in this way, and compares it with the change in the resistance value specific to the gas, so that any type of gas can be used as long as it is configured with a microcomputer or the like that identifies the type of gas to be detected. Such a mode may be sufficient.

The concentration calculation means 40 multiplies the output obtained by the detection element 10 and the compensation element 20 by a coefficient corresponding to the gas type determined by the gas type identification means 30 to calculate the concentration of the gas to be detected.
The detection element 10 generates heat when energized, whereby the catalyst is heated and reacts with the gas to be detected, and the resistance value changes according to the reaction heat (depending on the concentration of the gas to be detected). The concentration calculating means 40 calculates the concentration of the detected gas by multiplying the output value obtained by detecting the resistance value changing in this way by a coefficient corresponding to the gas type determined by the gas type identifying means 30. Any form may be used as long as it is constituted by a microcomputer or the like.
The coefficient is preferably a numerical value in which a specific value corresponding to the gas type is determined in advance.

  In the catalytic combustion type gas sensor X of the present invention, as shown in FIG. 2, the detection element 10 and the compensation element 20 form a bridge circuit A with the load resistances RL1 and RL2 and the opposite resistances R1 and R2. That is, in the bridge circuit A, the branch side where the detection element 10 and the load resistor RL1 are connected in series, the branch side where the compensation element 20 and the load resistor RL2 are connected in series, and the opposite side resistors R1 and R2 are connected in series. The branches are connected in parallel, and a predetermined voltage is applied based on the voltage supplied from the power supply E.

In such a bridge circuit A, when the gas type identification of methane and isobutane is performed, the voltage between the connection point a of the detection element 10 and the load resistance RL1 and the connection point b of the compensation element 20 and the load resistance RL2 is detected. Thus, the density detection output Vd1 is obtained (FIG. 3). The concentration detection output Vd1 includes a voltage between a connection point a between the detection element 10 and the load resistor RL1 and a connection point c between the opposite resistances R1 and R2, and a connection point b between the compensation element 20 and the load resistance RL2 and the opposite resistance. This is equivalent to the difference from the voltage at the connection point c of R1 and R2, and the influence of ambient temperature and humidity fluctuations is eliminated by the compensation element 20.

  Further, by detecting the voltage between the connection point c of the opposite resistances R1, R2 and the connection point b of the compensation element 20 and the load resistance RL2, a gas type identification output Vd2 is obtained (FIG. 4).

An example of gas type identification in the gas type identification unit 30 will be described below.
First, the concentration detection output Vd1 and the gas type identification output Vd2 are each normalized by the 100% LEL output of methane. Next, the ratio of normalized Vd1 and Vd2 (standardized Vd2 ÷ normalized Vd1) is calculated, and the result differs depending on the thermal conductivity specific to the gas.

  The concentration calculation means 40 multiplies the output obtained by the detection element 10 and the compensation element 20 by a coefficient determined in advance according to the gas type predicted by the gas type identification means 30 to thereby determine the concentration of the gas to be detected. Is calculated.

Examples of the present invention will be described.
The operation of the contact combustion type gas sensor with identification function X according to the present invention will be described.
First, after the warm-up process, zero point correction is performed on the AD conversion results of Vd1 and Vd2, and a span coefficient for conversion to a concentration value calibrated with the actual gas concentration of methane is multiplied. Thereby, it becomes the value normalized by the 100% LEL output of methane. Thereafter, gas type identification processing, concentration display processing, and alarm processing are performed.

(Gas type identification process)
When identifying methane and isobutane, the output of the gas type identification output Vd2 is easy to identify because the polarity differs between methane and isobutane with respect to the gas concentration as shown in FIG.
The concentration detection output Vd1 and the gas type identification output Vd2 were normalized with 100% LEL of methane, respectively, and the ratio of normalized Vd1 and Vd2 (standardized Vd2 ÷ normalized Vd1) was calculated (FIGS. 5 to 7). .

As a result, as shown in FIG. 7, the ratio of Vd1 and Vd2 of methane was about 1.0, whereas the ratio of Vd1 and Vd2 of isobutane was about -1.3 to about -2.0.

As an example of the contact combustion type gas sensor X with an identification function having a gas alarm value of 1/4 LEL (25% LEL), the lower limit of identification is 10% LEL, the threshold value for identifying isobutane is −0.5, and methane 100 If the concentration value normalized by% LEL is 10% or more and the standardized Vd2 ÷ standardized Vd1 is −0.5 or more in the negative direction, it is determined to be isobutane, and other than that, it is determined to be methane and the two gas types are determined. Identified.
The identification result of the gas type was displayed on the display unit (not shown) by LCD display or LED display as necessary.

(Density display processing)
If the identification result is not isobutane, further linearization processing is performed on the value Vd1 for concentration detection normalized to 100% LEL of methane, and the result is displayed as a concentration value of methane on the concentration display portion by a display portion (not shown). displayed.

  When the identification result is isobutane, the concentration detection output Vd1 is normalized by 100% LEL of methane, multiplied by a coefficient for converting the concentration of isobutane to approximately twice the concentration, and then linearized with isobutane. The result was displayed as a concentration value of isobutane on the concentration display section. A coefficient for conversion to the isobutane concentration may be included in the linearization treatment of isobutane at this time.

(Alarm processing)
When the concentration value after linearization processing reaches or exceeds the alarm set value, a gas concentration alarm is issued by the alarm unit (not shown).

  In general, gas detectors used for the purpose of preventing explosion accidents in city gas and sewage works are used in methane calibration. As shown in FIG. 3, since isobutane and propane output about 1/2 that of methane, an ordinary catalytic combustion type gas sensor does not report unless the concentration is about twice that of methane. For example, in city gas construction, there are sites where a city gas supply area and an LPG use area are mixed adjacent to each other. With regard to LPG leakage at such a site, the contact combustion type gas sensor X of the present invention is used. The danger of explosion can be detected safely.

  INDUSTRIAL APPLICABILITY The present invention can be used for a catalytic combustion type gas sensor having a detection element and a compensation element that are sensitive to the gas to be detected.

X catalytic combustion type gas sensor 10 detecting element 20 compensating element 30 Gas type identification manually stage

Claims (1)

In a contact combustion type gas sensor having a detection element and a compensation element that are sensitive to a gas to be detected,
A gas type identifying means for identifying the type of the gas to be detected by a resistance value that changes when the compensation element comes into contact with the gas to be detected;
A contact combustion type gas sensor comprising: concentration calculation means for calculating the concentration of the gas to be detected by multiplying the output of the detection element by a coefficient corresponding to the gas type determined by the gas type identification means.

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