Gas measuring device and gas measuring process for a target gas with improved compensation of an ambient condition

A gas measuring process for measuring a concentration of a combustible target gas in a spatial area, the process is performed using a gas measuring device comprising a detector, a compensator, a detector detection variable sensor and a compensator detection variable sensor, wherein the detector has a detector detection variable, wherein the detector detection variable correlates with the concentration of the target gas in a gas sample, wherein the compensator has a compensator detection variable, wherein the compensator detection variable correlates less than the detector detection variable with the target gas concentration or is not correlated with the target gas concentration in the gas sample, wherein the detector detection variable and the compensator detection variable are influenced or at least can be influenced by at least one ambient condition acting on the gas sample, wherein the gas measurement process comprises the steps of:

• causing a gas sample from the area to reach the detector and the compensator;
• with the detector detection variable sensor, measuring the detector detection variable;
• with the compensator detection variable sensor, measuring the compensator detection variable;
• and
• determining the concentration of the target gas in the gas sample as a function of the measured detector detection variable and the measured compensator detection variable,
• wherein, when carrying out the gas measuring process, the gas measuring device is operated in at least one of a pressure-compensating mode and a humidity-compensating mode,
• wherein in the pressure-compensating mode the influence of an ambient pressure on a determination result is compensated for such that a boundary condition is met that the influence of an ambient humidity on the determination result remains below a specified upper humidity influence threshold, and the influence of the ambient pressure on the determination result of the gas measuring device is compensated under this boundary condition, and
• wherein in the humidity-compensating mode, the influence of the ambient humidity on the determination result is compensated for such that a boundary condition is met that the influence of the ambient pressure on the determination result remains below a specified upper pressure influence threshold, and the influence of the ambient humidity on the determination result is compensated under the boundary condition, and
• wherein in the pressure-compensating mode the dependence of the determined target gas concentration on at least one of the detector detection variable on and the compensator detection variable is different from that in the humidity-compensating mode.

A calibration process for calibrating a gas measuring device, the gas measuring device being configured to measure a concentration of a combustible target gas in a spatial area,

• the gas measuring device comprising:
• a detector having a detector detection variable;
• a compensator having a compensator detection variable;
• a detector detection variable sensor configured to measure the detector detection variable;
• a compensator detection variable sensor configured to measure the compensator detection variable, wherein the gas measuring device is configured such that a gas sample from the spatial area reaches the detector and the compensator, wherein the measured detector detection variable is correlated with the concentration of the target gas in the gas sample and the compensator detection variable is correlated with the concentration of the target gas in the gas sample less than the measured detector detection variable or is not correlated with the target gas concentration, wherein the measured detector detection variable and the measured compensator detection variable are influenced or at least can be influenced by at least one ambient condition acting on the gas sample;
• and a signal-processing evaluation unit configured to determine the concentration of the target gas in the gas sample as a function of the measured detector detection variable and of the measured compensator detection variable, wherein the gas measuring device is configured to be operated during use in one of at least two different modes, wherein a first mode is a pressure compensating mode and a second mode is a humidity compensating mode, and wherein the evaluation unit is configured to apply, for determining the concentration of the target gas, a respective functional relationship for the mode to the measured detector detection variable and to the measured compensator detection variable;
• wherein the calibration process comprises the steps of:
• providing a sample and a set of predefined possible functional relationships, wherein the sample comprises several sample elements, wherein each sample element of the sample includes an identification of an ambient condition-target gas combination, which comprises a combination of an ambient temperature, an ambient pressure, an ambient humidity, and an actual target gas concentration, and wherein the sample includes a combination of signal values, which comprises the respective signal value of each detection variable sensor measured at the ambient condition-target gas combination;
• specifying at least one mode in which the gas measuring device is to operate be operated, and
• applying each specified possible functional relationship to the signal value combination of the sample element for each mode and for each sample element, thereby calculating a value for the target gas concentration;
• comparing the calculated value for the target gas concentration with the actual value of the target gas combination in the sample element;
• using the comparison results, selecting a possible functional relationship for each mode;
• and
• causing the selected functional relationship to be used by the evaluation unit as the functional relationship to be applied in the respective mode,
• wherein the selection of the functional relationship is performed such that in the pressure-compensating mode an influence of the ambient pressure on a determination result of the evaluation unit is compensated such that a boundary condition is met that an influence of the ambient humidity on the determination result remains below a specified upper humidity influence threshold, and the influence of the ambient pressure on the determination result of the gas measuring device is compensated under this boundary condition and
• in the humidity-compensating mode, an influence of the ambient humidity on the determination result is compensated for such that a boundary condition is met that the influence of the ambient pressure on the determination result remains below a specified upper pressure influence threshold, and the influence of the ambient humidity on the determination result is compensated under this boundary condition, and
• in the pressure-compensating mode the dependence of the determined target gas concentration on the detector detection variable and/or on the compensator detection variable is different from that in humidity-compensating mode.