Device for the detection of foreign components in a gas and an application of the device

An arrangement for detecting a foreign component contained in a gas, comprising:

• a measurement chamber accessible to the gas being investigated;
• a sensor provided for the measurement chamber for transmitting an output signal in dependence of the content of the foreign component of the gas being investigated;
• an electrical circuit for evaluating said output signal of said sensor;
• a reference chamber not directly accessible to the gas being investigated;
• a reference gas contained in said reference chamber and having a lower foreign component content than the gas being investigated;
• means defining at least one aperture for providing intercommunication between the reference chamber and said measurement chamber;
• the reference chamber comprising an air motion generator for periodically and alternatingly forcing said reference gas out of the reference chamber into the measurement chamber and for withdrawing the reference gas at least partially back into the reference chamber;
• the reference gas at least partially displacing the gas being investigated in the measurement chamber when forced thereinto;
• the gas being investigated entering the measurement chamber when the reference gas is withdrawn into the reference chamber;
• and
• said electrical circuit evaluating a modulated component of the output signal of the sensor as a criterion for the foreign component content of the gas being investigated.