hi I have put gas sensor in a vacuum chamber and tried to study its behavior I was expecting the sensor to read low value but as the vacuum goes down the sensor shoots up to the maximum it reads max ADC value 1023 I tried with different MQ gas sensors also but all the sensors show the same behavior when gas is not present the sensors should read low but it is reading max Why ? can any one help out
all electrochemical sensors like gas sensor gives an output based on concentration of gas under subject compared to clean air. for detecting presence of air respective to vaccum you must use some air flow sensor instead