Methods of analysing gas samples with apparatus having a duel inlet system

摘要

A method of analysing a property of a target gas sample relative to reference gas sample using a dual inlet system (valves SI and RI) comprises introducing each sample into a variable volume chamber 2 or 3 and the gas is then fed alternately from each chamber into measurement apparatus. The flow rate of gas into the measurement apparatus can be varied by varying the pressure of the gas in the respective chambers (e.g. with motors 6, 7 adjusting the size of the chambers configured as bellows). During each measurement the flow rate of the sample is sensed and after the end of a measurement period for that sample the volume of the respective chamber is adjusted to a new value dependent on the sensed flow rate while the apparatus is being used to carry out a measurement cycle on the other sample.