Abstract: A method and apparatus for improving measurement accuracy in a gas monitoring system is provided. The apparatus can be connected to a plurality of gas sample lines each containing a gas sample. The gas samples are routed through a number of delivery channels which are fewer in number than the plurality of sample lines. Each delivery channel is alternatively coupled to a detector which identifies contaminants present in the gas samples. Each delivery channel includes a voltage sensitive orifice (VSO). The VSO's are operated by a controller and provide gas samples at a constant flow and a constant pressure to the detector independent of the length of the gas sample line being measured.