High-accuracy stable gas flow dilution using an internally calibrated network of critical flow orifices

A network of critical flow orifices has been developed to form a gas flow dilutor capable of stable and repeatable operation, which is not influenced by environmental conditions. When used with a novel self-calibration method it achieves dilutions of up to 31:1 with a relative standard uncertainty of ±0.1%. This new approach avoids the uncertainty generated by setting and controlling the flow which is present in devices based on variable flow elements