Gas mixing system and method

A mixing system with proportional dilution gas sampling, and associated proportional dilution gas sampling methods are provided. The mixing system includes a mixing portion, a gaseous inlet, a dilution inlet, and a mixture outlet. A flow meter in flow communication with the dilution inlet has an output indicative of the dilution gas flow rate. A dilution sample line in flow communication with the dilution inlet collects samples of the dilution gas. A dilution sample flow controller along the dilution sample line is applicable to vary the dilution sample flow rate through the dilution sample line. Control logic receives the flow meter output, processes the flow meter output, and operates the dilution sample flow controller to vary the dilution sample flow rate. The dilution sample flow rate is varied in response to variations in the dilution gas flow rate such that the dilution sample flow rate tracks a value which is substantially proportional to the dilution gas flow rate.