Gas sampling system and method

摘要

A gas sampling system and method that utilizes a double aspirator design to precisely control the flow rate of a gas sample past a sensor (44, 46, or 48). The double aspirator design includes a primary aspirator (24) to draw a gas sample from the exhaust stack (14) at a first flow rate and a secondary aspirator (26) to draw a portion of the gas sample from the primary aspirator at a second flow rate past the sensors. In addition, a first pressure sensor (74) and second pressure sensor (76) are provided in order to monitor changes in the pressure differential across the sensor so that corresponding changes in the second flow rate can be accounted for by the control unit (18) when processing the measurement data from the sensor.