Calibration of a mass flow sensor or controller using a variable gas flow source

摘要

A mass flow calibrator 706 includes a variable flow gas source 708, a receptacle of predetermined volume 710, and a pressure differentiator 712. The variable flow gas source 708 may provide gas at varying rates to the mass flow sensor 702 being calibrated and at proportional rates to the receptacle of predetermined volume 710. The pressure differentiator 712 produces a signal representative of the time derivative of gas pressure within the receptacle of predetermined volume 710 and, from that, the actual flow into the receptacle. Given the actual flow, the proportionate flow into the mass flow sensor 702 may be determined and the flow signal from the mass flow sensor 702 correlated to the actual flow.