Mass flow controller and method for improved performance across multiple fluid types

摘要

A system and method for improving the control of a flow of a variety of fluid types is described. The method includes selecting a process gas type for the process gas that will be controlled and obtaining molecular mass information for the selected processed gas type. General characterization data is obtained that includes, for each of a plurality of flow and pressure value pairs, a corresponding control signal value and operating characterization data is generated by modifying the flow values in the general characterization data according to the equation Fadj=Fcal*(Mcal/Mpr)k, wherein Fadj is an adjusted flow value Fcal is the calibrated flow value, Mpr is the molecular mass for the selected process gas type, and Mcal is a molecular mass for the calibration gas. The operating characterization data is then used to operate a valve of the mass flow controller in open loop control mode.