Methods and apparatus for diagnosis on mass flow controller

Abstract

Mass flow controllers and associated methods are provided. A mass flow controller includes a control valve configured to control flow of a fluid in a flow path and first and second flow sensors. The second flow sensor includes a pressure sensor adjacent a flow restrictor disposed in the flow path. A controller is configured to control actuation of the control valve. The controller is configured to determine a first mass flow rate based on one or more first fluid flow parameters detected by the first flow sensor, determine a second mass flow rate based on one or more second fluid flow parameters detected by the second flow sensor, calculate an orifice area of the flow restrictor based on the determined first mass flow rate, and compare a nominal orifice area of the flow restrictor with the calculated orifice area to assess a condition of the second flow sensor.

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