Method and apparatus for pressure based mass flow control

Abstract

Mass flow controllers that can provide for improved bleeding time and can be manufactured with less complexity and cost are provided. A mass flow controller includes a body having a valve outlet bore defining a flow path and an adjustable valve configured to control flow of a gas through the flow path. A valve element includes an outlet orifice of the adjustable valve and is disposed within the bore. The mass flow controller further includes a pressure drop element disposed coaxially with the valve element within the bore. An upstream pressure sensor is configured to detect a pressure at a location in the flow path between the adjustable valve and the pressure drop element, and a controller is configured to determine a flow rate through the flow path based on pressure as detected by the upstream pressure sensor.

Dependencies are inferred from the claim text.