Patent ID: 9188989
Filing Date: 2015-11-17
Classification: F16K,G05D

Abstract:
1. A flow node for low flow delivery of process gas, comprising: an inlet to a conduit; a valve seat and poppet assembly controlled by an actuator to receive a process gas; a characterized restrictor, in series and directly adjacent with the valve seat, and to provide a primary flow restriction in accordance with one or more pressure set points while having a minimized volume between the valve seat and the characterized restrictor by being directly adjacent to each other so that bleed down time is minimized for low flow transitions, wherein a conductance of the characterized restrictor is low enough relative to the conductance of the valve seat to cause a pressure drop sufficiently large relative to the pressure drop of the valve seat assembly that the pressure drop of the valve seat poppet assembly can be ignored without introducing significant flow errors relative to the desired accuracy; and an outlet to exhaust the process gas from the conduit at a desired mass flow.