Patent ID: 9400004
Filing Date: 2016-07-26
CPC Classification: F15D,G01F,G05D,Y10T

Claim Text:
1. A method for measuring the transient response of a mass flow controller (MFC), the MFC being installed in a gas flow system comprising: a variable orifice positioned upstream of the MFC, wherein a position of the variable orifice controls the variable orifice's size; a sensor measuring the position of the variable orifice; a pressure transducer positioned between the variable orifice and the MFC; and, a controller/recorder for controlling the size of the variable orifice; the method comprising: configuring the controller/recorder to control the variable orifice such that regardless of the flow through the MFC, the pressure between the MFC and the variable orifice remains constant; storing in the controller/recorder a relationship between the position of variable orifice and flow rate through the variable orifice; configuring the controller/recorder to receive position data from the sensor; programming the controller/recorder to calculate the flow through the variable orifice at each instance using the position data and the relationship between the variable orifice's position and flow rate through the variable orifice; wherein prior to starting measurement of the transient response, a set pressure between the variable orifice and the MFC is established by performing the ordered steps comprising: a. setting the variable orifice to its maximum desirable position; b. turning on the MFC to its desired flow rate and allowing gas to flow until steady state is reached; c. determining the pressure drop across the variable orifice; d. closing the variable orifice and turning off the MFC, while making certain to maintain pressure between the control valve and the MFC that was established in Step c; e. changing the position of the variable orifice as needed to keep the reading of the second pressure transducer unchanged; f. starting transient response measurement by turning on the MFC to the desired flow rate while controlling the variable orifice so as to maintain the pressure established in step c.