IMPROVED PRESSURE TYPE FLOW CONTROL DEVICE

摘要

PROBLEM TO BE SOLVED: To develop an improved pressure type flow control device establishing an empirical flow formula fitted with high precession to an actual flow amount of a compressible fluid in a non-critical region and performing flow control with high precision using the empirical flow formula.

SOLUTION: The improved pressure type flow control device expressing the empirical flow formula for the compressible fluid in the non-critical region (non-sonic region) as Qc=KP2m(P1-P2)n(wherein K is a proportionality constant; m and n are each constants) and calculating the flow amount passing an orifice 4 using the formula Qc=KP2m(P1-P2)naccurately and speedily controls flow to be the target flow. A pressure ratio P2/P1=r obtained from an upstream pressure P1and a downstream pressure P2is always compared with a critical value rc. The flow amount is calculated using Qc=KP1for a critical condition (r≤rc), and using Qc=KP2m(P1-P2)nfor a critical condition (r>rc). The flow control device then accurately and speedily controls the flow amount to be the target flow amount while corresponding to all conditions of the fluid.

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