Patent ID: 6820632
Filing Date: 2004-11-23
Classification: G05D,Y10S,Y10T

Abstract:
A flow factor-based fluid-switchable pressure flow control method, comprising the steps of:calculating a flow rate Qc of gas passing through an orifice according to the formula Qc=KP1, wherein K=a constant with a pressure P1 on an upstream side of the orifice set at twice or more higher than a pressure P2 on a downstream side, wherein a flow factor FF for each kind of gas is calculated as follows: FF=(k/&ggr;s){2/(&kgr;+1)}1/(&kgr;âˆ’1)[&kgr;/{(&kgr;+1)R}]1/2 wherein: &ggr;s=concentration of gas in standard state; &kgr;=ratio of specific heat of gas; R=constant of gas; and K=proportional constant not depending on the type of gas; and when a calculated flow rate of a gas type A is QA and gas type B is allowed to flow through the same orifice under the same pressure on an upstream side and at the same temperature on the upstream side a flow rate QB is calculated as follows: QB=(FFB/FFA)QA wherein: FFA=flow factor of gas type A, and FFB=flow factor of gas type B.