FLOW RATE RANGE VARIABLE TYPE FLOW RATE CONTROL APPARATUS

摘要

A pressure type flow control device enabling a reduction in size and an installation cost by accurately controlling the flow of a fluid in a wide flow range. Specifically, the flow of the fluid flowing in an orifice (8) is calculated as Qc=KP1 (K is a proportionality factor) or Qc=KP2m(P1−P2)n (K is a proportionality factor and m and n are constants) by using a pressure P1 on the upstream side of the orifice and a pressure P2 on the downstream side of the orifice. A fluid passage between the downstream side of the control valve of the flow control device and a fluid feed pipe is formed of at least two or more fluid passages positioned parallel with each other. Orifices with different fluid flow characteristics are interposed in the fluid passages positioned parallel with each other. For the control of the fluid in a small flow area, the fluid in the small flow area is allowed to flow to one orifice. For the control of the flow in the large flow area, the fluid in the large flow area is allowed to flow to the other orifice by switching the fluid passages.