VARIABLE FLOW RANGE TYPE FLOW CONTROL DEVICE

摘要

It is so made that a flow rate control apparatus can be downsized and its installation costs can be reduced by achieving accurate flow rate control of a fluid over a wider flow quantity range with one set of flow rate control apparatus. Specifically, with a pressure type flow rate control apparatus wherein a flow rate of a fluid passing through an orifice 8 is computed as Qc=KP 1 (where K is a proportionality constant), or as Qc=KP 2 m (P 1 - P 2 ) n (where K is a proportionality constant, m and n constants), by using an orifice upstream side pressure P 1 and/or an orifice downstream side pressure P 2 , a fluid passage between the downstream side of a control valve and a fluid supply pipe of said pressure type flow rate control apparatus are made to be more than at least 2 fluid passages in parallel, wherein orifices having different flow rate characteristics are provided with the afore-mentioned fluid passages arranged in parallel, the afore-mentioned fluid in a small floe quantity range is made to flow to one orifice for the flow control of the fluid in the small flow quantity range, while the afore-mentioned fluid in a large flow quantity range is made to flow to the other orifice for the flow control of the fluid in the large flow quantity range.