FLOW CONTROL SYSTEM WITH BUILD-DOWN SYSTEM FLOW MONITORING

摘要

To provide a flow control system with build-down system flow monitoring that realizes flow monitoring close to real-time monitoring by combining build-down system flow rate measurement with the upstream side of the flow control system without using a thermal type flow sensor by effectively utilizing high pressure fluctuation resistance characteristics of the flow control system, and can be significantly downsized and reduced in cost.

主权项

1. A flow control system with build-down system flow monitoring comprising:
an upstream side valve AV that opens/closes distribution of a gas from a gas supply source having a desired gas supply pressure; a flow control system with supply pressure fluctuation resistance connected to the downstream side of the upstream side valve AV; a build-down capacity BC being an internal volume of a passage communicatively connecting the outlet side of the upstream side valve AV and the inlet side of the flow control system; a temperature detection sensor T arranged to detect the temperature of a gas distributed inside the passage forming the build-down capacity BC; a pressure sensor P arranged to detect the pressure of the gas distributed inside the passage forming the build-down capacity BC; and a monitoring flow rate arithmetic and control unit CPb operably connected to control opening and closing of the upstream side valve AV, and arranged to compute and output a monitoring flow rate Q by a build-down system by dropping the gas pressure to a set lower limit pressure value by closing the upstream side valve AV after a predetermined time oft seconds after setting the gas pressure inside the build-down capacity BC to a set upper limit pressure value by opening the upstream side valve AV, wherein the monitoring flow rate Q is computed by the following equation:Q=1000760×60×273(273+T)×V×ΔPΔt wherein T is a gas temperature (° C.), V is a build-down capacity BC (1), ΔP is a pressure drop range (set upper limit pressure value−set lower limit pressure value) (Torr), Δt is a time (sec) from closing to opening of the upstream side valve AV.