Patent ID: 6450200
Filing Date: 2002-09-17
Classification: G05D,Y10T

Abstract:
A flow control system for use within a fluid circuit having a source of pressurized gas to be delivered batchwise at a controlled flow rate to a destination by said flow control system, said flow control system being operable in a flow mode for delivering a batch of gas and, alternately, in a no-flow mode, said flow control system comprising:a flow line through which gas from said source of pressurized gas can be delivered, a pressure regulator in said flow line to establish a regulated gas pressure in said line, an on/off valve in said line downstream of said pressure regulator to start and stop said flow mode during which said gas is delivered for a delivery period of time, a reference capacity in said flow line upstream of said pressure regulator for use in measuring the actual flow rate of gas being delivered by said flow control system, a pressure sensor to measure a pressure drop of said gas in said reference capacity during a measurement period of time commencing after the start of a delivery period of time, means in said line upstream of said reference capacity for interrupting the flow of gas from said source of pressurized gas to said reference capacity during delivery of said gas by said flow control system, and a controller for determining from said measured pressure drop and the rate of pressure drop in said reference capacity during said measurement period, the actual flow rate of a batch of process gas being delivered and, in case said actual flow rate does not agree with a specified flow rate for said delivering, adjusting said controlled flow rate in the direction of said specified flow rate from said actual flow rate for a subsequent delivery period of time in which another batch of process gas is delivered.