Producing actual flow value for gaseous medium control - by drawing calibrated flow of atmospheric air into parallel flow subsequently returned to flow channel

摘要

A method of generating an actual flow value for controlling the flow of a gas involves extracting a parallel flow (3) of the gas from the flow channel (1) and feeding it back into the channel downstream. A calibrated (6) flow (8) of atmospheric air is drawn into the parallel flow (3) and this flow is detected (9) to produce the actual value for controlling the flow of gas in the flow channel. USE/ADVANTAGE - Controlling vol. flow in air conditioning systems. Prevents degradation of, or damage to, sensor by contaminants or corrosive substances in controlled flow whilst maintaining accurate control of esp. value in laboratory.