Patent ID: 7204158
Filing Date: 2007-04-17
Classification: G05D

Abstract:
1. A flow control apparatus for use within a fluid circuit having a source of pressurized gas to be delivered at a controlled flow rate to a destination by said flow control apparatus, said flow control apparatus comprising: a flow line through which gas from a source of pressurized gas can be delivered; a flow control system in said flow line to establish a controlled flow rate for delivery of gas at a specified flow rate in accordance with a calibration of said flow control system; a flow verification system including a known volume in said flow line upstream of said flow control system, a pressure sensor to measure gas pressure drop relative to time in the known volume when gas flow to the known volume is interrupted while gas flow from the known volume is continued, and a controller to calculate the actual flow rate of gas being delivered by said flow control apparatus using said measurement and, in case said actual flow rate does not agree with said specified flow rate, recalibrate said flow control system; a thermal reservoir provided in the known volume of the flow verification system, the thermal reservoir being de-coupled from ambient effects so that the temperature of the thermal reservoir will be driven to the gas temperature during steady state flow of gas through the known volume, and will transfer heat to maintain a constant gas temperature during gas expansion.