Patent ID: 7905139
Filing Date: 2011-03-15
Classification: G01F,G05D

Abstract:
1. A mass flow controller for measuring flow of a fluid, comprising: a flow meter for providing a signal corresponding to mass flow through the flow meter, the flow meter including a flow sensor; an adjustable valve for controlling the passage of fluid out of the mass flow controller; a fluid path through the mass flow controller, the fluid path including an inventory volume between the flow sensor and the adjustable valve; a pressure transducer for providing a signal corresponding to the fluid pressure at a position in the flow path before the adjustable valve; and a signal processor to determine the compressibility of the gas in the fluid path using the fluid temperature and pressure and to correct the signal from the flow sensor for inaccuracies caused by a change in pressure, the correction depending on the compressibility of the gas; and a controller to adjust the adjustable valve to control the flow through the mass flow controller in accordance with the corrected signal corresponding to the fluid flow.