Patent ID: 6813943
Filing Date: 2004-11-09
Classification: G01F,G05D

Abstract:
An apparatus for conditioning a gas flow to improve a measurement of rate of pressure change associated with the gas flow, comprising:a measurement chamber having an interior portion characterized by an internal volume, and an inlet port for receiving the gas flow; a pressure sensor for sensing a pressure within the interior portion of measurement chamber and for producing a pressure signal corresponding the pressure within the measurement chamber; a signal processor for receiving, sampling the pressure signal at a sampling frequency and filtering the pressure signal so as to produce a sampled pressure signal, and for calculating a time derivative of the sampled pressure signal; and, an inlet damper disposed at the inlet port, constructed and arranged such that the gas flow passes, at least partially, through the inlet damper prior to passing through the inlet port and into the measurement chamber, wherein the inlet damper modifies one or more characteristics of the gas flow as a function of a pressure drop across the inlet damper, according to a damper transfer function; wherein the internal volume and the damper transfer function are selected so as to limit a frequency associated with variations of the pressure within the measurement chamber to a predetermined fraction of the sampling frequency.