Patent ID: 6058761
Filing Date: 2000-05-09
Classification: G01N

Abstract:
A method for measuring the relative density of a gas, the method comprising:flowing a reference gas and a sample gas from a volume chamber through an orifice that is sized to be small relative to a connecting line and sized with respect to an initial pressure of the reference gas and the sample gas, respectively, such that the effects of a discharge coefficient of the orifice are not necessary to a computation of relative density;measuring an elapsed time of discharge when the reference gas reaches a target discharge pressure;measuring the pressure of the sample gas across the orifice at the elapsed time of discharge determined for the reference gas; andcomputing the relative density of a sample gas from a known relative density of a reference gas, from predetermined constants for the reference gas and the sample gas, respectively, and from a ratio of the pressure of the sample gas across the orifice to the pressure of the reference gas across the orifice.