Patent ID: 7204127
Filing Date: 2007-04-17
Classification: G01M

Abstract:
1. Apparatus for leak detection comprising: a test line configured to receive a sample containing a trace gas; a mass spectrometer configured to detect the trace gas and having an inlet for receiving the trace gas; a first vacuum pump characterized by a relatively high reverse flow rate for light gases and a relatively low reverse flow rate for heavy gases, said first vacuum pump having a pump inlet and a foreline, the pump inlet being coupled to the inlet of said mass spectrometer; a foreline valve coupled between the foreline of said first vacuum pump and the test line; a trace gas permeable member coupled between the test line and the inlet of said mass spectrometer, allowing the trace gas to pass and blocking other gases, liquids and particles; a controller configured to increase the trace gas permeability of the permeable member by closing said foreline valve at relatively high pressures and decreasing the trace gas permeability of the permeable member by opening said foreline valve at relatively low pressures in the test line; and a second vacuum pump having an inlet coupled to the test line.