Gas separation chamber and portable leak detection system

A portable leak detector is disclosed for use with, say, helium as a tracer gas. The leak detector includes an improved separation chamber, an air pump for pumping the sample gas, a high vacuum spectrometer, and a small and lightweight evacuation pump. The separation chamber is formed by an air-tight enclosure which has an inlet duct, an outlet duct, and a tubular separation membrane extending between manifolds connected to the ducts. Gas samples are collected by a gas sampling probe and pumped by an air pump into the inlet duct of the separation chamber, through multiple parallel tubes of the tubular membrane material, and out the outlet duct of the separation chamber where it is exhausted. The multiple tubes are formed of a selectively-permeable membrane material such as Tefzel which permits the rapid diffusion of helium therethrough but which has relatively low permeability for other gases contained in the gas sample. During operation, the sample gas collected by the probe and contained within the tubular membrane would have a relatively high partial pressure, while the surrounding separation chamber and spectrometer connected therewith, which include the extracted tracer gas, are maintained at high levels of operational vacuum by the evacuation pump, so that the partial pressure of the tracer gas, such as helium is relatively low