Apparatus for detecting leaks

A device adapted to be used in testing for leaks apparatus that is being evacuated by a vacuum pump, said device comprising in combination with said apparatus and vacuum pump a conduit interconnecting said apparatus and pump through which gases are drawn from said apparatus by said pump, a finely porous membrane mounted in said conduit to cause the gas adjacent the upstream face of said membrane to be enriched with respect to a heavy component of said gas, first thermal conductivity measuring means positioned adjacent the upstream face of said membrane in contact with said enriched gas, second thermal conductivity measuring means positioned in said conduit at a point sufficiently spaced upstream from said first measuring means that said second measuring means is in contact with unenriched gas from said apparatus, a probe, means for supplying to said probe a gas having diffusive characteristics different from those of air whereby said probe may be used to scan said leaks and said testing gas will be drawn through any leaks to vary the relationship between said first and second conductivity measuring means, and indicating means operatively associated with said first and second measuring means for indicating a change in the relation therebetween as an indication of the location of said leak.

A device adapted to be used in testing for leaks apparatus that is being evacuated by a vacuum pump, comprising in combination with said apparatus and pump, a conduit interconnecting said apparatus and pump through which gases are drawn from said apparatus by said pump, a finely porous membrane mounted across said conduit to cause gases immediately upstream of said membrane to be enriched with respect to a heavy component of said gases, a first electrical resistance element positioned adjacent to said membrane in contact with said enriched gas, a second electrical resistance element spaced upstream from said first element and in contact with unenriched gas flowing from said apparatus, means for supplying electrical energy to said first and second elements to heat said elements, whereby the temperature of said elements and consequently their resistances vary as a function of the thermal conductivity of the gases in contact therewith, electrical resistance measuring apparatus for measuring and comparing the resistances of said first and second elements, said measuring apparatus including indicating means for indicating changes in the relation between the resistances of said first and second element to indicate leaks in said apparatus.