| abstract |
A leak detector includes a leak detector inlet to receive a test gas; a vacuum pump coupled to the leak detector inlet; a test gas sensing unit connected through a passage to the leak detector inlet; and a membrane that is permeable to the test gas disposed in the passage between the leak detector inlet and the test gas sensing unit, the membrane having a permeance to the test gas that varies by less than five percent over a temperature range of T 0 −20 K to T 0 +20 K, where T 0 is a design temperature. In addition, methods are provided for making a composite membrane that includes a semi-permeable membrane and a porous membrane. Furthermore, a reference leak, which includes a composite membrane is provided. |