Leak detection—common problems and their solutions

The subject of leak detection will be considered from the viewpoint of a number of classical problem areas that are common to many different techniques. These will include such limitations as temperature change, system outgassing, virtual leaks, gas permeation, and long time constants from large volumes as well as from double leaks in series. The problems as well as their solutions will be discussed for a broad range of leak‐test methods, including various total and partial pressure gauges. Some specific advantages of air‐leak detection with either a residual gas analyzer or a small mass spectrometer mounted on its own pumping system will be illustrated. A clarification of common misconceptions about the nature of leaks and gas flow through leaks will also be included. This will be illustrated with several typical examples including the technique of high pressure helium bombing.