Overpressure method – Bombing test
The bombing test is a pressure/vacuum method of leak detection used for testing of hermetically sealed components containing a cavity which can be gas-filled or evacuated. The objects to be tested, get in a pressure chamber exposed to the helium search gas. During an exposure time of up to several hours at a high helium pressure, the helium will penetrate through any leaks present in the test object. This is the part referred to as the “bombing”. After the pressurisation or bombing the objects are tested for helium emission in a vacuum vessel, following the same procedure as in the hood test. This test permits detection of the smallest leak rates and is especially used for objects which can not be gas-filled by other means. The bombing test can for example be used for examination of transistors, ampoules etc..