In the past several different tracer gases have been used to find leaks and to measure leak rates, for example Ammonia or halogen gases. But since the leak test method with the tracer gas helium and the detection of this gas with a mass spectrometer was developed, all other methods became less significant compared to the superior sensitivity of the helium method. Also the measurement with a mass spectrometer ensures, that only helium and no other gases can influence the test.