The helium leak test is based on the detection of helium as the test gas, which only occurs in the ambient air in a very low natural concentration of approx. 5 ppm. Therefore, a reliable test statement is possible even by detecting a small amount of helium. Before a helium leak test, a rough leakage measurement is usually carried out first.
The test chamber is evacuated and the test specimen is pressurised with helium. Helium escaping through leaks is sucked in by a high vacuum pump and detected.
The test specimens are either filled with helium before sealing or subsequently subjected to helium overpressure for a certain time so that helium penetrates the test specimen. This is followed promptly by testing in a vacuum test chamber, where the amount of escaping helium is determined. A mass spectrometer, which consists of an ion source, the separation system and the ion detector, serves as the detection system for the test gas.
Some applications of helium: