Helium Leak testing is a non destructive method to verify the presence of a leak in a component or device.
The presence of a leakage could jeopardize the correct functioning of the component or device or its life span, and also be potentially dangerous for the environment and for the safety of its user.
Helium is the second lightest element after hydrogen: it can penetrate small leaks rapidly (where heavier elements could not) up to 10-11 mbar*L/s.
1. Is a noble gas: it is inert and does not react with other gases or with the part under test.
2. Is ecological: it is colourless, odourless, tasteless, non-toxic and does not create any problem in case of dispersion in the environment.
3. Is present in the atmosphere only in small quantities (5 ppm) and so the background noise for the leak detection instrument is very low.
The usage of helium as tracing gas to find and quantify leaks requires an instrument able to detect its presence.
The instrument is the mass spectrometer, that transforms the measurement of the mass of a gas into an electric signal. To do this, the air that enters the spectrometer is ionized and guided into a curved tube immersed in a magnetic field.
For a given value of the magnetic field only helium ions go through, while the others are destroyed. The electric current produced by the helium ions flow is measured to quantify the leak.