The accumulation method using trace gas, usually helium or forming gas (hydrogen/nitrogen mixture), is a good compromise between the highly sensitive vacuum integral method and the cost-effective pressure change methods using air.

In those two measurements, the test part is filled and measured in the same area (e.g., inside the battery housing). With this method, a simple accumulation enclosure is used to form a test space outside the test piece. Inside this enclosure, the increase in trace gas concentration is measured under atmospheric pressure over a period of time x. This allows significantly smaller leaks to be detected.

This makes it possible to detect much smaller leaks than with the pressure change method. The greatest advantage, however, is the independence from environmental influences such as the temperature of the test item or the environment, draughts, vibrations, etc. It allows, for example, leak testing of recently welded or otherwise thermally treated test specimens.

Even test specimens with very large and unstable volumes can be tested quickly and efficiently.