Abstract

Previously, in Europe, in gasket tests mainly Nitrogen was used as the test medium. This medium was easy to handle, safe and cheap to buy. With increased sealing requirements on the sealing elements, however, a test medium had to be used, with which smaller leakage quantities can be reliably measured. In laboratory testing, Helium prevailed, with which in the vacuum method using a mass spectrometer these tightness requirements could be easily achieved. Other media, such as hydrogen or Methane, were not used in standard tests because of their hazard potential and detection limitation.

Particularly in performance tests, a practice-oriented medium has always been favored in sealing tests in the USA. Methane is the first choice as the smallest hydrocarbon molecule. In ASME B16.20, a new performance test has been introduced, in which the tightness requirement of spiral wound gaskets in a leakage test with Methane should be checked. And also in the valve test in ISO 15848-1, Methane is defined as an alternative test medium for Helium.

In this paper, the difference in the leakage test between Nitrogen, Helium and Methane in terms of handling, use in the test laboratory, the measurement of leakage rates and the detection limits between Nitrogen, Helium and Methane will be shown.

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