INFICON :: LEAK TEST - Best Practices for Leak Detection

How to Select the Right Tracer Gas

There are a considerable number of tracer gases to choose from when performing leak testing with a test (tracer) gas. The tracer gas is used either in a pure form or is mixed with other gases. The basic requirements for a tracer gas include:

  • Non-toxic, non-flammable and inert
  • Low concentration in the atmosphere, not emitted by any technical processes (for a small detection limit)
  • Compliance with various environmental regulations

Below is a profile of the most commonly used tracer gases. Although INFICON offers leak detectors for all of these gases, helium remains the best solution for most applications; it is the only tracer gas that meets all requirements.

Requirement Forming gas = (H2) in (N2)* Helium (He) Argon (Ar) Refrigerants
Nontoxic F F F F
Nonflammable F F F F**
Inert F F F F
Low atmospheric concentration F F F F
No tracer gas emissions from technical processes -- F F (F)
Low detection limit (F) F -- (F)
Environmentally compatible F F F --

The leak testing experts at INFICON can advise on the appropriate tracer gas for a specific application that best meets the customer requirements.

F= fulfilled
(F) = more or less fulfilled
-- = not fulfilled

* Hydrogen itself is flammable. Hence, it is normally used in a mixture with nitrogen (N2). This forming gas has a concentration of only 5 % to 10 % hydrogen, which reduces the sensitivity by a factor 10 to 20!
** Some refrigerants are flammable.


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