Over the years leak detection techniques have varied from the use of a single application of "soap-based" solu-
tions for coarse leaks to the highly sophisticated use of a mass spectrometer, which can detect leaks at the ppb
level. In the context of the present application to gas cylinder / valve package, the use of specialized leak de-
tection fluids (LDFs) will be developed further. These specialized LDFs are far superior to household soap
based solutions, which could contain contaminants or other detrimental constituents. As such, household soap
based solutions should not be used.
There are various national regulations and international guidelines to ensure that cylinders and valves are
checked for gas tightness. Though such a post-fill check is an essential part of a quality control procedure to
ensure that customers receive a non-leaking package, the choice of the LDF needs to be carefully considered
because of potential hazards from LDFs. These potential hazards include stress corrosion cracking (SCC) and
incompatibility with materials and ladings such as oxygen.