Helium Leak Test  

Helium leak tests of compressor cylinders is available as an option. Once the cylinder has been hydro tested , the cylinder is submerged in a water tank and pressurized with Helium to the cylinder MAWP or 2000 psig , whichever is lower. Pressure must be maintained and no leaks observed for a period of thirty (30) minutes.
 
Helium testing is required for gasses 12 mole weight and below as well as gasses with 50% or more hydrogen by volume.
 
 
(reference ISO 8.2.4.8)

Ariel Corporation Application Manual  
21 December 2006