The most common form of leak detection is to add a trace of Helium Gas into the flow of a Nitrogen injection creating a mixture of 99% N2 / 1% Helium.
Systems are then pressurized to around 95% of PSV or design pressure and the Gas medium is then left to stabilize.
If any audible leaks are encountered during the pressurization phase then the system is depressurized and the repairs are made to the necessary joint. The system will again be pressurized.
Upon successful stabilization the system is then ready for probing. Prior to probing all mechanical joints will be covered with PVC tape to ensure that leakage is contained.
The most common form of measuring device is the UL – 300 . which has the capacity to measure up to 0.10 Scf/Yr.