Tracer-gas leak testing method is a nondestructive testing method.
Several tracer-gas leak testing methods exist among which the methods of choice are:
Helium mass spectrometer or helium leak detection, providing the highest sensitivity
Hydrogen leak testing or hydrogen leak detection, providing the best mobility
Refrigerant gas leak detection, for refrigeration applications.
The nature of the product or the process and the process gases will set the leak rate requirement:
Based on the target leak rate the table below wil help to choose the most suitable method.
Restriction of use (F-Gas Directive)
Typical applications of tracer gas leak testing include:
Chemical plant
Petrochemical plant: hydrocracker, vapocracker, catalytic reforming, steam reforming are all Hydrogen based processes were Hydrogen leak testing will be very appropriate,
Semiconductor industry; all processes taking place in a process chamber at atmospheric pressure or under vacuum; Diffusion, Oxidation, LPCVD, PECVD, PVD, Etch, Ion Implant, typically the later that implies vacuum will require Helium leak testing, while the other will make good use of Hydrogen leak testing,
Automotive: with airbag being the most demanding leak testing application (small gas tank, very high pressure, long shelf life) and air conditioning system (for best efficiency), fuel system (for low emission), exhaust system (for lowest pollution), engine and transmission (for no oil dripage), rims to keep tyre safe,
Medical: to ensure safe and long life implant (pacemaker) or a safe catheter
Airplane: to quickly and safely locate fuel leaks, to check oxygen distribution devices and cabin pressurization systems
Refrigeration and air conditioning systems-residential, commercial or industrial- in order to deliver best efficiency at the lowest loss rate of refrigerant gases (ozone depletion)
Power distribution for high voltage circuit breaker using SF6 as a dielectric
Drinking water distribution grid as today average leakage rate or efficiency is above 25%, wasting precious resources, water and power.
Sewage water collecting network as leaks can contaminate drinking water collection process;
Another element of consideration is the dimension of the part to be tested as well as to take into consideration the law of physics, specially the rules that govern the flow of gas at different pressure. <<stub>>
Standards
Several standards apply to leak testing and more specifically to tracer-gas leak testing methods, for example
BS EN 1779:1999; leak tightness by indication or measurement of gas leakage,
BS EN 13185:2001 Non-destructive testing. Leak testing. Tracer gas method,
BS EN 13192:2002 Non-destructive testing. Leak testing. Calibration of reference leaks for gases.
