Need for Leak Testing:

• To prevent material leakage loss which interferes with system operation.
• To prevent environmental contamination hazards.
• To detect unreliable components whose leakage, exceed the acceptable limit.
• To ensure reliability and serviceability and to prevent premature failure of systems under pressure or vacuum.

Why use helium for leak detection:
Helium is the best choice to find leaks because it is non-toxic, inert, non-condensable, non-flammable, present in the atmosphere in trace amounts (5 ppm). Due to its small atomic size, helium passes easily through leaks. The only molecule smaller than helium is hydrogen which is not inert. Helium is lighter than the next inert gas neon, which is more expensive. It is also relatively inexpensive and is available in various size cylinders and also, in pure form easily. There are other leak detection methods but none of them is as accurate in terms of localization and quantification, as helium leak detection method.

Leak Testing Form of NDT for:

• Detection & Location of Leaks.
• Measurement of fluid leakage in either pressurized or evacuated compo. Or systems.
• Measurement of fluid leakage in either pressurized or evacuated compo. Or systems. Leak Existence of Physical opening - May be Crack, Crevices, Hole, Fissures or Passage way which admits fluids escape.
• Leakage - Flow of fluid through a leak.

Principle of helium leak detector (HLD)
The HLD leak detector is based on the principle of field mass spectrometer. The leaked helium gas is ionized by the electron beam from the filament within the ion chamber of the analyzing tube. The ions are accelerated using added voltage and move out through a slit and then pass through the magnetic field generated by the analyzer. Since the circular trajectories of the ions depend on their mass, the collector can catch only the helium ions and detect helium. Using a special detector, the ion current is converted into an electric current. This current is accelerated and displayed on the screen using leak detection units. The ensured current is in direct proportion to helium concentration and therefore equal to the measured leak.