Types of Helium Leak Testing 

​

Sniffer Method

The test component is filled with Helium Gas. In Case of Leak the Helium gas escapes through the leakage and detected by the sniffer probe

 

​

​

 

 

 

 

 

 

 

 

To pinpoint the location of the leak(s) (but not measure the total leakage), the likely potential leak sites of the part are
scanned using a Sniffer Probe connected to the inlet of the leak detector.

​

Hard Vacuum Method :

​

Typically the leak detector is connected by means of a "tee" connected in between the foreline of the high vacuum pump and the inlet of its backing pump. A system should be capable of maintaining a foreline pressure low enough to operate the leak detector at this location. Helium is
pressurized into the Test Piece kept inside the vacuum chamber. If a leak exists, helium will enter the chamber and rapidly diffuse through it. The leak detector should respond within several seconds or less. ​

​​

​

​

​

​

​

​

​

​

​

​

​

​

Note that leak detector sensitivity will be diminished in systems with large backing pumps. A dynamic level system calibration captures this diminishing helium and factor in as Machine factor to calculate the actual leak rate of the test part.

​

​

Accumulation Testing Method :

​

This method can both locate and quantify leaks. Some type of shroud or hood is placed in such a manner as to envelop a
potential leak site. A certain amount of time is given to allow leaking helium to accumulate in the shrouded area, increasing
the helium concentration. The leak detector is then valved-in to the shrouded volume. If many potential leak sites exist in a
manifold or if many parts are to be tested at the same time, they can be sequentially valved-in to determine which site is leaking.