Helium Leak Detection

The Specialists at IVAC Group have over 50 years of combined experience with helium leak detection.

Unlike other companies, when you contract IVAC group for helium leak detection you are getting more than a technician that can spray or sniff helium with a mass spectrometer. You get a technician with many years of experience in Helium leak detection and machine repair. While others may be able to point and identify simple leaks, IVAC Group can detect and repair the leaks the others cannot find.

Generalized statements often made, such as “no detectable leaks” or “leak rate zero”, do not represent an adequate basis for acceptance testing. Experienced technicians and engineers know that properly formulated acceptance specifications will indicate a certain leak rate under defined conditions.

Some information about Helium Leak detection

Helium is best choice of gas used for leak detection because:

  • Inert and nontoxic
  • only present in trace amounts in atmosphere,
  • relatively cheap
  • Due its low atomic mass it easily flows through even very small leaks
  • non flammable
  • Only molecule smaller than hydrogen, hydrogen is not inert ( remember the periodic table)
  • it is available in variously sized cylinders and high grade is suitable for medical

 

Helium Leak Detector

Helium Leak Detection

A Helium Leak detector, also known as a Mass Spectrometer Leak Detector (MSLD), is used to locate and measure the size of leaks into or out of a system, machine or other assembly.   The tracer gas, helium, is introduced to a test part that is connected to the leak detector.  The helium leaking through the test part enters through the system and this partial pressure is measured and the results are displayed on a meter. Helium leak testing can be generally be between one thousand and one million times more sensitive than using pressure decay techniques.

Methods of Leak Testing Parts

There are two main methods to leak test parts using helium: Vacuum Testing (outside-in) and Pressure Testing (Inside-out).  The detection method should be selected based on the working conditions of the part to be tested.  It is important to maintain the same pressure conditions during the test as will exist during the actual use of the part.  Vacuum systems should be tested with a vacuum inside the chamber.  A device such as a compressed air cylinder should be tested with high pressure inside the cylinder.

Vacuum Testing – Spray testing (Outside-in)

In Vacuum testing, the part is evacuated with a separate pumping system for larger volumes, or within the detector itself for smaller volumes.  To locate a leak, helium is administered to the suspected leak sites and all connections of the part using a spray probe with an adjustable flow. With spray testing, you have the ability to test to a higher specification than with sniff testing.  The system needs to be evacuated with a portable vacuum pump with the helium leak detector connected to it.  Once an acceptable vacuum level has been reached, helium is sprayed outside of the component to check for leaks. In the event of a leak, the helium will be drawn into the pipe or component by the vacuum and detected by the leak detector.

Pressure Testing – Sniffer testing (Inside-out)

In Pressure Testing, the part or chamber is pressurized with helium or a mixture of helium and nitrogen.

In the sniffer-probe mode, the exterior is scanned with a probe that is attached to the inlet of the leak detector. The probe continuously admits (or "sniffs") some of the air directly surrounding the part or chamber. This gas is inducted to the analytical portion of the leak detector, where any of the tracer gas that may be leaking from the part or chamber.