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Leak Detection Systems

The helium leak detection systems enable checking of the leak tightness of very many components to ensure that they meet the required quality specifications.

The components in a pressurised fluid circuit should be leaktight. This is common in the refrigeration industry, the air conditioning, aerospace, automotive, electrical component and other industries. The tendency in refrigeration system design is to increase the operating pressure and reduce the refrigeration fluid load, which leads to higher demands on the systems' leak tightness.

Helum leak tests are very reliable, since they eliminate human error and are sensitive in the 1 to 10-8 mbar·litre·sec-1 range. The tests result in accuracy, repeatability and traceability levels that are difficult to obtain using other methods.

Telstar's machines enable several tests to be carried out in addition to a leak test, such as flow measurement, pressure resistance test, valve operation checking, etc.

Machine operation consists of filling the inside of the part being tested with pressurised helium gas and detecting the presence of helium in the outside environment. The part is placed inside a vacuum chamber, so that any leaks in the part increase the concentration of helium in the chamber, which is readily detected by a mass spectrometer.

 

Machine Description

The machines consist of one or several vacuum chambers with suitable dimensions and configuration to facilitate the manual or automatic loading and unloading of the parts. A suitably sized vacuum system enables the necessary vacuum level to be reached in the required time. The vacuum chamber also has a nitrogen scanning system which enables reduction of the partial pressure of helium in the chamber to extremely low levels, around 10-10 milibar. The mass spectrometer is capable of detecting very small concentrations of helium, which, added to the low background signal level, enables detection of very small leaks, around 10-8 mbar·l·s-1

To introduce helium into the component, to a pressure of 200 bar, a manifold, or valve system is assembled to expel the air, helium is introduced and then removed when the test is over. Carrying out the pressurised mechanical resistance test is also possible as is confirming that the gas flows correctly through the part.

The process is controlled by a PLC, connected to a computer that registers the test results and provides graphical and statistical processing on system operation.