Why helium is used in leak testing?
Why use helium for leak testing? Helium is one of the smallest gas molecules and is inert. Being inert, helium is relatively safe to use (rather than hydrogen) and will not react with any of the materials within the part to be tested.
How sensitive should your leak detector be?
Make sure your detector is sensitive to the refrigerant type you are testing. Allowed under the F Gas Regulations – the leak detector must have a sensitivity of 5 g/year and should be checked annually.
Why are leak tests used in so many industries?
Therefore, the leak test, also known as leak test , must be used in a wide variety of industries and areas. It is a particularly important test method for quality control, especially in the medical technology, plastics and automotive industries. Due to the different applications, various leak testing methods have become established.
Is it necessary to evacuate part of leak test?
Some tests are performed with a helium content of only 1 percent—which means that the proper distribution of the tracer gas is even more important. For proper leak testing it is absolutely mandatory to evacuate the test part before filling it with tracer gas. This is particularly important for long and narrow geometries.
How is the leak measured in a leak test?
Leak test by pressure measurement During pressure measurement, the amount of air escaping from the test specimen is not measured directly. The effect of the leakage quantity on the test pressure confined in the test specimen is measured. The drop or increase in pressure depends on the size of the volume to be tested.
Can a leak test be set too low?
The leak test only needs to be as accurate as necessary. If the leakage rate is set too low, there is a risk that an increased amount of rejects will be “tested” and thus increase the manufacturing costs. Carrying out leak detection tests is a tried and tested means.
Can a leak test or leak detection method be suitable?
Determining whether a leak test or leak detection method for a particular application is suitable is its leak rate. Unfortunately this simple rule is often violated. For example, plastic parts are tested using the pressure decay method without considering their deformability and changes in volume due to compressed air.
How is a gross leak detected in a vacuum test?
In a gross leak the helium escapes from the test piece before the actual test interval. In effect, you evacuate the vacuum test chamber and the helium from the test piece at the same time. Sometimes a simple pressure decay test is integrated into the tracer gas system to identify any gross leaks before filling the test piece with helium.
How do you do a leak down test?
But if you want to do a leak down test on the entire engine, go ahead and remove all the spark plugs now. To remove a plug, first, take off the attached spark plug wire or coil pack. Then slide the spark plug socket, with the extension attached, over the spark plug.
How does the leak rate of an integral leak test work?
Also consider that the leak rate of an integral leak test and subsequent leak detection have to work together. Sometimes the integral leak test is carried out in a helium chamber, but the subsequent localization of leaks is carried out using the bubble test method instead of using a more precise sniffer leak detection method with tracer gas.