A typically silent danger posed to any workplace –particularly those within the industrial sector- is a leakage of harmful compounds through the degradation of your piping or general machinery. Conventional testing is not the most accurate way of ensuring your safety but thanks to the innovation of helium leak testing, it’s become a whole lot simpler.
Helium Leak Testing: The Benefits
As a small, inert gas molecule, the application of helium won’t affect the materials in the testing radius. To call something inert is to say that it isn’t affected by outside interference. Think along the lines of electricity and rubber; there is no link with either. With a simple spectrometer, you can measure the danger effectively with a sensitivity that is roughly between one thousand and one million times more sensitive which is more beneficial when compared to pressure decay techniques of old.
For the application, there are two separate measuring thresholds: 1×10-12mbar.l.sec-1 (high pressure testing) and 1×10-6mbar.l.sec-1 (low pressure, utilising the sniffing technique). To discover which to choose, it’s advised to think about whether your equipment can survive high-pressure without effect on it.
Helium leak testing is ideal for finding smaller, preventable leaks in a variety of climates which can extend the liFe of your product.
Helium: An Overview
The classic association with helium is upon inhalation, the voice becomes high-pitched. The very same substance as its effectiveness in leak testing has been proven time and time again.
Its inert habits make it safer than hydrogen due to its abundance and is very much desired over its counterpart. Helium is everywhere around you, measuring at 5 ppm.
For a finer measure of the potential leak, there are two limits at which to test with helium.
Lower Limits (1 x10-9 and below)
For this procedure, there are a few extra things to check on before proceeding with the test. For instance, helium has a tendency to attach itself to any material with a standard concentration of 5 ppm. Therefore, it is highly-advised that the area be properly cleansed of any helium residue which will enhance the accuracy of testing.
In the case of a higher mass production with a high vacuum, it is advised to consider the length of time required to pump down the vacuum.
The size of the leaker has a direct effect on this. The bigger it is, the longer it will take for the present helium to dissipate, leading to incorrect measurement. Therefore, if you are to commence a higher-limit testing, you should build up to the standard levels steadily before flushing the mass spec with general harmless gas before starting again.
Should you be helium leak testing at higher speeds, it’s vital that you reduce your time constraints. Flush with nitrogen or begin a test with smaller quantities gradually to achieve this.
A universal factor to include for both limits is the durability of tooling and pipework and their resistance to testing. It’s necessary to make it airtight to a higher degree than the threshold. If the seals come under complication (right-angled), extra care is required.
After a test, it may be more viable to re-use the helium for economical purposes. For instance, if there’s an abundance of testing to be done at high pressure, the capacity of helium required will be greater. Utilise a pump and simple air cylinder to achieve this.
Mixing with other compounds to enhance its life is another process. Choose nitrogen or compressed air: these are ideal to lower the risk of comprising the helium.
Finally, you can extract the helium into a vessel (scientific equipment is essential) so it can be compressed for later use.
“Joshua Turner, Scientist” by Daniel Parks available under a Creative Commons Attribution 2.0. Full terms at http://creativecommons.org/licenses/by/2.0.