Tracer gas leak testing is a method typically used to test parts with very low leak rates, outside the range of conventional air-flow pressure decay and mass flow testing. It can also be used to locate leaks in parts that have been identified as leaking. It provides high sensitivity, accuracy, and repeatability.
While helium has long been the most common tracer gas used for leak testing, the use of alternatives is on the rise. The most popular alternative is forming gas, typically a mixture of 5% hydrogen and 95% nitrogen.
But what makes a manufacturer choose one over the other? I’ll explain this below:
Why is helium the most popular gas for tracer gas leak testing?
Helium has long been the most common tracer gas used in leak detection, mostly due to its ability to identify and locate very low leak rates—as low as 10-12 scc/s.
It is also a very safe gas to use in a manufacturing environment, being non-flammable, non-destructive, non-toxic, inert, and only has trace presence in our atmosphere, which makes it easier to control background. And since it can be used up to 100% concentration, it is capable of very fast cycle times.
Why have manufacturers started to use forming gas instead of helium?
Helium is popular for many uses and across many industries. As such, it has become prone to scarcity and supply issues, which leads to higher costs and potential unavailability for manufacturers. This has led manufacturers that don’t require helium to meet their specifications to opt for forming gas as a more cost-effective and easier-to-obtain alternative.
Learn more about the pros and cons of forming gas vs. helium
How to know if you can use forming gas instead of helium for tracer gas leak testing
While helium remains the best option for detecting the smallest leaks, not every leak test scenario requires meeting this specification. To determine whether your leak test requires the use of helium, there are two main factors to consider: target cycle time and environment.
Cycle time
The difference in concentrations between forming gas and helium (5% hydrogen maximum versus potential 100% helium) impacts the cycle times possible for your test. Forming gas takes longer to test because of the smaller concentration rate of rise. This will mean that depending on the size of your part and the relative test chamber, you may not be able to meet your target cycle time using forming gas, leaving helium as your best option.
Environment
As helium and hydrogen are both present in our atmosphere and can be off gassed in a plant environment, it is important to consider if there are any factors present on your plant floor that could skew your measurements. This could include certain processes happening around your leak test station, or motor machinery you have running on the plant floor, such as fork trucks. If these machines are running on natural gas, they output hydrogen into the air, which will likely mean you need to use helium for your test (dependent on target leak rate).
Download the application bulletin for more details:
Tracer Gas Leak Testing: Pros & Cons of Forming Gas vs. Helium
CTS is an industry leader in tracer gas leak testing technology
For over 40 years, CTS has worked with leading manufacturers across the globe, ensuring defective assemblies are caught before they leave the plant. CTS designed the TracerMate II to meet the needs of manufacturers on the plant floor.
The TracerMate II is a flexible solution for tracer gas leak testing, using helium, forming gas, or other gases (carbon dioxide, argon, VOCs, etc.). It can be used for various methods of tracer gas leak testing, including sniff leak testing, nitrogen purge, accumulation, and hard vacuum. Learn more by watching our latest trace gas webinar. CTS also offers portable, turnkey test solutions for quick, easy leak location on the production floor. Learn more ➡️
Need help with tracer gas leak testing? Contact the experts at CTS!
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