Helium sniff testing is one of the most precise leak test methods available, making it the ideal approach when particularly low permissible leak rates need to be adhered to – such as with batteries and other e-mobility components. Conversely, even under ideal conditions, leak testing with air is only able to achieve a rate of 0.1 ccm/min. That said, the best test method for a specific test part can really only be determined on a case-by-case basis, always taking into account the framework conditions.
Take for example a component to be used in an e-vehicle: If you want to check that you are compliant with the IP Code, a considerably less expensive leak test with air might do the job. That is because while the ISO 20653 standard stipulates that the amount of water entering an object must not cause any damage or affect performance, it does not rule out water ingress in general. As the likelihood of water ingress due to splashing water varies, criteria such as where the component is fitted play an important role (find out more about this in the section on mapping fuel cells below).
- Helium sniff testing
- Considerably more equipment needed
- More costly
- Complex to implement as robots need to be programmed
- More production space needed
- Higher test costs due the gas used
- Leak can be specifically located
- Even lower permissible leak rates can be measured
- Longer test times: After filling the testing space, the helium must first spread throughout the testing space and then be removed from the test part after completion of the test; no test gas may leak into the environment as this would cause the background concentration to rise too sharply.
What’s more, the permissible leak rate for leak testing depends on the test part itself. The calculation of the permissible leak rate is based on the volume of the test part, the maximum permissible pressure change during the measuring time, and the measuring time itself.
While the component is in operation, the following factors have an impact on the leak rate:
- Ambient temperature and temperature of the test part
- Operating pressure
- Test part material
- Equipment
With over 50 years of experience in leak testing, JW Froehlich maintains a comprehensive test database. Would you like to know which permissible leak rate is the right one for your test part? Then don’t hesitate to contact one of our sales representatives (details below).
Preliminary checks on fuel cell stacks are used to determine the most suitable method for leak testing the specific reaction rooms and the cooling system. Covering three different leak test methods, the Uni S500 leak test panel is particularly suited to this kind of mapping. The preliminary check of anode, cathode and cooling chamber determines the following points:
- Optimum test time
- Volume stability of the test part
- Potential leakage points in between chambers
Next to checking for possible leaks towards the outside, the Uni S500 is also able to detect leaks in between the individual reaction rooms:
- Hydrogen channel towards the outside
- Air channel towards the outside
- Cooling channel towards the outside
- Channels towards each other: hydrogen channel – air channel, hydrogen channel – cooling channel, air channel – cooling channel
The switchover of the valves is controlled by the device.
The ISO 20653 standard does not stipulate a specific leak rate for e-mobility components that need to comply with the IP67 or IP69K protection class. All the standard does specify in terms of water protection (second digit of the IP Code = 7) is that the amount of water entering the object must not cause damage or affect performance when the housing is submerged in water for a short, specified period of time under specific pressure conditions. One important factor in evaluating the test results is where a component will be fitted.
Ultimately, it is up to the manufacturer to decide on a leak test method. We would be happy to conduct some preliminary checks on your fuel cell stack to determine for you which method is most cost-effective and the best fit in terms of technology. Our Sales Team is here to help (contact details below)!