Gas leakage testing of fuel cell stacks is essential for ensuring safe and
efficient performance. In many fuel cell stack gas leakage tests, nitrogen and
helium are the most widely used test media. However, in some specific gas
leakage tests of a fuel cell stack, it is not clear which kind of testing medium
is better. This study aims to investigate the difference between gas leakage
test results using nitrogen and helium, respectively, as the working medium, and
then help us choose a suitable test medium. In this work, five types of leakage
tests, namely, the three-chamber pressure holding, three-chamber total leakage,
anode chamber pressure holding, anode-to-cathode crossover leakage, and
anode-and-cathode-to-cooling chamber crossover leakage, were performed
repeatedly on the same fuel cell stack using nitrogen and helium separately as
the test medium. These five kinds of gas leakage tests are most frequently
applied in the fuel cell field. The results of this study show that, for gas
leakage tests involving gas molecules passing through a proton exchange membrane
(PEM), the leak rates measured with nitrogen were significantly lower than those
with helium. This phenomenon is attributed to the larger diameter of the
nitrogen molecules than helium molecules. Therefore, for such leakage tests, it
is recommended to use helium as the test medium to obtain more accurate test
results.