In the hydrostatic test, a vessel is filled with a nearly incompressible liquid – usually water or oil – and examined for leaks or permanent changes in shape.
The helium is selected primarily because it penetrates small leaks readily, is inert and will not react with the test piece while having a naturally low quantity in air making detection less complicated.
Usually a vacuum inside the object is created with an external pump connected to the instrument.
Chemo-chromic hydrogen leak detectors are materials that can be proactively applied to a connection or fitting.
Chemo-chromic indicators can also be added to silicone tapes for hydrogen detection purposes.