What does hermetically sealed mean to your product?
Would that be watertight, oil-, air-, gas-tight, sterile, impermeable, durably technically tight, …?
Classic tests to assure product tightness include bubble tests and pressure decay tests. Those tests are sufficient when talking about water- and oil-tight. Stricter requirements ask for more sophisticated testing.
What about testing with Helium?
Helium is the second smallest element (after Hydrogen) and able to migrate into micro-cracks making it an ideal tracer gas for leak testing. Helium gas is inert meaning it won’t react with any substance. Also, it is environmentally friendly and by standard present in the atmosphere.
How is leak proof testing done?
To initiate testing, the object is installed and connected manually under a dome, and a vacuum is created to detect a possible pressure decay, as a rough leak test for larger cracks. After passing this test with success, the He fine leak test for micro-cracks is initiated. The object is filled with He gas whilst the dome is placed under vacuum. The residual air in the dome is sampled and passes a mass spectrometer to detect He at a threshold above the normal atmospheric concentration.
What about Helium recovery?
For certain He test applications, it is possible to recover and purify He gas consumed during the test. In this way, the He consumption is reduced for a lower operations cost. VHA has He recovery machines for sale.