The bubble point test is a test done on a filter and tells you the size of the largest pore in a filter and also determines the integrity of the filter.
The bubble point test is a non destructive test which can help to identify any leaks, faulty seals or other damage.
To perform the bubble test on a filter.
Rinse the filters membrane with some isopropyl alcohol or IPA to fill the filter's voids.
Then gradually apply some gas pressure to one side of the filter.
Next increase the pressure until a steady stream of bubbles emerges from the submerged tubing.
And the pressure at which the bubbles appear during the bubble test is the bubble point.
Other filter integrity tests include a pressure hold test, pressure diffusion test and a forward flow test.
A pressure hold test for a filter is used to assess the integrity of single round membrane filters.
A pressure diffusion test is used to assess the integrity of single and multiple round membrane filters.
And a forward flow test is used to indirectly measure gas flow by measuring pressure changes.