A Bubble Point test method applicable to filter elements used in Hydraulic fluid power system the concepts of filtration rating, efficiency or retention capacity and should be used for information only. Pressure at which the first bubble stream appears when a filter element is tested using the method specified in this International Standard. Verification of fabrication integrity defines the acceptability of the filter elements for further use or testing.

The first bubble point is established through continuation of the fabrication integrity test. It is under no circumstances a functional characteristic of a filter element; in particular, it cannot be used for extrapolation to the concepts of filtration rating, efficiency or retention capacity and should be used for information only.