It specifies a bubble-point test method for verifying the fabrication integrity of a filter element or determining the localization of the largest pore of the filter element by determining the first bubble point. Verification of fabrication integrity defines the acceptability of the filter elements for further use or testing. The first bubble noint is established throuah continuation of the fabrication intearity testIt 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.