Bubble point test

The bubble point test is a test method for determining the largest pore opening in a porous filter medium. A completely wetted filter fabric is successively subjected to increasing air pressure until the first continuous air bubble appears at one point on the outflow side. The pressure required for this (bubble pressure) is directly related to the maximum pore size of the medium.

The bubble point test can be used to check quickly and non-destructively whether a filter has the desired fineness or whether there is damage (leaks with larger pores), for example. It is a standardized procedure (e.g. in accordance with ISO 2942 for filter elements) that is used in sectors such as the pharmaceutical and food industries as well as for membrane and metal filters to ensure the quality and integrity of filters. The test is often performed after production or cleaning of a filter to verify performance. This specialized test is not used in architectural applications.