This international standard specifies a method, known as the bubble test method, for the determination of the pore size of permeable sintered powder metallurgical materials, i.e. filters, porous bearings, porous electrodes and other parts with interconnected porosity.
DS/ISO 4003:1994 history
1994DS/ISO 4003:1994 Permeable sintered metal materials - Determination of bubble test pore size