This part of ISO 29463 specifies the test procedure of the ??scan method??@ considered to be the reference method@ for determining the leakage of filter elements. It is applicable to filters ranging from classes ISO 35 H to ISO 75 U. It also describes the other normative methods@ the oil thread leak test (see Annex A) and the photometer leak test (see Annex B)@ applicable to classes ISO 35 H to ISO 45 H HEPA filters@ and the leak test with solid PSL aerosol (see Annex E). It is intended for use in conjunction with ISO 29463?1@ ISO 29463?2@ ISO 29463?3 and ISO 29463?5.