Method and apparatus for carrying out integrity tests of a non-wetted filter element

A method for carrying out integrity tests of at least one filter element (3, 3′) arranged within a filter housing (2, 2′) between an unfiltrate space (9) and a filtrate space (10), with porous filter materials, in which means are provided for measuring sound generated by a test fluid when the test fluid flows through the filter element (3, 3′), the method comprising:

• a) applying a test fluid that is a gas to a first side of the filter materials of the filter element (3, 3′) while the filter materials are in a not wetted state and while maintaining a constant fluid pressure sufficient to cause the test fluid to flow through the filter materials from the first side to a second side opposite the first side while maintaining the filter materials in the not wetted state,
• b) measuring at least one of body-borne sound and vibrations caused by the test fluid flowing through the filter materials by means of sensors (6, 15, 16, 18, 19, 20), and
• c) comparing at least one of the body-borne sound and the vibrations measured in step b) with at least one of the body-borne sound and the vibrations of an integral, identical filter element (3, 3′), measured under identical conditions.