This International Standard specifies a method for determining the resistance of a hydraulic filter element to flow fatigue after it has been loaded with particulate contaminant and subjected to a uniform varying flow rate and predetermined maximum element differential pressure. It establishes a uniform method for verifying the ability of a filter element to withstand the flexing caused by cyclic differential pressures induced by a variable flow rate. NOTE Annex A summarizes data from a round robin test performed to verify the procedure specified in this International Standard.