ISO 4020 specifies the types of test for fuel filters in accordance with their application. It applies to fuel filters provided for road vehicles with diesel engines and for test installations for fuel injection equipment and is intended for filters having a rated flow of up to 200 l ^.h^-1. By agreement, the tests, with some modifications, may be used for filters with higher rates of flow.

The test described may be used for fuel filters located either on the pressure side or on the suction side of the fuel supply pump.