This part of ISO 7440 specifies the flow-measuring system, including the fixture, to be used for flow-testing the single hole orifice plates used in an orifice plate type nozzle and holder assembly (described in ISO 7440-1) which are intended for testing and setting diesel fuel injection pumps on test benches. The flow-measuring system and fixture described in this part of ISO 7440 ensure accurate flow-testing of the entire range of orifices from 0,4 mm to 0,8 mm diameter as specified in ISO 7440-1. It is intended primarily for use by the manufacturers of single hole orifice plates.