This part of SAE J 968 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 which is intended for testing and setting diesel fuel injection pumps on test benches.

The flow measuring system and fixture ensure accurate flow testing of the entire range of orifices from 0.4 to 0.8 mm diameter as specified in SAE J 968-1. It is intended primarily for use by the manufacturers of single hole orifice plates.