ISO 3968:1981

Hydraulic fluid power — Filters — Evaluation of pressure drop versus flow characteristics

Specifies the method of measuring the pressure drop across a fluid filter under various conditions of flow. Two standards of measurement are specified: class A – for accurate evaluation for referee purposes – requiring laboratory conditions; class B – for evaluation for general purposes – requiring test facilities less stringent that laboratory conditions. Figure 1 shows an example for a suitable test circuit, and the typical reporting method is given in the table.