General:
Flow rate under nominal operating conditions. These are the conditions for which a device has been designed based on its application and when not subjected to a load (CETOP RP 100).
For continuously adjustable directional valves:
Flow rate at the nominal value (= 100%) for the input signal and at the nominal value for the valve pressure drop. Usually for servo valves this is 70 bar (Figure N 4) and for proportional valves 10 bar at two edges.
For proportional pressure valves:
Flow rate at the nominal value for the input signal and the functional pressure for which the pressure valve is approved (e.g. 10% higher than the nominal pressure for the system).
For switching directional valves:
Flow rate causing a pressure drop of 1 bar when it passes through the valve.
Figure N 4: Nominal flow rate for a servo valve (based on 100% cross section)