Hydraulic fluid power. Electrically modulated hydraulic control valves. Test methods for four-port directional flow-control valves|Test equipment, Electrical insulation, Thermal testing, Leak tests, Flow regulators, Electric coils, Flow measurement, Pressure impulse tests, Type testing, Valves, Direction-control valves, Electrically-operated devices, Electrical testing, Flow control, Testing conditions, Performance testing, Controllers, Pressure testing, Dynamic testing, Environmental testing, Endurance testing, Reports, Resistance measurement, Inductance measurement, Hydraulic transmission systems, Errors, Hydraulic equipment