APK21 is a pilot kick 2-port solenoid valve that is NC (open when energized). It has a piston-driven pilot kick poppet structure for air, low vacuum, water, kerosene and oil, with steam as an option. Ports are Rc1 1/4 to Rc2 and 32 to 50 flanges.


| Working Fluid | Air / low vacuum (1.33×10³ Pa (abs)) / water / kerosene / oil (20 mm²/s or less) (option: steam) |
| Valve Structure | Pilot kick poppet, piston drive, NC |
| Working Pressure Differential | 0 to 0.7 MPa |
| Max. Working Pressure | 1 MPa |
| Proof Pressure | 3.2 MPa (water pressure) |
| Fluid Temperature | -10 to 60 °C (no freezing) (steam option 5 to 180 °C) |
| Ambient Temperature | -10 to 60 °C |
| Thermal Class | Class 130 (B) (steam option Class 180 (H)) |
| Valve Seat Leakage | 1 cm³/min (ANR) or less (air) (steam option 800 or less) |
| Body/Seal Material | Bronze / NBR (steam option bronze / PTFE) |
| Port Size | Rc1 1/4, Rc1 1/2, Rc2 / 32, 40, 50 flange |
| Orifice Size | 35, 43, 53 mm (port 32, 40, 50A in order) |
| Weight | Threaded 4.5 / 5.5 / 7 kg, flanged 8 / 9 / 11.5 kg (32 / 40 / 50 in order) |
| Mounting Orientation | Vertical with the coil on top only |
| Rated Voltage | 100 VAC, 200 VAC, 12 VDC, 24 VDC, 48 VDC, 100 VDC (100 VAC also usable at 110 VAC (60 Hz), 200 VAC also usable at 220 VAC (60 Hz)) |