1, the solenoid valve is divided into three major categories from the principle:
Direct-acting solenoid valve
Principle: when energized, the solenoid coil produces electromagnetic force to close the piece of the valve from the valve seat lifting, the valve opens; power failure, the electromagnetic force disappeared, the spring closes the piece of the valve seat, the valve is closed.
Features: in a vacuum, negative pressure, zero pressure can work normally, but the diameter is generally not more than 25mm.
Step-by-step direct-acting solenoid valve
Principle: it is a combination of direct-acting and pilot-type principle, when there is no pressure difference between the inlet and the outlet, after the power is turned on, the electromagnetic force directly to the pilot and the main valve closure of the valve upward in order to lift the valve open. When the inlet and outlet to start the pressure difference, energized, electromagnetic force pilot small valve, the main valve lower chamber pressure rises, the upper chamber pressure drops, thus using the pressure difference to push the main valve upward; power failure, the pilot valve using spring force or medium pressure to push the closing member, move downward, so that the valve is closed.
Features: in zero differential pressure or vacuum, high pressure can also be * action, but the power is larger, the requirement must be installed horizontally.
Pilot operated solenoid valve
Principle: when energized, the electromagnetic force to the pilot hole open, the upper chamber pressure drops rapidly, the formation of a low pressure difference around the closing member, fluid pressure to push the closing member upward movement, the valve is open; power failure, the spring force to the pilot hole is closed, the inlet pressure through the by-pass hole quickly chamber in the shut-off valve around the formation of the lower lower on the high differential pressure, fluid pressure, push the closing member downward movement, closing the valve; the inlet pressure through the by-pass hole to the rapid formation of the pressure difference, the pressure is low, the pressure is low, the pressure is high. The fluid pressure pushes the closing member to move downward and close the valve.
Features: Higher fluid pressure range upper limit, can be installed at will (need to be customized) but must meet the conditions of the fluid differential pressure.
2, solenoid valve from the valve structure and material differences and the principle of difference, is divided into six sub-branches: direct diaphragm structure, step by step direct diaphragm structure, pilot diaphragm structure, direct piston structure, step by step direct piston structure, pilot piston structure.
3, solenoid valve according to functional classification: water solenoid valve, steam solenoid valve, refrigeration solenoid valve, cryogenic solenoid valve, gas solenoid valve, fire solenoid valve, ammonia solenoid valve, gas solenoid valve, liquid solenoid valve, miniature solenoid valves, pulse solenoid valve, hydraulic solenoid valve open solenoid valves, solenoid valve, oil solenoid valves, DC solenoid valves, high pressure solenoid valves, explosion-proof solenoid valves and so on.