1. Solenoid valve is divided into three categories in principle:
Direct acting solenoid valve
Principle: When energized, the electromagnetic force generated by the electromagnetic coil is lifted from the valve seat to open the valve; Power off, the electromagnetic force disappears, the spring to close the parts on the valve seat, the valve is closed.
Features: In vacuum, negative pressure, zero pressure can work normally, but the diameter is generally not more than 25mm.
Step direct acting solenoid valve
Principle: It is a combination of direct action and pilot principle, when there is no pressure difference between the inlet and outlet, energized, the electromagnetic force directly to the pilot small valve and the main valve closing parts in turn up, the valve open. When the inlet and outlet reach the starting pressure difference, energized, the electromagnetic force pilot small valve, the main valve chamber pressure rises, the upper chamber pressure drops, so as to use the pressure difference to push the main valve upward; When the power is off, the pilot valve uses spring force or medium pressure to push the closing parts, moving down, so that the valve is closed.
Features: In zero pressure difference or vacuum, high pressure can also be perfect action, but the power is large, must be installed horizontally.
Pilot solenoid valve
Principle: When energized, the electromagnetic force to open the pilot hole, the chamber pressure drops rapidly, forming a low and high pressure difference around the closing parts, fluid pressure to push the closing parts move up, the valve is opened; Power off, the spring force to close the pilot hole, the entrance pressure through the bypass hole quickly chamber around the valve close parts to form a low high pressure difference, fluid pressure to push the closing parts move down, close the valve.
Features: The upper limit of fluid pressure range is high, can be installed arbitrarily (need to be customized) but must meet the conditions of fluid pressure difference.
2, the solenoid valve from the valve structure and material and the difference in principle, is divided into six branch subclasses: direct acting diaphragm structure, step direct acting diaphragm structure, pilot diaphragm structure, direct acting piston structure, step direct acting piston structure, pilot piston structure.
3, solenoid valve according to function classification: water solenoid valve, steam solenoid valve, refrigeration solenoid valve, low temperature solenoid valve, gas solenoid valve, fire solenoid valve, ammonia solenoid valve, gas solenoid valve, liquid solenoid valve, micro solenoid valve, pulse solenoid valve, hydraulic solenoid valve normally open solenoid valve, oil solenoid valve, DC solenoid valve, high pressure solenoid valve, explosion-proof solenoid valve, etc.
