Principle: When the power is on, the electromagnetic force opens the pilot hole, and the pressure in the upper chamber drops rapidly, forming a pressure difference between the upper and lower parts around the closing part, and the fluid pressure pushes the closing part to move upward, thus opening the valve; When power is cut off, the pilot hole is closed under the action of spring force, the inlet pressure quickly forms a low-high pressure difference around the closing valve through the bypass hole, and the fluid pressure pushes the closing piece to move downwards to close the valve.
Features: Low power consumption, 0. 1-0.2w, which can be energized frequently and not burned for a long time. Moreover, it is energy-saving, and the upper limit of the fluid pressure range is high, so it can be installed at will (customized), but the fluid pressure difference condition must be met, but impurities in the liquid are easy to block the pilot valve hole. Not suitable for liquid use.
Direct acting solenoid valve:
Principle: When electrifying, the electromagnetic coil generates electromagnetic force to lift the closing piece from the valve seat and open the valve; When the power is cut off, the electromagnetic force disappears, the spring presses the closing piece on the valve seat, and the valve closes.
Features: The power consumption is larger than that of the pilot type, generally 5-20w, and the coil is easily burned by high-frequency electrification. But the control is simple and the application range is wide.