The two-way pilot piston solenoid valve has normally closed and normally open types. The solenoid valve is formed by connecting the pilot valve and the main valve (piston assembly) to form a channel combination. The normally closed solenoid valve is closed when it is not energized. When the coil is energized, electromagnetic force is generated to make the moving iron core and the static iron core attract, the pilot valve port opens, and the medium flows to the outlet. At this time, the pressure in the upper cavity of the main valve core (piston assembly) decreases rapidly, which is lower than that on the inlet side. The pressure forms a pressure difference, overcomes the spring force, and then moves upward to achieve the purpose of opening the main valve port, and the medium flows. When the coil is de-energized, the electromagnetic force disappears, and the movable iron core resets and closes the pilot port under the action of the spring force. At this time, the medium flows in from the balance hole, and the pressure in the upper cavity of the main valve port (piston assembly) increases, forming a pressure difference At the same time, under the action of the spring force, the piston assembly moves downward to close the main valve port. The working principle of the normally open type is just the opposite.

The pilot piston solenoid valve has a reasonable design structure and reliable action. It can work normally under the action of a small pressure difference (about 0.5bar). The solenoid valve can be designed with a large flow diameter and a small solenoid coil power. It is a piston type, so the solenoid valve working pressure is up to 500 bar. Even high working pressure, such as SLA, SMZ large-diameter series solenoid valves in Sanlixin products.
Solenoid valve application is based on the parameters of various media, temperature, pressure, flow, etc., the material of the main valve is selected, usually copper, stainless steel, cast iron, engineering plastics, etc., sealing materials include NBR, VITON, EPDM, Teflon, PEEK, etc. And the corresponding connection, size and flow diameter; the flow diameter is from DN10 to DN200 mm, which can automatically control water, liquid, gas, steam, oil and other media.

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