What is a Solenoid Valve

Definition of solenoid valve
Solenoid valve is an industrial equipment controlled by electromagnetic. It is an automation basic component used to control fluid. It belongs to actuator and is not limited to hydraulic and pneumatic.
It is commonly used in industrial control systems to adjust the direction, flow, speed and other parameters of the medium.
The solenoid valve can cooperate with different circuits to achieve the desired control, and the control accuracy and flexibility can be guaranteed.
There are many types of solenoid valves. Different solenoid valves play a role in different positions of the control system. The most commonly used ones are check valves, safety valves, directional control valves, speed control valves, etc.

Classification and Principles of Solenoid Valves Throughout the world, solenoid valves can be divided into three categories in terms of their action methods: direct acting, recoil, and pilot.

(1)Principle of direct-acting solenoid valve.
When the normally closed direct-acting solenoid valve is energized, the solenoid generates electromagnetic attraction to lift the valve core, so that the closing member is separated from the remote valve seat and the sealing pair opens; when the power is off, the electromagnetic force disappears, and the closing element is pressed against the valve by spring force The valve on the seat is closed (the opposite of the normally open type).
Features: It can work normally under vacuum, negative pressure, and zero pressure difference. It can be installed arbitrarily under DN50, but the electromagnetic head is relatively large.

(2)Principle of recoil solenoid valve.
Its principle is a combination of direct action and pilot. When energized, the solenoid valve opens the auxiliary valve first. The pressure in the lower chamber of the main valve is greater than the pressure in the upper chamber, and the valve is opened by the simultaneous action of the pressure difference and the solenoid valve; when the power is off , The auxiliary valve uses spring force or medium pressure to push the closing part, and moves downward to close the valve.
Features: It can work reliably even at zero pressure difference or high pressure, but the power and volume are large, and vertical installation is required.

(3)Principle of pilot solenoid valve
When energized, the electromagnetic force drives the pilot valve to open, the pressure in the upper cavity of the main valve drops rapidly, and a pressure difference is formed in the upper and lower cavities of the main valve. The closing part of the main valve is pushed up by the medium pressure, and the valve opens; when the power is off, the spring force controls the pilot The valve is closed, and the inlet medium pressure quickly enters the upper cavity of the main valve through the pilot hole to form a pressure difference in the upper cavity, thereby closing the main valve.
Features: small size, low power, but the medium pressure difference range is limited, and the pressure difference condition must be met.

solenoid valve

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