An electromagnetic valve is an automated basic component used to control fluids and belongs to the category of actuators. It is not limited to hydraulic or pneumatic systems. It is used in industrial control systems to adjust the direction, flow rate, speed, and other parameters of the medium. Of course, Kowei Na's electromagnetic valves are diverse. For instance, in terms of form, they are divided into normally open and normally closed types. As the names suggest (normally open type: closes when powered and opens when power is off; normally closed type: opens when powered and closes when power is off), it should be noted that electromagnetic valves are suitable for repeated opening and closing, which can save some electricity for our customers.
Electromagnetic valves belong to fluid control components, such as in pneumatic and hydraulic fields. Fluid systems are generally divided into air source (hydraulic source) components, control components, and actuator components. Valves belong to control components, not actuator components. Cylinders, hydraulic cylinders, etc., belong to actuator components.
Electromagnetic valves are one type of valve, different from manual valves or mechanical valves. Their actions are controlled by electromagnetic coils.
There are many types of electromagnetic valves, mainly serving the following functions: direction control, flow control, and pressure control. They mainly control the on-off state of fluid systems, the flow direction of fluids, the size of pressure, etc. For example, you can understand a faucet as a valve, but it is manually controlled.
They are generally used to control the direction of hydraulic flow. Most mechanical devices in factories are controlled by hydraulic cylinders, so electromagnetic valves are definitely needed. Let me give you a simple explanation of the working principle of an electromagnetic valve. There is a sealed cavity inside the electromagnetic valve, with different holes opened at different positions. Each hole leads to a different oil pipe. In the middle of the cavity is a valve, and on both sides are two electromagnets. When the coil of one side's electromagnet is powered, the valve body will be attracted to that side. By controlling the movement of the valve body, different oil outlet holes can be blocked or exposed. The oil inlet hole is always open, so the hydraulic oil will enter different oil outlet pipes. Then, the pressure of the oil will push the piston of the hydraulic cylinder, and the piston will drive the piston rod, which in turn drives the mechanical device to move. In this way, by controlling the current of the electromagnet, the mechanical movement can be controlled.

1. Main Categories of Solenoid Valves
1) Direct-acting solenoid valve:
Principle: When energized, the electromagnetic coil generates electromagnetic force to lift the closure from the valve seat, opening the valve; when de-energized, the electromagnetic force disappears and the spring presses the closure onto the valve seat, closing the valve.
2) Piston solenoid valve:
Principle: Normally closed type: When the coil is energized, the pilot valve core is attracted, the pilot hole opens, the upper chamber of the valve is depressurized, and the piston is pushed upward by the pressure of the medium in the lower chamber, opening the solenoid valve; when the coil is de-energized, the pilot valve core is reset by the spring, the pilot hole closes, and the upper chamber is pressurized by the piston throttle hole and the thrust of the reset spring, closing the solenoid valve.
Normally open type: When the coil is energized, the pilot hole closes, and the upper chamber is pressurized by the piston throttle hole and the thrust of the reset spring, closing the solenoid valve. When the coil is de-energized, the pilot valve core is reset by the spring, the pilot hole opens, the upper chamber is depressurized, and the piston is pushed upward by the pressure of the medium in the lower chamber, opening the solenoid valve.
3) Pilot-operated solenoid valve:
Principle: When energized, the electromagnetic force opens the pilot hole, the pressure in the upper chamber drops rapidly, creating a pressure difference with high pressure at the bottom and low pressure at the top around the closure. The fluid pressure pushes the closure upward, opening the valve; when de-energized, the spring force closes the pilot hole, and the inlet pressure rapidly pressurizes the upper chamber through the bypass hole, creating a pressure difference with low pressure at the bottom and high pressure at the top around the closure. The fluid pressure pushes the closure downward, closing the valve.
2. Based on the differences in valve structure, materials, and principles, solenoid valves are divided into six subcategories: direct-acting diaphragm structure, step-direct-acting diaphragm structure, pilot diaphragm structure, direct-acting piston structure, step-direct-acting piston structure, and pilot piston structure.
3. Solenoid valves are classified by function as: water solenoid valves, steam solenoid valves, refrigeration solenoid valves, low-temperature solenoid valves, gas solenoid valves, fire protection solenoid valves, ammonia solenoid valves, gas solenoid valves, liquid solenoid valves, miniature solenoid valves, pulse solenoid valves, hydraulic solenoid valves, normally open solenoid valves, oil solenoid valves, DC solenoid valves, high-pressure solenoid valves, explosion-proof solenoid valves, etc.

What are the classifications of solenoid valves based on materials?
1) Stainless steel solenoid valves: These are the most common solenoid valve products. Stainless steel is favored by users due to its good quality and stable performance.
* This series of products are widely used in textile, printing, chemical, plastic, rubber, pharmaceutical, food, building materials, mechanical, electrical, surface treatment and other production and research departments, as well as in daily life facilities such as bathrooms, canteens, and air conditioners.
2) Brass solenoid valves: Some users with lower requirements may choose brass solenoid valves. These solenoid valves are relatively inexpensive and suitable for ordinary working environments.
* This series of products are generally suitable for liquids, water, gas, hot water, oil, gas and other media.
3) Plastic solenoid valves: In some special working places and for special media, such as environments with acidic or alkaline media, brass and stainless steel solenoid valves are prone to corrosion. Therefore, plastic solenoid valves made of special materials (such as engineering plastics like PVC, CPVC, UPVC, ABS or PTFE) have particularly excellent corrosion resistance.