Working principle:

1. Direct acting solenoid valve

Principle: When the normally closed direct acting solenoid valve is energized, the electromagnetic coil generates electromagnetic suction to lift the valve core, causing the sealing element on the valve core to leave the valve seat port and open the valve; When the power is cut off, the electromagnetic force disappears, and the sealing element on the valve core is pressed against the valve seat port by spring force, causing the valve to close. (Normally open type is the opposite)

Characteristics: It can work normally under vacuum, negative pressure, and zero pressure difference. The larger the valve diameter, the larger the volume and power of the electromagnetic head. If our company introduces technology to produce direct acting solenoid valves, they can be used for 1.33 × 10-4 Mpa vacuum.


2. Step by step direct acting solenoid valve (i.e. recoil type)

Principle: Its principle is a combination of direct action and pilot. When energized, the electromagnetic valve first opens the auxiliary valve. The pressure in the lower chamber of the main valve is greater than the pressure in the upper chamber, and the pressure difference and electromagnetic force are used to simultaneously open the valve; When the power is cut off, the auxiliary valve uses spring force or medium pressure to push the closing seal and move downwards to close the valve port.

Characteristics: It can work reliably even at zero pressure difference or about a certain pressure. Generally, the working pressure difference does not exceed 0.6MPa, but the electromagnetic head has a large power and volume, requiring vertical installation.



3. Pilot operated solenoid valve

Principle: When energized, electromagnetic force drives the pilot valve to open the pilot valve, causing a rapid decrease in pressure in the upper and lower chambers of the main valve, forming a pressure difference between the upper and lower chambers. Relying on the medium pressure, the closing part of the main valve is pushed up, and the valve opens; When the power is cut off, the spring force closes the pilot valve, and the inlet medium pressure quickly enters the upper chamber of the main valve through the throttle hole, forming a pressure difference in the upper chamber, thus causing the main valve to close.

Features: Small size, low power, but limited range of medium pressure difference, meeting the pressure difference condition (0.01MPa).

Electromagnetic valve is an industrial equipment controlled by electromagnetism, which is an automation basic component used to control fluids. It belongs to actuators and is not limited to hydraulic or pneumatic systems. Electromagnetic valves are widely used in many products due to their control accuracy and flexibility. As a gatekeeper of circuit safety, the selection and application of electromagnetic valves should be safe and reliable. The model and function of solenoid valves required in different control systems may also vary. Therefore, choose the appropriate solenoid valve based on practical requirements.

Four selection principles:

1、 Security.

1. Corrosive media: It is recommended to use plastic king solenoid valves and all stainless steel (316); For strongly corrosive media, isolation diaphragm type is selected. Neutral medium, copper alloy can also be used as the valve body material for electromagnetic valves. Ammonia valves cannot be made of copper.

2. High temperature steam medium: It is recommended to use stainless steel or cast steel valve bodies, and use polytetrafluoroethylene seals. Copper alloy valve bodies can also be used for ordinary high temperatures (below 180 degrees). High temperature (350 degrees) heat transfer oil and steam are hard sealed with additional heat dissipation fins.


3. Explosive environment: Select corresponding explosion-proof grade products, and choose waterproof and dust-proof varieties for outdoor installation or dust prone situations.


4. The working pressure of the solenoid valve should exceed the high working pressure inside the pipe


2、 Applicability.

1. The selection of electromagnetic coils varies for products with different medium temperatures (such as high-temperature solenoid valves requiring high-temperature coils), otherwise the coils will burn out and seriously affect their lifespan.

2. Working pressure difference: Pilot operated solenoid valves can be selected for low working pressure differences above 0.03Mpa; For low working pressure differential close to or less than zero, choose direct acting or step-by-step direct acting solenoid valves.

3. Select the nominal diameter (DN) based on the flow rate and valve Kv value, or choose the same pipe inner diameter.

4. In environments with high relative humidity and water droplets, waterproof solenoid valves should be selected.

5. Priority should be given to selecting AC220V or DC24V for voltage specifications.


3、 Reliability.

1. Work format: divided into three types: long-term work, repetitive short-term work, and short-term work. For situations where the valve is opened for a long time and only closed for a short time, it is advisable to choose a normally open solenoid valve.

2. Working frequency: When the action frequency requirement is high, the structure should preferably be a direct acting solenoid valve, and the power supply should preferably be AC.


4、 Economy.

1. Economy is one of the criteria for selection, but for economy based on safety, applicability, and reliability, do not be greedy for small gains. Choose coils and materials that sound cheap but have poor quality.

2. Economy is not only about the price of the product, but also about its function and quality, as well as the cost of installation, maintenance, and other accessories.

Installation precautionsL:

1. During installation, it should be noted that the arrow on the valve body should be aligned with the flow direction of the medium. Do not install in areas with direct dripping or splashing water. The solenoid valve should be installed vertically upwards;

After the installation of the solenoid valve, there should be no reverse pressure difference in the pipeline. And it needs to be powered on several times to make it warm before it can be officially put into use.

3. Before installing the solenoid valve, the pipeline should be cleaned. The medium introduced should be free of impurities. Install a filter in front of the valve.

When the solenoid valve malfunctions or is cleaned, a bypass device (especially the steam pipeline) should be installed to ensure the continued operation of the system.