Introduction to the classification, applications, and selection of solenoid valves

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A solenoid valve is an industrial device controlled by electromagnetism, used in industrial control systems to adjust parameters such as the direction, flow rate, speed, and other aspects of a medium. The supply solenoid valve is controlled using electromagnetic effects, with relay control being the primary method of control. In this way, the solenoid valve can work in conjunction with different circuits to achieve the desired control, while both the precision and flexibility of the control are ensured. There are many types of solenoid valves, and different ones serve various functions within control systems. The most commonly used ones include check valves, safety valves, direction control valves, and speed control valves. Classification of solenoid valves 　　　Solenoid valves can be classified according to the medium present in the pipeline being controlled and the operating conditions, as follows: 　　　Liquid solenoid valves, gas solenoid valves, steam solenoid valves, gas fuel solenoid valves, oil solenoid valves, solenoid valves designed for fire protection purposes, refrigeration solenoid valves, corrosion-resistant solenoid valves, high-temperature solenoid valves, high-pressure solenoid valves, solenoid valves that operate without a pressure difference, ultra-low temperature solenoid valves (cryogenic solenoid valves), and vacuum solenoid valves. 　　 　　Based on the internal structure of the solenoid valve, they can be classified into: pilot-operated, direct-acting, combined, recoil-type, self-retaining, pulse-type, bistable, two-way types, etc. 　　 　　Based on the material used in their construction, solenoids can be classified as follows: cast iron bodies (gray cast iron, ductile iron), copper bodies (cast copper, wrought copper), cast steel bodies, all-stainless steel bodies (304, 316), and non-metallic materials (ABS, polytetrafluoroethylene). 　　 　　Based on the pressure of the medium in the pipeline, they can be classified as follows: vacuum type (-0.1~0 Mpa), low-pressure type (0~0.8 Mpa), medium-pressure type (1.0~2.5 Mpa), high-pressure type (4.0~6.4 Mpa), and ultra-high-pressure type (10~21 Mpa).

Based on the temperature of the medium, they can be classified as follows: normal-temperature type (5℃~80℃), medium-temperature type (100℃~150℃), high-temperature type (150℃~220℃), ultra-high-temperature type (250℃~450℃), low-temperature type (-40℃~0℃), and ultra-low-temperature type (-196℃). 　　 　　Classified by working voltage: Alternating current voltage: AC220V, 380V, 110V, 24V ； DC voltage: DC24V 12V 6V 220V ； The commonly used voltages are AC220V and DC24V; it is recommended that users choose the commonly used voltages, as the supply lead time for special voltages is longer. Based on the protection rating of solenoid valves, they can be classified into explosion-proof types, waterproof types, outdoor types, etc. 　　 　　Uses of solenoid valves 　　　Solenoid valves: They can only be used for on/off control; they are part of the DO control system and are suitable only for controlling small pipes. They are commonly used in pipes with a diameter of DN50 or less, and are rarely used in larger pipes. 　　 　　1. Switch type: The solenoid valve is driven by a coil and can only be turned on or off, with a short operating time when switching. 　　 　　2. Nature of operation: Solenoid valves generally have a very low flow coefficient, as well as a very small operating pressure difference. For example, the flow coefficient of a solenoid valve with a diameter of 25 is much lower than that of an electric ball valve with a diameter of 15. The actuation of solenoid valves is achieved through electromagnetic coils, which are prone to damage due to voltage surges. It functions like a switch, with two modes: on and off. Solenoid valves can generally be reset when the power is cut off, while electric valves require a reset mechanism to have this functionality. 　　 　　3. Applicable processes: Solenoid valves are suitable for certain special process requirements, such as leakage issues or specific fluid properties, but they are relatively expensive. 　　 　　Selection of solenoid valves 　　　The selection of solenoid valves should first adhere to four key principles: safety, reliability, suitability, and cost-effectiveness. More importantly, the cost of a single solenoid valve within an entire automatic control system or even within a production line is minimal; choosing the wrong one in an attempt to save money can result in significant damages. 　　 　　Features of solenoid valves 　　　Solenoid valves are automated basic components used to control the direction of fluids, and they belong to the category of actuators ； It is commonly used in mechanical control systems and industrial valves to control the direction of the fluid, thereby enabling control over the opening and closing of the valve.