I. Composition and Classification of Solenoid Valves

1. Composition of Solenoid Valves

The valve body of a solenoid valve is enclosed within a sealing tube and consists of a spool, a sleeve, and a spring base. The electromagnetic components of a solenoid valve consist of a fixed iron core, a moving iron core, and a coil, with the coil directly mounted on the valve body. Thus, the valve body and electromagnetic components form a simple and compact assembly.

2. Classification of Solenoid Valves

(1) Classification by the medium in the controlled pipeline and operating conditions

Solenoid valves can be classified according to the medium in the controlled pipeline and operating conditions into various types, including liquid solenoid valves, gas solenoid valves, steam solenoid valves, gas solenoid valves, oil solenoid valves, fire-fighting solenoid valves, refrigeration solenoid valves, corrosion-resistant solenoid valves, high-temperature solenoid valves, high-pressure solenoid valves, differential pressure solenoid valves, cryogenic solenoid valves, and vacuum solenoid valves. (2) Classification by Coil Driving Method

Solenoid valves can be classified into various types according to the coil driving method, including pilot-operated, direct-acting, compound, recoil-type, self-holding, pulse-type, and bistable.

(3) Classification by Valve Operating Mode

Solenoid valves are classified into two types according to their operating mode: normally closed and normally open. A normally closed valve is closed when the coil is not energized, while a normally open valve is open when the coil is not energized.

(4) Classification by Internal Structure

Solenoid valves can be classified into various types according to their internal structure, including two-position two-way valves, two-position three-way valves, two-position four-way valves, and two-position five-way valves. Among them, a 2-position 2-way solenoid valve has one air (liquid) inlet and one air (liquid) outlet; a liquid 2-position 3-way solenoid valve has one liquid inlet and two liquid outlets (one normally open and one normally closed); a pneumatic 2-position 3-way solenoid valve has one air inlet, one air outlet, and one exhaust outlet; and a hydraulic 2-position 3-way solenoid valve has one oil inlet, one oil outlet, and one return oil outlet.

(5) Classification by Material

Solenoid valves can be classified according to the material used, including cast iron (gray cast iron, ductile iron), copper (cast copper, forged copper), cast steel, all stainless steel (304, 316), and non-metallic materials (ABS, PTFE).

(6) Classification by Medium Pressure in the Pipeline

Solenoid valves can be classified according to the pressure of the medium in the pipeline into several types, including vacuum type (0.1～0MPa), low-pressure type (0～0.8MPa), medium-pressure type (1.0～2.5MPa), high-pressure type (4.0～6.4MPa), and ultra-high-pressure type (10～21MPa).

(7) Classification by Medium Temperature

Solenoid valves can be classified according to the medium temperature into several types, including 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℃).

(8) Classification by Operating Voltage

Solenoid valves can be classified according to operating voltage into two types: AC voltage type and DC voltage type. The AC voltage type is further divided into several types based on the power supply voltage, such as AC 24V, AC 110V, AC 220V, and AC 380V. DC voltage type valves are further divided into several types based on the power supply voltage, such as DC 6V, DC 12V, and DC 24V. Currently, AC 220V and DC 24V are the most commonly used.

(9) Classification by Protection Level

Solenoid valves can be classified into several types according to their protection level, such as explosion-proof, waterproof, and outdoor types.