Solenoid Valve Selection: 2/2 vs 3/2, Direct vs Pilot Operated
Technical Guide / April 2026 / 7 min read / By Shengshi Engineering Team
Quick answer: A solenoid valve should be selected by function first, then by operating principle, body material, seal material, voltage and hazardous-area approval. Most ordering mistakes happen when the valve function or minimum differential pressure is not checked.
2/2 or 3/2 Function
A 2/2 valve has two ports and two positions, commonly used to open or close a fluid line. A 3/2 valve has three ports and two positions, commonly used to pilot pneumatic actuators or vent a control line.
Direct Acting vs Pilot Operated
Direct acting valves work from zero differential pressure and are common for small flow rates. Pilot operated valves use process pressure to open the main valve, so they need a minimum differential pressure but can handle larger flow.
Material Checklist
Check body material, seal material, fluid compatibility, ambient temperature, process temperature, voltage, duty cycle, cable entry and explosion-proof requirements before quoting.
Common Brands
ASCO, Burkert, SMC, Festo, Norgren and Parker all offer strong ranges. Send the full code or a nameplate photo and we can identify an equivalent if the original model is obsolete.
Procurement tip: send the complete model code, nameplate photo or process datasheet. Shengshi engineers can verify the configuration before quoting so you avoid wrong-code purchases.
Need Help Choosing?
Send us your model codes, process conditions or photos. Our engineers will compare available options and reply with price, lead time and documentation requirements.
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Send model codes or process data. We verify configuration, availability and lead time.