Solenoid Valve Function and How to Choose One
A solenoid valve controls air flow electrically and links the controller to the cylinder in a pneumatic system. Design, directional function and flow size decide switching behaviour, throughput and response time. This guide walks through how they work and the key selection criteria step by step.
View solenoid valvesHow does a pneumatic solenoid valve work?
A solenoid valve opens or blocks the air path electrically. When current flows, the coil pulls an armature that shifts the valve spool directly or through a pilot channel. The ports connect or separate and the cylinder extends or retracts. Direct-acting valves switch with no minimum pressure, while pilot-operated valves use the air itself to boost the switching force and need a minimum control pressure.
Which directional function does my application need?
The directional function describes ports and switching positions, such as 3/2 (three ways, two positions) or 5/2. A 3/2 valve drives single-acting cylinders or turns air on and off. A 5/2 valve feeds double-acting cylinders for both extend and retract. A 5/3 valve adds a mid-position to hold or exhaust the cylinder.
- Monostable: spring returns to the rest position, a defined home state.
- Bistable (impulse): holds the last position even without current.
- Choose the rest position open or blocked to match your safety needs.
How do I check flow size, actuation and voltage?
The flow size and flow rating (Kv or Nl/min) set how fast the cylinder moves. An undersized valve slows the motion. Check the coil voltage, ingress protection and actuation type so the valve fits your controller. Watch the port size and whether a manual override is needed for commissioning.
Size flow to cylinder volume and cycle time, do not choose it too tight.
Compare valves24 V DC is standard; check ingress protection and connector for your line.
Valve overviewFrequently asked questions
What is the difference between a 3/2 and a 5/2 directional valve?
A 3/2 valve has three ports and two positions and drives single-acting cylinders or turns air on and off. A 5/2 valve has five ports and feeds double-acting cylinders for both the extend and retract stroke.
Why does my pilot-operated solenoid valve not switch?
Usually the minimum control pressure is missing. Pilot-operated valves use the air itself to boost the force and typically need about 1.5 bar or more. For very low pressure or vacuum use a direct-acting valve.
What do monostable and bistable mean for a solenoid valve?
Monostable springs back to a defined home position on power loss. Bistable or impulse holds the last switched position without current and uses less power, but it does not enforce a safe rest state.
Find the right solenoid valve
Our pneumatics specialists help with directional function, flow size and voltage for your controller.
Vetted selection
Recommendations from maker data and field values.
Correct directional function
3/2, 5/2 or 5/3 matched to the motion.
Reliable switching
Control pressure and flow size clearly explained.
Expert advice
Pneumatics specialists support your selection.