Solenoid Valve
Acts as the electrically-operated pilot that commands a pneumatic actuator: it routes or vents instrument air to the actuator ports in response to a signal from the DCS, PLC or ESD system.
How It Works
An energised coil creates a magnetic field that shifts an internal plunger, directing compressed air to the actuator. De-energising the coil (including on power loss) returns the plunger by spring force, venting or redirecting air so the actuator drives to its fail-safe position. 3/2-way valves serve single-acting (spring-return) actuators; 5/2-way valves serve double-acting actuators; 5/3-way valves can lock the actuator in its last position on de-energisation.
When Is It Required?
- -The valve must be operated remotely/automatically from a DCS, PLC or ESD system rather than manually
- -A defined fail-safe action (fail-open or fail-closed) is required on loss of electrical power
- -The application needs the actuator to lock in its last position rather than fail open or closed (5/3-way)
Compatible Actuation Types
Compatible Valve Categories
Governing Standards
Codes shown are the governing references for this device class; confirm the specific edition and project spec before procurement.
Selection Considerations
- -Coil voltage (24V DC, 110V AC, 220V AC) must match the plant's instrumentation power standard
- -Ex-proof coil and enclosure are mandatory in classified hazardous areas
- -Way configuration (3/2, 5/2, 5/3) is set by the actuator action, not by preference — confirm against the actuator's air port configuration before ordering
Commonly Specified In
FAQ
What's the difference between a 3/2-way and a 5/2-way solenoid valve?
A 3/2-way solenoid valve has three ports and two positions, and is used with spring-return (single-acting) actuators — it supplies air in one direction and vents in the other, with the spring providing the return stroke. A 5/2-way valve has five ports and two positions, used with double-acting actuators where air must be actively supplied in both directions.
Does a solenoid valve fail safely if power is lost?
Yes, by design. Standard solenoid valves are de-energised-to-vent: on loss of electrical power the coil de-energises and the internal spring returns the plunger, driving the actuator to its designed fail-safe position (fail-open or fail-closed, set by the actuator's spring configuration).
Other Automation Accessories
Sourcing a Solenoid Valve?
We supply certified solenoid valves matched to your actuator and valve, with documentation, under one PO.