Solenoid valves convert electrical energy into mechanical energy, giving engineers precise, remote control over the flow of fluid or gas in a system. This guide covers how solenoid valves work, the most common valve types —direct-acting, normally closed (NC), and normally open (NO)—and several specialized configurations including three-way, pilot-operated, and Namur-mounted variants. Browse MISUMI’s full solenoid valve selection to find the right type for your application.
What is a solenoid valve?
A solenoid valve is an electrically controlled valve used to regulate the flow of liquids or gases. It combines a standard valve body with a solenoid—an electromagnetic coil assembly mounted on top—that replaces the need for manual operation or a separate actuator.
The result is a compact, self-contained valve that can be switched on and off remotely, integrated into automated control systems, and cycled at high speed without mechanical wear on external components.
- ✓Remote and autonomous control—operates via electrical signal, enabling integration with PLCs, sensors, and automated systems
- ✓Fast response—typical switching times of 10–100ms make solenoid valves suitable for high-cycle and time-critical applications
- ✓Compact and self-contained—no external actuator required; coil and valve body are integrated into a single unit
- ✓Leak detection—on production lines, solenoid valves can be integrated with sensors to detect and isolate leaks automatically
How solenoid valves work
All solenoid valves share the same fundamental operating principle regardless of type. The solenoid coil sits on top of the valve body and surrounds a ferromagnetic plunger (also called an armature) that can slide up and down inside the valve.
When electrical current flows through the coil, it generates a magnetic field. This field exerts a force on the plunger, moving it against a return spring to either open or close the flow path through the valve body. The direction of this movement, and therefore whether the valve opens or closes on energization, determines whether it is a normally closed or normally open type.
Direct-acting solenoid valve
The simplest and most widely used configuration. The solenoid coil sits directly on top of an armature assembly comprising a plunger and spring. When energized, the coil directly moves the plunger to open or close the orifice—no intermediate mechanism required.
Because the coil acts directly on the plunger without relying on line pressure, direct-acting valves can operate at zero differential pressure, making them the right choice for gravity-fed systems, vacuum lines, and low-pressure circuits where pilot-operated valves would fail to actuate.
Normally closed (NC) solenoid valve
In a normally closed (NC) valve, the return spring holds the plunger in the down (closed) position when the coil is de-energized. The valve blocks fluid flow until electrical current is applied.
When the electrical current stops, the electromagnetic field dissipates and the spring immediately returns the plunger to the closed position, cutting off flow.
Normally open (NO) solenoid valve
In a normally open (NO) valve, the return spring holds the plunger in the up (open) position when the coil is de-energized. Fluid flows freely through the valve until electrical current is applied.
When current stops, the spring returns the plunger to the open position and flow resumes. The fundamental operating principle is identical to NC, only the spring orientation and plunger resting position are reversed.
Other common solenoid valve types
Has three ports (inlet, outlet A, outlet B) and routes flow between two paths depending on the energized state. Used to divert flow between two circuits, to exhaust a downstream line while supplying another, or to actuate single-acting pneumatic cylinders by alternately pressurizing and venting them. See also: Directional Control Solenoid Valves on the MISUMI blog.
Rather than the solenoid directly opening the main orifice, it controls a small pilot orifice. The resulting pressure differential then drives the main valve open or closed. This allows a compact, low-power solenoid to control high-pressure systems or large orifices that would require an impractically large direct-acting coil. Requires a minimum differential pressure to operate—not suitable for zero-pressure applications. Browse pilot-operated solenoid valves at MISUMI.
Designed to mount directly onto a pneumatic actuator using the Namur interface standard (per VDI/VDE 3845). Eliminates the external tubing between solenoid and actuator, reducing response time and minimizing potential leak points. Commonly used in process plant environments where compact, direct-mounted pneumatic control is preferred. Browse NAMUR-compliant solenoid valves (SMC VFN2000N series) at MISUMI.
Solenoid valve type comparison
| Type | Default state | Ports | Min. pressure needed | Best for |
|---|---|---|---|---|
| Direct-acting Most common | NC or NO | 2 | Zero (0 bar) | Low/zero pressure, small orifices, wide pressure range |
| Normally Closed (NC) | Closed | 2 | Depends on design | Safety shutoffs, on-demand flow, fail-closed systems |
| Normally Open (NO) | Open | 2 | Depends on design | Fail-open systems, cooling circuits, default-flow applications |
| Three-Way | NC or NO | 3 | Depends on design | Flow diversion, mixing, single-acting pneumatic actuators |
| Pilot-Operated | NC or NO | 2+ | Yes (min. ΔP required) | High pressure, large orifices, low-power control |
| Namur-Mounted | NC or NO | 3–5 | Depends on design | Direct actuator mounting, process plant, compact installations |
Industrial applications
Solenoid valves are used across a broad range of industries wherever automated fluid or gas control is needed:
- ▸Medical and laboratory equipment—precise fluid dispensing in diagnostic instruments, infusion systems, and analytical devices
- ▸Automotive manufacturing—Body-in-White welding lines, paint spray systems, coolant circuits, and leak test stations (see also: Directional Control Solenoid Valves)
- ▸Warehouse and logistics automation—pneumatic sortation, clamping fixtures, and pick-and-place systems (see also: Pneumatic Circuits overview)
- ▸Food and beverage processing—ingredient dosing, CIP (clean-in-place) wash systems, and carbonation control
- ▸Process and chemical plants—shutoff and diverter valves in pipelines handling corrosive or high-pressure media (see also: Pneumatic Filters for automation)
- ▸Semiconductor fabrication—ultra-clean gas and chemical delivery systems requiring precise, contamination-free switching
Shop MISUMI solenoid valves
MISUMI stocks a wide selection of solenoid valves, including direct-acting, three-way, pilot-operated, and Namur-mounted configurations. Use the filters on the product page to search by valve type, port size, operating pressure, coil voltage, and media compatibility.
