Direct-Acting Valves
The electromagnetic plunger directly opens or closes the main flow orifice without relying on a separate pilot pressure mechanism.
VALV / SOL — ELECTROMECHANICAL FLOW CONTROL
Solenoid Valves.
Solenoid valves combine an electromagnetic coil with a fluid-control valve so liquids or gases can be switched or regulated using an electrical signal. They are widely used in pneumatic machinery, hydraulic circuits, water systems, process automation, HVAC equipment, chemical handling, dosing systems, packaging equipment, laboratory devices, and automated manufacturing. Selection depends on valve function, port configuration, normally open or normally closed operation, voltage, current, coil duty, pressure range, differential pressure, flow capacity, media, temperature, materials, seals, response time, electrical connection, environmental protection, and control architecture.
OPERATING PRINCIPLE
Electrical energy moves the valve mechanism.
When current flows through the solenoid coil, the coil produces a magnetic field. That field acts on a movable plunger, armature, or pilot mechanism and changes the state of the valve.
Depending on the design, energizing the coil may open a normally closed valve, close a normally open valve, shift a directional spool, or change the opening of a proportional flow path.
Because the valve bridges an electrical control system and a fluid system, replacement compatibility requires checking both sides of the component.
BASIC SOLENOID VALVE IDENTIFICATION
Voltage
Electrical coil supply such as a specified AC or DC voltage.
Ports
Number and arrangement of fluid connections.
Position
Normally open, normally closed, or directional operating state.
Pressure
Permitted inlet, outlet, and differential pressure range.
Orifice
Internal opening that influences fluid-flow capacity.
Media
Air, water, gas, oil, chemical, steam, or another compatible fluid.
SECTION / 01
Common Solenoid Valve Types
Solenoid valves can be classified by operating principle, port arrangement, flow behavior, coil configuration, and normal state.
Pilot-Operated Valves
A smaller solenoid-controlled pilot passage uses fluid pressure to assist movement of a diaphragm, piston, or primary valve element.
2-Way Valves
Two fluid ports provide a straightforward inlet-to-outlet path for opening or closing a single flow circuit.
3-Way Valves
Three ports allow the valve to supply, exhaust, divert, select, or switch flow between multiple passages depending on the valve configuration.
4-Way & 5-Way Valves
Multi-port directional valves are commonly used to control pneumatic cylinders, actuators, and other devices requiring alternating flow paths.
Proportional Valves
Rather than simply switching between open and closed, proportional designs vary valve opening in response to a controlled electrical input.
Normally Closed
The valve blocks the designated flow path when electrical power is removed and changes state when the coil is energized.
Normally Open
The designated flow path remains open without coil power and changes state when the solenoid receives the required electrical input.
Latching Valves
Specialized solenoid designs can retain a commanded state without requiring continuous coil power, depending on the mechanism and control method.
ELECTRICAL / COIL
The coil is part of the valve specification.
Correct fluid performance is not enough. The solenoid coil must also match the available voltage, electrical controls, duty cycle, connector, ambient conditions, and required switching behavior.
ELECTRICAL & CONTROL CHECKPOINTS
Voltage
Confirm the exact AC or DC coil voltage required
by the valve and supplied by the machine.
Current / Power
Control outputs, relays, power supplies, and wiring
must support coil inrush and steady-state requirements.
Duty Cycle
Determine whether the coil is rated for continuous
energization, intermittent use, or another specified duty.
Connector
Verify terminal, DIN-style plug, flying lead,
cable, conduit, or other electrical connection.
Response
Switching speed can affect machine timing,
dosing, cylinder movement, and process sequencing.
Environment
Electrical enclosure and coil construction must suit
moisture, dust, washdown, temperature, outdoor,
or hazardous-area requirements.
Controls
PLC outputs, relays, timers, safety circuits,
sensors, and other logic must command the valve correctly.
SECTION / 02
Flow, Pressure & Media
The fluid side of the valve determines required orifice size, operating method, pressure range, wetted materials, seals, and expected service behavior.
Pressure
Verify minimum, normal, and maximum inlet, outlet, and differential pressure conditions. Some pilot-operated designs depend on differential pressure for reliable operation.
Flow Capacity
Port size alone does not define flow. Internal orifice geometry and valve construction determine restriction and usable capacity.
Media Compatibility
Body, plunger, diaphragm, seat, seal, spring, and other wetted materials must tolerate the fluid chemically and thermally.
Temperature
Fluid and ambient temperature influence seals, coil heating, pressure rating, viscosity, chemical resistance, and enclosure requirements.
SECTION / 03
Solenoid Valve Specifications
A replacement must satisfy both the electrical control specification and the fluid-control specification of the original installation.
Specification
What to Verify
Why It Matters
Valve Function
2-way, 3-way, multi-way, shutoff,
directional, proportional, or another function.
Determines how the machine fluid circuit operates.
Normal State
Normally open, normally closed,
spring return, or another unpowered condition.
Determines valve behavior during power loss
and normal machine operation.
Voltage
Required AC/DC coil voltage and frequency where applicable.
Incorrect electrical supply can prevent operation
or damage the coil.
Pressure Range
Minimum and maximum operating pressure
and allowable differential pressure.
Determines whether the valve mechanism can
open, close, and seal reliably.
Port Size
Thread, tube, manifold, flange,
or other connection size and standard.
Controls physical installation and contributes
to available flow capacity.
Flow
Required flow or applicable flow coefficient
at the actual pressure conditions.
Undersized valves can create excessive restriction
and poor system performance.
Materials
Body, plunger, diaphragm, seal,
seat, spring, and other wetted materials.
Determines chemical resistance, temperature
capability, wear, and fluid compatibility.
Electrical End
Plug, terminal, cable, conduit,
pinout, grounding, and suppression requirements.
Determines compatibility with the machine wiring
and control system.
Environment
Indoor, outdoor, washdown, dusty,
corrosive, sanitary, or hazardous location.
Determines enclosure, connector,
materials, approvals, and coil construction.
SECTION / 04
Solenoid Valve Selection
Define the fluid circuit and electrical control system together before selecting the valve.
01
Define the Valve Function
Determine whether the valve must open and close
one line, switch between multiple passages,
exhaust an actuator, divert flow, or provide
proportional regulation.
02
Define the Media
Identify the fluid or gas, temperature,
viscosity, contamination level, chemical behavior,
solids, cleanliness, and required wetted materials.
03
Establish Pressure & Flow
Record inlet pressure, outlet pressure,
differential pressure, required flow,
port size, acceptable restriction,
and any minimum-pressure requirements.
04
Match the Electrical Supply
Verify voltage, AC or DC operation,
frequency where applicable, power consumption,
current, control output, connector,
suppression, and grounding.
05
Select Operating Method
Compare direct acting, pilot operated,
normally open, normally closed, latching,
directional, and proportional designs
against the actual system conditions.
06
Verify Integration
Confirm mounting, manifold pattern,
tubing or pipe connections, flow direction,
response time, duty cycle, ambient conditions,
PLC logic, fail-state behavior, maintenance access,
and applicable safety requirements.
Compatibility / Note 13
Matching port size does not make two solenoid valves interchangeable.
Solenoid valves with similar physical dimensions can differ in coil voltage, current, AC/DC operation, normally open or normally closed state, number of ports, internal flow paths, direct or pilot operation, minimum differential pressure, allowable pressure, flow capacity, seal material, body material, media compatibility, connector pinout, duty cycle, response time, manifold pattern, and fail behavior. Verify both electrical and fluid specifications before substitution. See the Industrial Valves Reference, Pump & Valve Selection Guide, and Component Compatibility Guide.
SECTION / 05
Solenoid Valve Resources
Additional industrial references for general solenoid valves, proportional valves, 3-way configurations, low-voltage valves, and broader industrial fluid control.
Solenoid Valves
Industry resource covering solenoid valve configurations, manufacturers, materials, applications, flow-control requirements, and related technical considerations.
Research Solenoid ValvesProportional Solenoid Valves
Focused reference for valves that provide variable flow or pressure response rather than simple two-state switching.
Research Proportional Valves3-Way Solenoid Valves
Supporting resource for three-port valve configurations used to supply, exhaust, divert, or switch pneumatic and hydraulic circuits.
Research 3-Way Valves12 Volt Solenoid Valves
Reference for low-voltage DC solenoid valves used in mobile equipment, compact machinery, vehicles, automated systems, and portable applications.
Research 12V Solenoid ValvesIndustrial Valves
OpenType reference covering ball, butterfly, gate, globe, check, diaphragm, solenoid, and other industrial valve families.
Valve ReferencePump & Valve Selection
Compare fluid-control components using media, pressure, flow, materials, connections, actuation, electrical controls, and compatibility.
Selection Guide
Reference note:
External resources are provided for additional research
and do not establish product compatibility,
interchangeability, certification, approval, or endorsement.
Verify valve function, normal state, number of ports,
pressure range, differential pressure, flow capacity,
media, materials, seals, coil voltage, current,
duty cycle, connector, response time, manifold pattern,
environmental conditions, controls, and fail-state behavior
before specifying or replacing a solenoid valve.
RELATED / FLUID CONTROL
Continue the Fluid Control Reference
Continue into industrial valves, pneumatic systems, hydraulic systems, and electrical control components.