3 Way Solenoid Valve – Working Principle, Types and Industrial Applications
Industrial automation requires accurate control over the movement of liquids, gases and compressed air. Manufacturing machines, pneumatic actuators, chemical plants and process equipment often need to change the direction of fluid flow automatically.
A three-way solenoid valve is designed to perform this function.
A 3 way solenoid valve is an electrically operated valve with three ports and two or more operating positions, depending on the design. It uses an electromagnetic coil to move an internal plunger or sealing mechanism, changing the connections between the ports.
This allows the valve to supply a fluid, stop its supply, release pressure or redirect flow according to the valve configuration.
Three-way solenoid valves are commonly used in pneumatic actuator control, industrial automation, water systems, gas control and other process applications.
However, not every three-way solenoid valve works in the same way. Direct-acting, pilot-operated, normally closed, normally open and NAMUR configurations have different operating characteristics.
In this guide, we will explain how a three-way solenoid valve works, its different types, applications and the important factors to consider before purchasing one.
CBT Flow Solutions Pvt. Ltd. supplies industrial solenoid valves from Rotex and other product ranges for different automation and flow-control applications.
Explore the CBT Solenoid Valve Range for available products.
What Is a 3 Way Solenoid Valve?
A three-way solenoid valve is an electrically operated valve that controls the flow between three ports.
The three ports generally have the following functions in a common 3/2 pneumatic arrangement:
- Port 1 (P): Compressed-air supply.
- Port 2 (A): Working port connected to the actuator or equipment.
- Port 3 (R): Exhaust or return connection.
The solenoid coil operates the internal mechanism when an electrical signal is supplied.
Depending on the valve’s position, the supply may connect to the working port, or the working port may connect to the exhaust.
This arrangement is useful for controlling single-acting pneumatic actuators, cylinders and other equipment that requires a supply and exhaust path.
Other three-port solenoid designs are used to divert or select fluid flow between different connections. Their exact operation depends on the internal port arrangement.
How Does a 3 Way Solenoid Valve Work?
The working principle of a three-way solenoid valve is based on electromagnetic force.
Let us understand the operation step by step.
Step 1: Electrical Power Is Supplied
The solenoid coil receives an electrical signal from a PLC, control panel, timer or another compatible control device.
The applied voltage must match the coil specification.
Step 2: The Coil Creates a Magnetic Field
When electrical current passes through the coil, it produces a magnetic field.
This magnetic force moves the internal plunger or pilot mechanism.
Step 3: The Valve Changes Position
The movement changes the connections between the valve ports.
In a normally closed 3/2 valve, energising the coil generally connects the pressure supply to the working port.
In the de-energised position, the supply is blocked and the working port connects to the exhaust.
Step 4: Fluid or Air Moves Through the Required Port
Depending on the valve position, compressed air or another compatible medium can enter the connected equipment or leave through the exhaust passage.
Step 5: The Valve Returns to Its Normal Position
When the electrical signal is removed, the internal spring returns the valve to its normal position in a spring-return design.
This allows the control system to operate equipment automatically without manual intervention.
The exact sequence depends on whether the valve is normally closed, normally open, universal or another configuration.
What Is a 3/2-Way Solenoid Valve?
A 3/2-way solenoid valve has three ports and two operating positions.
The number 3 represents the three ports, while 2 represents the two positions.
It is commonly used in pneumatic control systems to operate single-acting cylinders and spring-return actuators.
For example, consider a pneumatic actuator connected to a butterfly valve.
When compressed air enters the actuator, it moves towards its operating position. When the solenoid valve changes position, the air is released through the exhaust, allowing the actuator’s internal spring to return it.
A 3/2-way solenoid valve manages this supply and exhaust operation.
CBT Flow Solutions lists several 3-port solenoid valve configurations for pneumatic applications, including direct-acting and NAMUR-mounted models.
Types of 3 Way Solenoid Valves
Three-way solenoid valves are available in different designs. Each type has a specific working mechanism and application.
1. Direct Acting 3 Way Solenoid Valve
A direct-acting solenoid valve uses the magnetic force generated by the coil to move the main sealing element directly.
It does not depend on the line-pressure difference to assist the opening mechanism in the same way as a conventional pilot-operated valve.
Depending on the model, this construction can be useful in applications where pressure conditions vary or where a minimum differential pressure cannot be guaranteed.
Common applications include:
- Pneumatic control systems.
- Water-control equipment.
- Gas-control circuits.
- Vacuum systems.
- Industrial machinery.
- Single-acting actuator control.
CBT offers a 3 Port Direct Acting Solenoid Valve.
Its published specifications include:
- Models: 30125, 30126, 30201, 30206, 30301 and 30302.
- Orifice options: 1.2 mm to 4 mm.
- Connection size: 1/4 inch.
- Body materials: Aluminium, brass and SS316.
- Seal options: NBR, Viton and EPDM.
- Pressure range: 0 to 63 kg/cm², as listed for the product range.
- Temperature range: -20°C to 80°C.
- Compatible media listed: Air, water, vacuum, free-flowing liquids, inert gases and selected oils and fuels.
The exact model’s pressure range, media compatibility and electrical configuration should be confirmed before ordering.
2. Pilot Operated 3 Way Solenoid Valve
A pilot-operated solenoid valve uses a smaller pilot mechanism to control the main valve opening.
When the coil is energised, it operates the pilot passage. The pressure of the medium assists the movement of the main sealing element.
This arrangement can allow a relatively small solenoid mechanism to control a larger main passage.
Pilot-operated valves are commonly considered when a larger flow capacity is required.
Applications include:
- Industrial fluid-control systems.
- Water distribution equipment.
- Pneumatic actuator operation.
- Chemical process equipment.
- High-pressure control systems, where the model is rated for the service.
One important requirement is the minimum operating differential pressure. If the available differential pressure is below the specified requirement, the valve may not operate properly.
CBT lists a 3 Port 2 Position Internal Pilot Operated Normally Closed/Open High Pressure Solenoid Valve.
The listed configurations include brass and SS316 body options, NBR, Viton and EPDM sealing options, and normally closed and normally open models.
Its individual product specifications should be checked for the exact model and operating conditions.
3. Normally Closed 3 Way Solenoid Valve
A normally closed solenoid valve remains in its normal closed-flow configuration when electrical power is removed.
For a common 3/2 normally closed pneumatic arrangement:
- In the de-energised position, the supply port is blocked and the working port connects to exhaust.
- When energised, the supply port connects to the working port while the exhaust is blocked.
This arrangement is commonly used with spring-return pneumatic actuators.
If the electrical supply is interrupted, the valve returns to its normal position in a spring-return design. The resulting actuator movement depends on the complete pneumatic arrangement.
4. Normally Open 3 Way Solenoid Valve
A normally open solenoid valve has a different default port connection.
In a common 3/2 arrangement, the working port is connected to the pressure supply when the coil is de-energised.
When the coil is energised, the supply is blocked and the working port connects to exhaust.
The correct configuration depends on the required operating sequence.
Normally open valves are useful where the control arrangement requires this default flow condition.
5. Universal 3 Way Solenoid Valve
A universal three-way solenoid valve can be configured for different flow arrangements, depending on its internal design and manufacturer specifications.
This flexibility can be useful when a system needs a particular normally open or normally closed configuration.
However, universal does not mean that every valve can operate in every possible direction or with every type of medium.
Always check the manufacturer’s port diagram, pressure requirements and media compatibility.
CBT lists the 3 Port Direct Acting High Orifice Universal Solenoid Valve.
Its published specifications include:
- Models: 30308, 30309, 30329 and 30333.
- Orifice options: 5 mm, 7 mm and 10 mm.
- Connection size: 1/4 inch.
- Body options: Aluminium, brass and SS316.
- Seal options: NBR, Viton and EPDM.
- Listed pressure range: 0–10 kg/cm² for the specified configuration.
- Temperature range: -20°C to 80°C.
- Compatible media listed include air, water, vacuum, free-flowing liquids and selected gases and oils.
The valve is listed for applications including single-acting actuators, cylinders and control-valve actuation.
6. NAMUR 3 Port Solenoid Valve
A NAMUR solenoid valve is designed to mount directly onto a compatible pneumatic actuator.
Instead of installing the solenoid valve separately and connecting it through external pneumatic tubing, the valve can be mounted on the actuator’s standardised interface.
This arrangement helps create a compact valve automation assembly and can reduce external tubing.
NAMUR solenoid valves are commonly used with compatible pneumatic ball valves and butterfly valves.
CBT supplies a 3 Port Regulating NAMUR Solenoid Valve.
Its published specifications include:
- Model: 30138.
- Orifice: 5 mm.
- Connection: 1/4 inch.
- Body material: Aluminium or SS316.
- Seal options: NBR and Viton.
- Pressure range: 0–10 kg/cm².
- Temperature range: -20°C to 80°C.
- Listed media: Air and inert gases.
- Application: Single-acting pneumatic actuator operation.
This particular NAMUR product is listed for air and inert gases, not general liquid-water service.
3 Way Solenoid Valve vs 2 Way Solenoid Valve
One common question is whether a two-way or three-way solenoid valve should be used.
The answer depends on the number of connections and the function required.
| Feature | 2 Way Solenoid Valve | 3 Way Solenoid Valve |
|---|---|---|
| Number of ports | 2 | 3 |
| Typical positions | 2 | 2 |
| Main function | Open or stop flow | Switch, supply or exhaust flow paths |
| Connections | One inlet and one outlet | Supply, working and exhaust in a common 3/2 arrangement |
| Common applications | Water control and fluid isolation | Pneumatic actuator and cylinder control |
| Flow arrangement | Single flow path | Multiple connection states |
| Common configurations | Normally closed and normally open | Direct acting, pilot operated, NC, NO and universal |
A 2-way valve is generally suitable when you need to open or close a single fluid line.
A 3-way valve is useful when the application requires a supply, exhaust or alternative flow connection.
The correct choice should follow the actual process or pneumatic circuit diagram.
Where Are 3 Way Solenoid Valves Used?
Three-way solenoid valves are used across many industries because they provide flexible control of compressed air and compatible fluids.
1. Pneumatic Actuator Control
This is one of the most common applications.
A 3/2 solenoid valve can control the air supply and exhaust of a compatible single-acting pneumatic actuator.
When the valve receives an electrical signal, it changes the air path and operates the actuator.
2. Industrial Automation
Manufacturing machines use solenoid valves to control cylinders, positioning devices, clamps and other pneumatic equipment.
A suitable 3-way valve can help automate repeated movements.
3. Water Treatment Plants
Certain three-way solenoid valve models can be used in compatible water-control arrangements.
The valve design, body material, seal, water pressure and flow characteristics must match the application.
4. Chemical and Process Industries
Three-way solenoid valves may be used in selected process-fluid control systems and pneumatic actuator arrangements.
For chemical applications, wetted materials and seals must be compatible with the chemical concentration and operating temperature.
5. Pharmaceutical Manufacturing
Solenoid valves can support compatible pneumatic and auxiliary utility systems.
For product-contact or critical pharmaceutical duties, the complete valve must satisfy the required material, cleanliness and documentation requirements.
6. Air Compressors
Suitable 3/2 solenoid valves may be used in compressor loading and unloading control arrangements, depending on the compressor’s design.
The correct valve must match the compressor’s control circuit, working pressure, coil voltage and required port arrangement.
7. Packaging Machinery
Packaging equipment often uses pneumatic cylinders to push, clamp, lift or position products.
Three-way solenoid valves can operate suitable single-acting cylinders by controlling their supply and exhaust connections.
Benefits of Using a 3 Way Solenoid Valve
Three-way solenoid valves offer several benefits for suitable industrial applications.
Automatic operation: An electrical signal can operate the valve without requiring manual movement.
Compact control arrangement: A single three-port valve can provide the supply and exhaust connections required by a suitable pneumatic circuit.
Remote control: The valve can be integrated with PLCs, control panels and other automation equipment.
Flexible configurations: Different normally open, normally closed and universal designs support different control requirements.
Fast switching: Direct-acting designs can provide quick operation, subject to the model, coil and operating conditions.
Industrial compatibility: Available body and sealing materials allow engineers to evaluate different products for air, water and other compatible media.
The actual benefits depend on the selected valve design and operating conditions.
How to Select the Right 3 Way Solenoid Valve
Before purchasing a three-way solenoid valve, consider the following factors.
1. Identify the Application
Determine whether the valve will control a pneumatic actuator, cylinder, water circuit, gas line or another system.
Different applications require different port arrangements and valve constructions.
2. Check the Port Configuration
Confirm how the three ports need to connect in each operating position.
For pneumatic systems, identify the pressure supply, working port and exhaust.
For fluid-diverting applications, confirm the required inlet, outlet and return connections from the manufacturer’s diagram.
3. Select Normally Closed or Normally Open
Decide which valve position is required when electrical power is removed.
For automated actuator systems, also consider the required behaviour of the actuator during loss of electrical power or control air.
4. Check Operating Pressure
Confirm the normal, minimum and maximum pressure.
For pilot-operated models, pay particular attention to the minimum differential pressure.
5. Confirm the Medium
Identify whether the valve will handle compressed air, water, gas, oil or another fluid.
Always check the manufacturer’s media compatibility list.
6. Select Suitable Body Materials
Common body materials include brass, aluminium and stainless steel.
SS316 may be considered for applications where suitable corrosion resistance is required, but the final selection must account for the actual medium and conditions.
7. Check Seal Material
Common sealing materials include NBR, Viton and EPDM.
Each has different chemical and temperature compatibility. The correct option depends on the medium and operating environment.
8. Confirm the Coil Voltage
Check whether your control panel provides 24 V DC, 110 V AC, 230 V AC or another voltage.
The selected coil must match the electrical supply.
9. Check Connection and Orifice Size
Confirm the required connection size and orifice.
The orifice and valve flow capacity influence the amount of fluid or compressed air that can pass through the valve.
10. Consider the Mounting Arrangement
For actuator control, check whether you need a NAMUR-mounted valve, sub-base-mounted valve or an inline configuration.
The mounting interface must match the actuator or installation arrangement.
Common Problems With 3 Way Solenoid Valves
Like other industrial components, three-way solenoid valves can develop problems because of incorrect selection, contamination or installation issues.
Valve Does Not Switch
Possible causes include incorrect coil voltage, electrical supply failure, damaged coil or mechanical blockage.
Check the electrical supply and valve specifications.
Insufficient Airflow
A restricted orifice, undersized supply connection, blocked filter or inadequate air pressure can affect actuator movement.
Check the complete pneumatic circuit.
Continuous Air Leakage
Damaged seals, contamination or worn internal components may cause leakage through the valve.
Inspect the valve according to the manufacturer’s service instructions.
Wrong Actuator Movement
An incorrect port connection or unsuitable normally open/normally closed configuration can result in the actuator moving in the wrong direction or failing to return correctly.
Always verify the port diagram before installation.
Slow Operation
Low pressure, inadequate airflow, undersized tubing or incorrect valve selection may reduce operating speed.
Check the actuator and control-valve requirements together.
Before servicing a solenoid valve, isolate the electrical supply and release stored system pressure safely.
3 Way Solenoid Valve Supplier in India – CBT Flow Solutions
CBT Flow Solutions Pvt. Ltd. supplies industrial solenoid valves and automation products for various process industries.
The company is an authorised Rotex channel partner and provides different three-port solenoid valve configurations for pneumatic control and compatible fluid applications.
Its product range includes:
- Direct-acting three-port solenoid valves.
- Pilot-operated three-port valves.
- Universal three-port valves.
- High-orifice solenoid valves.
- NAMUR-mounted solenoid valves.
- Normally open and normally closed configurations.
You can explore the following products:
1. 3 Port Direct Acting Solenoid Valve
For applications requiring direct operation, with aluminium, brass and SS316 construction options.
2. 3 Port Direct Acting High Orifice Universal Solenoid Valve
For compatible applications requiring a larger orifice and universal port configuration.
3. 3 Way Large Orifice Solenoid Valve
For applications requiring a suitable larger-flow three-port configuration.
4. 3 Port 2 Position Internal Pilot Operated Solenoid Valve
For compatible pilot-operated applications with specified normally closed and normally open configurations.
5. 3 Port Regulating NAMUR Solenoid Valve
For compatible single-acting pneumatic actuator applications.
You can also explore the complete Rotex Solenoid Valve Range for additional products and configurations.
Frequently Asked Questions
What is a 3 way solenoid valve?
A 3 way solenoid valve is an electrically operated valve with three ports. It changes the connection between these ports to control the supply, exhaust or direction of fluid flow, depending on its design.
What is the difference between a 3 way and a 3/2 way solenoid valve?
A 3/2-way valve specifically has three ports and two operating positions. The term three-way is often used for this configuration, although some three-port designs may have other operating arrangements.
What is a 3 way solenoid valve used for?
It is commonly used for pneumatic actuator control, single-acting cylinders, industrial automation, fluid switching and compatible water or gas-control systems.
What is the working principle of a 3 way solenoid valve?
An electromagnetic coil moves an internal plunger or pilot mechanism when energised. This changes the connections between the three ports and controls the movement of air or another compatible medium.
What is a normally closed 3 way solenoid valve?
It is a valve that remains in its normally closed port configuration when the coil is de-energised. When energised, the valve changes position and creates a different connection between the ports.
What is the difference between direct-acting and pilot-operated 3 way solenoid valves?
A direct-acting valve uses the magnetic force of the coil to operate the main sealing element. A pilot-operated valve uses a smaller pilot mechanism, with line pressure assisting movement of the main valve element.
Can a 3 way solenoid valve operate a pneumatic actuator?
Yes. A compatible 3/2-way solenoid valve is commonly used to control a spring-return, single-acting pneumatic actuator by supplying and exhausting compressed air.
Are 3 way solenoid valves available in stainless steel?
Yes. CBT lists several three-port solenoid valve configurations with SS316 body options. The exact body and seal materials should be selected according to the operating medium and environment.
How do I choose the right 3 way solenoid valve?
Check the application, port arrangement, normally open or closed configuration, operating pressure, medium, orifice size, coil voltage, mounting and seal material.
A 3 way solenoid valve is an important component in industrial automation and fluid-control systems.
Its three-port arrangement allows it to control the supply, exhaust or direction of a medium according to the internal design. Direct-acting, pilot-operated, normally open, normally closed and NAMUR configurations are available for different applications.
The correct valve depends on the process requirements, operating pressure, flow capacity, medium, electrical supply and mounting arrangement.
For pneumatic actuators, it is particularly important to match the three-way solenoid valve to the actuator’s single-acting design and required return action.
Careful selection helps support reliable operation, reduce installation problems and improve the performance of automated systems.
Need a 3 Way Solenoid Valve for Your Industrial Application?
CBT Flow Solutions Pvt. Ltd. supplies industrial solenoid valves, pneumatic actuators and flow-control products for a wide range of applications.
Whether you require a direct-acting three-port valve, a pilot-operated high-pressure model, a high-orifice universal valve or a NAMUR solenoid valve, our team can help evaluate your requirements.
Share your application, medium, operating pressure, coil voltage, connection size and required flow configuration to help identify a suitable product.
CBT Flow Solutions Pvt. Ltd.
Valves | Automation | Flow Control
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