Valves may appear to be simple components, but their simple design makes them critical to the operation of systems in a broad range of industries. While you may find two-way solenoid valves to be a touch more complex than other types, they remain relatively straightforward to operate and install. These valves play a vital role in enhancing the efficiency of fluid and gas control processes across the medical, automotive, aerospace, and industrial manufacturing sectors.

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This article provides an in-depth look at the construction and functionality of two-way solenoid valves, as well as the diverse applications where they are most beneficial. It also outlines the key advantages and limitations of this valve type and explores scenarios in which selecting a two-way solenoid valve offers distinct benefits over alternative valve configurations.

What is a Two-Way Solenoid Valve?

At its most basic level, a two-way solenoid valve is an electromechanical device used to control the flow of liquids or gases in a system. These valves are designed to open or close the flow path, allowing or preventing the passage of media based on electrical signals. Two-way solenoid valves are commonly found in on/off flow control applications, such as irrigation systems, water treatment, fuel control, and industrial process automation.

You’ll typically encounter two configurations: a normally closed (NC) or normally open (NO). These names refer to the default position the valve goes back to when it’s not electrically activated, and therefore you’ll find a normally closed valve stays shut and closed off, whereas a normally open valve will allow the material to flow out in its default position.

As the name suggests, a two-way solenoid valve has two separate ports: an inlet (for fluid or gas entry) and an outlet (for discharge). . The valve operates using an electric current that energizes the solenoid coil, which generates a magnetic field. This field moves an internal plunger or armature, which closes or opens the internal passage between the two . This mechanism enables the user to start or stop the flow of media with precision and reliability.

Two-Way Solenoid Valves vs. High-Pressure Solenoid Valves

High-pressure solenoid valves are a category that you may find some two-way solenoid valves fall under. A high-pressure label just means that a solenoid valve is made of materials that can handle strong flows and highly pressurized systems, better or more reliably than a standard two-way solenoid valve could.

The term “two-way” refers to the valve’s design, specifically that it has two ports—an inlet and an outlet—allowing for simple on/off flow control. In contrast, “high-pressure” refers to the valve’s pressure rating, indicating that it has been engineered to manage greater internal forces than standard valves, often through reinforced materials, precision machining, and specialized seals.

A Look at the Main Components

When you disassemble a two-way solenoid valve, these are the parts you’ll find:

1. Solenoid Coil: The coil powers the valve. When an electric current passes through its copper windings, a magnetic field is generated, which activates the plunger. Most coils are built to withstand high temperatures, vibration, and voltage fluctuations, making them dependable even in harsh environments.
2. Valve Body: This houses the internal components and directs fluid flow. It is commonly made from stainless steel, brass, or reinforced thermoplastics, especially in high-pressure versions where strength and corrosion resistance are critical.
3. Plunger or Armature: The plunger is a movable iron or ferritic stainless steel core that shifts when the coil is energized. To prevent residual magnetism, the plunger is often coated with brass, glass-filled nylon, PTFE (Teflon), or electroless nickel.
4. Orifice: This is the opening inside the valve body that allows media to flow. The plunger opens or seals this orifice to control the flow of fluid or gas.
5. Spring: The spring returns the plunger to its default position (either open or closed) once power is removed from the coil. It ensures fail-safe operation, especially in normally closed configurations.
6. Seals and Gaskets: Usually made of rubber, seals and gaskets stop leaks from happening, and they should fit impeccably well when you install a valve.
7. Electrical Connection: This is where the coil is wired to the power source, usually via lead wires or terminal connectors. A typical setup includes a ground and a live connection, and proper insulation is essential to avoid shorts or corrosion.
8. Inlet Port: The entry point for the fluid or gas, usually marked or sized to match system plumbing.
9. Outlet Port:The exit point for the controlled media, leading to the next stage in the process or discharge.
10. Lead Wires: A two-way solenoid valve will lean on lead wires to get the electrical current that powers up the coil.

Advantages and Disadvantages

Prior to installing a two-way solenoid valve, you’ll want to think about the following advantages and disadvantages.

Advantages

• Precise control: These valves give you extremely precise control over the flow of liquids and gasses within a system. Two-way solenoid valves offer precise control over the flow of liquids and gasses.
• Fast-acting: Two-way solenoid valves can move quickly, rapidly responding to the electric signals you program into the system.
• Durable and reliable: These valves are made of long-lasting strong materials that allow you to use them in environments that work with harsh chemicals, liquids, and gasses without seeing them quickly deteriorate.
• Adaptable to many applications: You can use two-way solenoid valves in all kinds of industries, whether you work with automotive parts, medical equipment, or water and chemical processing.
• Compact form factor: You’ll find these valves are compact and easy to install, but still able to offer a high-quality performance.
• Low maintenance: These valves won’t ask you for much. If you install them correctly and stay on top of maintenance, they won’t often lead to long stretches of downtime or expensive replacements and system failures.
• Easy system integration: These valves are easily incorporated into automated control systems, safety shutdown systems, and remote actuation setups via PLCs or control circuits.

Disadvantages

• A stable power supply is required: Two-way solenoid valves don’t do well with unstable power sources and voltage fluctuations, so you’ll want to ensure that they’re connected to a reliable system so they remain functional.
• High flow rates can be difficult: While these valves can handle a certain extent, you may want to lean on another type for very high flow rates.
• Performance affected by extreme temperatures: Extremely hot or cold temperatures can impact how well these valves work, so if you’re aware they’ll be installed in these kinds of environments or that they’ll see major fluctuations in temperatures, make sure you choose specially designed versions that can handle this.

Two-Way Solenoid Valves—Uses and Applications

There are several instances in which you’d want to use a two-way solenoid valve over other types. This model is great for controlling high-pressure fluids and gasses or regulating hydraulic fluids, oils, gasses, and water. If you’re curious about what industries and processes rely most heavily on two-way valves, read on below.

1. Automotive Industry

Two-way solenoid valves are essential components in various vehicle systems, including fuel injection, emissions control, and power transmission. They precisely manage the timing and volume of fuel injection, regulate hydraulic fluid flow, and control exhaust gas release, making them critical for efficiency, emissions compliance, and engine performance.

2. Medical Equipment

In healthcare, these valves are valued for their precision and reliability. Common applications include dialysis machines, ventilators, oxygen concentrators, and automated medication delivery systems, where accurate flow control of air, gas, or fluids is essential for patient safety and treatment outcomes.

3. Research and Development

Laboratories and research facilities use two-way solenoid valves to accurately dispense or isolate chemicals, gases, and fluids during experiments. Their fast response times and ability to handle small volumes with high repeatability make them ideal for analytical and R&D environments.

4. Consumer Products

Many everyday appliances incorporate two-way solenoid valves. You’ll find them in washing machines, dishwashers, espresso machines, and gas cooktops, where they control water or gas flow based on timed or sensor-activated inputs.

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5. Industrial Applications

In industrial systems, two-way solenoid valves are used in chemical processing, water treatment, HVAC systems, and automated production lines. They contribute to system safety, fluid efficiency, and automated control, allowing for consistent, hands-free operation in critical processes.

Key Factors to Consider When Selecting a Two-Way Solenoid Valve

When you’re choosing a two-way solenoid valve, here are the top considerations to run through before making your selection:

1. Media Type (Fluid, Gas, or Chemical Properties)

Think about the chemicals, fluids, or gasses you’ll send through the valves. If they’re particularly abrasive, corrosive, or hot, it can have an impact on how well the valve functions and how quickly it deteriorates over time. Once you know what’s flowing through it, you can select valves made of the right materials. For example, you can use plastic valves for cooler substances, metal valves for hot and corrosive fluids and gasses, and stainless steel for food-grade or medical purposes.

2. Valve Function (Normally Closed vs. Normally Open)

You’ll also need to determine if a normally closed or normally open valve is necessary. The former blocks the flow of materials as default, whereas the other allows for the flow in its default position after you stop the electric current.

3. Valve Operation Type (Direct, Semi-Direct, or Pilot-Operated)

There are different types of two-way solenoid valves, and you’ll find direct-acting, semi-direct, and indirect (pilot) operated. When you just need a simple on and off system, you’ll likely use direct-operated valves. Higher pressures and flow rates will require pilot-operated valves, and semi-direct are a good happy medium between these two.

4. System Pressure and Flow Requirements

Match the valve’s pressure rating and flow capacity (CV rating) to the demands of your system. Oversized or undersized valves can lead to inefficiency, control issues, or mechanical strain.

5. Valve Size and Connection Type

Accurately measure your piping layout to ensure proper valve sizing and thread or flange compatibility. Mismatched fittings can result in leaks, reduced performance, or damage.

6. Seal Material Compatibility

Make sure the seal material that’s part of the valve can handle the physical properties of the liquid or gas flowing through. Seals are usually made of rubber, ethylene propylene diene monomer rubber, nitrile butadiene rubber, and fluoroelastomers, so select based on whether or not the material will deteriorate, melt, burn, or corrode.

7. Voltage and Coil Type (AC vs. DC)

Ensure the solenoid coil voltage matches your system’s power supply—either AC or DC. Mismatched voltage can cause coil burnout or erratic operation, while proper matching improves energy efficiency and longevity.

8. Response Time

Although most valves will be remarkably quick, different valves will have different speeds, so you’ll want to choose one that can handle your reaction time requirements.

How to Install Two-Way Solenoid Valves

Here are the steps to follow if you need to install a two-way solenoid valve:

1. Start by ensuring you have the correct valve for your system and the necessary tools. Then shut down the power supply and any running pressurized systems.
2. Clean the interior and exterior surfaces of the pipes you’ll connect to. This helps remove contaminants like debris, rust, or oil, ensuring a clean seal and preventing downstream blockages or valve damage.
3. Once the cleaning is done, cut the pipe ends square and smooth to ensure proper alignment. If the valve uses threaded connections, apply pipe thread sealant or PTFE (Teflon®) tape to the male threads to help prevent leaks. Avoid excessive wrapping, which can interfere with sealing.
4. Next, align the valves to your pipes and mount them. Make sure they’re in the correct position and that the flow direction on the valve (normally an arrow) matches the system’s flow direction.
5. Secure the valve fittings. Tighten to the manufacturer’s recommended torque to avoid over-compression, which can damage threads or crack valve bodies, especially if plastic components are involved.
6. Check that the valve’s coil voltage matches your system’s power supply (AC or DC, and voltage rating). Connect the solenoid coil using terminal connectors or lead wires as specified. Ensure all connections are insulated, sealed, and moisture-protected to prevent shorts or corrosion.
7. Once all mechanical and electrical connections are made, gradually restore power and slowly repressurize the system. Watch for leaks and listen for unusual sounds during this stage.
8. Once you’ve tested and done a final inspection for leaks or improperly functioning parts, your system is ready to go.

Maintenance and Replacement Costs for Two-Way Solenoid Valves

Maintaining a two-way solenoid valve is essential to ensure reliable performance and avoid costly system disruptions. Routine inspections help detect early signs of wear, contamination, or electrical failure, allowing you to address issues before they escalate. When replacement becomes necessary, the cost can vary widely depending on the valve’s size, construction material, and the type of application. Entry-level or small residential-use valves typically cost around $20 to $50. Mid-range models, often used in commercial or industrial systems, generally fall between $75 and $300. For high-performance or specialty applications—such as those involving high pressure, corrosive media, or medical-grade standards—replacement valves can exceed $500, especially when made from stainless steel or chemical-resistant materials.

You’ll know a two-way solenoid valve may be failing if you notice persistent leaks, uncontrolled or continuous flow, failure to actuate, or system shutdowns linked to valve malfunction. These symptoms indicate internal wear, seal failure, or solenoid coil issues, and should be addressed promptly. Ignoring them can lead to equipment damage, production delays, and more expensive repairs. By staying on top of regular maintenance and replacing faulty valves as needed, you can extend the lifespan of your system and maintain operational efficiency.

Where Can I Source Two-Way Solenoid Valves?

Thomas, a Supplier Discovery Platform, has many suppliers in Two-Way Solenoid Valves. To learn more, view our Two-Way Solenoid Valve Suppliers for your needs.

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Copyright and Trademark Notices

1. More cost-effective for diverting and mixing applications than using multiple 2-way valves 1. If used for mixing purposes, a 3-way valve can only be used at low differential pressures