5/2 Way vs. 3/2 Way Solenoid Valves: Functions and Applications Explained

In the world of industrial automation and pneumatic control, selecting the correct solenoid valve is critical for the safety, efficiency, and longevity of your system. Whether you are operating in water treatment, petrochemicals, or power generation, the two most common configurations you will encounter are the 3/2 way and 5/2 way solenoid valves.

At Zhejiang KGSY Intelligent Technology Co., Ltd., we specialize in high-tech valve intelligent control accessories. This guide will demystify the differences between these two valve types, explain how they interact with pneumatic actuators, and help you choose the right solution from KGSY’s extensive product lines, such as the 4M, 4V, and KG800 series.

The Basics: What Do “Ways” and “Positions” Mean?

Before diving into the specific differences, it is essential to understand the terminology used in pneumatic valve sizing:

• Ports (Ways): The number of connection points on the valve (Inlet, Outlet, Exhaust).

• Positions: The number of states the valve can switch between (typically Open and Closed).

Therefore, a 3/2 way valve has 3 ports and 2 positions, while a 5/2 way valve has 5 ports and 2 positions.

3/2 Way Solenoid Valves: The Specialist for Single-Acting Actuators

How It Works

A 3/2 way solenoid valve is designed to control a single-acting pneumatic actuator (also known as a spring-return actuator).

• Port 1 (Supply): Air enters the valve.

• Port 2 (Output): Air flows to the actuator to open (or close) the valve.

• Port 3 (Exhaust): When the solenoid is de-energized, air escapes from the actuator through this port.

The “Spring Return” Application

The defining feature of a 3/2 system is the “fail-safe” mechanism. When the electrical signal is cut, the air supply stops, and the exhaust port opens. The spring inside the pneumatic actuator forces the valve back to its original position (either fully open or fully closed).

KGSY Solutions: 3V Series and KG810

For these applications, KGSY offers the 3V310 and 3V320 Series. These valves feature an internal pilot-oriented mode and a sliding column structure that ensures good tightness and sensitive reaction.

• No Lubrication Required: Our internal holes use special processing technology to reduce friction, ensuring a low start pressure and long service life without the need to add oil.

• Specifications: Available in standard voltages like AC220V, DC24V, and others, with a proof pressure of 1.2 Mpa.

For specialized applications, the KG810-ZI Series and FC800-XE Series are specifically designed as 3/2 way valves with explosion-proof capabilities, suitable for hazardous environments.

How It Works

A 5/2 way solenoid valve is the industry standard for controlling double-acting pneumatic actuators. Unlike single-acting actuators, double-acting units require compressed air to move in both directions (open and close).

• Port 1: Air Supply.

• Ports 2 & 4: Output ports connected to the two chambers of the actuator.

• Ports 3 & 5: Exhaust ports.

The “Double Acting” Application

When the coil is energized, air flows to one side of the actuator to open the valve while exhausting air from the other side. When the valve switches, the flow reverses to close the valve. This provides precise control over the valve’s position but does not have a mechanical “fail-safe” spring return unless a dual-coil setup with specific programming is used.

KGSY Solutions: 4M and 4V Series

KGSY provides a robust range of 5/2 way valves, including the 4M Series (NAMUR Standard) and the 4V Series (4V210, 4V310, 4V410).

• NAMUR Mounting: The 4M Series is designed with a NAMUR standard mounting interface, allowing it to be installed directly onto the side plate of the actuator without piping, saving installation space and reducing leak points.

• Memory Function: Our double control (double coil) solenoid valves feature a memory function, maintaining the valve’s last position even after power loss until a new signal is received.

• High Performance: Like the 3V series, these feature low friction coefficients and do not require lubrication.

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Comparison Summary: 3/2 vs. 5/2 Way Valves

The KGSY Advantage: The Universal Convertible Valve

Choosing between 3/2 and 5/2 valves can complicate inventory management. To solve this, KGSY has developed Universal Solenoid Valves that can switch between both functions.

KG800 and FC800 Series

The KG800-X Series and FC800 Series are premium, pilot-operated valves that are universal for both 5/2 way and 3/2 way valve applications.

• Versatility: By simply adjusting the orientation of the seal plate or utilizing the convertible design, a single valve model can service both your single-acting and double-acting actuators.

• Explosion-Proof Safety: These series are built for the toughest environments. They carry SIL3, CE, CCC, ATEX, and IECEx certifications, ensuring compliance in the oil, gas, and chemical industries.

• Material Options: Available in Aluminum Alloy or Stainless Steel 316 (KG800-XC-SS), offering superior corrosion resistance for offshore or chemical processing applications.

Installation and Environmental Considerations

When selecting your valve, you must consider the operating environment. KGSY valves are engineered to withstand extreme conditions:

1. Temperature:

• Standard models operate between -20°C and 60 °C.

• Low-temperature options (L-Type) can handle -40°C to 60°C, ideal for freezing climates.

2. Protection Ratings:

• Our valves meet IP66 and IP67 weatherproof standards, preventing water and dust ingress.

• We offer explosion-proof ratings such as Ex db IIC T6 Gb, critical for hazardous zones.

3. Air Quality:

• To maximize the life of your solenoid valve, we recommend using an Air Filter Regulator (like our AW2000 or AW3000 series) to filter air to 40μm. While KGSY valves do not require lubrication, clean air is vital for preventing blockage in the internal pilot holes.

Conclusion: Which Valve Do You Need?

The choice between a 5/2 way and a 3/2 way solenoid valve ultimately depends on your actuator:

• Use a 3/2 Way Valve (KGSY 3V Series) if you have a Single-Acting (Spring Return) Actuator and require a fail-safe position.

• Use a 5/2 Way Valve (KGSY 4M/4V Series) if you have a Double-Acting Actuator and need control over both opening and closing movements.

For maximum flexibility and inventory efficiency, consider upgrading to the KGSY KG800 or FC800 Universal Series, which offers the ability to perform both functions with a single, high-performance, certified unit.

Ready to optimize your pneumatic control system?

Contact Zhejiang KGSY Intelligent Technology Co., Ltd. today. Our professional R&D team and extensive manufacturing capabilities ensure we have the right valve for your application.

• Website: www.chinakgsy.com

• Email: manager@zjkgsy.com

• Phone/WeChat: 086-13587661980