
Solenoid Valve
Explore All Types of Solenoid Valves We Offer
A solenoid valve is an electromagnetically operated device that controls the flow of liquids or gases by opening or closing when an electric current is applied. Finding the right solenoid valve for your application is crucial for efficient fluid control. At KUHNWAY, we provide a wide range of high-quality water solenoid valves and specialized options designed for various pressure, temperature, and fluid types. Here’s an overview of our key sol valve series:
-
MD Series – Direct-Acting Diaphragm Solenoid Valves
Designed for air, water, and light oil, these valves offer fast opening and closing speeds and can operate at zero pressure differential with larger flow openings. Available with maximum pressure ratings of 10, 15, or 20 kgf/cm², they suit various pressure conditions. The diaphragm options include NBR, EPDM, and VITON, while the body materials are bronze, SUS304, and SUS316, ensuring compatibility with different fluid media.
-
MT Series – Pilot-Operated Piston Solenoid Valves
Engineered for steam and heavy oil applications, these valves feature a dual-piston ring and guide rod design for enhanced durability and precise operation. The stainless steel guide seat ensures smooth performance while minimizing flow restrictions. They withstand temperatures up to 200°C and are available with maximum pressure options of 10, 16 (for steam), and 20 kgf/cm², making them ideal for high-temperature and high-pressure systems.
-
BMF Series – Large-Diameter Pilot-Operated Solenoid Valves
Built for high-flow applications, these valves include a manual override knob, allowing operation without power when needed. The valve body is available in threaded or flanged connections, with flange sizes ranging from 2" to 16" to accommodate different pipe diameters. Material choices include cast iron, bronze, graphite cast iron, SUS304, and SUS316, making them suitable for a wide range of fluid media and industrial applications.
Our solenoid valve products are also available in normally closed, normally open, and explosion-proof options, catering to a broad range of applications. Whether you need a water solenoid valve, steam control, or a high-flow system, we have the perfect solution for you. Contact us today to find the right solenoid valve for your needs!
.
A normally closed solenoid valve stays closed when de-energized, blocking the flow. When energized, the coil creates a magnetic field, lifting the plunger to open the valve and allow flow. When power is cut, the spring returns it to the closed position, stopping the flow automatically.
.
A normally open solenoid valve allows flow when de-energized and closes when energized. It’s ideal for continuous flow applications like cooling and drainage systems and ensures fail-safe operation by opening during power loss.
.
An explosion-proof solenoid valve is built for flammable and hazardous environments, such as petrochemicals, natural gas, and pharmaceuticals. Its sealed housing prevents sparks or heat from igniting explosive gases or dust. Designed to meet strict safety standards, it ensures safe operation in high-risk areas by eliminating ignition risks.
What is a Solenoid Valve and Its Functions?
A solenoid valve is an electromechanical valve that uses an electromagnetic actuator (solenoid) to control fluid flow. The solenoid converts electrical energy into mechanical motion, using a magnetic field to move a plunger or core, which either opens or closes the valve. In simple terms, when the solenoid is energized, the valve changes its state—either allowing fluid to pass through or stopping it. These valves function in a binary manner, fully open or fully closed without intermediate positions.
Solenoid valves are widely used in various applications, such as controlling water flow in dishwashers, managing air in pneumatic systems, and regulating fuel in engines. Their ability to provide quick, remote, and precise control makes them essential components in many automated systems.
Solenoid valves and motor valves both use electrical energy, but solenoid valves rely on electromagnetic coils for rapid open/close switching with digital (DO) control. They suit small pipelines (≤DN50), offering fast action, low power use, and good sealing. However, they only provide on/off control, require clean fluids, allow one-way flow, and need a minimum pressure difference.
As for motor valves, they use reversible motors for analog (AI) control and precise flow adjustment, ideal for larger pipelines. They handle impure fluids, support bidirectional flow, and stay powered safely, though slower operation and reset needs are trade-offs. To sum up, solenoid valves are best for quick-switching, low-pressure applications, while motor valves excel in large-scale flow regulation where precise control is needed.
Components of Solenoid Valve
A solenoid valve has two primary components: the solenoid and the valve body. The solenoid is an actuator that uses an electromagnetic coil, while the valve body contains the parts that come into contact with the fluid. The specific parts of the solenoid may vary, but the valve body components are generally consistent, although their design and material may differ.
The following are the general components of a solenoid valve and their functions:
-
Coil (A)
The coil is made of insulated copper wire wound around the outer part of the magnetic core tube. When energized, the coil generates a magnetic field that drives the movement of the plunger, thereby controlling the opening and closing of the solenoid valve. -
Spring (B) and Plunger (C)
The plunger (or piston) is the core actuating component of the solenoid valve. It is typically cylindrical and made of ferromagnetic material, located inside the solenoid tube. The spring provides initial preload force. In a normally closed valve, the spring pushes the plunger downward to close the orifice; in a normally open valve, it supports the plunger upward, keeping the valve open when de-energized. -
Diaphragm Return Spring (D)
The diaphragm return spring connects the diaphragm to the plunger. It helps return the diaphragm to its original position and stabilizes the valve’s operation. -
Valve Cover and Body (E)
The valve cover protects the upper internal components. The valve body is the main pressure-bearing part, housing the diaphragm, inlet and outlet ports, and flow passages. It is the core structure for controlling fluid flow. -
Solenoid Tube (F)
The solenoid tube is a hollow guiding component that directs the up-and-down motion of the plunger. Any defects or accumulation of debris inside the tube may cause the plunger to stick, overheat, or lead to valve failure. -
Shading Ring (G)
The shading ring is a single or a few turns of a conductive material (such as copper or aluminum). It creates a phase shift in the magnetic field, reducing noise and vibration during AC operation and allowing for smoother valve performance. -
Seal (H)
The seal is responsible for closing or opening the orifice, preventing medium leakage. In normally closed valves, when energized, the plunger moves upward, lifting the seal and opening the orifice. In normally open valves, the plunger moves downward to close the orifice. -
Diaphragm and Pilot Hole (I)
In diaphragm-type solenoid valves, the diaphragm isolates the electromagnetic components from the fluid. The pilot hole provides pressure balancing, reducing the force required to open the diaphragm. This is a key design feature in pilot-operated solenoid valves. -
Orifice (J)
The orifice connects the inlet and outlet ports. The plunger opens or closes this orifice to regulate the flow of fluid through the valve. Depending on the valve design, there may be one or more orifices to suit its operating mechanism.

How Does a Solenoid Valve Operate?
Solenoid valves come in various types, each designed for specific functions and configurations. These valves are essential in pneumatic and hydraulic systems. Let’s take a closer look at how solenoid valves work in these applications.
-
Pneumatics
Pneumatic solenoid valves control the flow of compressed air in a system, which is used to actuate cylinders, drive machinery, or regulate vacuum applications.
3/2-Way Valves: These valves have three ports—one for the inlet, one for the outlet, and one for the exhaust. They are commonly used in single-acting pneumatic cylinders and vacuum applications. The valve works by directing compressed air into the cylinder, extending it, and then venting the air to allow the cylinder to return to its original position.
5/2-Way Valves: These valves feature five ports—two inlets, two outlets, and one exhaust. Their primary function is to control double-acting cylinders, where air needs to be alternated between two ports to extend and retract the actuator. The exhaust port allows for smooth operation by venting used air. These valves are widely used in automation, robotics, and packaging machinery, where precise motion control is required.
5/3-Way Valves: Similar to 5/2-way valves, these also have five ports but include three positions, offering greater control over the actuator’s movement. These valves are useful for applications that require intermediate stops or controlled holding positions in motion control systems. The center position can be configured in different ways:
-
All ports blocked: Holds the actuator in position.
-
All ports open: Allows free movement of the actuator.
-
Pressure applied to both outlets: Ensures equalized pressure on both sides, keeping the actuator balanced.
-
Hydraulic
Hydraulic solenoid valves regulate the flow of pressurized oil or fluid in hydraulic systems, which operate under high pressure to drive actuators and motors.
4/2-Way Valves: These valves have four ports—two inlets and two outlets—allowing control of the flow direction in hydraulic systems. They are used for double-acting hydraulic cylinders, where shifting the valve redirects fluid to extend or retract the actuator. When the solenoid is energized, it changes the valve’s position, altering the fluid path and controlling movement.
4/3-Way Valves: Like 4/2-way valves, these also have four ports, but they include three positions to provide additional control. The neutral (center) position allows for different configurations:
-
Closed-center position: All ports are blocked, stopping fluid movement and maintaining pressure in the system.
-
Float-center position: The actuator is left free to move, allowing it to return to its original state.
-
Pressure-relieved position: The system pressure is reduced to prevent overloading.
These valves are useful in systems that require intermediate holding positions, precise fluid control, or pressure relief functions.
For a 2/2-way valve, the way it works depends on its internal design. Let’s break down how the three main types—direct-acting, semi-direct-acting, and pilot-operated—function in detail.
-
Direct-acting
In a direct-acting 2/2-way valve, the plunger (core) directly blocks or opens the valve orifice. When no power is applied, a spring holds the plunger down, sealing the orifice and stopping flow. When the coil is energized, the magnetic field pulls the plunger upward, overcoming the spring and lifting the seal, allowing fluid to pass through. There's no need for a pressure differential—this valve type operates independently of system pressure.

-
Semi-direct-acting
A semi-direct-acting valve combines both direct and pilot principles. It has a diaphragm or piston with a small pilot orifice and a plunger connected to the diaphragm. When energized, the plunger lifts and opens both the pilot hole and assists the diaphragm to rise. This allows the line pressure to help open the valve fully, enabling high flow rates even at zero pressure differential.











