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What Is a Solenoid Valve and How Does It Work?
A solenoid valve is an electromechanical device that plays an important role in many industrial applications and systems. In this article, we will explain in detail what solenoid valves are, how they work, their types, body components, and their applications across different industries.
What Is a Solenoid Valve?
A solenoid valve is a valve that is electrically and magnetically controlled to allow or stop the flow of fluid through a pipeline. It is a type of valve that controls fluid flow using an electromagnet. The electromagnet is created by an electric current flowing through a coil, which generates a magnetic force on a magnetic material inside the valve. This magnetic force moves a piston or other control mechanism within the valve, thereby controlling the passage of the fluid.
How Does a Solenoid Valve Work?
The operating principle of a solenoid valve is based on a core (plunger) that moves up and down in response to the magnetic field generated by the electrical solenoid. This core opens or closes an orifice within the valve. Solenoid valves are available in various circuit functions, designs, and construction materials, allowing them to be selected and engineered for different applications and fluids. Their ability to be controlled remotely and automatically makes them ideal for a wide range of industries, including water treatment, automotive, and food processing.
What You Need to Know About Solenoid Valves
Clean fluids/gases only:
Solenoid valves are designed to be used with clean, non-sticky, and particle-free fluids or gases.
Precise flow control:
They provide accurate regulation of liquids or gases, making them ideal for medical devices and precision manufacturing processes.
Fast opening and closing response time:
Rapid open/close actions are critical for safety applications, allowing quick response to potential hazards.
Long service life:
Durable and reliable performance reduces maintenance requirements and withstands demanding operating conditions.
Wide range of applications:
They are versatile and suitable for various industries, including water treatment, air systems, and food processing.
Body Types
Brass:
Brass is commonly preferred for applications involving non-aggressive fluids such as water and air.
Stainless steel:
It offers high temperature resistance, rapid cooling capability, and excellent chemical resistance.
PVC is used in acidic environments.
Aluminum:
Aluminum offers moderate strength, low cost, and high thermal conductivity. It is not preferred for high-pressure applications.
Iron is low cost and corrosion-resistant, and is preferred in applications involving high temperatures and vibration.
Diaphragm Types
NBR:
NBR is highly compatible with oils and petroleum-based fluids.
EPDM seals are the right choice for air, water, and ozone applications.
FKM (Viton) is used in chemical applications, oily air, and petroleum-based fluids, and offers high temperature resistance.
PTFE (Teflon) is preferred for steam and aggressive chemical applications.
Special Solenoid Valve Features
You can find the special features of solenoid valves below.
Power reduction:
To actuate the valve, the nominal voltage is applied for a short period, after which it is reduced to a holding voltage that is sufficient to keep the valve in position while lowering power consumption.
Latching:
Latching or pulse-coil versions provide a solution for low-frequency switching applications. The valve is energized by a short electrical pulse that moves the plunger. A permanent magnet then holds the plunger in position without the need for additional springs or continuous magnetic fields. This reduces power consumption and heat generation in the coil.
High pressure:
The high-pressure version is designed for pressure requirements of up to 250 bar.
Manual operation:
Optional manual operation increases safety and convenience during commissioning, testing, maintenance, and power outages. Depending on the version, if manual operation is locked, the valve may not be electrically actuated.
Media separation:
The media isolation design allows the process medium to be separated from the valve’s actuating components, making it a suitable solution for aggressive or slightly contaminated media.
Vacuum:
Valve that does not require vacuum.
Adjustable response time:
The time required for the valve to open and close can usually be adjusted by turning a screw on the valve body. This feature helps prevent water hammer.
Open/close feedback:
The switching status of a solenoid valve can be indicated via electrical or optical position feedback in the form of a binary signal or a NAMUR signal. NAMUR is a sensor output that indicates whether the valve is in the open or closed position.
Noise reduction:
The valve features a damping design to reduce noise when it closes.