Solenoid valves range from the simple diaphragm and piston valves to more complex valve types with electromagnetic or hydraulic actuation. In this article, you’ll learn what all the different types are and how they tick.
A solenoid is a coil of wire wrapped around a core, such as iron or steel. When current flows through the wire coil, it generates a magnetic field, which in turn creates a torque on the core and compresses it. As this happens, the valve opens or closes based on how much pressure needs to be released from or applied to an area of piping.
- 1 What is a Solenoid Valve?
- 2 What Does a Solenoid Valve Look Like?
- 3 What are Solenoid Valves Made of?
- 4 Which Types of Solenoids Are There?
- 5 Solenoid Valve Uses and Applications
- 6 How Does a Solenoid Valve Work?
- 7 Solenoid Valves Are Used in Hazardous Environments
- 8 What to Consider When Purchasing a Solenoid Valve
Solenoid valves are used to control the flow of liquids and gases in piping systems. The term “solenoid” comes from the original meaning of the word—a metal finger that could be twisted to open a lock or pushed back and forth to control water flow.
A solenoid is a mechanical device that uses an electromagnetic coil wrapped around a steel or iron core. This coil generates a current, which produces a magnetic field within the core, causing it to expand or contract. The amount of pressure this field can generate affects how much it expands or contracts and how much it expands, which in turn affects the valve opening and closing.
When a solenoid valve is switched on, the operator manually pulls or pushes a plunger attached to it in order to open or close the valve. The plunger moves the valve by moving the core into or out of the path of pressurized fluid.
With a conventional solenoid valve, the plunger is connected to one end of a lever arm, which is attached to an arm on a shaft. On one side of the shaft is an operating handle. This handle consists of levers and gears that allow you to move this end of the lever arm back and forth in order to control how much pressure is required for fluid flow through an area.
Solenoid valves are made of a variety of materials and considerations. The basic design of each type of solenoid valve is the same, but it can be constructed in a variety of materials based on its application and the environment where it is being used.
Solenoid valves are available in metal, plastic, alloy, and composite materials. The choice depends on the part’s properties, such as its corrosion resistance, temperature utility, and cost.
The most common types of solenoid valves are shown below. Each type has a different electrode assembly that contributes to its operating characteristics and/or mechanical requirements. Each type is also designed for one specific application.
Solenoid Valves made of metal and plastic, shown above, are the most common type of solenoid valve. This type is also called a “solenoid” made up of two parts: one, a base plate with a handle on the end; and two, an assembly including an electrode that’s inserted into the handle. Other names for this type are “plastic-metal” or “plastic-metal-with-handle” valves.
The base comes in various sizes to handle a variety of applications. It can be made of brass, aluminum, or steel. The size depends on the diameter sizes and pressure requirements of the equipment it will be used in. The handle is made of either plastic or metal, depending on the application.
Solenoid Valves made of alloy and composite materials, shown below, have been designed to replace metal solenoids. These types are widely used in industry or are deployed in hazardous environments where the risk of material corrosion is a concern. They are generally easier to manufacture and maintain than metal solenoids and may be easier to clean.
The base can be made from steel and/or plastic. The electrode assembly is also metal or plastic, depending on the application and environment it will be used in.
Solenoid valves are used in a variety of applications, including:
Industrial control valves. These valves can be used to control the flow of liquids and gases, while solenoid actuators are used to open or close them.
Air-handling systems. These valves help manage airflow and pressure in airlines, raising and lowering the pressure to distribute air or fix leaks. They help maintain an even temperature scale by keeping an airline at the same operating temperature. They can be operated manually or automatically, with the most common being spring-load action for on/off operation, manual actuation for adjustable settings, or “dual operators” that use two separate actuation mechanisms.
Conveyor systems. These valves are used in the transfer of materials and products on the production line. They can open and close to regulate the flow of a material, or they can regulate the speed at which a product moves through a machine.
Environmental control systems. These valves are used to control temperature and pressure in an area by regulating fluid flow. They can be used for processes such as cooling, heating, or refrigeration, as well as for maintaining water pressure in firefighting systems.
Drainage systems. Solenoid valves are used as a component of drainage systems to regulate the flow of water and sewer gases.
Pipe cleaning and maintenance. These valves can be used to clear blockages or convert a pipe into a vacuum to clean internal parts within the pipe. They are also used in ventilation systems to help remove gasses that have been released from an area and prevent them from escaping through a non-ventilated opening.
Water treatment systems. These valves can control the pressure of water being sent through hydrant lines, fire hydrants, spigots, or anywhere that water is being routed for use in an application such as fire suppression or air conditioning units.
Automotive applications. These valves are used in steering systems, brake systems, and auxiliary equipment that’s operated by a push-button or other on/off switch. They can also be used to control exhaust gas recirculation systems, climate control units, transmission lockout solenoids, and throttle body joints – among other things.
A solenoid valve’s action is similar to that of a diaphragm valve. It is open at a certain pressure and closes when the pressure drops. But unlike a diaphragm valve, it does not stop at a certain point but continues to move once the pressure is released.
The difference between the two valves can be seen in how they open and close:
- On/Off Solenoid Valves. These valves are designed to automatically close or open depending on the amount of pressure applied to them. They normally adjust from 0 psi (0 kPa) to 100 psi (690.3 kPa), but they can handle pressures up to 250 psi (1756.5 kPa).
- These valves are designed to automatically close or open depending on the amount of pressure applied to them. They normally adjust from 0 psi (0 kPa) to 100 psi (690.3 kPa), but they can handle pressures up to 250 psi (1756.5 kPa). Spring-Load Solenoid Valves. These valves are typically manually operated, with the use of a lever or push button, or have a spring behind the handle that holds it shut once pressure is released. These valves typically handle pressures up to 300 psi (2120.7 kPa).
- These valves are typically manually operated, with the use of a lever or push button, or have a spring behind the handle that holds it shut once pressure is released. These valves typically handle pressures up to 300 psi (2120.7 kPa)—dual Operators. Dual-operator solenoid valves are designed for “dual” actuation – two separate mechanisms for opening and closing the valve. They can be used in applications where there’s the risk of damage from one mechanism activating while another is still in use or if there needs to be more than one position available for normal operation of the valve body.
Solenoid valves are designed to withstand high pressure and temperature that can cause metal corrosion. They are also used in hazardous environments to ensure that gasses released by equipment or equipment components cannot escape. They must also be able to handle severe conditions that would damage a metal solenoid and offer noxious gasses, no window through which they could escape.
Choosing the right solenoid valve is important when it comes to fulfilling your needs. These valves have a variety of sizes, options, and functions that can help you create the ideal solution. They are also built to handle various applications while staying secure and being able to withstand harsh conditions.
When you don’t know what you need, it’s best to contact an expert for help. A knowledgeable salesperson can provide you with valuable information on these valves, including their differences and options that are available for certain applications and industries. They can also assist in helping choose the right solenoid valve based on your needs – including the ones that will most effectively meet them – based on your industry, environment, size, and other factors.