What is a solenoid valve?
The definition of a solenoid valve is an electro-mechanical valve that is commonly employed to control the flow of liquid or gas. There are various solenoid valve types, but the main variants are either pilot operated or direct acting. Pilot operated valves, the most widely used, utilize system line pressure to open and close the main orifice in the valve body.
While Direct operated solenoid valves directly open or close the main valve orifice, which is the only flow path in the valve. They are used in systems requiring low flow capacities or applications with low pressure differential across the valve orifice.
How solenoid valves function
How a solenoid valve works is by controlling the flow of liquids or gases in a positive, fully-closed or fully-open mode. They are often used to replace manual valves or for remote control. Solenoid valve function involves either opening or closing an orifice in a valve body, which either allows or prevents flow through the valve. A plunger opens or closes the orifice by raising or lowering within a sleeve tube by energizing the coil.
Solenoid valves consist of a coil, plunger and sleeve assembly. In normally closed valves, a plunger return spring holds the plunger against the orifice and prevents flow. Once the solenoid coil is energized, the resultant magnetic field raises the plunger, enabling flow. When the solenoid coil is energized in a normally open valve, the plunger seals off the orifice, which in turn prevents flow.
Why is a solenoid valve used?
In most flow control applications, it is necessary to start or stop the flow in the circuit to control the fluids in the system. An electronically operated solenoid valve is usually used for this purpose. By being solenoid actuated, solenoid valves can be positioned in remote locations and may be conveniently controlled by simple electrical switches.
Solenoid valves are the most frequently used control elements in fluidics. They are commonly used to shut off, release, dose, distribute or mix fluids. For that reason, they are found in many application areas. Solenoids generally offer fast and safe switching, long service life, high reliability, low control power and compact design.
Where is a solenoid valve used?
Solenoid valve applications include a broad range of industrial settings, including general on-off control, plant control loops, process control systems and various original equipment manufacturer applications, to name but a few.
Solenoid valves can be found in many different sectors, including:
- Water supply
- Treatment of drinking water
- Waste water treatment
- Purification/ treatment of grey and black water
- Machine and plant engineering
- Cooling, lubrication and dosing
- Building services
- Large heating systems, climate control
- Safety engineering
- Water mains protection and fire extinguishing systems
- Compressors
- Pressure relief and drainage
- Fuel supply
- Transport and tank facilities
- Firing systems
- Oil and gas burner control
- Gas chromatography
- Gas mixture regulation
- Blood analysis instruments
- Control of cleaning processes
How to replace solenoid valves
For correct and accurate control functioning, solenoid valves must be configured and selected according to the particular application at hand. The most important parameters for selecting a solenoid control valve are the Kv value (given in cubic meters per hour) and the application’s pressure range.
The lower the valve’s orifice, or the stronger the coil, the higher the pressure the valve can shut-off. On the basis of the calculated Kv value, and the pressure range of the planned application, a correspondingly appropriate valve type and its required orifice can be determined.
