Control valves are industrial valves specifically designed to control liquid media and gases transmitted through a pipeline. A Control Valve is a valve used to control fluid flow by varying the size of the flow passage as directed by a signal from a controller. Control valves are applied in a variety of environments, water and heat supply systems, oil and gas pipelines, the chemical industry, combined heat and power stations, hydroelectric power stations and nuclear power stations, etc.
Control Valve consists of three main parts in which each part exist in several types and designs.
- Valve actuator – which moves the valve’s modulating element, such as ball or butterfly.
- Valve positioner – Which ensures the valve has reached the desired degree of opening. This overcomes the problems of friction and wear.
- Valve body – in which the modulating element, a plug, globe, ball or butterfly, is contained.
Types Of Control Valves
1.Linear Motion Valve (3-way / globe / diaphragm / pinch type)
2.Rotatory Motion Valve (ball / butterfly / plug type)
3.Flow Control Valve
1.Linear Motion Valves
Linear valves, also known as multi-turn valves, have a sliding-stem design that pushes a closure element into an open or closed position. These types of valves are extremely versatile with many different trim sizes and design options available. A linear-motion valve is also more resistant to cavitation compared to a rotary valve. Although linear valves are typically more expensive, they offer precise accuracy and 1:1 linear flow control. Linear valves are also known as multi-turn valves.
2.Rotatory Motion Valves
Rotatory Motion Valves rotate a disc or ellipse about an angular or circular shaft extending across the diameter of an orifice. They are also known as quarter turn valves. Quarter turn valves will be in their fully open or fully closed state (0°) after a 90° turn of the stem. Their operation is much quicker than linear motion valves.
3.Flow Control Valve
Flow control valves include simple orifices to sophisticated closed-loop electrohydraulic valves that automatically adjust to variations in pressure and temperature. A Flow control regulates the flow or pressure of a fluid. Control valves normally respond to signals generated by independent devices such as flow meters or temperature gauges.