Control Valves
Description
Control valves are mainly used to control operating parameters like pressure, temperature, flow and liquid level by opening or closing partly or completely as per the signals received from the controllers. Control valves are also known as proportional valves. The valve actuation methods used for control valves can be pneumatic, electric, hydraulic, and manual systems. The end configurations on control valves include butt-weld or socket-weld, threaded, push on, clamp, flangeless wafer-style, grooved end, lugged, flanged, mechanical joint and solder end. Control valves are available in various materials like stainless steel, steel, bronze, cast iron, brass, copper, ductile iron, PVC and CPVC.
Types
Basic types of industrial control valves are listed below:
Globe valves
Diaphragm valves
Pinch valves
Knife or gate valves
Needle valves
Butterfly valves
Ball valves
Plug valves
Based on the operating conditions, control valves are broadly classified as:
Features
Control valves have the following features:
Specifications
The performance criteria of the control valves depend on the following specifications:
Diameter
Working pressure
Operating temperature
Flow coefficient
End connection
Number of ports
Material of construction
Applications
Control valves find applications in like oil or fuel, wastewater, process control, sanitary, irrigation, steam, water, gas or air, cryogenic, chemicals, refrigeration, laboratory or medical, and fire fighting services. They serve industries such as aerospace, petrochemical, pulp and paper, pipeline, power, refining, etc. Control valves are used for automatic operation of dryers and generators.