A control valve is a type of valve used to control your process.

There are many different types of control valves each serving a different purpose.
A control valve has many different uses. Some of the more common types of flow control valves are:
•    Flow Control Valves (FCV) – Valves that are used to control the flow in a process. This might be in the form of an automatic shutdown valve or it might installed downstream of a centrifugal pump. A flow control valve on the discharge of a pump holds back pressure on the pump, which in turn forces the pump to operate at a specific rate.
•    Pressure Control Valves (PCV) – Valves that are used to control the pressure in a process. An example of this might be a gas choke, which reduces high pressure gas from a pipeline to a lower pressure in the burner of a steam generator. It also might be used to control the back pressure on a vessel to keep entrained gas in the process.
•    Temperature Control Valves (TCV) – Valves that control the process to maintain a desired temperature range. This might be a flow control valve that controls steam in a heat exchanger to keep the fluids at a certain temperature.
•    Level Control Valve (LCV) – Valves used on the discharge of a tank or a vessel to maintain a liquid level in that piece of equipment. LCVs typically work off of a level transmitter, installed on the tank or vessel. If the valve is an on/ off valve, it may also be referred to as a dump valve. However, on P&IDs, it will still be referred to as a LCV.

•    Characteristics:

•    Fast Opening:
The fast opening characteristic valve plug will give a large change in flowrate for a small valve lift from the closed position. Typically fast opening valves are used for on/off type applications.
•    Equal Percentage:
An Equal Percentage characteristic has a flow capacity that increases exponentially with valve trim travel. Equal increments of valve travel produce equal percentage changes in the existing Cv. This provides excellent rangeability and the control resolution at small increments of stem travel.
•    Linear:
The linear characteristic valve plug is shaped so that the flowrate is directly proportional to the valve lift, at a constant differential pressure. A linear valve achieves this by having a linear relationship between the valve lift and the orifice area. For example, if the valve stem position is 25% open, 25% of the flow rate is allowed to pass at a constant differential pressure.

Sonwaysupply is an industrial provider of valves used in a wide variety of global infrastructure industries.