CONTROL & MODULATING VALVES

Fisher Wike Rosemount Emerson

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. This enables the direct control of flow rate and the consequential control of process quantities such as pressure, temperature, and liquid level.

An automatic 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 – Who 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. , which can be summarized as per the following main groups :
- Sliding Stem Control Valve ( Angle Seat Piston Type / Globe Valve)
- Rotary Control Valve ( Butterfly / Ball Valves / V Notch Ball Valves)
- Pinch Valve
- Diaphragm Valves