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A Beginners Guide to Motorized Valve

What is a Motor Operated Valve or Motorized Valve?

The motorized Valve or motor-operated valve (MOV) is an important item of the Plant & Piping system. These valves are generally of a wide size range and are used for different applications such as Pump discharge etc. Motor Operated. Valves are often called as On-Off valves as the motors serve the purpose of fully opening or fully closing valves in pipelines. For example, in cooling water lines, and process pipelines where controlling fluid is not required, motor-operated valves can be used to fully allow or fully stop the fluid flow. These valves are not used for throttling purposes as they serve mainly On-Off applications. Motor-operated valves can be of various types e.g. Gate/ Ball/ Butterfly etc. with actuator control. The design of Motors and valves can be different. An electric motor is mounted on the valve and geared to the valve stem so that when the motor operates the valve will open or close. For this MOV, a motor operated with actuator control from the local panel or, from the control room is required. There is a requirement for coordination among Piping-Electrical-Instrumentation-Process engineers and vendors for the design and procurement of such motor-operated valves.

Applications of Motorized Valves

  • Whenever a frequent operation is required.
  • Valves located in remote, inaccessible or hazardous places.

Motorised control valve / Motor operated valves are usually for full open and full close applications. 
However, there are places where they are used for position control as well.

Types of motor-operated valves

Motorised control valves can be classified into three types. However, it must be noted that the main application of motorised valves are for flow control and flow isolation.

Used to automate manual open-close valves Examples include, pump discharge/suction valves, boiler feed water isolation valves, drum vent valves, product line valves etc.

Used were some degree of control. For example, a gradual opening and closing are required, applications include reflux lines, boiler start-up vents, boiler IBD valves, boiler main steam valves etc.

This is a precision inching valve, in inching valve the motor operates in steps configured in the controller, e.g. 5%, 10% opening steps. In precision flow valves, a continuous control is enabled by the use of proper feedback from the field to the controller which is not usually found in other motor operated valves. An example is steam injection valve / water injection valves used in GT for Nox control.

Key Elements of Motor Operated Valves

motor operated valve basic flowchart

Operation Process

  1. Control Signal: The process starts with a control signal, which can be manual (via a switch) or automated (from a control system or programmable logic controller, PLC).
  2. Motor Activation: The control unit sends an electrical signal to the motor based on the desired valve position (open, closed, or anywhere in between).
  3. Actuator Movement: The motor generates rotational or linear movement, which is transferred to the actuator. The actuator then moves the valve mechanism accordingly.
  4. Valve Adjustment: The valve mechanism (e.g., ball, disc, or gate) moves to the required position, adjusting the flow rate through the valve.
  5. Feedback: Many motorized valves include position sensors that provide feedback to the control unit, ensuring the valve has reached the desired position. This feedback loop helps maintain precise control.


  • Automation: Enables automated control and integration with complex systems.
  • Precision: Provides accurate control over fluid flow rates.
  • Remote Operation: This can be operated remotely, which is useful for inaccessible or hazardous environments.
  • Efficiency: Reduces the need for manual intervention, improving operational efficiency.

Basic Wiring diagram

SA3-01 Circuit Diagram

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