Actuators

An actuator is a vital component in automation and control systems, used to convert energy into mechanical motion. Actuators play a crucial role in operating control valves, industrial machinery, and automation systems, ensuring precise control over fluid flow, pressure, and other process variables. Whether used in industrial valves, robotics, or HVAC systems, actuators enable mechanical movement without manual intervention, improving efficiency, safety, and precision.

Actuators function by receiving an input signal—either electrical, pneumatic (air pressure), or hydraulic (fluid pressure)—and converting it into motion. The specific working principle depends on the type of actuator used, but most actuators contain the following essential components:

Power Source: This can be electricity, compressed air, or hydraulic fluid, depending on the actuator type.
Control Signal: The actuator receives a control signal, typically from a programmable logic controller (PLC) or a distributed control system (DCS).
Mechanism: The internal mechanism whether it be a piston, diaphragm, or motor—translates the energy into movement.
Output Shaft or Stem: This component moves to control the position of the connected control valve.

For example, a spring diaphragm actuator is a common pneumatic actuator that uses compressed air to move a diaphragm, which in turn adjusts the valve’s position. Similarly, hydraulic actuators use pressurised fluid to create movement, while electric actuators use motors to achieve the same function.

Actuators come in various types, but the three most widely used are:

1. Pneumatic Actuators

Pneumatic actuators use compressed air to create movement. They are widely used in industrial settings due to their fast response time and reliability. Spring diaphragm actuators are a type of pneumatic actuator that consists of a diaphragm and a spring, allowing for smooth and precise control of valves, specifically they are the favoured type for Control Valve operation.

2. Hydraulic Actuators

Hydraulic actuators use pressurised fluid to generate force. They are commonly used in heavy-duty industrial applications where high force output is required, such as in large control valves.

3. Electric Actuators

Electric actuators use electric motors to create motion. They are gaining popularity in automation and process control due to their precision and ease of integration with digital control systems.

Actuators control a mechanism by converting energy into movement, while sensors detect and measure environmental changes, providing critical data for automation. Sensors monitor variables such as temperature, pressure, or flow rate, while actuators respond by taking action, like adjusting a valve. For example, in a control valve manufacturer system, a temperature sensor may detect high temperatures and send a signal to an actuator, which then adjusts a control valve to regulate flow and maintain optimal conditions.