What are the different types of actuators and positioner?

Great things about industrial valves that you need to know
October 31, 2017
atex valve
ATEX valve: ATEX certified pneumatic valve parts
October 31, 2017

What are the different types of actuators and positioner?

There are five main types of actuator – hydraulic, pneumatic, electric, thermal or magnetic and mechanical. Transmission is a type of engine that moves or controls a mechanism or system.

It is operated by an energy source, typically electric current, hydraulic pressure, or compressed air pressure, and converts that energy into motion.

The executive structure is the mechanism by which the control system acts on the environment. The control system can be simple (a fixed mechanical or electronic system), based on software (eg printer drivers, robot control systems), humans, or any input any other.


Hydraulic transmission consists of a cylinder engine or fluid using hydraulic power to facilitate mechanical operation. Mechanical movement produces an output of linear motion, rotation or oscillation.

Because the fluid is almost impossible to compress, the hydraulic transmission can cause considerable pressure. The drawback of this approach is the limited acceleration.

Hydraulic cylinders consist of a hollow cylindrical tube in which a piston can slide. The term single-acting is used when liquid pressure is applied to one side of the piston.

The piston can move in one direction, one spring is used frequently to make the motor piston return. The term “double acting” is used when the pressure is applied on either side of the piston; Any difference in pressure between the two sides of the piston moves the piston aside or else.


Valve controls and wing valves

pneumatic fan to control water valves The pneumatic energy converters convert energy generated by vacuum or compressed air at high pressure into linear or rotational motion.

Compressed air power is desirable for main engine control because it can react quickly at start and stop because the power supply does not need to be stocked to reserve.

Pneumatic drives allow large forces to be generated from relatively small pressure changes. These forces are often used with valves to move the film to affect the flow of liquid through the valve. It is responsible for transforming the pressure into reality.


An electric actuator is provided by a motor that converts electrical energy into mechanical torque. Electric power is used to operate equipment such as multi-ring valves. This is one of the cleanest engines and it is the easiest to operate because it does not involve oil.

Heat or magnetic (memory shape) sets

Drives can be activated using thermal energy or from already used in commercial applications. They tend to be compact, lightweight, economical and have high energy density.

These drives use shape-memory materials (SMMs), such as shape-memory alloys (SMA) or magnetic-shape alloys (MSMA). [1] Some of the popular manufacturers of these devices are Finland Modti Inc. and Dynalloy USA.

Heat or magnetic (shape memory)

Actuators can be activated using thermal energy or magnetic energy that has been used in commercial applications. They tend to be compact, lightweight, economical and have high energy density.

The actuators use shape-memory materials (SMMs), such as shape-memory alloys (SMA) or magnetic-shape alloys (MSMA). [1] Some of the popular manufacturers of these devices are Finland Modti Inc. and Dynalloy USA.


A functional drive mechanism that converts rotational motion into linear motion for motion. It includes gears, rails, pulleys, chains and other devices for operation. An example is a rack and a gears.



The valve positioner compares a control signal to the position of the valve actuator and moves the actuator accordingly. They are used with both linear and rotary valves. Valve positioning valve is used when the pressure from 0.2 to 1 bar in the membrane chamber can not cope with friction and high differential pressure.

The positioner is mounted on the yoke of the actuator and is connected to the spindle of the actuator with a feedback arm to monitor the valve position. When a control signal differs from the position of the valve actuator, the positioner will send the power needed to move the actuator until it reaches the correct position. This uses high air supply.

Placements need to be installed if the valve is used in a control application.

Valves for positioning

There are four basic types of valve positions: pneumatic, electronic, electric, pneumatic and digital. Positioning valves

Compressed air equipment sends and receives compressed air signals. They are safe and can provide a large force to close the valve.

The one- or three-way pneumatic positioner transports air and exhaust from only one side of the one-way valve actuator against one spring.

Two-way or four-way air compressor sends and pulls air from both sides of the actuator.

Electric valve position transmitter and receiver. There are three types of electrical activity: single phase and three phase (AC) and one (DC).

An electronic valve positioning valve converts the current control signal into an equivalent pneumatic signal.

Digital or “smart” devices use microprocessors to locate valve actuators and track and record data. They are very accurate, use less air than similar positioning devices and allow online digital diagnosis.

Performance Parameters

The performance parameters for the valve locator vary according to the compressed air input range, the maximum supply pressure, the milliampere input range, the dividing band, the operating temperature and the output operation.

Positioning valve

The input air pressure range and maximum supply pressure are in units per inch (psi).

The dividing bands usually consist of 4 – 10 mA and 12 – 20 mA. There are two ways of dividing two dimensions, three dimensions and four dimensions.

There are three types of action outputs: direct, reverse, and reverse fields.

Direct acting devices increase the output signal when the input signal is increased.

Reverse devices reduce the output signal when the input signal is increased.

The reversible field products can be switched between direct and reverse operation.

Features, characteristics

Valve locating the safety valve from inside (IS) does not generate sparks or other heat effects that can burn specific gas mixtures. Equipment made of stainless steel is used in corrosive environments or at high temperatures. The valve position should also be accompanied by a valve position indicator suitable for the intended application.


Valve positioning varies on application, features and approval. Some products are designed for automotive, aerospace, marine, medical or military applications. Other products suitable for food or pharmaceutical processing. General purpose devices are usually available.


The pneumatic valve control valve adjusts the valve position by converting the air pressure into linear or rotary motion. There are two main types: piston drive and diaphragm actuator.

The piston drive is used when the stroke of the diaphragm actuator may be too short or the thrust is too small. Compressed air is applied to a solid piston contained in a solid cylinder. Simple design with air entering the central chamber and the air pushing the piston up.

When the air pressure is removed, the shaft moves in the opposite direction as the spring reverses. The piston drive can also operate in two ways, meaning that the air can be placed on either side of the piston because there is no spring return.

The film actuator has a soft thin film that operates by supplying compressed air. This type of actuator works alone because the air is only supplied to one side of the diaphragm and they can be operated directly (rotated to shorten) or vice versa (seasonal increase).

The advantages of pneumatic valve control valves are they are strong, lightweight, simple and fast. The disadvantage is that precise position control is impossible, except at full stops.

Control valves

Each type of actuator is designed for a specific valve. Valves can be arranged in motion and function.

Valve movement

Rotary Hydraulic Valve Actuators – Rotary actuators are used for motion valves such as ball valves, ball valves and butterfly valves through a quarter or more from open to closed. The closing element is a disk or ellipse that rotates back to an axis. Valve characteristics include:

Torque Moment – Torque is the force required to generate rotational motion. It is determined by the force applied by the distance from the turning point to the point at which force is applied.

Range of rotational motion – Popular ranges of motion include 90 ° (quarter-turn), 180 °, 270 ° and 360 ° (multi-turn).

Linear hydraulic valve control – Linear actuators convert linear valves such as gate valves, diaphragms, and thrusters by sliding a body to control the valve. Linear motion linear features include:

Stem length of the valve stem. – Stroke is a term used to determine the transport required by the valve from fully open to fully closed. The stroke of an actuator is determined by the actuator if the actuator selected has a stroke that is smaller than the stroke of the valve.

Using actuators with less strokes the valve will “short stroke” the valve and fully appreciate the valve’s CV will not be performed.

Actuator or thrust-sealing device The actuator must provide sufficient force to overcome the pressure in the system to close the closing element and keep it closed.