Different types of Actuator

Process engineers have many options with respect to actuators for manual, pneumatic, hydraulic and electric lift rod valves. Manual actuators meet simple on and off needs. Pneumatic valve actuators are fast and economical. Hydraulic systems can be a solution for powerful applications and remote installations.

However, for critical process control applications, electric valve actuators can provide the work that process engineers do: increase productivity, increase efficiency and reduce downtime. In other words, electric actuators improve the process and reduce costs.

There are pros and cons for each valve operation option and we will see it here.

Electric actuators:-

Electric valve actuators, especially electric valve actuators with brush-less servo motors, handle complex motion profiles, provide high strength and high speed, and provide excellent accuracy and repeat-ability. These advantages make electric actuators particularly suitable for process control applications. Although the cost of the electrical valve operating system may be higher than other options, the electrical system requires little maintenance and provides up to 75-80% system efficiency.

Advantages:-

High accuracy and repeat-ability

Can handle complex motion profiles

Powerful features

Low total cost of ownership (TCO)

Disadvantages:-

The purchase price can be high

Start-up can be more complicated than other options.

Pneumatic actuator:-

Simple, fast and economical pneumatic actuators have been a popular process control solution for many years. Compressed air is often readily available in industrial process environments. However, it is better to handle only simple motion profiles, especially in sliding conditions, which is less accurate. In addition, the pneumatic system provides 15% efficiency.

Pneumatic actuators require regular maintenance and frequent replacement, resulting in longer downtime. This, combined with low efficiency, creates a high total cost of ownership (TCO).

Advantages:-

Familiar skills that is easy to understand.

Quickly reach the set points

The purchase price is low.

Disadvantages:-

Only suitable for simple motion profiles

Low overshoot / under boost applied

TCO is high

Hydraulic cylinder:-

Hydraulic valve drive systems are often used for remote installations because they are independent. Especially suitable for high pressure applications, the hydraulic actuator accumulates a lot of energy in a compact package. Like pneumatic cousins, hydraulic cylinders are easy to install and operate and inexpensive to buy. But there are advantages and disadvantages of pneumatic systems. Maintaining fluid pressure requires constant force, does not work well at extreme temperatures and is prone to oil leaks.

Advantages:-

The purchase price is low.

Independent systems are suitable for remote installation.

Suitable for proper positioning applications

High power density

Disadvantages:-

Inefficient (hydraulic systems with up to 45% efficiency)

Leakage

Low accuracy

Continuous Maintenance Required

Temperature sensitivity

High total cost of ownership

Manual actuators:-

A simple and easy to operate crank or flywheel may be some valves necessary for operation. Sometimes it is necessary to open or close the valve frequently.

Advantages:-

Without complications

Easy to use

Cheaper to buy and install

Disadvantages:-

Not good for a precise fit

Disadvantage to use often

May require continuous maintenance