Pneumatic or Electric Actuators?

Posted in Uncategorised, on April 26, 2021 By Admin

One of the key products needed in industrial facilities are actuators. There are two main types: pneumatic and electric actuators. Many businesses struggle to identify which product will be better for their needs.

In today’s blog, McRae Engineering Equipment Ltd. will go over the pros and cons of pneumatic and electric actuators.

Obviously, the main difference between these two products is in how they are powered. Typically, electrically powered equipment will have higher levels of precision, though this is not to say the pneumatic version is not precise. It all comes down to how much precision you need, and therein lies the main principle of choosing between pneumatic and electric actuators: that is  it all depends on your applications.

As a business, you will need to work with your equipment supplier to understand your performance needs, budget for components and systems, and productivity needs.

Pneumatic Actuators

A pneumatic control valve actuator converts energy (typically in the form of compressed air) into a mechanical motion. The motion can be rotary or linear, depending on the type of actuator.

This version of actuators is able to provide high force and speeds at low unit costs, with a smaller footprint. The force and speed can also be easily adjusted and are independent of each other. The cost of the product and its associated components are known to be low, though the maintenance and operation of these units can be high.

Pros of Pneumatic Actuators

1. Explosion proofing relatively simple
2. Relatively insensitive to corroding environments if control air is used
3. Unsophisticated design
4. Use of control gas possible
5. Logic interlocking of signals can be realized easily Relatively low cost
6. High stroking velocities can be realized
7. “Fail safe outages of the auxiliary energy do not prevent reaching of safe position (spring loaded actuator)”

Cons of Pneumatic Actuators

1. Distance to the source of energy is limited (dead time problems)
2. Actuating force of spring loaded units is limited
3. Auxiliary energy must be generated and made available (cost implications)
4. Auxiliary energy system requires considerable maintenance
5. Small systems are normally not economical
6. Sensitive to changing process pressure

Electric Actuators

An electric actuator is powered by a motor that converts electrical energy into mechanical torque. The electrical energy is used to actuate equipment such as multi-turn valves.

Additionally, a brake is typically installed above the motor to prevent the media from opening valve. If no brake is installed, the actuator will uncover the opened valve and rotate it back to its closed position. If this continues to happen, the motor and actuator will eventually become damaged. It is one of the cleanest and most readily available forms of actuator because it does not directly involve oil or other fossil fuels.

Compared to pneumatics, electric actuators can provide more precise controls and positioning. They are typically used to help adapt machines to flexible processes while still maintaining a relatively low operating cost. Electric actuators will have a higher initial cost compared to pneumatic types. That said, their operating costs are more manageable, especially if you are careful about your energy efficiency and savings. 

Pros of Electrical Actuators

1. Large distance to the source of energy is no problem
2. Accessories and parts are standard supplies Easy interlocking of signals
3. High regulation and control accuracy can be realized easily
4. Large actuating force easy to achieve
5. Remote control and monitoring functions can be implemented easily

Cons of Electrical Actuators

1. Larger actuating forces difficult to achieve
2. Limited stroking velocity
3. Explosion proofing costlier in comparison to pneumatic or hydraulic actuators
4. “Reaching of safe position in case of auxiliary energy outages must be ensured by additional measures”
5. High maintenance costs

In a nutshell, the main difference in performance comes down to higher closing forces versus higher precision. There is also an important consideration to be made regarding the scale of your operations, with electric actuator being more suitable for small to medium loads while their pneumatic counterpart can handle larger scale deployment. Factors like operating and initial product costs should not factor that highly into your decision because at the end of the day, you need to choose the right product for your needs regardless of price.

McRae Engineering Equipment Ltd. is glad to provide advice and consultation for those seeking actuator products. Visit our website today to learn more about our products!