The major difference between pneumatic actuators and electronic actuators is the speed of operation. The two technologies are so different that one cannot be a drop-in replacement for the other.
Pneumatic Actuators and Electric Actuators
Each has inherent advantages and disadvantages.
Advantages of Pneumatic Actuators
The biggest advantage of the pneumatic actuators is their failsafe action. By design of the compressed spring, the engineer can determine if the valve will fail closed or open, depending on the safety of the process.
Provide high force and speed, which are easily adjustable and are independent of each other
Have a delayed response which makes them ideal for being resilient against small upsets in pressure changes of the source.
Most economical when the scale of deployment matches the capacity of the compressor.
Provide inherent safety and are ideal for hazardous and explosive environment.
Low component cost and smaller footprint. Prices for non-repairable, rod-type cylinders range from $15 to $250 depending on body diameter, stroke and options.
Limitations of Pneumatic Actuators
Maintenance and operating costs can be high, especially if a serious effort has not been made to quantify and minimize the costs.
Maintenance costs include replacement cylinder costs and plugging air-line leakages whereas the operating costs include the cost of compressed air, i.e. electricity for the compressor.
Advantages of Electric actuators
Provide precise control and positioning in comparison to pneumatic actuators.
Response time is essentially instantaneous.
High degree of stability.
Help adapt machines to flexible processes.
Low operating cost. Controllers and drivers low voltage circuitry consume power to a far lesser degree.
Disadvantages of Electric actuators
The primary disadvantage of an electric actuator is that, should a power failure occur, the valve remains in the last position and the fail-safe position cannot be obtained easily unless there is a convenient source of stored electrical energy.
Higher cost than pneumatic actuators. The total cost ranges from $800 to $3,000 and up. High component costs often deter the use of electric actuators because savings in operating costs compared to pneumatics are often not adequately considered or are outright ignored.
The actuator needs to be in an environment that is rendered safe. Generally not recommended for flammable atmospheres.