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Centrifugal Compressor Valve Actuation Comparison

Centrifugal Compressor Valve Actuation Comparison

Compressor Control Valves

Centrifugal compressors usually include the major valves in the original equipment manufacturer’s scope of supply, such as inlet valve or guide vane, unloading control valve, discharge check valve, and sometimes the shut-off valve when needed. The inlet and unloading valves are automatic control valves regulated by the control panel or control system actuators and are essential for safety and energy efficiency during the compressor operation.

Valves need actuation systems to provide the necessary force to open or close them. Two standard actuation systems are pneumatic and electric valve actuators, with different pros and cons. Understanding more actuator features will help make the right decision on a compressor valve. 

Valve Actuation

Pneumatic Valve Actuators
Compressed air powers pneumatic valve actuators, which consist of a piston or diaphragm to convert compressed air into mechanical force. It is a simple, reliable option for operating valves, ideal for applications requiring compressed air, and popular among many industries. Pneumatic Valve Actuators receive a signal from a current-to-pneumatic (I/P) transducer.  This transducer receives an electrical current signal from the compressor control system to ensure the proper valve position.

Electric Valve Actuators
Electric valve actuators use an electric motor to operate the valve. They are becoming increasingly popular due to their precision and don’t require an air supply. Electric actuators consist of a motor, a gearbox, and a set of controls. They are ideal for applications requiring precise control and complex automation compatibility. Due to the intricate design of electric valve actuators, the reliability is less stable than pneumatic valves and requires additional maintenance. Electric valve actuators receive an electrical current signal directly from the compressor control system to ensure the proper valve position.

Valve Comparison

Below lists a table of detailed analyses of the comparisons.





Force Availability

Extremely High but smaller size

High larger size

No impact

Explosion Proof

Need to build per safety code compliance

Does not generate sparks or heat

Pneumatic is a safer option

Overload Ability

High risk of overload shutdown from motor heat protection; Risk of gearing wearing out

Normally designed with larger margin for overloading

Pneumatic will be a better option for instantaneous overloading


Relatively shorter but adequate

Excellent especially for frequently varying loads

Not a big difference

Fail Safe

Feasible but cost is higher

Common and low cost (Spring return option)

Pneumatic is a better option

Responding Time

Relatively slower; Could be faster but with an impact on cost

Excellent response with low cost

Pneumatic is a better option and more economic

Hazardous Conditions

Delicate electronic components. Requires certifications for specific environments.

Rugged, can withstand higher pressures and temperatures.

Pneumatic offers more options in hazardous environments.

Control Efficiency

Operation is approximately 80% efficiency

Greater than 80% when coupled with PID control efficiency. 

Both offer excellent efficiency during operation.


More complex design; Good for design conditions

Simple and mature design; Robust and better reliability

Pneumatic is more mature and reliable

Lead Time

Around 12 weeks

Around 12 weeks

No impact


Complex for service; usually need replacement

Simple and easy service for the actuator, but not for electrical accessories

Pneumatic is more convenient for service

Control Integration

Direct Signal

I/P Transducer

Not big impact

Utility Requirement

Electricity only

Electricity and air

Not big impact for most industries

Noise Level


Slightly higher noise

No impact



Slightly Bigger

No impact


Slightly heavier


Not big impact


Less expensive

More expensive

Electric may cost less initially, but have higher maintenance costs



The choice between pneumatic and electric valve actuators depends on the specific requirements and constraints of the application. When selecting a valve actuator, it is crucial to consider the application requirements, such as torque, speed, and control options, and any environmental factors, such as temperature or hazardous environments. FS-Elliott’s compressors come with a standard pneumatic actuator due to its reliability and fast response time to protect the compressor. Optional electric actuators can also be provided if required.

For more information, download our inlet upgrade guide or contact your authorized FS-Elliott channel partner. Let us help you improve your plant efficiency!



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