Are you a beginner new to the valve world, ready to learn more about the various types of valve actuation options? Perhaps you've come across terms like linear actuators, double-acting actuators, solenoid and pneumatic valves, and are looking to expand your knowledge? Fear not, the team at ValveMan is here to help!
Valve Actuators
Valve actuators are, put simply, devices used to open and close a valve. A valve actuator may be operated manually (by hand), or powered by an external source such as electricity, compressed fluid (hydraulics) or compressed air (pneumatics). We’ll go over each type of valve actuator, to help you understand your options and make an informed actuator selection.
Note that besides the power source, the valve actuator motion type must also be specified. Rotary valve actuators produce a rotational or ‘turning’ type of motion, which is suited to operating quarter-turn valves such as ball, butterfly and plug valves. Linear valve actuators produce a linear or ‘straight-line’ type of motion, which is suited to operating gate, globe and pinch valves.
Types of Valve Actuators
Manual Valves (not really actuators)
Manual valves are not actually actuators, but we included them in this list. They are operated by hand. Examples of these types of valve operations include levers, handwheels, T-keys, and gear drives. Manual valves are often used in systems where automation is not required. They are cheaper than their actuated counterparts, and are generally suited to low-pressure applications. Manual valves may also be used as backup shutdown valves, in case the primary automated emergency shutdown valve (ESD) fails. Examples of hand-controlled valves include manual ball valves, handwheel gate valves, and lever or gearbox butterfly valves.
Advantages of manual valves
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It is the cheapest type of valve operation.
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Does not depend on an external power source.
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Simpler design with fewer components, making these valves less likely to fail and easier to maintain.
Disadvantages of manual valves
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Operating large valves can be difficult, particularly in high-pressure applications. Bypass or balancing valves may be required.
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Not suitable for automated systems, as they can’t be operated remotely, automatically, or based on control system feedback.
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Can be slow to open and close, especially for large, linear motion valves, such as gate valves.
Common manual valve applications
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Maintenance valves
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Residential and commercial plumbing
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Bulk pipeline isolation valves
Electric Valve Actuators
Ball valve fitted with an electric actuator
Electric actuators use electricity to develop mechanical motion, typically through an electric motor and gear assembly. Electric valve actuators are suited to applications that require precise control over valve position, as well as automated plants that require remote valve actuation and integration with plant control systems. Linear or rotary motion can be provided to open and close valves. Examples of electric-actuated valves include solenoid valves used for on-off control, and electric-actuated globe valves used to regulate fluid flow in a process.
Advantages of electric valve actuators
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Offers a high degree of precision.
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Simple to integrate with automated control systems.
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Provides an energy-efficient actuation solution.
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Clean and silent when compared to other powered actuators.
Disadvantages of electric valve actuators
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May overheat and degrade if used outside its duty class or service classifications.
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Not as fast-acting as pneumatic or hydraulic actuators
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Generally not suitable for very large valves or high-pressure applications, where a high output torque is required.
Common electric actuator applications
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Automated water plants
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Process control in manufacturing facilities
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Heating, ventilation and air conditioning (HVAC) systems
Pneumatic Valve Actuators
Butterfly valve fitted with pneumatic actuator
Pneumatic actuators use air pressure to generate motion. The compressed air builds up within a chamber and pushes against a piston or diaphragm, which in turn moves the actuator and valve stem, opening or closing the valve. Pneumatic valve actuators are commonly found in systems that require fast, regular motion.
Advantages of pneumatic valve actuators
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Relatively inexpensive, when compared to other actuators.
- Easy to add a "fail position" in the case of loss of power
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Provides fast response times and rapid movement.
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Simple to set up and maintain.
Disadvantages of pneumatic valve actuators
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Requires separate air supply infrastructure.
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Air leaks tend to reduce efficiency.
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Operation is noisy, with a hissing or blowing sound accompanying air release.
Common pneumatic actuator applications
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Operating machinery in manufacturing processes
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Controlling conveyor systems
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Automating assembly lines in production facilities
Hydraulic Valve Actuators
A hydraulic cylinder, which is an integral component of linear hydraulic actuators
Hydraulic actuators use pressurized fluid, usually oil, to push a piston or vane housed within a cylinder, developing linear or rotary motion. Hydraulic valve actuators can be used to move a valve open and closed, or control a valve’s position. Double-acting actuators apply pressure to both sides of the piston, allowing for controlled movement in both open and closed directions. Single acting actuators apply pressure to one side of the piston only, relying on gravity, springs, or other forms of assisted closure.
Hydraulic actuators are commonly found in applications that require very large operating forces, such as heavy-duty industrial processes within the oil and gas, power generation, and mining industries
Advantages of hydraulic valve actuators
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Capable of generating substantial forces; hence, they can operate large valves in high-pressure applications.
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Durable and robust design which can withstand harsh conditions.
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Can maintain valve position in the event of a pump or power failure, allowing for added safety.
Disadvantages of hydraulic valve actuators
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Requires many auxiliary components, including a fluid reservoir, pumps and valves.
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Hydraulic fluid leaks can compromise performance and pose environmental hazards.
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Relatively high cost compared to other actuator types.
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Complex maintenance is required.
Common Applications
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Turbine main inlet valves typically employ hydraulic-actuated brake units
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Large diameter control valves subjected to high differential pressures commonly use hydraulic actuators. An example is hydraulic-actuated sleeve valves used for dam outlet flow control.
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Vehicle braking systems
Closing Thoughts on Valve Actuators
Understanding the different types of valve actuators is crucial in selecting the best actuated valve for your system. Whether you're installing new valves or maintaining an existing system, choosing the best, high-quality actuated valves can enhance your system’s performance and longevity.
If you’re still not sure which type of actuated valve suits your application, or if you have any technical questions, be sure to discuss your needs with a valve professional.
