Guide to Choosing Between Quarterturn and Multiturn Valve Actuators

Imagine a scenario where an oil pipeline needs immediate shutdown during an emergency, or where a precision chemical reactor requires slow, meticulous adjustment of material flow. These critical operations rely on actuators - the workhorses of automated control systems that convert control signals into mechanical motion to operate valves and other mechanisms.

Among various actuator types, quarter-turn (angular) and multi-turn actuators represent two fundamental designs with distinct characteristics, functions, and applications. This article examines their technical properties, operational principles, and selection criteria to aid professionals in choosing appropriate solutions.

Quarter-turn actuators, as their name suggests, provide rotational movement limited to 90 degrees (one-quarter turn). These devices excel in applications requiring rapid operation or proportional control, making them ideal for quick-opening/closing valves or precise flow regulation.

• Rapid operation: Capable of completing full travel within seconds, these actuators enhance process efficiency, minimize material loss, and ensure safety during emergencies.
• Limited rotation: The 90-degree operational range simplifies mechanical design and control requirements.
• Simplified construction: Compared to multi-turn variants, quarter-turn actuators feature more straightforward mechanisms, reducing manufacturing costs and simplifying maintenance.
• High breakaway torque: These actuators generate sufficient starting torque to overcome initial resistance in valves or mechanisms.

Quarter-turn actuators employ three primary drive technologies:

• Pneumatic: Utilizing compressed air, these actuators convert linear piston motion into rotation through linkage mechanisms. They offer simplicity and cost-effectiveness but depend on consistent air supply pressure.
• Electric: Motor-driven units employ gear reduction to transform high-speed, low-torque input into controlled rotational output. They provide superior precision and remote operation capabilities at higher complexity and cost.
• Hydraulic: Using pressurized fluid, these actuators deliver exceptional torque in compact packages, suitable for demanding applications, though requiring more complex maintenance.

• Ball, butterfly, and plug valve operation in process industries
• Damper control in HVAC and ventilation systems
• Flow regulation in chemical processing plants
• Automated control systems for manufacturing processes

Multi-turn actuators complete multiple full rotations to operate valves or mechanisms, offering extended travel ranges and superior positioning accuracy for applications requiring fine adjustment.

• Extended rotation capability: Multiple complete turns enable precise control over long-stroke mechanisms.
• Enhanced positioning accuracy: Superior control resolution supports exact flow, pressure, or temperature regulation.
• Slower operation: The multi-turn requirement results in longer actuation times compared to quarter-turn models.
• Complex construction: More sophisticated mechanisms increase manufacturing complexity and maintenance requirements.

Multi-turn actuators primarily utilize two drive systems:

• Electric: Motor-driven units with gear reduction and position feedback provide accurate multi-turn positioning, commonly integrating position sensors for closed-loop control.
• Hydraulic: Fluid-powered versions deliver high torque output with position monitoring, suitable for heavy-duty applications.

• Gate and globe valve operation in water treatment facilities
• Precision control valves in oil and gas pipelines
• Industrial process control systems requiring exact flow regulation
• Power generation plant control systems

• Operational requirements: Assess speed, precision, and travel range needs. Quarter-turn suits rapid operation while multi-turn enables precise adjustment.
• Valve compatibility: Match actuator type to valve design - quarter-turn for ball/butterfly valves, multi-turn for gate/globe valves.
• Environmental conditions: Consider temperature extremes, hazardous areas, or corrosive atmospheres when selecting materials and designs.
• Lifecycle factors: Evaluate maintenance needs and expected service life relative to application criticality.
• Economic factors: Balance performance requirements with budget constraints, considering total cost of ownership.

Quarter-turn and multi-turn actuators serve distinct purposes in industrial automation. The former excels in rapid, limited-rotation applications while the latter provides precise multi-turn positioning capability. Proper selection requires thorough analysis of technical requirements, operational conditions, and economic factors to ensure optimal system performance and reliability.