High Speed Actuators: What Qualifies Them as High Speed?

“High speed” cannot be judged from one number alone. A short travel time matters only when linked to output torque, valve load, duty cycle, and operating conditions.

This article focuses on electric quarter-turn actuators for ball and butterfly valves, where speed is normally measured by the time required to rotate through 90 degrees.

What Does High Speed Mean for a Quarter-Turn Actuator?

Measure Speed by the Time Required for a 90-Degree Stroke

A quarter-turn actuator moves a valve between closed and open positions through approximately 90 degrees. Speed is commonly expressed as stroke time, operating time, or travel time.

This differs from a linear actuator, which is often compared by distance traveled per second. For a high-speed quarter-turn actuator, the relevant value is the time required to complete the specified angular stroke.

Engineers should distinguish three measurements:

1. Signal response time: the delay between the command and initial movement.

2. Mechanical travel time: the time required to complete the stroke.

3. Total process response: the time from the command to the resulting flow change or isolation.

Compare Stroke Time Only at the Same Torque and Load

Stroke time should not be compared without output torque. A compact unit moving a lightly loaded valve may complete its stroke in seconds, while a larger actuator must overcome much higher breakaway and seating torque.

Published value	What it tells the engineer
Stroke time only	Incomplete because the load is unknown
Motor speed only	Does not show output speed after gearing
Torque plus stroke time	Supports comparison within the same torque class
Torque, time, and duty cycle	Better reflects repeatable performance

AOITEC’s high speed actuator can achieve up to a 2-second stroke at 50 Nm output. AOITEC has also developed high-speed technology that is 5 to 20 times faster than conventional models, but final selection still depends on valve torque and service conditions.

Which Performance Factors Qualify an Actuator as High Speed?

Motor Power and Gear Ratio Determine the Available Speed

The motor generates rotational power, while the gearbox determines how that power reaches the valve stem. A higher reduction ratio increases output torque but lowers output speed. A lower ratio can shorten travel time only when sufficient torque remains available.

A high speed electric actuator should be evaluated as a complete electromechanical system. Motor output, gearing, efficiency, and valve requirements must work together. Butterfly-valve torque can vary with disc position, differential pressure, and hydrodynamic forces, while ball valves typically require peak breakaway torque at the start of travel because of seat friction, differential pressure, and static friction.

Acceleration and Deceleration Affect the Total Stroke Time

A fast acting electric actuator must start, accelerate, travel, decelerate, and stop at the required position. Aggressive acceleration can increase inertial loads on gears, couplings, valve stems, and mounting components. Abrupt deceleration near an end position can create impact loads in the drivetrain and valve assembly.

Genuine fast-acting performance combines short travel time with controlled movement and repeatable end positioning. Dependable seating is often more important than reducing a laboratory result by a fraction of a second.

Duty Cycle and Thermal Control Determine Repeatable Speed

One rapid stroke does not prove that an actuator can operate repeatedly. Frequent starts generate heat, and thermal limits may require operating pauses or reduce service life. Engineers should review cycles per hour, ambient temperature, running time, and repeated emergency commands.

Why Is the Fastest Actuator Not Always the Best Choice?

Rapid Valve Closure Can Create Pressure and Mechanical Stress

Closing a liquid pipeline too quickly can create a pressure surge. The risk depends on pipeline length, fluid velocity, valve type, operating pressure, and closure profile. A fast-closing valve actuator may therefore require a controlled stroke rather than the shortest possible time.

Rapid movement can increase inertial and impact loads if deceleration is not properly controlled. Emergency shutdown applications should meet a specified closing-time requirement, while normal operation may use a slower or staged closing profile to limit hydraulic transients and mechanical shock.

On-Off and Modulating Actuators Require Different Speed Behavior

An on-off actuator travels between fully open and fully closed positions, so complete stroke time is the primary speed value. A modulating actuator must also stop accurately at intermediate positions and respond smoothly to changing control signals.

On-off control prioritizes reliable full-stroke movement. Emergency isolation requires rapid travel and dependable final positioning. Modulating control emphasizes stable response, feedback, and positioning accuracy. Frequent cycling adds the need for repeatable speed without excessive heat buildup.

If actuator travel is too fast relative to the process dynamics and controller tuning, the control loop may overshoot or hunt. Selection should therefore consider travel time together with positioning resolution, deadband, feedback accuracy, controller tuning, and process response.

How Should Engineers Compare High Speed Electric Actuators?

Read Torque and Stroke-Time Data as a Pair

The first comparison should pair rated torque with full-stroke time. Engineers should then confirm that the available torque covers the valve’s breakaway, running, and seating requirements.

Review:

1. Required valve torque and engineering margin.

2. Opening and closing time through 90 degrees.

3. Supply voltage and voltage tolerance, and—for AC models—the frequency used for the published stroke-time test.

4. Expected operating frequency and duty cycle.

5. Ambient temperature and enclosure requirements.

6. Valve type, differential pressure, and process medium.

AOITEC designs high speed part-turn actuator solutions for ball valves and butterfly valves. Our high-speed products serve emergency shutdown applications, oil and gas pipelines, chemical processing, industrial automation, and power and energy systems requiring rapid valve operation.

Check Power Supply, Control Mode, Feedback, and Mounting

Speed alone does not establish compatibility. Engineers should check the power supply, on-off or modulating command, position feedback, manual operation, installation space, environmental protection, mounting dimensions, and stem connection.

Validate Fast-Acting Performance Under Real Valve Conditions

Final validation should use the valve or a representative load. Multiple cycles should confirm consistent travel, feedback, and thermal behavior at the maximum expected differential pressure and process temperature.

Factory acceptance testing should verify actuator travel time, end-position accuracy, feedback, consecutive-cycle repeatability, and thermal behavior under a representative load. Pipeline response during rapid closure should be evaluated during site commissioning or through a hydraulic-transient analysis based on actual operating conditions.

Application example: oil and gas or petrochemical operators may require remote electric control for storage tanks, loading systems, and pipeline isolation valves. In these installations, rapid shut-off must be combined with reliable operation and dependable final positioning. AOITEC actuator solutions have been applied in such isolation duties to improve automation, operational safety, and response capability.

AOITEC has more than 30 years of electric valve actuator experience. Our patented high-speed technology supports time-critical automation, while production capabilities cover standard, OEM, and customized solutions.

FAQ About High Speed Actuators

Q: What is considered a high speed actuator for a quarter-turn valve?

A: No single stroke-time value defines a high-speed quarter-turn actuator. It should be classified relative to a stated torque class, 90-degree travel, valve load, duty cycle, supply conditions, and service environment.

Q: How fast can a high speed electric actuator open or close a valve?

A: Operating time depends on torque, valve type, differential pressure, power supply, and mechanical load. AOITEC’s high speed actuator can achieve up to a 2-second stroke at 50 Nm output, while larger or more heavily loaded valves require separately matched solutions.

Q: Is a fast acting electric actuator faster than a pneumatic actuator?

A: Either technology can provide rapid movement. Pneumatic speed depends on air pressure, tubing, solenoid capacity, and exhaust flow. Electric speed depends on the motor, gearing, torque, and power supply. Compare complete valve packages under equivalent loads.

Q: Can a fast acting valve actuator cause water hammer?

A: Yes. Rapid closure in a liquid pipeline can create a pressure surge. Valve closing time should be based on pipeline conditions and process safety analysis rather than the shortest available actuator stroke.

Q: How do I size a high speed quarter turn actuator for a ball or butterfly valve?

A: Start with the valve manufacturer’s torque data at the maximum expected differential pressure and process temperature, including break-to-open, running, and end-to-close or seating torque as applicable. Apply a documented engineering margin, then verify the required stroke time, duty rating, power-supply limits, control mode, and environmental protection under the worst-case operating conditions.