electric actuator for industrial valves

1. Identify the Valve Type

The first step is to identify the valve that the actuator will operate. Different valve designs require different types of motion and torque characteristics.

Ball valves

Ball valves typically use quarter-turn movement. The actuator rotates the valve stem, usually through approximately 90 degrees, to open or close the valve.

When selecting an electric actuator for a ball valve, consider the valve's breakaway torque, running torque, seating requirements, and pressure differential.

Butterfly valves

Butterfly valves also typically use quarter-turn movement. The actuator must provide sufficient torque to rotate the disc through the required operating range.

Torque requirements can vary depending on valve size, seat material, differential pressure, and operating conditions.

Control valves

Control valves are designed to regulate flow, pressure, temperature, or other process variables. Depending on the valve design, they may require a modulating actuator capable of positioning the valve in response to a control signal.

Before selecting an actuator, confirm whether the valve requires simple open/close operation or continuous position control.

Selection tip: Check the valve manufacturer's recommended actuator interface, mounting dimensions, required travel, and torque data before choosing an actuator.

2. Calculate the Required Torque

Torque is one of the most important factors in electric actuator selection. The actuator must generate enough torque to operate the valve reliably under the actual working conditions.

Insufficient torque may prevent the valve from opening or closing fully. An unnecessarily large actuator, on the other hand, may increase purchase cost and installation requirements.

What affects valve torque?

The torque required to operate a valve depends on several factors:

• Valve type and nominal size

• Seat and sealing materials

• Operating pressure and differential pressure

• Medium properties and temperature

• Valve condition and friction

• Operating frequency

• Manufacturer-specified safety margin

Do not estimate torque from valve diameter alone. Obtain the valve manufacturer's torque data for the intended operating conditions.

How to select the actuator torque

A practical selection process is:

1. Obtain the valve's required operating torque from the valve manufacturer.

2. Confirm whether the value covers breakaway, running, and seating torque as applicable.

3. Identify the actuator's available output torque at the required voltage and operating conditions.

4. Apply the manufacturer's recommended safety factor.

5. Confirm that the actuator's torque output is suitable throughout the required travel.

For example, if a valve requires 100 N·m under the specified operating conditions, the actuator should not be selected solely because its catalog lists a nominal torque close to that value. The buyer should check the manufacturer's sizing guidance, the relevant torque curve, and the required margin.

Important: Avoid excessive oversizing. The actuator, valve stem, coupling, and mounting structure must all be compatible with the applied torque.

3. Choose the Operating Mode: On/Off or Modulating

Electric actuators are commonly configured for either on/off operation or modulating control. These functions are not interchangeable, so the control requirement should be identified before ordering.

On/off electric actuators

An on/off actuator is designed to move the valve between its required open and closed positions.

Typical applications include:

• Pipeline isolation

• Water treatment systems

• HVAC systems

• General industrial fluid control

• Automated process shut-off

If the process only requires the valve to open or close, an on/off actuator may be sufficient.

Modulating electric actuators

A modulating actuator is designed to position a valve at intermediate openings in response to a control signal. This is useful when the process requires continuous adjustment rather than simple isolation.

Potential applications include:

• Flow regulation

• Temperature control

• Pressure regulation

• Process systems requiring variable valve positioning

Modulating capability may require a suitable actuator model, control electronics, feedback signals, and compatible control-system interfaces.

Selection tip: Do not assume every electric actuator supports modulating control. Confirm the exact model's functions, input signals, positioning accuracy, and operating duty before purchase.

4. Check the Power Supply and Control Signals

An electric actuator must be compatible with the available electrical supply and the plant's control system.

Before selecting a model, confirm:

• Rated supply voltage

• AC or DC power requirements

• Frequency requirements, where applicable

• Rated current and starting current

• Wiring and terminal arrangement

• Control input and feedback output

• Compatibility with the PLC, DCS, or other control equipment

Depending on the model, control options may include discrete open/close commands, analog positioning signals, or communication interfaces.

For modulating applications, confirm the required input signal and whether position feedback is needed. Also check how the actuator behaves during a power interruption, signal loss, or control-system fault.

Important: Verify electrical specifications from the exact model's datasheet and wiring diagram. Never assume that two actuators with similar appearances have the same voltage, control functions, or wiring requirements.

5. Select the Right Protection Level

Industrial electric actuators may be exposed to dust, rain, humidity, washdown, corrosion, or temperature changes. The required enclosure protection depends on the installation environment.

Ingress protection (IP)

An IP rating indicates protection against the ingress of solids and water under specified test conditions. The required rating should be selected according to the actuator's installation location and exposure.

For example, outdoor installation or locations exposed to water may require a different protection level from a clean, dry indoor control room.

However, an IP rating alone does not prove that an actuator is suitable for every outdoor, corrosive, submerged, or hazardous-area application.

Corrosive environments

In chemical plants, coastal facilities, or other corrosive environments, consider the housing material, surface treatment, fasteners, cable entries, and other exposed components.

Hazardous areas

If the actuator will be installed in an area where flammable gases, vapors, or combustible dust may be present, verify the applicable hazardous-area requirements. The actuator must have the appropriate certification and marking for the specific area classification.

Important: Waterproof or dustproof protection is not the same as explosion protection. Do not use a standard actuator in a hazardous area unless its certification and suitability have been confirmed.

6. Consider Operating Temperature and Duty Cycle

Operating temperature and duty cycle affect the suitability of an electric actuator for a particular application.

Operating temperature

High or low temperatures may affect motor performance, seals, lubricants, electronic components, and positioning accuracy.

Check the manufacturer's specified ambient-temperature range and confirm whether additional protection or a different configuration is required.

Duty cycle and switching frequency

The duty cycle describes how much operation an actuator is designed to perform over a given period. Some actuators are intended for intermittent open/close operation, while others are designed for frequent or modulating duty.

If an actuator operates repeatedly throughout a production shift, verify its rated duty and switching frequency. An actuator that is suitable for occasional isolation may not be suitable for continuous modulating control.

For high-frequency applications, consider motor temperature rise, operating time, allowable starts per hour, and the manufacturer's maintenance recommendations.

7. Check Fail-Safe and Emergency Requirements

A standard electric actuator does not necessarily return to a predefined position when power is lost.

If a process requires a valve to move to a safe position during a power failure, determine the required behavior before selecting the actuator.

Questions to ask include:

• Should the valve remain in its last position?

• Must it move to a fully open or fully closed position?

• Is backup power required?

• Is a spring-return or other fail-safe mechanism needed?

• What should happen during a control-signal failure?

Some applications may require a battery backup, a dedicated fail-safe actuator design, or a separate safety system. These capabilities should never be assumed to be included in a standard electric actuator.

The correct solution depends on the process risk assessment and the system's safety requirements.

8. Evaluate Mounting and Mechanical Compatibility

A suitable actuator must fit the valve mechanically and transmit torque safely.

Before ordering, check:

• Valve mounting standard and flange dimensions

• Stem or drive-shaft dimensions

• Coupling type and material

• Available installation space

• Required rotation angle or linear travel

• Manual override requirements

• Access to wiring and maintenance points

Incorrect mounting or coupling can cause misalignment, excessive mechanical stress, incomplete valve travel, or damage to the stem and actuator.

For automated valve assemblies, evaluate the valve, actuator, bracket, coupling, and accessories as a complete system rather than as independent products.

9. Consider Accessories and Feedback Functions

Depending on the application, electric actuators may be supplied with additional features or accessories.

Common options include:

• Position indicators

• Limit switches

• Torque protection

• Local control switches

• Position feedback

• Control modules

• Manual override mechanisms

• Communication interfaces

Not every model includes every function. Confirm which features are standard, which are optional, and which require additional wiring or control equipment.

For remote monitoring, check whether the actuator provides the required open/closed feedback or continuous position feedback. For modulating service, verify that the feedback resolution and positioning performance meet the process requirements.

10. Compare Total Cost of Ownership

Purchase price is important, but it should not be the only factor in actuator selection.

A lower-cost actuator may be suitable for a simple, low-duty application. For a critical process, a model with the required control features, environmental protection, and service support may offer better long-term value.

Consider the following cost factors:

For OEM and ODM projects, it is also useful to consider consistency across production batches, documentation, customization requirements, and long-term spare-parts availability.

11. Electric Actuator Selection Checklist

Use this checklist before requesting a quotation.

Providing these details helps the supplier recommend a suitable actuator and reduces the risk of ordering an incompatible model.

12. KINKO Electric Actuators for Industrial Valve Automation

KINKO supplies electric actuators and industrial valve automation products for a range of applications. When evaluating a KINKO electric actuator, buyers should confirm the exact model's torque output, power supply, control functions, protection rating, and compatibility with the target valve.

Depending on the selected configuration, product features may include an aluminum-alloy housing, a tempered-glass cover, sealing components designed to help limit moisture ingress, stainless-steel identification plates or connectors, and internal gear components designed for reliable operation. The availability of these features and their specifications should be confirmed for the individual model.

For OEM and ODM projects, KINKO can discuss application requirements such as:

• Valve and actuator matching

• Required torque and operating mode

• Electrical and control-system compatibility

• Housing and protection requirements

• Mounting dimensions and accessory configuration

• Branding and product customization

By confirming the application details before ordering, buyers can select an actuator that better matches the valve, control system, and operating environment.

Frequently Asked Questions

1. How do I choose the right electric actuator torque?

Obtain the valve manufacturer's operating-torque data for the actual process conditions. Then check the actuator's available output torque at the required supply and operating conditions, following the manufacturer's sizing guidance and safety margin.

2. Can one electric actuator operate both ball valves and butterfly valves?

Some electric actuators can be used with both valve types if the torque, rotation angle, mounting interface, coupling, and control requirements are compatible. Always verify the complete assembly specifications.

3. What is the difference between on/off and modulating electric actuators?

On/off actuators move the valve between defined positions, usually open and closed. Modulating actuators can position the valve at intermediate openings in response to a control signal, provided the model supports that function.

4. Is an IP-rated electric actuator explosion-proof?

No. An IP rating describes protection against the ingress of solids and water under specified conditions. Explosion protection requires the appropriate hazardous-area design, certification, and marking.

5. What information should I provide when requesting a quotation?

Provide the valve type and size, required torque, operating mode, power supply, control signals, environmental conditions, protection requirements, duty cycle, mounting details, and any required certifications.

Conclusion

Choosing the right electric actuator requires more than matching a motor to a valve. The actuator must provide sufficient torque, support the required operating mode, match the electrical and control system, and withstand the installation environment.

By checking valve specifications, torque requirements, power supply, control signals, protection ratings, duty cycle, mounting compatibility, and maintenance needs, engineers and buyers can reduce selection errors and improve the reliability of valve automation systems.

Looking for an electric actuator for your industrial valve project? Contact KINKO to discuss your valve specifications, torque requirements, control functions, and OEM/ODM needs.