QT Series Electric Actuator

At Liangfa, we supply electric actuators for industrial valve automation where reliable quarter-turn operation, mechanical protection and practical maintenance are essential. Our QT Series Electric Actuator is designed for 90° rotary equipment, including butterfly valves, ball valves, plug valves and air dampers. 

It is available in on-off and modulating configurations, with standard IP67 protection and an optional Ex d IIB T4 flameproof version. As a high-tech enterprise, Liangfa provides product selection assistance, technical documentation and after-sales support to help customers choose equipment that matches their valve and operating requirements.

Choose the Right Control Mode

Different pipeline systems have different control objectives. Some valves only need to open or close on command, while others must adjust their opening according to flow, pressure or liquid-level requirements. We offer two main control configurations to suit these needs.

On-Off Control for Isolation

The QT-S on-off type is intended for applications where the valve moves between fully open and fully closed positions. It provides passive dry-contact feedback for the end positions, allowing a compatible control panel to receive valve-status signals. Typical applications include general water supply and drainage, fire-protection water systems and pipeline isolation where continuous flow regulation is not required.

Modulating Control for Process Adjustment

The QT-T modulating type accepts a 4–20 mA DC command and provides 4–20 mA valve-position feedback. This supports continuous positioning across the 0–90° operating range for compatible closed-loop control systems. It can be used in HVAC water circuits and process pipelines where the control system adjusts flow or pressure in response to changing operating conditions.

When ordering, please tell us whether the application requires simple end-position control or proportional adjustment. The control mode affects the required wiring, feedback signals and commissioning procedure.

Size the Actuator by Valve Torque

Nominal valve size is only a starting point for actuator selection. The torque required to move a valve can change with its design, seat material, differential pressure, medium viscosity and operating conditions. Selecting a model based only on DN size may result in insufficient output torque or unnecessary equipment cost.

We recommend obtaining the valve manufacturer's operating-torque data and applying a suitable safety factor. The selection guidance supplied for this series suggests a factor of approximately 1.2–1.5 for general water supply and drainage, and 1.8–2.0 for applications involving sediment, viscous media or high differential pressure. The final factor should be confirmed against the valve manufacturer's recommendations and actual process conditions.

The following examples from our selection information are intended for preliminary reference. Final model selection must be checked against the actual valve torque and mounting specifications.

These valve-size references apply to preliminary matching of soft-seated PN10/PN16 butterfly valves and must not replace the valve manufacturer's torque data. Hard-seated and double-eccentric butterfly valves may require substantially higher torque than soft-seated designs.

Plan for Speed and Operating Duty

QT Series Electric Actuator speed affects both valve response and the mechanical stress placed on a pipeline. For this series, the source selection guidance lists a speed of approximately 1.0 r/min for a 90° stroke time of around 10–15 seconds, and 0.7 r/min for a stroke of around 20 seconds. Actual operating time depends on the selected model and configuration, so please confirm it before placing an order.

For large butterfly valves and systems sensitive to water hammer, a slower operating speed may help reduce sudden changes in flow. The appropriate speed still depends on the process design, valve characteristics and required response time.

Understand the 10-Minute Duty Rating

The QT series is rated for 10-minute short-time duty. It is not intended for high-frequency, continuous back-and-forth modulation. If the process repeatedly moves the valve through short strokes without sufficient rest, motor heating and accelerated wear may occur.

For applications that demand continuous-duty modulation, we recommend discussing a suitable continuous-duty actuator rather than using this series outside its rated operating duty. This check is especially important for automatic control loops that frequently adjust valve position.

Mechanical Protection and Manual Operation

Valve jamming, excessive torque and incorrect travel settings can damage an actuator or its connected valve. The QT series combines mechanical and electrical protection features to help reduce these risks.

• Torque protection: Detects excessive operating load and helps stop the actuator during an overload condition.
• Mechanical and electrical limits: Help control end-of-travel movement and reduce the risk of over-travel damage.
• Motor thermal protection: The enclosed Class F insulated motor incorporates over-temperature protection.
• Power-off self-locking: The dual worm-gear transmission helps prevent unwanted valve movement when power is interrupted.
• Manual operation: A semi-automatic handwheel mechanism supports local operation during a power interruption, with automatic changeover to electric operation when power returns.
• Position indication: A visual position window helps operators check valve position locally.

These features do not eliminate the need for correct sizing and commissioning. If the actuator repeatedly trips on torque protection, check for valve obstruction, excessive differential pressure, incorrect model selection or a misaligned mechanical connection. Do not increase the torque-protection setting arbitrarily to force a jammed valve to move.

Protection for Outdoor and Hazardous Sites

The QT series uses a die-cast aluminum alloy housing with anodizing and epoxy coating. Standard IP67 protection is intended for demanding industrial environments, including outdoor installations and humid indoor areas. It also permits short-term immersion under the conditions defined by the rating, but it does not make the actuator suitable for permanent underwater operation.

For applications involving flammable or explosive gas, we offer an optional Ex d IIB T4 flameproof configuration. Ordinary IP67 protection is not explosion-proof certification, so the complete actuator must be selected according to the site's hazardous-area classification and applicable certification requirements. Appropriate explosion-proof cable glands and installation procedures are also necessary.

Temperature and Condensation

The standard ambient temperature range is -20°C to +70°C. This is the permitted surrounding-air temperature, not the process-medium temperature. When the QT Series Electric Actuator is mounted on a hot valve, an extended stem and heat-dissipation bracket may be required to limit heat transfer.

For outdoor sites with large day-to-night temperature changes or humid conditions, an optional dehumidifying heater can help reduce internal condensation. If the ambient temperature falls below -20°C, ask us to confirm a suitable low-temperature configuration. The standard unit should not be assumed to operate normally outside its specified range.

Match the Mounting Interface

The bottom flange follows ISO 5211 mounting dimensions in F05, F07 and F10 options. Before installation, confirm that the actuator flange matches the valve flange and that the output connection fits the valve stem.

The series can accommodate compatible square and round valve shafts using suitable shaft sleeves. If the flange dimensions do not match, an appropriate adapter bracket is required. Forcing an incompatible connection into place may damage the flange or twist the output shaft.

QT actuators are designed for 90° partial-turn valves and compatible air dampers. They are not suitable for directly driving multi-turn gate or globe valves. Those applications require a suitable multi-turn actuator.

Where the QT Series Is Used

Water Supply and Fire-Protection Systems

In waterworks, pump stations and fire-protection water systems, the on-off configuration can operate compatible butterfly valves for isolation and switching. End-position feedback can be connected to a compatible control panel where required by the system design. For large valves, the operating speed should be assessed to help manage water-hammer risk.

Wastewater Treatment

Wastewater and reclaimed-water facilities often have humid operating environments and may contain suspended solids. The actuator can be matched with compatible butterfly valves for isolation or flow control. Correct torque sizing is important where sediment or deposits increase valve resistance, while heavily corrosive gases may require additional protection or a different configuration.

HVAC and Building Services

For heating, ventilation and air-conditioning systems, the modulating configuration supports 4–20 mA control of compatible valves. It can be applied to chilled-water circuits and other systems requiring valve-position adjustment. Because the QT series has a short-time duty rating, it should not be selected for applications that require continuous, high-frequency reciprocating modulation.

Chemical and Petrochemical Facilities

For general chemical process lines without explosive hazards, the standard configuration may be suitable when the medium and ambient conditions are compatible with the housing and valve materials. Where a hazardous atmosphere is present, a properly certified flameproof version must be selected. Strongly corrosive gases and extreme temperatures require additional engineering review.

Power and Utility Systems

The series can be used for compatible rotary valves in power-plant circulating-water systems, ventilation and other utility applications. Mechanical self-locking and torque protection support valve operation, while model selection should account for vibration, torque demand and the required operating frequency.

Other Industrial Installations

Additional applications include municipal heating networks, industrial water treatment, dust-removal ventilation and selected marine or port utility systems. For salt-laden or highly corrosive environments, confirm the coating and material suitability before specifying the actuator.

Manufacturing and Quality Support

At Liangfa, we support customers from technical selection to production, inspection, shipment and after-sales service. As a high-tech enterprise, we provide product information and configuration guidance to help customers match the QT Series Electric Actuator with the intended valve and working conditions.

Our stated production service covers mold development, casting, precision machining, coating, assembly and export packaging. Factory inspection and applicable inspection documents can be arranged according to the order. Before production, we can review technical drawings, power supply, mounting interface, torque requirements and control mode with the customer.

We also provide installation guidance, operating and maintenance advice, and spare-parts support. The stated warranty period is 12 months from the date of shipment, subject to the applicable order terms.

Factory Tour

The following images show our manufacturing and production facilities. Please contact us if you need additional drawings or configuration details for your project.

Packaging and Delivery

We arrange export packaging and shipment according to the order requirements. Sea freight and land transportation are available, with shipping details and export documentation confirmed before dispatch.

Technical Service

Before the Order

We provide model-selection guidance based on valve type, operating torque, nominal size, medium, pressure, power supply and control requirements. Technical drawings, product parameters, quotation support and discussions about customized configurations can be arranged according to the project.

During Production and Shipment

We coordinate production updates, applicable factory inspection documents, export packaging and shipping information. The required export documents are confirmed according to the destination and order terms.

After Delivery

Our support includes remote installation guidance, operating instructions, maintenance advice, spare-parts assistance and technical consultation for valve replacement or pipeline upgrades. The stated response time for quality feedback is within 24 working hours.

Frequently Asked Questions

Can the QT series operate a gate valve?

No. This series is designed for 90° partial-turn equipment such as compatible butterfly valves, ball valves, plug valves and air dampers. Gate valves and globe valves generally require multi-turn actuation, so a suitable multi-turn actuator should be selected instead.

How do I reduce water hammer when operating a large butterfly valve?

The required response depends on the pipeline design and valve characteristics. The selection information lists a slower 0.7 r/min option with an approximately 20-second 90° stroke as a possible choice for large valves. Confirm the actual stroke time and system requirements before ordering.

Can the actuator run continuous modulation all day?

The QT series is rated for 10-minute short-time duty and is not intended for high-frequency, continuous reciprocating modulation. If your control loop frequently moves the valve back and forth, discuss a suitable continuous-duty actuator with us.

Does IP67 mean the actuator can remain underwater?

No. IP67 does not establish suitability for permanent underwater operation. If the application involves long-term submersion, a specifically designed and confirmed IP68 configuration is required.

What is the difference between the standard and Ex versions?

The standard model has IP67 protection but is not intended for explosive atmospheres. The optional Ex d IIB T4 version is designed for specified hazardous-area applications. Confirm the site classification, product certification and cable-entry requirements before purchase.

What details are needed for a quotation?

Please provide the valve type and size, operating torque or valve datasheet, ISO 5211 flange, shaft dimensions, required control mode, power supply, stroke-time requirement and site conditions. For hazardous-area installations, also provide the required area classification so we can review the appropriate configuration.

What payment and warranty terms do you offer?

The supplied commercial terms specify a 30% deposit after order confirmation, with the balance paid before shipment. The stated warranty period is 12 months from shipment, subject to the agreed order terms. Please confirm the applicable payment and warranty conditions with us when requesting a quotation.