The Belimo CQKB24-LL Fail-Safe Actuator is a compact, high-performance solution designed for safety-critical HVAC and building control applications. Featuring an integrated spring return mechanism, the actuator automatically drives connected dampers to a predefined safe position in the event of power loss, ensuring predictable and secure system behaviour during faults or emergencies.

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Nominal voltage	AC/DC 24 V
Nominal voltage frequency	50/60 Hz
Nominal voltage range	AC 19.2...28.8 V / DC 21.6...28.8 V
Power consumption in operation	2.5 W
Power consumption in rest position	0.5 W
Transformer sizing	5 VA
Electrical Connection	22 GA plenum cable, 3 ft [1 m], with 1/2" NPT conduit connector
Overload Protection	Electronic thoughout 0...90° rotation
Electrical Protection	Actuators are double insulated

The Belimo CQKB24-LL fail-safe actuator is built for spaces where precision and protection must coexist. Compact in size yet powerful in performance, it delivers dependable damper control during normal operation and instant, predictable positioning when power is lost. Designed for confined HVAC environments and safety-critical airflow systems, it ensures ventilation remains stable, controlled, and secure—no matter the conditions.

Bridging time (PF)	2 s
Pre-charging time	5...20 s
Angle of rotation	90°
Angle of rotation note	Adjustable with mechanical stop
Running Time (Motor)	75 s / 90°
Running time fail-safe	<60>
Noise level, motor	35 dB(A)
Noise level, fail-safe	35 dB(A)
Position indication	Pointer
Power source UL	Class 2 Supply
Degree of protection IEC/EN	IP40
Degree of protection NEMA/UL	NEMA 2
Enclosure	UL Enclosure Type 2
Quality Standard	ISO 9001

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Datasheets and Brochures

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Datasheets and Brochures

It is used to control HVAC dampers in applications where safety is critical, ensuring the damper moves to a predefined safe position if power is lost.

The actuator uses an internal spring return mechanism. When power is removed, the stored spring energy automatically drives the damper to its safe position.

It operates on a 24V supply, making it ideal for low-voltage HVAC and building automation systems.

Yes. The actuator can be set to move either open or closed on power loss, depending on the safety requirement of the installation.

It is commonly used in air handling units, VAV boxes, fire and smoke dampers, and compact ventilation systems in commercial and industrial buildings.

Yes. Its compact design makes it ideal for applications where space is limited, such as ceiling voids and small duct sections.

The spring return mechanism moves the damper to its safe position within seconds, providing rapid protection during emergencies.

Yes. It supports standard HVAC control methods, allowing easy integration into building management and control platforms.

Maintenance is minimal, typically limited to periodic functional testing and visual inspection. The spring mechanism is sealed for long service life.

Yes. The CQKB24-LL is designed for continuous duty and high cycle applications in HVAC environments.

Fail-safe actuators prevent uncontrolled airflow during faults, protect equipment, support fire and smoke strategies, and improve overall system safety.

Selection depends on damper size, torque requirement, control method, and safety needs. Matching these factors ensures reliable operation and compliance with system design requirements.

Please feel free to request information and advice using the form below or call us on 0151 547 1221

Belimo CQKB24 LL Failsafe Actuator