BELIMO LM24AX-S-TP 5NM LMA T20 1TP 000 AC/DC 24V

The BELIMO LM24AX-S-TP is a 24V AC/DC spring-return rotary actuator. It is designed to automatically control the position of quarter-turn (90°) ball valves or butterfly valves in heating, ventilation, and air conditioning (HVAC) systems. Its primary function is to regulate the flow of water, glycol mixtures, or steam in pipes to control temperature, pressure, or energy usage in a building.

Detailed Breakdown of the Model Code

BELIMO model numbers are highly descriptive. Here’s what each part means:

• BELIMO: The manufacturer, a Swiss leader in HVAC field devices.

• LM24: LM = Actuator Family (Linear/Multi-voltage), 24 = 24V AC/DC power supply.

• A: A = Modulating (Analog) Control. This actuator can position the valve to any angle between 0° and 90° based on a received control signal.

• X: X = Extra Torque. Indicates this is a higher torque version.

• -S: S = Spring-Return. This is a critical safety feature. In the event of a power failure, an internal spring automatically returns the actuator and the connected valve to a predefined “fail-safe” position (either fully open or fully closed).

• -TP: TP = Two-Potentiometer. It has two internal potentiometers for feedback:

  • One provides a 0-10V DC or 20-1000Ω feedback signal to the controller, reporting the actual valve position.

  • The other is used for setting the mechanical endpoints during commissioning.

• 5NM: 5 Newton Meters. This is the output torque. 5 Nm is a medium-high torque, suitable for operating larger or slightly stuck valves.

• LMA: L = Standard Profile, M = Manual Override, A = With Auxiliary Switch.

  • Manual Override: Allows a technician to manually operate the valve for testing or maintenance without power.

  • Auxiliary Switch: A built-in switch that can be used to send an on/off signal to another device (e.g., a pump or an alarm) based on the valve’s position.

• T20: T = Thermal Protection, 20 = 20 Amps. The actuator has an internal thermal protector that disengages the motor if it overheats, preventing damage.

• 1TP 000: This is a factory configuration code related to the specific internal setup (e.g., potentiometer values, auxiliary switch settings).

• ACDC 24V: AC/DC 24V. The actuator can operate on either 24 Volts Alternating Current (VAC) or 24 Volts Direct Current (VDC), making it very versatile for different power supplies.

Key Features

1. Modulating Control: Allows for precise, proportional control of fluid flow, leading to better temperature stability and energy efficiency compared to simple on/off actuators.

2. Spring-Return (Fail-Safe): Essential for safety and energy management. The valve can be set to automatically open or close if power is lost (e.g., close a heating coil valve to prevent overheating, or open a cooling valve to prevent freezing).

3. High Torque (5 Nm): Provides the strength to operate larger quarter-turn valves and valves that may be stiff from scale or disuse.

4. Manual Override: Crucial for system commissioning, troubleshooting, and maintenance without needing to disconnect the actuator from the valve.

5. Position Feedback: The control system receives a signal confirming the valve’s actual position, allowing for closed-loop control and fault detection.

6. Auxiliary Switch: Provides an additional control point, often used to interlock a pump with the valve’s position.

7. Universal 24V AC/DC Power: Simplifies inventory and can be used with a wide range of transformers and power supplies.

Typical Applications

This actuator is used in various HVAC applications, including:

• Control valves on heating and cooling coils in Air Handling Units (AHUs).

• Control valves for radiant heating/cooling systems.

• Zone control valves in hydronic heating systems.

• Two- and three-way mixing valves for temperature control.

• Domestic hot water recirculation systems.