Duct component selection
Combine damper dimensions and documented torque factors to estimate actuator torque and selection margin.
Estimate actuator torque from the actual damper area and manufacturer torque rate, apply an explicit allowance, and compare a supplied actuator rating.
An area-based actuator estimate scales a documented damper torque requirement by damper area and an explicit allowance factor. The torque rate must describe the actual assembly and operating pressure; seals, bearings, blade geometry, and linkage can change the needed torque. If the manufacturer provides total assembly torque directly, that requirement deserves separate attention rather than an invented area rate.
The actuator rating is compared with the calculated requirement to obtain a signed torque margin. A positive margin answers only the torque question under the entered conditions. Stroke, control signal, fail-safe behavior, operating time, and environmental suitability are separate parts of selecting an actuator.
Required torque = damper area × specified torque per area × selected allowance factor; margin = rating − requirement
A negative margin is an entered-rating shortfall. A positive margin supports further actuator review but does not select or approve a product.
Inputs: Historical Belimo example: 8 ft² damper area and a selected 4 in-lb/ft² torque rate; factor 1. For comparison, enter an actual rating of 40 in-lb.
Calculation: 8 × 4 × 1 = 32 in-lb required.
Result: 32 in-lb required and an 8 in-lb arithmetic margin against the entered 40 in-lb rating.
No. It leaves the area-based requirement unchanged. Any additional allowance must be explicitly justified for the damper and project.
It establishes only the entered torque comparison. Confirm the applicable rating, fail-safe direction, linkage, travel, and service conditions for the real actuator.