Sizing Actuators for Damper Applications

The number of actuators required depends on several factors. Follow these steps to determine the quantity of actuators required for the installation.
STEP 1: Obtain damper torque ratings (ft-lb/ft2 or Nm/m2) from the damper manufacturer.

STEP 2: Determine the area of the damper.

STEP 3: Calculate the total torque required to move the damper as follows:

Enter Torque Rating of Damper (see "Caution" below) (in-lb/ft2):
Enter Damper Area Width (inches):
Enter Damper Area Height (inches):
 
Total Required Torque is:
in-lb

Caution: To ensure proper actuator sizing use the manufacturer's recommendation for torque requirements.

Manufacturer's torque requirements very greatly depending on seals, static pressure, velocity and damper design. If no additional information is available, use the following rule of thumb: 6 in-lb/ft2.

DEI Operational Torque for Control Dampers:

CONTROL DAMPERS:

Torque:

When Static Pressure = 1/2 inch W.C. and Velocity = 100 fpm:
with seals: 4.6 in-lb/sq. ft.
without seals: 3.1 in-lb/sq. ft.
When static pressure = 1 inch W.C. and Velocity = 1000 fpm:
with seals: 6.0 in-lb/sq. ft.
without seals: 3.5 in-lb/sq. ft.
ROUND DAMPERS:

Torque:

Actuator Torque Required for Closing at 1500 fpm Velocity
4 to 8 inch Diameter Damper: 5 lb-in minimum
9 to 16 inch Diameter Dampers: 15 lb-in minimum
17 to 22 inch. Diameter Dampers: 25 lb-in minimum

 

STEP 4: Select the total quantity of actuators required:

Total Damper Torque Req'd:
Safety Factor1:
Enter Actuator Torque*:
 
Number of actuators needed:
*Refer to Damper Manufacturer's Specifications

1 Safety Factor: When calculating the number of actuators required, a safety factor should be included for unaccountable variables such as slight misalignments, aging of the damper, etc. A suggested safety factor is 0.80 (or 80% of the rated torque).

Mechanical coupling of the actuator is allowed if:

  • The same type of actuator is used.
  • The power trunk can handle added components.
  • The same control input goes to both actuators (parallel wiring) for 2 position and tri-state control.

For modulating actuators, 2 methods may be used. Call DEI for details.

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