Brochure

6
Physical Properties: Know the Measurements
Finding these four data points are crucial to understanding what torque is required for the application,
so that the right actuator is chosen.
#1 Evaluate the total area of the damper
First, find the square footage of your damper. Check if
the damper section is longer than 96". If it is, then it
must have two total actuators on the shaft - one on
either side of the damper. This eliminates any deflection
or binding that may happen when operating a damper
of that length.
#2 Determine blade configuration
Next, determine the blade configuration or blade
action. This is critical since the torque required to
operate these dampers differs. This is due to the airflow
passing between the damper blades while rotating
open or closed. Depending on the configuration and
the direction of the airflow, there may be an assistance
provided during a part of the actuator stroke.
#3 Type of damper seal – blade or edge?
While looking at the blade configuration, it will be easy
to determine if there are edge, blade seals or both on
the damper. This typically depends on the leakage
rating of the dampers, and what the supplier has
specified.
If seals are located on the damper, the torque value
would increase compared to an assembly that had no
seals. This is due to the seals needing to be properly
engaged at the start or end of the actuator stroke to
make sure the damper assembly meets the leakage
specification.
#4 Air velocity, static pressure or designed CFM to be used in the system?
The last major point is knowing the maximum air
velocity, maximum static pressure or the maximum
designed CFM that this damper will be subjected to.
Knowing this is a critical piece of information since the
manufacturer’s torque tables, along with the Siemens
table, has varying torque factors based on the max air
velocity or pressure differences.
L” x W” = (Total sq. inches / 144) = Total sq. Ft.
W"
L"
Opposed Blade
Airflow through
opposed blade damper
at one-third closed
Parallel Blade
Damper
Blade Seal
Damper
Blade
Damper
Blade Pin
End Seal
Bottom
Seal