Technical Instructions
POWERS™ Controls No. 6 Pneumatic Damper Actuator
Document No. 155-029P25
December 3, 2004
Actuator Sizing
The quantity of actuators required depends on several torque factors. To determine the
quantity of actuators required for the installation:
1. Obtain damper torque ratings (ft-lb/ft
2
) from the damper manufacturer.
2. Determine the area of the damper.
3. Calculate the total torque required to move the damper:
Total Torque = Torque Rating x Damper Area
4. Calculate the total quantity of actuators required:
Number of
Total Damper Torque Required
Actuators
=
SF
1
× Actuator Torque (see Table 2)
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).
See
AB-300 Damper Actuator Sizing and Selection Application Bulletin in the HVAC
Systems/Controls Reference Data
(125-1853) for additional sizing information. See
TB-181 Powers™ Controls Maximum Thrust Ratings of Pneumatic Damper Actuators
Technical Bulletin
(155-219P25
)
for additional torque requirements.
Table 2. Thrust and Torque Rating.
Maximum Thrust lb. (N)
Torque Rating* lb-in (Nm)
Full Stroke Forward
2-Position Operation
or Positioner
Nominal
Spring
Range
15psi
(103 kPa)
18 psi
(124 kPa)
25 psi
(172 kPa)
Spring
Return
(No Stroke)
0 psi (0 kPa)
Gradual
Operation
15 psi
(103 kPa)
18 psi
(124 kPa)
25 psi
(172 kPa)
3-8 psi
(21-55 kPa)
125 (556) 179 (796)
304
(1352)
54 (240)
50 (5.6)
75 (8.5)
75 (8.5)
75 (8.5)
3-13 psi
(21-90 kPa)
36 (160)
89 (396) 214 (952)
54 (240)
50 (5.6)
75 (8.5)
75 (8.5)
75 (8.5)
8-13 psi
(55-90 kPa)
36 (160)
89 (396) 214 (952)
144 (640)
50 (5.6)
202 (22.8) 202 (22.8) 202 (22.8)
*
With maximum hysteresis of 2.5 psi (17.2 kPa) @ 90° rotation.
Page 4
Siemens Building Technologies, Inc.
