# Siemens 331-2856, 332-2856 AP 331-3 Technical Instructions page 4

Powers controls no. 6 pneumatic damper actuator

Technical Instructions
Document No. 155-029P25
December 3, 2004
Actuator Sizing
Nominal
Full Stroke Forward
Spring
Range
15psi
(103 kPa)
3-8 psi
125 (556)
(21-55 kPa)
3-13 psi
36 (160)
(21-90 kPa)
8-13 psi
36 (160)
(55-90 kPa)
With maximum hysteresis of 2.5 psi (17.2 kPa) @ 90° rotation.
*
Page 4
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. 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
=
Actuators
SF
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)
18 psi
25 psi
(124 kPa)
(172 kPa)
179 (796)
304
(1352)
89 (396)
214 (952)
89 (396)
214 (952)
POWERS™ Controls No. 6 Pneumatic Damper Actuator
2
) from the damper manufacturer.
Total Damper Torque Required
1
× Actuator Torque (see Table 2)
Spring
Return
Operation
(No Stroke)
0 psi (0 kPa)
54 (240)
50 (5.6)
54 (240)
50 (5.6)
144 (640)
50 (5.6)
Torque Rating* lb-in (Nm)
2-Position Operation
or Positioner
15 psi
18 psi
(103 kPa)
(124 kPa)
75 (8.5)
75 (8.5)
75 (8.5)
75 (8.5)
202 (22.8) 202 (22.8) 202 (22.8)
Siemens Building Technologies, Inc.
25 psi
(172 kPa)
75 (8.5)
75 (8.5)