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Damper Actuator Sizing Chart

One of the most frequent problems that technicians face is how to determine the correct torque actuator for their damper. These tables should help. First determine the size and type damper, then determine the air flow that the damper needs to open and close against. From that point, use the charts below to determine the amount of torque needed.

Damper Type Up to 1000 fpm 1000-2500 fpm 2500-3000 fpm
Opposed Blades without Seals 3 in.-lbs./sq.ft. 4.5 in.-lbs./sq.ft. 6 in.-lbs./sq.ft.
Parallel Blades without Seals 4 in.-lbs./sq.ft. 6 in.-lbs./sq.ft. 8 in.-lbs./sq.ft.
Opposed Blades with Seals 5 in.-lbs./sq.ft. 7.5 in.-lbs./sq.ft. 10 in.-lbs./sq.ft.
Parallel Blades with Seals 7 in.-lbs./sq.ft. 10.5 in.-lbs./sq.ft. 14 in.-lbs./sq.ft.


Opposed Blades without Seals
Torque required (in.lbs.)
sq.ft. <1000 fpm 1000-2500 fpm 2500-3000 fpm
5 15 23 30
10 30 45 60
15 45 68 90
20 60 90 120
25 75 113 150
30 90 135 180
35 105 158 210
40 120 180 240


Opposed Blades with Seals
Torque required (in.lbs.)
sq.ft. <1000 fpm 1000-2500 fpm 2500-3000 fpm
5 25 38 50
10 50 75 100
15 75 113 150
20 100 150 200
25 125 188 250
30 150 225 300
35 175 263 350
40 200 300 400


Parallel Blades without Seals
Torque required (in.lbs.)
sq.ft. <1000 fpm 1000-2500 fpm 2500-3000 fpm
5 20 30 40
10 40 60 80
15 60 90 120
20 80 120 160
25 100 150 200
30 120 180 240
35 140 210 280
40 160 240 320


Parallel Blades with Seals
Torque required (in.lbs.)
sq.ft. <1000 fpm 1000-2500 fpm 2500-3000 fpm
5 35 53 70
10 70 105 140
15 105 158 210
20 140 210 280
25 175 263 350
30 210 315 420
35 245 368 490
40 280 420 560

If possible, refer to the damper manufacturer’s torque specification, to be sure.