Model 3300 Round Counterbalanced Backdraft Dampers

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Vent_3300 Vent_3300dm1 Vent_3300dm1 Vent_3300dm2

STANDARD SPECIFICATIONS

  • FRAME: 6" to 7" dia. 14 ga. x 2" Galv. Steel.
  • BLADES: .080 aluminum.
  • AXLES: 1/2" x 2" plated steel rod.
  • BEARINGS: 1/2" dia. ball bearings (12" dia. and larger).
  • ADJUSTABLE WEIGHTS: 1 1/4" steel blocks on aluminum brackets (12" dia. and larger).
  • COUNTERWEIGHTS: 1/4" x 1 1/4" galvanized steel bars.
  • FINISH: Standard Mill.
  • MINIMUM SIZE: 6" dia.
  • MAXIMUM SIZE: 24" dia.
  • MAX. VELOCITY: 1500 f.p.m.

NOTES

  1. 11" dia. and less requires .063 aluminum blade (non-adjustable).
  2. 11" dia. and less require retractable bearing pins (axles).
  3. D is opening dimension. Unless otherwise specified, dampers are made 1/4" undersize.
  4. Multi-blade models not available.
  5. Model 3300 not recommended for fan discharge.

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