Model BSI (Square or Rectangular) and Model BRI (Round) more info page

Model BSI (Square or Rectangular) and Model BRI (Round)

Heavy duty industrial grade butterfly dampers are custom designed for use in high temperature and pressure applications where special flanges and other custom features are required.

Flange size and drilling is to customer specifications.

Designs and material options are available for operating temperatures up to 2000° F and differential pressures to 6 PSI.


We can build our butterfly dampers integrally into a tee or “Y” duct section with an operator mounted to one damper and a slave linkage to the other damper. The linkage can be arranged so that as one damper opens, the other damper will close, These are widely used for process air or gas diversion applications. The complete pre-assembled and adjusted unit is shipped to the job site for easy installation, saving time and cost.

FRAME: Carbon steel body band with continuous welded flanges. Our standard flange drilling. FRAME: Stainless steel, corten, aluminum or any other weldable material. Structural channel is available for larger size dampers.
VANES: Single thick plate offset and formed at shaft for extra strength. reinforcing ribs are provided as required for intended service. The vane is welded to a continuous thru shaft. VANES: Stainless, corrosion and abrasion resistant materials.
SHAFTS: C-1018 CRS continuous through shaft. Shaft ends are marked to indicate vane position. SHAFTS: Stainless steel continuous or stub shafts.
BEARINGS: Ball bearings mounted outboard on stand-offs, over adjustable packing glands. BEARINGS: High temperature carbon sleeve bearings. (Stainless steel shafts are recommended when using these bearings.)
GLANDS: Adjustable plate & follower design with fiberglass rope packing. GLANDS: Ceramic rope packing or any other commercially available packing material.
SEALS: No internal vane seals provided. Swing clearance between vanes and frame for approximately 90% shut-off when fully closed. SEALS: Optional seals for up to 99% shut-off available.
PAINT: Damper is hand cleaned and painted one shop coat of our standard industrial primer.  PAINT: Special surface preparation and coatings are available.
OPERATOR: None. Extended operator shaft is provided for customer use.  OPERATOR: Wide range of manual, electric, pneumatic and hydraulic operators with options for modulating, fail safe, switches, etc.

  • Mounting of customer supplied operator and accessories.
  • Inlet screens, mating flanges, special duct sections. (tees, transitions, weather hoods, etc.)
  • Castable refractory linings, heat shields, position indicating switches, slave linkages.