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SCD-LL-HD - Heavy Duty Control Dampers Low Leakage

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SCD-LL-HD - Heavy Duty Control Dampers Low Leakage


The SCD-LL-HD series dampers have been designed and tested to provide rigid, robust and yet cost effective control dampers for special applications involving high pressure up to 9.0” w.g.

The SCD-LLHD dampers have a pressure sensitive jamb and the blade edge seals to provide the ultimate in sealing characteristics without unduly increasing torque requirements. The SCD-LL-HD series damper’s rigid frame and integrally braced corners provide true damper alignment that greatly resists being installed out of square or out of flat. This ensures on site performance equal to test results. Factory installed electric motors are available.
Consult factory for details.

  • FRAME: roll-formed galvanized steel hat section with staked corners with integral bracing & roll-formed galvanized steel C channel insert welded to provide equivalent of 12 gauge steel.
  • BLADE: 16 gauge roll-formed galvanized steel & 18 gauge roll-formed galvanized steel continuous rigidizing section to provide equivalent of 10 gauge steel.
  • BLADE STYLE: Opposed blades are standard; parallel blade on request
  • BEARINGS: bronze oilite, press fit into frame.
  • AXLES: square, plated steel PVC.
  • SEALS: pressure sensitive, dual durometer blade edge seals and flexible metal jamb seals.
  • LINKAGES: concealed in frame. Leakage bars are 12 gauge thick galvanized steel.
  • FINISH: mill galvanized.
  • EXTENDED SHAFT: 0.5” diameter, plated steel.
  • SIZES: Minimum size: 8” W x 8” H (203 mm x 203 mm); Maximum size: single section - 60” W x 72” H (1524 mm x 1829 mm); Multiple section - unlimited size.
  • See Controls & Thermostats section for Belimo motor options.

Note: Non-standard shutters are non-returnable and cannot be cancelled.


  • BEARINGS: nylon, press fit into frame
  • Silicone blade edge seals


Ordering Method

NOTE: dampers are furnished approximately 1/4” smaller than given duct dimensions. Not recommended with blades running vertically. All dampers 32” and over are supplied with Jack shafting.


The SCD-LL-HD dampers have been tested to AMCA Standard 500-D with the following results: 
AT 1.0" w.g.AT 4.0" w.g.AT 8.0" w.g.AT 8.0" w.g.