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Butterfly Dampers

Butterfly dampers are typically used to intercept or regulate gas flows; they are similar to single-louver dampers with one blade and they can be used in round or square/rectangular ducts.

Blade is typically designed with air-foil configuration which minimizes the pressure drop; shafts are made of solid section and “stub” type to be connected to the blade by keys and blocks. This basic rule of design will optimize the assembly operations reaching high accuracy; in addition, in case of need, the blade can be removed from the damper frame without removing the complete unit from ductwork.

Actuation system is normally by electric actuator, pneumatic actuator or manual by irreversible gear box.

Butterfly dampers can be supplied with internal or external fiber insulation or, when required, with internal concrete (refractory) insulation. A large variety of metals are used in design and fabrication, from simple carbon steel to stainless steel and low-alloy/high-alloy materials.

Several types and configurations of Butterfly dampers are available: feel free to contact us for any request or application you need.


  • Flow Control of gas in round ducts is best accomplished with round opposed-blade .
  • Butterfly dampers provide excellent control of static pressure and volume in mid-range, but less than adequate low-flow control when compared to opposed-blade louvers.
  • Radial vane dampers are preferred for control of gas entering centrifugal or radial fans.
  • Flap diverter dampers are designed to control flow during startup of waste heat equipment.
  • Positioning devices with analog or digital inputs are available to maintain reliable flow control on most damper configurations.
  • Feedback instrumentation is available to provide exact positioning data


  • Scrubbers
  • Precipitators
  • Oxidizers
  • Bag houses
  • Heaters

The body of butterfly damper is fabricated from different type of material suitable for site condition and client requirement. Standard materials of construction for critical parts of butterfly damper are-

  1. Body :A36, IS 2062, A516, IS 2002, Corten, SS 304,SS 316, Inconel etc.
  2. Blade :A36, IS 2062, A516, IS 2002, Corten, SS 304,SS 316, Inconel etc.
  3. Shaft :En8, SS 410, SS 304,SS 316, Inconel etc.
  4. Seal : SS 316Ti, Inconel etc.
  5. Bearing : C.I lined Bush type with Grafoil Sheet maintenance free/ Antifriction
  6. Shaft Packing :SS 316Ti/ Braided Graphite.

Other materials of construction can be used as required by client.

These dampers are design for sealing up to 99.9% without seal air system and 100% with seal air system. Type of seals: Omega seal/ Solid seal

Butterfly dampers can be provided with one side or double side drive as required by client.
Types of drive
   – Manual by Hand Wheel/ Lever/ Chain/ Winch Pulley Arrangement
– Motorized
– Pneumatic


CEMENT      STEEL            POWER


performance advantages

  • 99% sealing efficiency with standard structural seal

(99.5% with optional jamb seals and blade edge seals)

  • Low pressure drop airfoil blade design
  • Superior flow and pressure control with opposed blades
  • Superior flow isolation and fan spin control with parallel blades
  • High structural rigidity to eliminate frame distortion and blade jamming

standard design features

  • Welded monocoque airfoil blades
  • Fixed linkage employs hardened steel pivots with thin-film PTFE (Teflon®) bushings
  • Ball bearings on blade shafts
  • Shaft seal gland consists of two compressible rings mounted separately from bearing
  • Actuator is mounted directly to driving shaft, reducing frame flex and hysteresis.

” Since 1996 Miteck systems have earned a reputation on designing & manufacturing of Butterfly Dampers also we have expertise in Guillotine Dampers, poppet dampers, lover dampers, Hoisting dampers, Recently we have supplied Marine ship scrubber gas dampers which are approved by American Bureau of the society of shipping, please send us an email on for more information “