Louver Damper Square/Rectangular

Design Sheet
Louver Dampers
Damper Installation Manual

Precision Flow Control, Man Safe Isolation in Hostile Environments

Flextech’s complete line of multi-blade louver dampers provides reliable modulation and isolation in many applications. All designs are heavy-duty and have multiple blades of an airfoil or monocoque profile, outboard bearings, and individual packing glands to achieve zero leakage around the shafts. Our designs offer quick response and fast operating cycles.

The louver damper is capable of providing accurate and repeatable flow control for all applications. The sealing efficiency of single louver dampers will vary from 91% to 99.5%. 100% isolation can be achieved with the double louver damper, which is equipped with Seal Air Purge.

Single Louver Dampers

Single louver dampers provide a combination of isolation and flow control. The assembly consists of a single row of blades, all of which are externally linked in a parallel or opposed configuration depending upon the desired flow pattern. The parallel arrangement is often used on fan inlets to optimize fan performance. The opposed arrangement is used where a more linear flow is desired—such as fan outlets.

Double Louver Dampers

Single louver dampers provide ‘man safe’ isolation by incorporating two rows of blades that are equipped with flexible metal seals and a seal air system. When both rows of blades are closed, the seal air fan is energized, thereby pressurizing the space between the
blade rows to a pressure that is typically 3” W.G. above the duct operating. As a result, gas leakage across a damper assembly is prohibited.

The double louver damper can be supplied with one row of blades operating in the parallel and the other in the opposed configuration, thereby allowing modulation as well as isolation in a single unit.

Advantages –Flextech Louver Dampers
  • Good modulation and control characteristics.
  • Fast operating speeds.
  • Little or no outside space requirements for support structure.
  • All seals are internal to the duct, no leakage to the ambient side
  • Lower Cost

The louver damper is capable of providing accurate and repeatable flow control for all applications. 100% isolation can be achieved with the double louver damper, which is equipped with Seal Air Purge. The sealing efficiency of single louver dampers
will vary from 90% to 99.5%.

Louver Damper Applications Include:

Scrubber Systems – Stack Isolation – Control Air Systems – Balancing Systems – Incinerators – Bag House

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Blade Types

Flextech offers two basic blade types for its louver dampers:

Airfoil Blade

The airfoil blade is recommended for modulation or isolation of clean to moderately dirty gas applications. The blade is constructed of two plates that are formed around a center shaft. Our rugged design resists both bending and torsional twisting of the blade. It will
also reduce vibration and fluttering while minimizing pressure loss. This configuration is used in moderate pressure and temperature environments where flow velocity does not exceed 4,000 to 5,000 feet per minute..

Monocoque Blade

The monocoque blade is recommended for modulation and isolation in high-pressure and -temperature, dirty, or corrosive applications. The blade is constructed of two skins and an internal stiffener and is rigidly assembled using welded construction. For severe operating conditions, alternate blade design and construction is available.

  • Relatively high strength-to-weight ratio maximizes stability and minimizes profile depth and pressure drop
  • Efficient use of materials makes this design effective in applications requiring stainless steel or other alloys
  • Corrosion-resistant stub shafts are welded to an internal structure at each end of the blade, forming a secure connection
  • Capable of isolating extremely high temperatures without being damaged
Seals

Depending on the degree of isolation desired, the damper can be equipped with an assortment of flexible seals. A full set of seals consists of blade to blade, blade to frame, and blade to side frame. (The design of the shaft seal may vary.)

Linkages

Fixed linkages are standard; however, adjustable linkages are available. The design is heavy-duty, low-cost, and ideal for both modulation and isolation.

Louver Damper Actuator Systems

Flextech’s louver dampers are supplied with a range of actuator and control systems, including Manual, Pneumatic, Hydraulic, and Electric.

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Common Louver Damper Materials

Frame and Blade Materials:

  • ASTM A36 Carbon Steel
  • ASTM A242/588 Cor-Ten-Steel
  • 310 Stainless Steel
  • 221 Stainless Steel
  • 330 Stainless Steel
  • HR120
  • Hastelloy C276

Seal Material:

  • 304 and 304L Stainless Steel
  • 316 and 316L Stainless Steel
  • 310 Stainless Steel
  • 221 Stainless Steel
  • 330 Stainless Steel
  • HR 120
  • Hastelloy c276

Other material available

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