This is the most basic of rectangular dampers in that it possess multiple rotating blades each hinged with two (2) stub shafts or a through-shaft. Rectangular frames are designed to limit deflection and combined stresses resulting from combined live and dead loads.
Blades are engineered to minimize static pressure loss while limiting deflection and combined stresses within ASME allowable stresses. All blades are welded airfoil shapes specifically designed to maximum design pressure, temperature and flow rate. Each blade is aligned with stub shafts or through shaft on a fixture prior to welding to ensure blade rotates concentric with bearings. Various blade stiffeners and design modifications are available enabling this airfoil design to isolate high pressures and temperature differentials.
Bearings are carefully selected for the maximum gas temperature considering heat transfer through gland and shaft. The packing gland is a 2-bolt design having formed packing rings, the number of which depends on the maximum design pressure. Leakage through the packing gland is zero (0) at design pressure.
A variety of seals are offered to provide isolation from 5% to 0.5% leakage downstream. A louver damper is the ideal solution for rectangular ducts for either gas isolation or flow control using parallel or opposed blade configurations.
Parallel and opposed blade linkage assemblies are designed to compensate for thermal gradients between frame and linkage. FE&M linkage components are maintenance-free designed to last the life of the damper. ‘Non-adjustable’ linkage with permanently lubricated high-cycle bushings is standard with ‘adjustable linkage’ offered as an option. Adjustable linkage features spherical rod ends for smooth operation and long life.
Standard actuators include electric, pneumatic, hydraulic and manual systems. Controls include directional valves for 2-position operation, positioners (electric & pneumatic) for flow control, position transmitters and position indicator switches.
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