This is the most basic of dampers in that it possess a single rotating butterfly blade hinged by two (2) stub shafts.
The heavy-duty frame is available in ‘flanged’ and ‘weld end’ configurations. The blade is a thick flat plate inspected to ensure flatness to desired tolerances. It is aligned with stub shafts on a fixture prior to welding to ensure blade rotates concentric with bearings.
Various blade stiffeners are available enabling the 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 seats are offered to provide isolation from 5% to 0.25% leakage downstream.
While the standard butterfly damper is ideal for isolation, it is also used for control of gas as well. 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.
