Damper Butterfly Valve

The butterfly or wafer damper can be a stack damper where leakage is not all-important. This type has also been tried as an isolating damper for flue-gas scrubbers. The butterfly damper is lightweight, simple, quickly actuated, and often comparatively low in cost. Its frame shape is a handicap in power plant work, however, where much ducting is rectangular. In process work, oval shapes adapt to that shape of duct, but conversion of a round butterfly to a rectangular one results in a louver damper. Occasionally, a double-disc butterfly appears, resembling a circular two-bladed louver damper.