Butterfly valve and system employing same and method for using same field

Abstract

A butterfly valve comprises: a body including a valve opening; and a flapper rotatably mounted about a rotation axis so as to be movable relative to the valve opening. The flapper is rotatable at least 180° about the rotation axis so that the flapper is movable to at least one fully opened position, at least one fully closed position 90° apart from the fully opened position, and a third position, either fully opened or fully closed, 180° from the other like position. In one embodiment the flapper is rotatable at least 360° about the rotation axis so that the flapper is movable to each of two opened positions 180° apart, and two closed positions 180° apart from each other and 90° and 270° apart from each of the fully opened positions. The valve can be easily calibrated and controlled, and cleaned to extend the useful service life between cleanings.

Dependencies are inferred from the claim text.