Mks Instruments, Inc.

Robert Krmpotich

Paul D Lucas

David Brian Chamberlain

Jaroslaw Wojciech Pisera

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&#xb0; about the rotation axis so that the flapper is movable to at least one fully opened position, at least one fully closed position 90&#xb0; apart from the fully opened position, and a third position, either fully opened or fully closed, 180&#xb0; from the other like position. In one embodiment the flapper is rotatable at least 360&#xb0; about the rotation axis so that the flapper is movable to each of two opened positions 180&#xb0; apart, and two closed positions 180&#xb0; apart from each other and 90&#xb0; and 270&#xb0; 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.

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Salem, NH, United States of America

Robert Krmpotich