JOHN FISCHER
Engineers in Brady, PA

4565305, Jan 21, 1986

May 31, 1983

6/499783

John Fischer - Montgomery PA
Kenneth A. Heaton - Lewisburg PA
John W. Pfeiffer - Hughesville PA

Koppers Company, Inc. - Pittsburgh PA

G01F 1124

222368

A rotary vane valve having a cylindrical housing with a pair of opposed end bells and an interior axial shaft. Opposed inlet and outlet openings on the side of the cylindrical housing allow transverse fluid flow through the housing and radial vanes project from the axial shaft to facilitate the transfer of fluid from the inlet at one pressure to the outlet at a different pressure. A pair of spaced shroud structures are fixed to the shaft at the ends of the vanes to generally separate the interior of the cylindrical housing from the end bells. These shroud structures are spaced from the cylindrical housing at their outer peripheral edges, but an annular throttle plate is spaced axially outwardly at a close distance from these shrouds and adjacent at its outer edge to the cylindrical housing to increase the velocity of purge gas flowing inwardly between the cylindrical housing and the outer peripheral edge of the shroud so that the escape of gas from the interior of the cylindrical housing is effectively prevented.