Magnetic operator flow device

Claim 1

A magnetically operated flow device disposed within a flow passage defined by an encircling inwardly facing wall and defining upstream and downstream directions, said flow passage being at 1east generally regular in transverse cross-sectional shape about a central zone of said flow passage, a thin, lightweight, flat and magnetically attracted flow responsive valve plate disposed in said flow passage and movable therein in upstream and downstream directions between upstream and downstream limit positions and constituting a partial drag obstruction to fluid flow through said passage outwardly of said central zone and thus being biased in a downstream direction by fluid flow through said passage in said downstream direction, support means mounted in said central zone upstream from said upstream limit position in spaced relation relative to the wall of said flow passage for fluid flow through said passage in said downstream direction about said support means, said support means including an abutment portion in said central zone projecting from said support means in said downstream direction and defining a downstream facing abutment against which said valve plate may abut to define said upstream limit position thereof with said valve plate disposed generally normal to the longitudinal extent of said passgge, magnet means mounted from said support means centrally in said passage and spaced a predetermined distance upstream from said upstream limit position of said valve plate to define a predetermined gap between said magnet and said valve plate when the latter is in said upstream limit position, said valve plate occupying a sufficient cross-sectional area of said passage outwardly of said central zone to effect said partial drag obstruction, said gap being of a dimension measured longitudinally of said flow passage and the magnetic attraction between said magnet and said valve plate when the latter is in the upstream limit position thereof being sufficiently low such that low gas flow at low differential pressure less than one PSI will be sufficient to shift said valve plate in said downstream direction from said upstream limit position to said downstream limit position, an annular seat body mounted transverse in said passage from said wall with one axial end thereof positioned for abutment by said valve plate when the latter is in said downstream limit position and disposed generally normal to said passage, said valve plate including a central imperforate portion thereof of greater area than the area bound by the inner periphery of said annular seat body, the magnetic attraction between said magnet and valve plate, when the latter is in said downstream limit position and said valve plate is free of differential pressure acting thereon, being sufficient to effect positive magnetic retrieval of said valve plate in said upstream direction from said downstream limit position to said upstream limit position, said valve plate including an outer periphery defining peripherally spaced guide projections in close proximity to said flow passage all for guiding movement of said valve plate between said upstream and downstream limit positions.