Stabilizing check valve

A check valve comprising a housing, an annular abutment in the housing forming a central opening, and a check valve assembly mounted on said abutment, said abutment having a valve seat thereon,

• said assembly comprising a guide, a spring mounted between portions of the guide and said abutment normally tending to hold the check valve assembly substantially in upstream closed position,
• a head on said guide, said head being located at the downstream side of the abutment, said head having a base facing the abutment,
• an elastomeric disc between the base of the head and the abutment, said elastomeric disc having a diameter greater than the opening through the abutment, and the base of the head having a recess therein facing the disc and receiving portions of said disc under conditions of retropressure, the disc having a stability normally maintaining it generally free of the recess,
• said head being substantially conical and having a flat apex area facing downstream, a fastener having a fastener head located in the flat apex area of said conical head and a part of the fastener passing through said conical head and secured with respect to said guide, said recess in the base of said head comprises an annular groove facing said disc, said groove having a bottom inclined with respect to the axis of the housing and of the check valve assembly, said inclined bottom extending from a central portion of the base of said head outwardly and in a downstream direction, said elastomeric disc having a rounded surface facing said abutment and said valve seat, and means on the guide to anchor said spring at the end thereof opposite said abutment.