Valve assembly for reciprocating plunger pump

A replaceable discharge valve assembly for a reciprocating high pressure plunger pump having a cylinder block forming a generally cylindrical valve chamber, said valve chamber including a first chamber portion of a first diameter intersecting and opening into a cylinder bore in said block, a second chamber portion of a second diameter larger than said first diameter extending from a transverse endwall between said first and second chamber portions toward an outer wall of said block, and a third chamber portion having a wall of a diameter larger than the diameter of said second chamber portion and disposed between said second chamber portion and said outer wall, and a discharge port opening into said valve chamber, said valve assembly comprising:

• a cylindrical tubular valve seat member including a first portion of a first diameter for insertion in said first chamber portion, a second portion of a second diameter for insertion in said second chamber portion, said seat member being slidably insertable into said valve chamber in close fitting relationship thereto and with a surface of said seat member abutting said endwall;
• a seal ring disposed around the outer circumference of one of said portions of said seat member for sealing engagement with only the bore wall forming one of said first and second chamber portions;
• a seating surface formed on one end of said seat member and an inner cylindrical surface defining a flow passage extending from the other end of said seat member and delimiting said first portion of said seat member;
• a valve member slidably disposed in said seat member for movement relative to said seat member and engageable with said seating surface;
• and
• a generally cylindrical discharge valve cover having means on one end engageable with said seat member for retaining said seat member in said valve chamber in abutting engagement with said endwall, said valve cover including a cylindrical portion dimensioned to be disposed in said third chamber portion in close fitting relationship to said block in said third chamber portion, a seal ring disposed around said cylindrical portion of said cover and engageable with said wall of said third chamber portion, an exit formed in a sidewall of said cover and opening to the outer surface of said cylindrical portion of said cover between said seal rings for conducting pressure fluid from said valve chamber to said discharge port, a recess formed in one end of said cover for receiving said valve member during movement of said valve member relative to said seat member, said recess forming a chamber for conducting fluid from said flow passage in said seat member to said exit, and a threaded portion between said cylindrical portion of said cover and an end of said cover opposite said one end and engageable with a cooperating threaded portion formed in said valve chamber between said third chamber portion and said outer wall for retaining said cover in said valve chamber and sealed from exposure to fluids in said valve chamber.