Fluid retention apparatus for fluid end of positive displacement pump and related method

A fluid retention apparatus for a positive displacement pump, comprising:

• a tubular body extending along a body axis from a first end of the tubular body to a second end of the tubular body, wherein the tubular body forms a sealing body configured to be received in a packing chamber of the positive displacement pump adjacent a transfer chamber of the positive displacement pump receiving a piston to move fluid therethrough;
• wherein the tubular body is made from a composite polymeric material which is wearable;
• a passageway in the tubular body and extending along the body axis thereof, wherein the passageway opens at the first and second ends of the tubular body, as to have first and second openings of the passageway, and is configured to matably receive the piston therethrough, wherein the passageway comprises a first end portion at the first end of the tubular body, a second end portion at the second end of the tubular body, and an intermediate portion therebetween, wherein the intermediate portion is substantially cylindrical and the first and second end portions have respective diameters which are reduced relative to a diameter of the intermediate portion, wherein the diameter of the intermediate portion is configured to be sized larger than a diameter of the piston to form a circumferential gap between the intermediate portion of the passageway and the piston, wherein said respective diameters of the first and second end portions are sized to be configured to form friction-fit seals around the piston to resist passage of the fluid;
• one or more annular end recesses in each of the first and second ends of the tubular body between a corresponding one of the first and second openings of the passageway and an outer surface of the tubular body configured to face walls of the packing chamber when the tubular body is received therein, wherein each of the annular end recesses has a base spaced from a corresponding one of the first and second ends of the tubular body in an axial direction of the tubular body, and opposite sidewalls interconnecting the base and the corresponding one of the first and second ends, wherein the opposite sidewalls are spaced apart in a diametric direction of the tubular body;
• a biasing device forming a closed loop and respectively disposed within the one or more annular end recesses in the first end, wherein the biasing device has opposite sides which are interconnected and configured to be urged apart in a biased condition of the biasing device, wherein the opposite sides of the biasing device are engaged with the sidewalls of said annular recess in a manner as to subject the biasing device to the biased condition such that the opposite sides exert a force on said sidewalls directed radially of the tubular body, whereby the first end portion of the passageway is urged radially inwardly to exert a pressure on the piston to enhance the seal therearound as to resist leakage of the fluid from the transfer chamber and into the passageway of the tubular body;
• and
• an end sealing gasket respectively disposed in the one or more annular end recesses in the second end and configured to form a fluidic seal with a downstream closure component configured to retain the sealing body in the packing chamber.