Patent ID: 6571876
Filing Date: 2003-06-03
Classification: E21B

Abstract:
A pressure reversible check valve, comprising:an axially extending tubular tool body having an inlet end and an outlet end, an axially movable check valve assembly disposed within said tubular tool body intermediate said inlet end and said outlet end, said check valve assembly being movable between first and second axially spaced locations within said tubular tool body, a flow passage extending within said check valve assembly for conducting fluids in said tubular tool body through said check valve assembly, a valve closure element in said check valve assembly movable between opened and closed flow passage positions respectively permitting fluid flow through said flow passage and preventing fluid flow through said flow passage, a bypass flow passage in said tubular body for conducting fluids from a location within said tubular body to a location external to said tubular body, said bypass flow passage being closed to fluid flow when said check valve assembly is at said first location and being opened to fluid flow when said check valve assembly is at said second location, and a pressure independent biasing element for exerting a biasing force to urge said check valve assembly from said second location toward said first location.