Patent ID: 8281806

Claim:
A check valve, comprising: a housing; a nipple having a first portion that is selectively positionable within an opening in the housing, wherein a second portion of the nipple extends from the housing when the first portion of the nipple is selectively positioned within the opening in the housing; and a seal movably disposed within the housing; a cage connected to the seal; and a spring surrounding a first portion of the cage and located between a seat and a second portion of the cage; wherein the spring biases the seal against the seat when the first portion of the nipple is removed from the housing; wherein the first portion of the nipple bears against the second portion of the cage when the first portion of the nipple is selectively positioned within the opening in the housing so that the spring is between the first portion of the nipple and the seat; wherein the check valve is configured to allow fluid flow through the check valve in either a first direction or a second direction when the first portion of the nipple is selectively positioned within the opening in the housing; wherein the check valve is configured to prevent fluid flow through the check valve in the first direction when the first portion of the nipple is removed from the housing; wherein the housing comprises a stop that extends, in a direction toward the opening, into a circumferential groove formed only in an interior wall of the housing; and wherein one or more pins that protrude from an exterior of the first portion of the nipple are configured to move circumferentially within the groove in response to the nipple being rotated.