Check valve assembly

Abstract

A check valve may include a housing having a bore therethrough, the bore including an inner surface and a bearing face; a check seat adaptor coupled to the housing; a seal in the housing, the seal including a seat bore; and a dart disposed in the bore between the seal and the bearing face and axially moveable between closed and open positions. The dart may include a tail and a head that has at least one dart inlet and sealingly engages the seal when the valve is closed. The tail defines an inner chamber having an outlet that is in fluid communication with the bore. The dart inlet(s), the inner chamber, and the outlet may be in fluid communication and together define a dart flow path through the dart. A biasing device may urge the dart toward the seal.

1 . A check valve adapted for use in an oil and gas well, comprising:
 a housing having a housing flow path between a first end and a second end of the housing;   a dart positioned in the housing flow path and adapted to move between at least: (1) a first position in which the dart substantially blocks a portion of the housing flow path, and (2) a second position in which the dart does not block the portion of the housing flow path;   the dart further including a dart flow path between a first end and a second end of the dart;   the dart further including a plurality of inlet ports in fluid communication with the housing flow path and the dart flow path;   a biasing device for retarding movement of the dart between its first position and its second position, wherein the biasing device is positioned in the housing flow path but not the dart flow path;   whereby, when the dart is in its second position, the check valve is configured such that flow travels through the housing flow path at the first end of the housing, the plurality of ports in the dart, the dart flow path, and the housing flow path at the second end of the housing.   
     
     
         2 . The check valve of  claim 1  wherein the housing includes a check housing and a check seat adaptor, wherein said check housing is connected to said check seat adaptor. 
     
     
         3 . The check valve of  claim 2  wherein the dart includes a longitudinal axis and one or more of the plurality of dart inlet ports includes a centerline, wherein the centerline of the one or more plurality of dart inlet ports forms an angle with the longitudinal axis of the dart. 
     
     
         4 . The check valve of  claim 3  wherein the dart further includes at least one outlet port configured to allow fluid communication between the dart flow path and the housing flow path. 
     
     
         5 . The check valve of  claim 4  wherein the outlet port is open to fluid communication between the dart flow path and the housing flow path when the dart is in its first position. 
     
     
         6 . The check valve of  claim 5  wherein the outlet port is closed fluid communication between the dart flow path and the housing flow path when the dart is in its second position. 
     
     
         7 . The check valve of  claim 6  wherein the dart includes a biasing shoulder configured to receive a first end of the biasing device. 
     
     
         8 . The check valve of  claim 7  wherein the housing includes a seat configured to receive a second end of the biasing device. 
     
     
         9 . The check valve of  claim 8  wherein the housing includes a dart seat configured to receive the second end of the dart when the dart is in its second position. 
     
     
         10 . The check valve of  claim 9  wherein the dart includes a region having a head diameter and a region having a tail diameter, where the head diameter is larger than the tail diameter. 
     
     
         11 . The check valve of  claim 10  wherein the biasing device is located in the region having the tail diameter. 
     
     
         12 . A check valve, comprising:
 a dart having an inner chamber;   the dart adapted to move between at least a first position in which the dart substantially blocks a flow path in the check valve and a second position in which the dart does not block the flow path in the check valve;   the dart including at least one inlet opening, wherein the inlet opening has a centerline at an angle with a longitudinal axis of the check valve.   
     
     
         13 . A check valve, comprising:
 a bore;   a dart positioned within the bore and adapted to move between at least a first position in which the dart substantially blocks the bore and a second position in which the dart does not block the bore;   a biasing device for retarding movement of the dart between its first position and its second position, wherein the biasing device is positioned on an outside surface of the dart substantially free of flow in the bore.