| 摘要 |
<p>An improved pressurized fluid check valve is provided which, when incorporated into a drill string powered by a rotary table of a drilling rig, prevents drainage of fluid from the stand pipe and rotary hose when the flow of fluid through the drill string is interrupted, such as during the attachment of another section of drill pipe to the drill string. The improved pressurized fluid check valve comprises (a) a tubular body member (22) having a bore (32) extensive therethrough between first and second end portions thereof, the bore having an enlarged medial portion (34) forming a valve chamber (36); (b) a flow restricting assembly (24) supported within the valve chamber of the tubular body member for selectively closing the valve chamber to fluid flow in a pressurized mode; and (c) a loading valve (26) supported in an access bore (38) formed through the side wall of the body member so as to communicate with the valve chamber. The loading valve permits an annular pressure cavity (57) formed between the internal wall (58) of the valve chamber and an elastomeric sleeve (60) of the flow restricting assembly to be pressurized with a gas so that the elastomeric sleeve of the flow retention assembly is compressed to close the valve chamber until such time as the pressure of the fluid flowing through the drill string is sufficient to compress the gas in the annular pressure cavity and permit the elastomeric sleeve to be moved to a non-compressed condition so that the valve chamber is in the open mode.</p> |
