04258801 is referenced by 12 patents and cites 8 patents.

A dump valve having a valve seat and a valve member is located in a string of drill pipe above a downhole motor. The dump valve connects the inside of the drill string with the annulus and allows drilling mud to flow freely therebetween when drilling mud is not being pumped through the drill string to operate the downhole motor. The valve member is made of a deformable resilient material such as rubber. It is held away from the valve seat by spacers until the pressure drop across the valve member is sufficient to deform the valve member and move it past the spacers into engagement with the valve seat. When the pressure differential is relieved, the valve member will return to its normal, unstressed shape opening the valve.

Title
Dump valve for use with downhole motor
Application Number
6/47560
Publication Number
4258801
Application Date
June 14, 1979
Publication Date
March 31, 1981
Inventor
John B Poston
Houston
TX, US
Agent
Marvin B Eickenroht
Jennings B Thompson
Assignee
Eastman Whipstock
TX, US
IPC
F16K 15/14
F16K 15/04
E21B 21/10
E21B 4/02
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