US PATENT SUBCLASS 175 / 42
.~ Indicating agent released in drilling fluid


Current as of: June, 1999
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175 /   HD   BORING OR PENETRATING THE EARTH

40  DF  WITH SIGNALING, INDICATING, TESTING OR MEASURING {8}
42.~ Indicating agent released in drilling fluid


DEFINITION

Classification: 175/42

(under subclass 40) Subject matter comprising a drilling fluid system and a step or means for releasing an identifiable substance into the drilling fluid stream which substance when carried above ground by the circulating fluid will indicate to an observer the presence of a condition.

(1) Note. The substance is something which is specifically disclosed for indicating.