CPC Subgroup
E21B 21/06 Arrangements for treating drilling fluids outside the borehole
Full Title
Methods or apparatus for flushing boreholes, e.g. by use of exhaust air from motor (freeing objects stuck in boreholes by flushing E21B31/03) > Arrangements for treating drilling fluids outside the borehole
4 direct subcodes
Child Classifications
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- E21B 21/07 for treating dust-laden gaseous fluids