ROTARY BIT WITH JET NOZZLES

摘要

The bit comprises a first strainer element 11 allowing the passage of drilling fluid carrying small-sized particles, but preventing relatively coarse particles from passing to the nozzles 20 of the bit.
The first strainer element 11 is continuously cleaned by part of the drilling fluid flowing to a larger-sized nozzle 18. Prior to passing through said latter nozzle, the relatively coarse particles are trapped on a second strainer 14.