MAXA Technical Support
Uphole Flushing Velocity
When drilling, it is important to clear the cuttings from the bit face and carry them to the hole surface continuously and efficiently. Otherwise, it will shorten the bit life, slow down the drilling speed, and create more dust. Therefore, uphole velocity cannot be too low to flush the drill debris. The uphole flushing velocity is recommended between 4000 and 7000 feet per minute. It is dictated by the air output (CFM), bit diameter, and drill pipe diameter.
Uphole flushing velocity (ft./min.) can be calculated by the following formula
(Air output CFM X 183.4) / (Bit Dia. Inch2 - Pipe Dia. Inch2)