Drilling equipment depends on compressed air for two jobs at once: powering the down-the-hole hammer and flushing cuttings out of the borehole. If either demand is under-supplied, penetration slows and the bit life drops sharply.
DTH hammer airflow
The hammer consumes most of the air and its requirement rises with hammer size. Read the hammer specification for CFM at the working pressure, then add the flushing requirement. The flushing velocity in the annulus between drill pipe and hole wall must be high enough to lift cuttings, which depends on hole diameter and depth.
Pressure considerations
Pressure must overcome the water column and the pressure drop of the full drill string. Deep holes and wet conditions need a higher-pressure machine. For most water well and exploration work, 8–25 bar covers the range, with larger rigs using two-stage or boosted air.
Portable and rugged
Remote drill sites usually have no grid power, so a diesel portable compressor with heavy-duty filtration is standard. Confirm altitude derating and ensure the machine can run continuously for a full shift without overheating.