How does Air Core & Reverse Circulation Work?

Air Core and Reverse Circulation are methods of drilling using high pressure air and a dual-walled drill pipe. High pressure air is forced down the drill rod annular between the inside pipe (sample tube) and the outside pipe. When the air reaches the bit face the air is forced around and creates a vacuum (a ventury). The samples are sucked up the inside pipe, through the top drive of the rig and delivery hose, then into the cyclone where the sample drops out to be logged and labeled in bags.

Brown Bros Drilling offer three different Reverse Circulation and Air Core drill sizes: a large 4.5” diameter system; a mid sized 3.5" diameter system; and a smaller light weight 3” diameter system. All three systems can be used for Air Core drilling and the operation of Reverse Circulation Down-Hole Hammers. The 4.5”, 3.5", and 3” systems are the dual-tube style, which provides two major benefits: a representative sample, and no cross contamination of samples.

The smaller 3” and 3.5" Reverse Circulation/Air Core system may be of special interest as a fast and inexpensive prospecting tool. It suits locations where large Reverse Circulation drill rig access is a problem, or where budgets do not justify several Wire-line drill holes.

The air core system is great to drill quickly through overburden to the top of rock deposits, and then simply switch to Reverse Circulation Down-Hole Hammer to efficiently sample the hard rock zone.

Advantages of Air Core & Reverse Circulation drilling:

  • Faster than coring
  • Cost effective drilling
  • No cross contamination of sample
  • Drill in and through loss circulation zones
  • Continuous and instant sample returns
  • 100% representative sample