Numa’s new Vortex backhead is designed to improve drilling performance and hammer/bit life. It is available for Numa’s 12-in. hammer line when drilling conditions require a significant amount of water injection. The company explained that, typically, when water is injected into the air supply of a conventional backhead, the water will travel through all hammer components and exhaust out the bottom of the bit to improve hole cleaning. This is not usually a concern, but a drop-off of drilling performance can occur when significant amounts of water are required.
The Vortex backhead avoids this by ejecting water out the top of the backhead before it can go through internal hammer components. Numa accomplished this by creating a spinning process, or vortex, in the backhead that leverages the density difference between water and air. Fluids entering the top end of the hammer are spun, pushing water to the outside where it is ejected out the top of the backhead. Air stays to the inside and travels down the feed tube to power the hammer and clean the bottom of the hole. The amount of water ejected by the Vortex backhead can be controlled by two chokes at the top of the backhead. A standard hammer is supplied with 1/8-, 3/16- and 1/4-in. chokes that can be changed to control water injection according to drilling preference and conditions.