Numa has released a new Vortex Backhead design that improves drilling performance and hammer/bit life. It is available for Numa’s 12-inch hammer line when drilling conditions require a significant amount of water injection.

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. Water is not a concern when small volumes are used, but a drop in drilling performance can occur when significant amounts of water are required.  Drawbacks can include slower drilling due to wet bottom conditions and a reduction in hammer/bit life due to cavitation from water.

The Numa Vortex Backhead avoids a drop in drilling performance by ejecting water out the top of the backhead before it can go through internal hammer components.  The design allows for drillers to realize the benefits of water injection without the wear and loss of hammer performance.

Numa engineers have accomplished this by creating a spinning process (vortex) in the backhead that leverages the density difference between water and air. Fluids entering the top end of the hammer are spun, pushing heavy material (water) to the outside to be ejected out the top of the backhead. Lighter material (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 the two jets, or chokes, found at the top of the backhead. 

Benefits of using the Numa Vortex Backhead while injecting significant amount of water include:

  • Improved drilling performance through higher impact energy and limited wet bottom conditions.
  • Reduced wear from a reduction in non-productive exhaust flow up the outside of hammer/bit.
  • Increased hammer/bit life due to the removal of solid particulate from passing through components.

Numa is a global leader in the design and manufacturing of down-hole hammers and bits for drilling vertical, horizontal, and reverse circulation holes from 3½ to 48 inches in diameter. Numa’s products are used in more than 105 countries, drilling in a wide range of industries including construction, foundation, micro piling, oil and gas, quarry, mining, utility, geothermal, environmental, horizontal, and water well. To learn more, go to