Sandblaster nozzles life is difficult to predict accurately because of the many variables such as the vast range of abrasive media, their size, their shape, their hardness, varying air pressure at sandblaster nozzle, nozzle bore size and mouth diameter vs. hose I.D. at countless measurements during blast pipe life, methods of abrasive cut-off or machine shut-down, and a marsh of others.
A sandblaster nozzles bore shape determines its blast pattern. Sandblaster nozzles generally have either a straight bore or a restricted venturi bore. Straight Bore blasting Nozzles create a tight blast pattern for spot blasting or blast vessel work. Straight Bore sandblaster Nozzles are most suitable for smaller jobs such as parts cleaning, carving stone, weld seam shaping, cleaning handrails, steps, or grillwork, and other materials. Venturi Bore blasting Nozzles create a wide blast pattern and increase abrasive velocity as much as 99% for a given pressure. Venturi blasting nozzles are the best option for greater productivity when blasting larger surfaces. Long venturi style nozzles yield approximately a 40% rise in productivity compared to straight bore nozzles, while abrasive consumption can be cut around 40%.
The versions of long venturi style nozzle are Double venturi and wide throat nozzles
The Double Venturi style can be thought of as two nozzles in a series with a gap and holes in between to allow the insertion of atmospheric air into the downstream segment of the nozzle. The exit end is too wider than a conventional nozzle. In sandblasting Both corrections are made to increase the size of the blast pattern and minimize the loss of abrasive velocity. In sandblasting Wide Throat Nozzles feature a large entry throat and a large, diverging exit bore.