Schematic Drawing of a Venturi Nozzle

So what is the real difference between these two types of nozzles, and why should you care?  Well, for starters, you should know that the introduction of venturi nozzles over thrity years ago still remains the last major advance in nozzle technology.  Thirty years is a long time!

You see up until the mid 1950’s, all sandblasting nozzles were straight bore.  They had a tapered converging entry, a parallel throat section, and a full length straight bore and straight exit.  Over time, blast operators noticed that as the interior of these nozzles began to wear and erode away, a larger and more efficient blast pattern resulted.  This observation led to the development of the venturi design.

A long venturi nozzle is characterized by having a long tapered converging entry, with a short flat straight section, followed by a long diverging end which widens as you reach the exit end of the nozzle.  A long converging entry introduces the air and abrasive mix into the nozzle, then is constricted into a short flat straight section, and then forced out the flared exit end.  Venturi nozzles can increase productivity by as much as 70% due to the larger abrasive pattern that results as well as due to the increase in velocity of the abrasive as it exits the nozzle.  In fact, velocity (outlet speed) of the exiting abrasive can be nearly double that of a straight bore nozzle, and this is force that cleans a surface faster!

So if you are in the market looking to upgrade your operation, perhaps changing to a venturi nozzle might be a good place to start.  More on that later…