Blasting Efficiency depends on proper nozzle selection
Perhaps the most critical component for reaching production goals is the nozzle chosen for the job. The nozzle’s bore shape determines its blast pattern as needed for the application:
- Straight bore nozzles create a tight blast pattern and are ideal for blasting small areas.
- Venturi bore nozzles create a wide blast pattern and increase particle velocity, improving productivity when blasting larger surfaces.
Venturi type of pressure blast nozzles are generally used. They are designed with unique internal shape to achieve different objectives. The Airblast Venturi shaped nozzles gradually tapers outward from the orifice to the exit-end of the nozzle. This gradual exit expansion allows a mixing of air and media within the nozzle causing them to expand uniformly before leaving the nozzle. A Venturi nozzle provides excellent peening intensity and cleaning capability with a broad pattern. The performance of the Venturi nozzle depends on a precise ratio of length to orifice size, and to entry and exit tapers. This design creates a large blast pattern that produces maximum acceleration for cleaning. As nozzles wear from continuous exposure to high-velocity media, more air and media are allowed to pass through the orifice. The resulting larger area within the nozzle consumes more air volume placing greater demand on the compressed air source. Unless air volume can keep up with the increased flow, pressure at the nozzle will drop. With reduced pressure, peening intensity and productivity falls and efficiency goes downs. A rule of thumb to follow for ensuring continuous high production is to replace the nozzle when the orifice wears to the next larger size. Download the PDF to read more