Sand Blasting Nozzle

For sand abrasive blasting, the most commonly-used air blast nozzle orifice sizes range from 3/8″ inner diameter to 3/4″, increasing by increments of 1/16″. An 8mm air blast nozzle is constructed to generate pressure at a 120 CFM air compressor. A 10 mm sandblasting nozzle is enough to generate an effective blasting pressure at a 210 CFM air compressor.

It’s important to notice that when we double the diameter of the orifice, we quadruple the size of the orifice and the volume of air and abrasive media that can pass through the sandblasting nozzle.

To find our optimally productive sand blasting nozzle, determine what nozzle pressure (PSI) we need to maintain for productive blasting, and sand blast nozzle air consumption or what volume of air our available air compressor can supply per minute (CFM).

Sand blasting Nozzles are of two basic shapes: straight bore and Venturi, with several different variations of venturi, sand blast nozzle.

As compressed air enters the converging (left) end of a straight bore nozzle it accelerates, accelerating the abrasive media particles suspended in the flow. These abrasive media particles exit the nozzle in a tight stream and produce a narrow, concentrated blasting pattern upon the impact surface.

Blast Pattern: 3″ at 18″ distance
Production Rate: 4.5/5

Venturi nozzles have a converging entry and a diverging exit. This shape is designed to produce an effect that greatly accelerates the airflow and media particles.

The Venturi effect is an observation that when an airflow accelerates while passing through construction, there is a corresponding drop in pressure level.

Besides producing tremendous acceleration, the angled shape nozzle of the diverging end spreads out the flow, producing a large blast pattern and a more uniform particle distribution than a standard bore nozzle.

Long Venturi nozzles give up to 40% better production rates and consume less abrasive material compared to straight bore nozzles.

Blast Pattern: 3″ at 18″ distance
Production Rate: 4/5

A double Venturi nozzle is with an extra-wide exit opening and holes at the diverging end.

According to the Venturi effect, as the velocity of the flow increases, the pressure drops, creating a vacuum between the shockwave and the throat, reducing abrasive material velocity. With a double Venturi type nozzle, atmospheric air is inserted through the holes into the low-pressure area, expanding the airflow to produce a huge blast pattern on the blast surface. 

Blast Pattern: 3″ @ 18″ dist.
The Rate of Production: 5/5

When used in coincidence with a hose pipe with matching inside diameter (and with a corresponding air volume increase), the wide throat nozzle can improve productivity level up to 15% over a long Venturi nozzle.

Blast Pattern: 5″ at 48″ distance
The Production Rate: 3/5

These are extra-long nozzles accelerating media particles over a longer distance, achieving higher exit velocities, allowing the blaster to stand further back from the surface being blasted, and producing a larger blast pattern and higher production rates.

Sand Blasting Nozzle Material

The third consideration while choosing a nozzle is the material of the lining inside the bore. Harder materials will be more resistant to wear, but are more costly to replace and are prone to cracking under rough handling. There are two basic types of the nozzle and their details.

Durability: 1/5
Impact Resistance: 5/5
Price: Low

This tungsten carbide nozzle is the least durable of the carbide nozzles, but relatively less costly and resistant to impact. Essentially suitable for blasting including copper, glass, and mineral abrasive media.

Durability: 3/5
Impact Resistance: 1/5
Price: High

Boron carbide nozzle is extremely hard and durable, but brittle in nature. It can give up to ten times the longevity of tungsten carbide.