Matching Nozzle Size and Grit Size

Question: I would like to know if there is a standard for matching Nozzle opening size to media size. I am just starting out and I am not sure what size media I can use with my sand blaster. The literature on the blaster doesn't say. Can you help?

Response: Generally, the nozzle size you use should be at least 3-4 times the diameter of the grit size.

{If the grit is still getting stuck in the nozzle, try reducing the blasting pressure (psi) and making sure there is no moisture in the system.}

Blasting - CFM vs PSI

There are a few variables that need to be addressed when determining the blasting system that will work best for your application. Two critical issues are the blasting pressure (PSI) and the air requirement (CFM).

PSI {pounds per square inch} indicates the force that the blasting media is being discharged from the nozzle. The PSI measurement is independent of the nozzle size being used and is directly related to the pressure setting on the air compressor and/or the blasting pot. The most common abrasive blasting pressure used is 80 psi.

CFM {cubic feet per minute} is the volume (cubic feet) of air that is being sent threw an opening per unit time (the minute part). The CFM required during blasting is based mostly on the nozzle size being used. A larger nozzle will require more air just like a larger hose will need more water. Abrasive blasting is using air continuously so the compressor used must be able to supply enough CFM to 'keep up with' the blaster. For comparison, pneumatic (air powered) tools only use air in small increments so much less CFM is required.

Side note: For a given nozzle size, the CFM requirement will go down with lower blasting pressures (PSI). Using the garden hose comparison, more water will come out of the hose if the spigot is turned to a higher pressure, less if the spigot is turned down.