Abrasive Blasting 101
Have you ever wondered why some Sandcarving machines have a compressed air drier? Moisture, dampness, and static are often created during the Sandcarving process. These byproducts can have a disastrous effect on abrasive flow, particularly when using the finer abrasives used for sandcarving details.
Real World Example: You may not even realize your abrasive is damp enough to need a compressed air drier, just like you don’t really see moisture in a saltshaker. But neither a blast cabinet nor a salt shaker are fun to use when they’re soggy.
A small air tank gets warmed very quickly by the piston pump frictional heat of 400 to 500 degrees Fahrenheit that occurs during operation of any piston compressor. This heats the compressed air that is leaving the tank quickly due to the small tank capacity.
If the tank has a maximum capacity less than 60 gallons, it’s likely the compressed air is leaving the tank too quickly after entering the tank. The tank passes hot air to the blast nozzle, warming the hose to the machine as it travels. Now the compressed air enters the cold steel walls of the blast cabinet, and the problem then starts to appear after one complete cycle of the abrasive inside the pot. If you feel heat at the hose entrance it’s over 98.6 F!
If this sounds like your set up, make sure you install a compressed air drier. We advise an ambient dryer because it is located at the point of use. This type of dryer cools the air so it is only warming up and not cooling down as it enters the cabinet.
ProTip: make sure to install in the direction of the arrow on the dryer.
Keep in mind the air tank itself is the first dryer on any piston compressor. You have to remove the water daily or weekly depending on usage. If you leave water in the compressor tank it lowers capacity storage but also humidifies the compressed air making it harder to use without a compressed air drier.
If you don’t want to use a compressed air drier, make sure you buy the right-size tank for your blasting application. For a typical 3/32” pressure delivery nozzle blasting at 30 psi, we recommend a compressor size of 12 cfm at 90 to 100 psi allowing the compressor to stop and cool during operation. We also advise a 100% duty cycle rating on any piston compressor because they are moving pistons slower with less temperature. Even this may not eliminate the drier requirement.
Often people buy a “TOO SMALL” compressor because it is light and easy to install. This is the wrong choice. Never buy a compressor that is too small for the direct pressure nozzle you are using and remember; nozzles wear out and get larger. A larger nozzle requires more air to maintain any set blasting pressure. Buying just enough air will have you quickly running out of compressed air as the nozzle wear out demanding more and more.
A compressed air drier is one of the best ways to help reduce moisture in your abrasive delivery system. Having “wet air” is often a by-product of using a smaller air tank than you really ought to be using.
Before you buy any compressor, read “How to Size a Small Piston Air Compressor.”
For more information about compressed air, check out “Air Compressor 101: Everything You Need to Know.”
If you have questions about compressed air and buying Sandcarving equipment, please contact us. Our team is happy to help you find the right machine (and air!) the first time!