For beginners, abrasive blasting (sandblasting) can initially seem quite overwhelming. A new operator is immediately bombarded with jargon related to air compressors, nozzle sizes, grit selection etc. Before you get too caught up in the more extensive setup of abrasive blasting, it is vital to take a step back and look at the first essential component – the compressor.
Most people simply assume that the more pressure a compressor can produce, the faster they will be able to blast. This, however, is far from the truth. It is one thing to have pressure, but another thing to maintain that pressure at an open end. When it comes to abrasive blasting, the correct pressure will only be achieved if you have the sufficient air volume necessary to maintain that pressure. Because of this, selecting a compressor will depend on whether or not it will able to produce the required air volume (measured in CFM/LPM). Below is a simple conversion chart that will help you determine the CFM/LPM output of your compressor.
BAR x 14.5 ≈ PSI
KW x 1.4 ≈ HP
HP x 4 ≈ CFM
CFM x 28 ≈ LPM
As a rule of thumb, the pressure for abrasive blasting should never exceed 7 bar. Exceeding a 7 bar pressure will tire the blaster out faster, resulting in unnecessary operator’s fatigue. When a blasting operator gets tired quickly he puts his own safety, as well as the safety of the blast operation, in danger. This further re-enforces the need to focus on the CFM the compressor can produce rather than the pressure.
We now know that we need to find a compressor that will be able to produce the sufficient CFM. Great! But how do we know how much CFM is required? The answer to this is relatively simple. The amount of CFM that is required is determined by the size of the blast nozzle!
From this you can see that the larger the nozzle size, the more CFM is required. This then leads to another question! What size nozzle will you require?
Nozzle selection depends on the size of the blast pattern you are looking for. If you are blasting large sheets of metal and require a larger blast pattern, a 9.5 -12.5mm nozzle will suit your application. If you are, however, blasting steel structures and require a smaller blast pattern we would then recommend a 6 .5– 8mm nozzle.
There are so many factors to take into consideration when it comes to abrasive blasting, but by having the right foundation with the correctly sized compressor, you are already one step ahead of the game and improving your production.