Two figures decide whether an air compressor suits your job: airflow (cfm) and pressure (bar). If either falls short, the nozzle runs out of air, tools lose power and blasting slows down.
The short formula
Add up the airflow (cfm) of every tool or nozzle working at the same time, add a 25–50% reserve, then make sure the compressor's working pressure matches or exceeds what the tools need. For sandblasting, the nozzle size drives everything.
CFM and bar
- CFM (cubic feet per minute) is the volume of air delivered each minute. 1 m³/min ≈ 35.3 cfm.
- Bar is air pressure. 7 bar ≈ 100 psi, 10.3 bar ≈ 150 psi.
Pressure sets how hard a tool works. Airflow decides whether the compressor can hold that pressure for the whole job.
Sandblasting nozzle air consumption
Air consumption of blast nozzles at 7 bar (100 psi):
| Nozzle | Bore diameter | Air consumption |
|---|---|---|
| No. 4 | 1/4" (6.4 mm) | ±81 cfm |
| No. 5 | 5/16" (8 mm) | ±137 cfm |
| No. 6 | 3/8" (9.5 mm) | ±196 cfm |
| No. 7 | 7/16" (11 mm) | ±254 cfm |
| No. 8 | 1/2" (12.7 mm) | ±338 cfm |
The nozzle bore widens as it wears, and consumption rises with it. Add a 25–50% reserve, plus the air for the blast helmet (breathing air) and any other connected equipment.
Example: one No. 7 nozzle (±254 cfm) with a 40% reserve needs about 355 cfm. A 350–400 cfm compressor runs one No. 7 nozzle. For two nozzles or more, choose the 800 cfm class or above.
Pressure: 7, 10.3 or 14 bar?
- 7 bar is the standard for most pneumatic tools: breakers, impact wrenches, grinders and general sandblasting.
- 10.3 bar gives higher nozzle pressure for faster blasting and offsets pressure loss in long hoses.
- 14 bar is for specialist applications that need high pressure.
Long or narrow hoses lower the pressure at the tool. Measure the pressure you need at the nozzle or tool, not at the compressor.
Other pneumatic tools
Air demand varies by tool size and brand. As a guide, a breaker (jackhammer) typically needs from a few dozen up to about 100 cfm at 6–7 bar. Check your tools' specifications and add up everything that runs at once.
Units for hire or purchase
Every unit in our fleet is a portable diesel compressor: you can tow it to site and run it without a grid connection, which suits projects, shipyards and open areas.
| Airflow | Pressure | Brand | Roughly enough for |
|---|---|---|---|
| 185 cfm | 7 bar | Atlas Copco, AIRMAN | Pneumatic tools, one small nozzle |
| 350 cfm | 10.3 bar | Atlas Copco | One No. 7 nozzle |
| 400 cfm | 7 bar | Atlas Copco, AIRMAN | One No. 7 nozzle |
| 800 cfm | 10.3 bar | Atlas Copco | Two No. 7 nozzles |
| 830 cfm | 10.3 bar | AIRMAN | Two No. 7 nozzles |
| 900 cfm | up to 14 bar | AIRMAN | Two nozzles, high pressure |
| 920 cfm | 10.3 bar | AIRMAN | Two No. 7 nozzles |
| 950 cfm | 10.3 bar | AIRMAN | Two No. 7 nozzles |
| 1,200 cfm | 10 bar | Atlas Copco | Three No. 7 nozzles |
The last column is an estimate with a 40–50% reserve. Recalculate with your own nozzle size and hose length.
Ask for a recommendation
Send the type of work, nozzle or tool size, number of work points and hose length on WhatsApp. Our team matches them to the air compressors available and sends a rental quote or purchase price.
