Understanding Air Compressor Requirements for Sandblasting
Compressor PSI and CFM
To run a sandblaster effectively, you need an air compressor with 90 to 100 PSI. The air tank will drain while you’re sandblasting. It is important to maintain a working PSI of around 50 to 90. If it drops below 50 PSI, the pressure won’t be sufficient to take material off.
The best kinds of air compressors for sandblasting are higher CFM models. For smaller sandblasting tasks, a compressor that can produce between 10 CFM – 20 CFM is ideal. For a powerful sandblasting experience, you need a compressor that can produce between 18 and 35 CFM. Industrial sandblasting requires compressors with 50 to 100 CFM.
Selecting the Right Air Compressor
For those who sandblast often, a higher PSI air compressor is recommended. Though more expensive, it’s worth it in the long run due to time savings.
A 14 CFM compressor with a 50% duty cycle can be used for an air sandblaster rated at 14 CFM if used intermittently with a sufficiently large air tank. The size of the compressor is determined by the volume of air the tool uses, and the pressure it requires. To determine the size of air compressor you need for your sandblaster, consult the tool’s owner’s manual.
Nozzles and Air Consumption
For vapor abrasive blasting, nozzle orifice sizes typically range from 3/8” inner diameter to 3/4”, increasing by increments of 1/16”. A 3/8” nozzle produces effective blast pressure with a 185 CFM compressor. Ceramic nozzles are ideal for lower pressure jobs, such as 5 CFM. When blasting pressure is lowered, it reduces frictional heat but increases the time it takes to blast.
Different projection systems that use compressed air include pressurized systems, suction systems, and gravity systems.
Nozzle Chart – Air Consumption
Air and Abrasive consumption per blast nozzle are measured in CFM of air consumption per blast nozzle.
Harbor Freight Sandblaster and CFM Requirements
For a Harbor Freight sandblaster, a #6 nozzle, requires at least 6 CFM of airflow. The 3-Gallon Oil-Free Air Compressor (item number 61615) has a max pressure of 100 PSI and delivers 2.6 CFM @ 90 PSI – enough power for most small sandblasting jobs. Harbor Freight’s 40 lb cabinet type blaster requires 9.5 CFM at 90 psi with a maximum pressure of 135 psi. For best results and to avoid frustration, ideally, you want above 14-16 CFM.
The Harbor Freight blast cabinet requires a minimum of 4 CFM to work properly. Considerations for selecting a compressor include the sandblaster’s CFM requirements, the nozzles used, and ensuring the compressor’s CFM rating meets or exceeds these.
Dust Collection and Air Flow
When considering dust collectors, CFM is critical. For Harbor Freight dust collectors, the CFM ranges from around 1200 to 1550 CFM at the source but is lower with extended ducts. The CFM estimates and corresponding dust collection performance for a 2 HP Harbor Freight tool can be summarized in a table:
- Number Of Ducts/Pipes: Average CFM
- 1: 650
- 2: 300
It is recommended not to use more than two ducts if the tool has a high output of dust and shavings.