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How to Size an Air Compressor For Sandblasting

How to Size an Air Compressor For Sandblasting

Sandblasters are used to clean difficult substances like rust or paint from solid surfaces like metal. A sandblaster can make a huge sanding job suddenly simple. To get the best performance from your sandblaster, you need to select the right compressor for the job. Use these tips and guidelines to help you make the best choice for your project.

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Compressor Sizing

Compressors and sandblasters are sized based on:

  • CFM (cubic feet per minute): The volume of air that the system can move in a minute
  • PSI (pounds per square inch): The pressure generated by the system

You must consider both numbers to make sure your compressor and sandblaster will work together. The size of your sandblaster and nozzle will determine the necessary size for your compressor.

How Sandblasters Work

To properly size the compressor for your sandblasting project, it’s important to understand exactly how a sandblaster works. Sandblasters clean rough surfaces by abrading them with sand. The sandblaster fires sand out of an air-powered pressure gun at high velocity. There are several types of sandblasters. Each one introduces sand to the air in a different way.

  • Gravity-Fed Sandblasters: These sandblasters feature a pressure gun with a hopper on top. The force of the compressed air firing through the gun opens the hopper. The pull of the air then draws sand through the hopper and out the barrel along with the air.
  • Pressure Blasters: This sandblasting gun connects directly to a canister containing the sand. Air and sand are pushed through the canister and into the gun together.
  • Siphon Sandblasters: A siphon sandblaster features two hoses. When compressed air flows through the first hose, it creates pressure which pulls sand from a tank through the second hose. The air and sand then exit the sandblasting gun together.

The compressor doesn’t simply provide a single burst of air. It must sustain the proper pressure. To do so, your compressor needs to have the right air volume. Too little and it won’t be able to keep up with your job.

Compressor Size and Efficiency

You should use a tank with a minimum of 100 PSI for optimum efficiency with any abrasive sandblasting project. If you work with a lower PSI, you’ll add a significant amount of time to your project. If you reduce your blasting pressure by half, your pressure cleaning project will take four times as long. If you’re going for speed, bigger is better in this area. Increasing the cabinet’s gun size can decrease your work time by over two-thirds.

Compressor Size and Nozzle Selection

As the size of your blast nozzle increases, so too does the necessary air volume and air reserve. The larger your nozzle, the more CFM you’ll need from your air compressor. You must also consider the necessary PSI for your project. A higher PSI correlates to a higher CFM. For example, if you’re using a No. 2 nozzle at 100 PSI, your air compressor needs to provide a CFM of 20. If the same nozzle is being used with 140 PSI, the CFM must increase to 28.

For efficiency, you should choose the largest nozzle possible for your project. If you’re blasting large pieces of sheet metal, consider a #6, #7, or #8 model. These range in size from 3/8 inch to 1/2 inch. If you’re working with a more precise project that requires a smaller blast pattern, a #4 nozzle measuring 3/16 inch, or a #5 1/16-inch nozzle will work better.

Putting it All Together

You have many parts to consider when you’re sandblasting. Check the guidelines for your sandblaster to make sure it’s compatible with your nozzle. You need a nozzle that’s durable enough to withstand the pressure from your chosen sandblaster. Next, check the PSI and CFM of your sandblaster. Increase the size of your compressor in line with the size of your other equipment. Working at 100 PSI, the recommended compressor sizes are:

  • #2 1/8-inch nozzle: 20 CFM
  • #3 3/16-inch nozzle: 45 CFM
  • #4 1/4-inch nozzle: 81 CFM
  • #5 5/16-inch nozzle: 137 CFM
  • #6 3/8-inch nozzle: 196 CFM
  • #7 7/16-inch nozzle: 254 CFM
  • #8 1/2-inch nozzle: 338 CFM

Remember to increase the size of the compressor for projects with a higher PSI. When in doubt, look to the manufacturer’s guidelines for your tools.

With the right compressor, you can power any sandblasting project efficiently. Though a compressor is essential for this job, you don’t have to invest in one for your company. An affordable equipment rental will give you the functionality you need with minimal expense.

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