Choosing an Air Compressor for Sandblasting
Air is the key component in sandblasting. The amount and pressure of air that your air compressor provides will be one of the key factors in determining the size of your blast pattern and the speed at which the surface can be cleaned. Your air compressor will also be one of the highest cost items as they can easily cost between $8,000 and up depending on the style of compressor.
What you need to know to Choose an Air Compressor for Sandblasting
To choose an air compressor for your sandblast process the key is to know the size sandblast nozzle you will use for sandblasting. Additionally, you will need to know the pressure you want to blast at. The higher the pressure and larger the nozzle the more air your sandblasting will require. To figure out the proper pressure and nozzle size you typically will want to coordinate with a sandblast manufacturer that has test labs to run trials of various medias, pressure, and nozzle sizes. They will then provide a report to provide the nozzle size, air pressure, and sandblast media as well as the potential production achievable with different sizes. Once you have the pressure and nozzle size recommendation you can proceed to better determine the proper air compressor size.
How to Determine the Proper Air Compressor Size
Take the sandblast nozzle you are using and the pressure you plan to blast at from your test above or the maximum size you plan on using if you will be blasting a variety of profiles on a variety of surfaces. Then reference the chart below that shows how many CFM different sandblast nozzles will require at different pressures and find the proper CFM rating for your nozzle at the pressure you will use. Once you have the proper amount of air you will want to have 30-50% additional compressor capacity. The reason you will need extra compressor capacity is that as the sandblast nozzle wears the nozzle size will start to become closer to the next size nozzle. For a quick example will say your using a No. 4 Sandblast Nozzle at 80 PSI, you would want to have a compressor to support 82 – 102 CFM of air Delivery. Most compressors will provide air at 100 or 125 psi but you will want to make sure your compressor will provide both the pressure and CFM that you will need based on your nozzle size. If you do not choose an air compressor with extra capacity you will notice issues like your blast pattern being irregular as well as not having the pressure to achieve your desired profile.
Choosing a Compressor
After you have determined the size of compressor you will need you will want to evaluate different types of compressors as well as how they provide the air required. There are numerous options to power a compressor including diesel and electric. Compressors also come in single or two stage (the two stage compressor provides more CFM per horse power and will be needed for sandblasting). Finally compressors have a variety of ways they compress air including screw style, reciprocating, Screws are a higher cost but can generate more volume of air typically. For a greater overview of compressors, their design, and benefits / drawbacks here is a great article.
Chart courtesy of Clemco Industries