5 Things to Know Before Buying an Air Compressor

So you’re going to buy an air compressor for abrasive blasting – great! Before you start shopping around and doing competitive research, there are five things you need to know.

5 Tips For Buying an Air Compressor

1. Are using siphon or direct pressure abrasive delivery? If you’re not sure, we’ll explain how you can tell at the bottom of this blog post.

2. Your gun blasting nozzle size. All blasting cabinets and portable pots have a standard published gun or nozzle size which determines how much compressed air you will be using and what air compressor size you need. Each delivery method will publish the compressed air usage for the machine, direct pressure models blast at half the pressure rating that siphon models use to produce the same abrasive speed. The compressor storage tank must never drop below 90-100 psi for proper operation of the machine controls on almost all models today. Siphon guns and pressure nozzles come in different sizes all shown on our compressed air usage chart, make sure you reference your size correctly. Cabinets recycle abrasives and never exceed maximum impact velocity, portable pots that don’t recycle blast using as high a blasting pressure as the cfm volume you have will hold.

3. The abrasive type you will be using. Without this information, it’s impossible to know how much compressed air to purchase. Cabinets recycle abrasive and use higher quality (harder) abrasives than portable pots, which only use abrasive once. If you are using a portable pot, and not recycling the abrasive, you will be blasting at the highest possible pressure regardless of the abrasive’s maximum impact velocity because you know the abrasive will not be used again. Knowing your nozzle size will allow you to see the air need at nothing less than 100 psi blasting pressure for a portable pot, and that’s critical because blasting at half the maximum allowable pressure will mean 4 times longer to clean!

4. Your electrical power supply voltage. Residential power supply is normally 208 or 230 volt, single-phase power supply. This is all you need to operate heat pumps, large air conditioners and electric dryers. If you’re using this power, you’re limited to air compressors with 5 horse power motors, some motors are listed at ratings higher than 5 hp but they are still only 5 hp motors. You may need to access the main power panel to install a circuit breaker capable of running your air compressor. Be aware that motors listed as 6 or 6-1/2 and even 7-1/8 or 8 horse power are not really different than standard motor listings of 1, 2, 3, 5 and 7-1/2 hp. For now, know it is possible to purchase 25 to 27 cfm air compressor for home shop use that operates using only a 5-hp, 208 or 220 volt, single-phase motor. If you go that route, you’ll likely to purchase a horizontal tank compressor. Double the cfm used and you square the frictional creating faster and faster part processing so 25 cfm usage is much faster than 16 cfm usage!

5. If you have 3-phase power you will know you have it. Manufacturing facilities use 3-phase power to operate machinery. Do not attempt to purchase anything for a smaller shop or home use that requires 3-phase power and know that phase converters don’t work with compressor pumps that require the rpm speed remains the same.

Pro Tip: Siphon delivery uses a gun with two hoses attached, one for compressed air and one for abrasive delivery to the gun. Direct Pressure only has one hose that contains both abrasive and compressed air. You get the same abrasive speed with direct pressure using only half the blasting pressure.

To Sum it Up

Once you have the information above in hand, do your due diligence and review all models available to ensure sure you buy the right air compressor for your machine, abrasive delivery method, the gun size used, abrasive type being used and the electrical power source you have!  As with all purchases, budget can always drive your decision, but beware of buying a compressor that isn’t powerful enough – you may end up having to buy another one in the near future!

For more information about buying an air compressor check out Air Compressor 101: Everything You Need to Know or contact us.