Selecting the Right Air Compressor

An air compressor is a tool, specifically it is a tool to run other tools, unless you just need a volume of air compressed for an air tank or to inflate a tire. What sort and how big of a compressor you need is going to depend a lot on what sort of tools you need to run with it. A body shop running DA sanders and a paint booth all day long needs a much more robust compressor than an engine shop running impact guns and occasionally a media blast booth.

Before you begin, you ought to write down what tools you want to run with this compressor, and how many at the same time? If you are buying one for your home shop, the answer is usually just 1 at a time, but if you have a thriving business with several employees that should be taken into account. Refer to the tool’s air requirements on the Eastwood or other manufacturer’s website or documentation, or use this general table:
Here are some other important considerations to bear in mind when shopping for a compressor.
 

Shop use or portable? – if you are setting up shop you likely want something big and 220v powered that can provide air all day without breaking a sweat. If you are headed to the race track, or use a compressor for both automotive and roofing or carpentry tasks, you likely want a portable compressor with wheels on it, or small enough to carry.

110v, 220v, gas powered? – Gas powered compressors are almost always used on construction sites, or in the back of trucks doing mobile tire services. Jackhammers typically are run by a big gas powered compressor on a trailer towed to the site. For your jobs, chances are you will be using 110 or 220 volt power. If your shop is wired for 220v power, go for it, it will cost you less in electricity and the compressor is likely professional quality or close to it. All portable compressors are 110v, but 110v shop compressors do exist if you can’t justify rewiring the whole shop just to power a compressor. 

Single or 2 stage? – Depending on what you are using the air for you may want the higher pressure of a 2 stage compressor. Single stage compressors tend to produce a greater volume of air, but not at the pressure a 2 stage can attain. Painting with a HVLP gun requires a greater volume of air, while most air tools run on a greater pressure.

Where will it fit? – Of course if you are working in a single car garage you may not have room for a big 80 gallon compressor inside. Decide where the compressor is going to go before you start shopping.  Compressors come in all shapes and sizes but the actual compressor size is rarely an issue, the storage tank size is the main factor to consider.  Unless you need 5000+ CFM @ 125 PSI  which this 1000 HP Ingersoll Rand can produce, you will easily be able to find on  that fits your space check out our wide selection of compressors on the Eastwood Site. 

How loud can it be? – Many industries use compressed air, but chances are you’ve never heard the sound of an air compressor running at your dentist’s office, or spray tanning salon. Big reciprocating piston compressors are loud, so take that into account when shopping and deciding where in the shop you want it. Buying a compressor with a bigger tank than you need means the compressor doesn’t have to run as often, which is great if you have to work right next to it. There are also rotary screw compressors that are less like piston engines and more like a supercharger, with 2 screws spinning to squeeze the air instead of a piston.

What quality of air do you need? – If you are setting up a shop with a paint spray booth or for powder coating, the extra cost of a compressor with built in aftercooler and air dryer is totally worth it. Most air tools are not that picky about clean dry air, but just a little oil or water in the air supply can ruin a paint job that took hours to spray and days to prep.  If you don’t want to shell out the extra cash to buy a compressor with these functions built in you can always add them on to your current compressor.  The Eastwood 2 or 3 stage Dryer/Filter Systems are a great value because you can buy a premade set or build buy each component individually to get exactly what you need.

What Output? – Now that you have determined what type, and what quality, it’s time to add up your list of tools and find out how much air you you need the compressor to deliver. Remember, don’t just buy one that is close to what you need, buy more than you need. Having yourself or employees standing idle while the compressor runs to fill itself benefits nobody. A good rule of thumb is to get a compressor that can deliver 1 ½ times the needed CFM of your most air hungry, continuous use tool at its rated PSI. For a basting cabinet rated at 7 CFM at 90 PSI you would want a compressor able to produce at least 12 CFM at 90 PSI, otherwise once you deplete the air in the tank, the compressor may run continuously and never catch up.

How many people are in the shop? – Of course if you have 4 guys using air at the same time you need to add up their needs. Use the rule of thumb above, but you can round down some, since it’s not likely all 4 will be using the air continuously with their most air hungry tools.

Finding the right compressor isn’t magic, it just requires a little addition. Think about the typical day at your shop, add up the requirements of the tools in CFM and PSI, and add in a reserve of 50% or so. Buy a good compressor from a reputable name brand, and you can’t go wrong. You may think you can save money by buying a compressor a little smaller than your needs, but you will waste a ton of time waiting for the compressor to fill the tank after over using it.

Check out the Eastwood Blog and How-To Center for more Tips and Tricks to help you with all your automotive projects.  If you have a recommendation for future articles or have a project you want explained don’t hesitate to leave a comment.