Choosing An Air Compressor

Because there are so many different applications for air compressors, there are a wide range available in the retail market.  Understanding all of the different ratings when choosing an air compressor can be confusing.

Purpose

First things first.  Why in the world are you shopping for an air compressor?  What do you need it for?

This is the most important question you need to answer.  Going any further is impossible without certain information.  Airing up tires and sporting equipment is much different than continuously running a paint sprayer.

Gather your air tools and write down the requirements for each.  They will be listed on the box and/or in the owner’s manual.  An example of a requirement might be 4 CPM per HP @ 90 PSI.  You now have 4 of the 5 key considerations for choosing an air compressor.  The first is what level of usage the compressor needs to be able to perform to.  Then, you have your formula that tells you the CPM, HP, and PSI.

The last consideration is your budget.  Once you find the right specifications, you may have more than one brand or model to choose from.  Choosing an air compressor is less about getting the most for your money and more about getting the right air compressor to run your tools.

HP, PSI, and CPM

HP, horsepower, is the rating for the strength of the motor, the amount of power it is capable of producing.  If it is listed as 5 HP at 110 volts, it is highly unlikely that it will make it to that 5 HP.  The motor may have a 5 HP capacity, but will not be able to generate that from the 110 volt outlet and ultimately may only get to about 2 HP.  When choosing an air compressor, remember this, there will be air compressors from about 1 HP to around 6.5 HP available.  The higher HP models will require a 220 volt circuit.

PSI, pounds per square inch, is the measure of the pressure of the air.  The engine compresses the air and it is measured as the pounds of air compressed into a square inch.  Light duty usage will be fine with a single stage unit with a  shut-off around 125 PSI.  If you are going to be doing anything more than light duty, look for a two-stage shut-off  where the second stage shuts-off around 175 PSI.

CFM, cubic feet per minute, is the measure of the amount of air released.  This is a volumetric measure, but it does not reference the amount of air in the tank.  This is how much air comes out of the hose per minute.

There may be several ratings given for different PSI listed as you are choosing an air compressor.  You need to match the CFM for the required PSI for your tool.  All other PSI are irrelevant, therefore the corresponding CFM are as well.

If you have trouble finding a good match, or they seem to be misleading, ask questions and make sure you are comfortable with the answers before you ultimately finish choosing an air compressor.  Getting it right is worth the effort.