CFM & PSI

CFM & PSI

When Selecting An Air Compressor For Sale Online Or In A Store, Take Care To Check The Following:

Horsepower Rating

Compressors are measured by the horsepower (HP) the compressor motor produces. Compressor motors generally run from 1.5 HP to 6.5 HP. Industrial applications require more powerful units. Usually higher horsepower motors yield greater psi and are capable of carrying a heavier workload.

Cubic Feet Per Minute – CFM

Compressor Storage Tanks, rated in gallons, store more compressed air at higher pressures the larger the tank. The amount of air a compressor delivers is measured in cubic feet per minute (CFM). The higher the pressure of the stored air (measured in pounds per square inch or psi) the more air delivered or higher CFM rate. Change the psi and you affect the CFM.
Most air tools require differing CFM /psi rates for the tool to function properly. You must take into account the tools you want it to operate when choosing a compressor. A good rule of thumb is to select the tool requiring the highest CFM at the highest psi, then add 50% as a fudge factor or safety margin. If a tool requires 3 CFM at 90 psi, select a compressor that delivers at least 4.5 CFM at 90 psi. This formula will ensure the tool always gets enough air to function properly and safely.

How To Decide How Much CFM You Will Need
We have put together a chart that covers most common air tools and their average CFM measurements. You can refer to this chart to determine the correct continuous CFM rating that is required of your air compressor.

Air tools are often rated as being “Average CFM.” “Average CFM” is based on a 25% duty cycle (15 seconds out of every minute). This can be problematic with tools used on a continuous basis such as orbital sanders, grinders and so forth. Nailers and impact wrenches don’t have the same problem since they are used more intermittently.

If you plan on using an air tool continuously, multiply the “Average CFM” x 4 to get a more accurate and appropriate CFM rating for the tool.

AIR TOOL DESCRIPTION
AVERAGE CFM @ 90 PSI

Angle Disc Grinder – 7″ 5-8
Brad Nailer 0.3
Chisel/Hammer 3-11
Cut-Off Tool 4-10
Drill, Reversible or Straight-Line 3-6
Dual Sander 11-13
Framing Nailer 2.2
Grease Gun 4
Hydraulic Riveter 4
Impact Wrench – 3/8″ 2.5-3.5
Impact Wrench – 1/2″ 4-5
Impact Wrench – 1″ 10
Mini Die Grinder 4-6
Needle Scaler 8-16
Nibbler 4
Orbital Sander 6-9
Ratchet – 1/4″ 2.5-3.5
Ratchet – 3/8″ 4.5-5
Rotational Sander 8-12.5
Shears 8-16
Speed Saw 5

Some Maintenance Considerations:

Oil-Free Compressors with their sealed bearings require less maintenance than oil-lubricated compressors. Oil-free compressors have plenty of power for most non-commercial or around the home uses.

Oil-Lubricated Compressors require the oil to be changed regularly in accordance with the owner’s manual specifications. Most industrial compressors are oil-lubricated.

Power Supply:
Electric-Powered Compressors are the most common and are limited only by the length of the extension cord reaching back to the electrical supply.

Gas-Powered Air Compressors are a good choice for areas where there is no electricity or there is limited availability. The use of gas-powered compressors in confined or unventilated areas is dangerous due to fumes, similar to running a car engine with the garage door closed.