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The chart below shows some common air tools and their average CFM air volume measurements. Use this chart to determine what continuous CFM rating is required of your air compressor. Air tools are often rated as “Average CFM.” “Average CFM” is usually based on a 25% duty cycle (15 seconds out of a minute.). Tools that require continuous power output (ex. orbital sanders, angle grinders, etc) may run into the problem of requiring a greater CFM to run continuously. Nailers, staplers and impact wrenches typically do not have the same problem since by their nature are used more intermittently.
*Note - If you plan on using an air tool on a continuous basis, it is a good idea to multiply the “Average CFM” x 4 to get a continuous CFM rating for the tool.
|AIR TOOL||AVERAGE CFM @ 90 PSI|
|7" Angle Grinder||5-8|
|3/8" Impact Wrench||2.5-4|
|1/2" Impact Wrench||4-5|
|1" Impact Wrench||10|
|Mini Die Grinder||4-6|
Single-Stage compressors have one piston that compresses and pushes air to the storage tank. The single-stage system is normally found on light-duty compressors with a maximum rating below 150 pounds of pressure per square inch (PSI). Single-stage compressors are adequate for most home users and small DYI projects.
Two-Stage compressors have two pistons that compress and deliver air to the storage tank. The first piston compresses the air and pushes it through a check valve to the second piston. The second piston further compresses the air and delivers it to the storage tank. A two-stage system is usually found on commercial heavy-duty compressors with maximum ratings above 150 PSI. Two-stage compressors are good choices for continuous use or shop environments.
Horsepower Ratings are a measurement of the horsepower (HP) the compressor motor produces. Compressor motors generally range from 1.5 HP to 6.5 HP. More powerful units are available for industrial applications. Higher horsepower motors generally have greater psi and are capable of carrying a heavier workload.
Compressor Storage Tank Size is rated in gallons. Larger tanks store more compressed air at higher pressures. The amount of air a compressor delivers is measured in CFM (cubic feet per minute). Do note that the CFM a compressor delivers changes at varying psi. Most air tools have very specific running requirements for volume and pressure. These requirements must be met for the tool to function properly and effectivly. When choosing a compressor, consider the tools you want it to operate. Select the tool that requires the highest CFM at the highest psi, and add 50% to the required CFM for a margin of safety. For example, if a tool requires 3 CFM at 90 psi, select a compressor that delivers at least 4.5 CFM at 90 psi. Use this formula to be sure that the tool receives enough air to function the way it was intended.
Oil-Free Compressors have sealed bearings and require less maintenance than oil-lubricated compressors. Oil-free compressors have plenty of power for most non-commercial/home uses.
Oil-Lubricated Compressors require the user to change the oil regularly. (Consult the owner's manual for specific intervals and oil type). Most industrial/commercial compressors are oil-lubricated.
Electric-Powered Compressors are the most common and are easy to use in any area with a ready electrical supply.
Gas-Powered Air Compressors are a good choice for areas where electricity is limited or unavailable. Don't use gas-powered compressors in confined or unventilated areas.