Choosing the Right Size Air Compressor
When choosing an air compressor, amount of air (cubic feet per minute or CFM) and pressure (pounds per square inch or PSI) are the two most important factors.
Air Volume (CFM)
When deciding how much air is required, simply add together the amount of CFM each individual machine or tool uses and then add 25% to allow for system variation and future requirements.
Listed here are examples of some tools (used 25% of the time) and their CFM requirements:
| Tool |
CFM Required |
| Drill 1/4" |
6 |
| Drill 1/4" |
6 |
| Drill 1/2" |
9 |
| Impact Wrench 1/2" |
8 |
| Impact Wrench 3/4" |
9 |
| Small Die Grinder |
4 |
| Sander with 2" Pad |
5 |
| Sander with 6" pad |
15 |
| Paint Spray Gun |
5 |
For example, if you were using a 1/2" drill and a spray gun, your total CFM requirements would be (9 + 5) + 25% = 17.5 CFM
Pressure (PSI)
Most hand tools such as air drills and impact wrenches will operate at 90 psi. But different types of machines operate anywhere from 40-150psi, so please check the owner manual for details.
Determine which tool or machine requires the highest pressure, and that is the pressure you need your compressor to be able to deliver.
If your pressure requirement is below 100psi, then a single-stage unit is required. If the maximum pressure is above 100psi, then a two-stage (high pressure) unit is required. |
