How to Size a Piston Compressor
October 19, 2017
Learn how to properly size your piston compressor based on your needs
Air compressors should be sized based on the volume of air (cfm/m3h) and air pressure (psi/bar) needed to do the job and not horse power. Single stage air compressors have a maximum pressure of around 130 psi (9 bar) while two stage air compressors have a maxinum air pressure of 175 psi (12 bar). Tank size is typically not a critical factor in sizing a compressor.
Calculating your need
- What is the maximum pressure you need? (refer to the table below for a general guideline)
- What is the electrical requirements (voltage/phase)?
- How many people will be using air at any time (maximum)?
- Is this a body shop or mechanical shop?
- Body Shop: 12-15 cfm/person X # of people
- Mechanical Shop: 3-5 cfm/person X # of people
- Now add at least 25% to your total cfm required in order to allow for duty cycle.
Typical cfm consumption by tool
| Tool/Equipment | Air Pressure (psi) | Air Pressure (bar) | Air Consumed (cfm) | Air Consumed (l/s) |
| Impact Wrench 3/8-1/2 | 70-90 | 4.8-6.2 | 5 | 2.36 |
| Impact Wrench 1/2-3/4 | 70-90 | 4.8-6.2 | 10 | 4.72 |
| Impact Wrench 3/4-1 3/4 | 70-90 | 4.8-6.2 | 20 | 9.44 |
| Air Ratchet | 70-90 | 4.8-6.2 | 3-5 | 1.42-2.36 |
| Body Sander (Oribital) | 70-90 | 4.8-6.2 | 12 | 5.66 |
| Tire Changer | 125-150 | 8.6-10.3 | 2 | 0.94 |
| Bead Breaker | 125-150 | 8.6-10.3 | 12 | 5.66 |
| Blow Gun | 70-90 | 4.8-6.2 | 3 | 1.42 |
| Die Grinder | 70-90 | 4.8-6.2 | 7 | 3.3 |
| Screwdriver #2-6 Screw | 70-90 | 4.8-6.2 | 5 | 2.36 |
| Screwdriver #6-5/16 Screw | 70-90 | 4.8-6.2 | 10 | 4.72 |
| Paint Spray Gun (Touch Up) | 70-90 | 4.8-6.2 | 4 | 1.89 |
| Paint Spray Gun (HVLP) | 40-60 | 2.7-4.1 | 15 | 7.08 |
| Nailers/Staplers | 70-90 | 4.8-6.2 | 2-4 | 0.94-1.89 |