Considerations for Selecting a Vacuum/Compressor Pump
Dry Pumps (nonlubricated) provide a clean vacuum over the entire vacuum range. Dry pumps require little maintenance and don't generate any waste material
See Air Admiral Vacuum Pump
Water-Lubricated Pumps provide a rough vacuum at low initial cost and are very simple to operate. These pumps are corrosion resistant but are not suitable for water vapor sensitive systems
See Cole-Parmer Water Jet Aspirator Pump
Oil-Lubricated Pumps offer high capacities, high vacuum/pressure levels, and lower noise levels. Diffusion pumps feature an ultra-high vacuum. Oil-lubricated pumps, however, require routine maintenance and oil changes, and the oil may contaminate your vacuum
See Cole-Parmer Rotary Vane Pumps
To determine which pump is right for your application, calculate your free-air capacity by adding up the free-air requirements for all air-powered instruments. Add an additional 25% to allow for system variables and to provide capacity for future needs. Then determine the maximum vacuum or pressure required for your application — see the "Vacuum/ Pressure Conversion Table" below for any necessary values.
Vacuum/Pressure Conversion Table
Table scrolls horizontally
| Absolute vacuum | Relative vacuum |
| torr/mm Hg | mbar | psia | atm | % vacuum | " Hg |
| 760 | 1013 | 14.696 | 1.0 | 0.0 | 0.0 |
| 750 | 1000 | 14.5 | 0.987 | 1.3 | 0.42 |
| 500 | 667 | 9.7 | 0.658 | 34 | 10.22 |
| 400 | 533 | 7.7 | 0.526 | 47 | 14.22 |
| 300 | 400 | 5.8 | 0.395 | 61 | 18.12 |
| 200 | 267 | 3.9 | 0.264 | 74 | 22.07 |
| 100 | 133.3 | 1.93 | 0.132 | 87 | 25.98 |
| 70 | 93.4 | 1.35 | 0.0921 | 90.8 | 27.16 |
| 50 | 66.7 | 0.97 | 0.0658 | 93.5 | 27.95 |
| 25.4 | 33.8 | 0.4912 | 0.034 | 96.6 | 28.92 |
| 10 | 13.33 | 0.193 | 0.0132 | 98.7 | 29.53 |
| 1 | 1.33 | 1.934 x 10-2 | 1.32 x 10-3 | 99.9 | 29.88 |
| 0.1 | 0.133 | 1.93 x 10-3 | 1.32 x 10-4 | 99.99 | 29.916 |
| 1 x 10-2 | 1.33 x 10-2 | 1.93 x 10-4 | 1.32 x 10-5 | 99.999 | 29.9196 |
| 1 x 10-3 | 1.33 x 10-3 | 1.93 x 10-5 | 1.32 x 10-6 | 99.9999 | 29.91996 |
| 1 x 10-4 | 1.33 x 10-4 | 1.93 x 10-6 | 1.32 x 10-7 | | 29.91999 |
Did You Know:
For every 1000 feet above sea level, the listed maximum vacuum for your pump will be reduced by 1" Hg.
