Vacuum/Compressor Pump Selection Guide

Cole-Parmer Technical Library

Vacuum/Compressor Pump Selection Guide

Pump Types
Dry Pumps (nonlubricated) provide a clean vacuum over the entire vacuum range. Dry pumps require little maintenance and don't generate any waste material

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

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

Vacuum/Pressure Pumps Selection
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

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

1 bar = 14.5 psi
1 cubic foot = 28.32 liters
1 micron (1µ) = 0.001 mm
(29.92 - " Hg) x 25.4 = torr/mm Hg
1" H2O = 0.0361 psi
1" H2O = 0.0735" Hg

Did You Know:
For every 1000 feet above sea level, the listed maximum vacuum for your pump will be reduced by 1" Hg.

	Chemical Compatibility

	Safety Glove Chemical Compatibility Database