The table below can be used to convert between commonly used vacuum units:
% Vacuum |
Torr (mm Mercury) |
Micron | psia, (lb/in2 abs) |
Inches Mercury Absolute |
Inches Mercury Gauge |
kPa abs |
---|---|---|---|---|---|---|
0.0 | 760.0 | 760,000 | 14.7 | 29.92 | 0.00 | 101.4 |
1.3 | 750.0 | 750,000 | 14.5 | 29.5 | 0.42 | 99.9 |
1.9 | 735.6 | 735,600 | 14.2 | 28.9 | 1.02 | 97.7 |
7.9 | 700.0 | 700,000 | 13.5 | 27.6 | 2.32 | 93.5 |
21.0 | 600.0 | 600,000 | 11.6 | 23.6 | 6.32 | 79.9 |
34.0 | 500.0 | 500,000 | 9.7 | 19.7 | 10.22 | 66.7 |
47.0 | 400.0 | 400,000 | 7.7 | 15.7 | 14.22 | 53.2 |
50.0 | 380.0 | 380,000 | 7.3 | 15.0 | 14.92 | 50.8 |
61.0 | 300.0 | 300,000 | 5.8 | 11.8 | 18.12 | 40 |
74.0 | 200.0 | 200,000 | 3.9 | 7.85 | 22.07 | 26.6 |
87.0 | 100.0 | 100,000 | 1.93 | 3.94 | 25.98 | 13.3 |
88.0 | 90.0 | 90,000 | 1.74 | 3.54 | 26.38 | 12 |
89.5 | 80.0 | 80,000 | 1.55 | 3.15 | 26.77 | 10.7 |
90.8 | 70.0 | 70,000 | 1.35 | 2.76 | 27.16 | 9.3 |
92.1 | 60.0 | 60,000 | 1.16 | 2.36 | 27.56 | 8 |
93.0 | 51.7 | 51,700 | 1.00 | 2.03 | 27.89 | 6.9 |
93.5 | 50.0 | 50,000 | 0.97 | 1.97 | 27.95 | 6.7 |
94.8 | 40.0 | 40,000 | 0.77 | 1.57 | 28.35 | 5.3 |
96.1 | 30.0 | 30,000 | 0.58 | 1.18 | 28.74 | 4 |
96.6 | 25.4 | 25,400 | 0.49 | 1.00 | 28.92 | 3.4 |
97.4 | 20.0 | 20,000 | 0.39 | 0.785 | 29.14 | 2.7 |
98.7 | 10.0 | 10,000 | 0.193 | 0.394 | 29.53 | 1.3 |
99.0 | 7.6 | 7,600 | 0.147 | 0.299 | 29.62 | 1.0 |
99.87 | 1.0 | 1,000 | 0.01934 | 0.03937 | 29.88 | 0.13 |
99.90 | 0.75 | 750 | 0.0145 | 0.0295 | 29.89 | 0.1 |
99.99 | 0.10 | 100 | 0.00193 | 0.00394 | 29.916 | 0.013 |
99.999 | 0.01 | 10 | 0.000193 | 0.000394 | 29.9196 | 0.0013 |
100 | 0.00 | 0 | 0 | 0 | 29.92 | 0 |
- 1 psi (lb/in2) = 6,894.8 Pa (N/m2) = 6.895×10-3 N/mm2 = 6.895×10-2 bar
Convert from % Vacuum to Unit of Pressure
The % of vacuum is a relative value where pressure at normal or standard atmosphere is the base value.
pv% = 100% – (pv / patm) 100% (1)
where
pv% = vacuum (%)
pv = absolute pressure (psia, kPa, bar ..)
patm = absolute presure at normal or standard conditions (psia, kPa, bar ..)
Example – Pressure in kPa and % Vacuum
The vacuum with absolute pressure 4 kPa and standard pressure 101.4 kPa can be calculated as
pv% = 100% – ((4 kPa) / (101.4 kPa)) 100%
= 96.1 %
Example – Pressure in kPa and % Vacuum
The vacuum with absolute pressure 0.1 bar and standard pressure 1 bar can be calculated as
pv% = 100% – ((0.1 bar) / (1 bar)) 100%
= 90 %
Vacuum Ranges
Pressure (Pa) |
|
---|---|
Low vacuum | 1×105 to 3×103 |
Medium vacuum | 3×103 to 1×10-1 |
High vacuum | 1×10-1 to 1×10-7 |
Ultra high vacuum | 1×10-7 to 1×10-10 |
Extremely high vacuum | 1×10-10 |
Perfect vacuum | 0 |
- Outer space 1×10-4 to < 3×10-15