Pressure
Pressure (p) = Force (F) ÷ area (A) [N/m² = Pas]
SI-Units
| Pas | hPas / mbar |
bar | Torr / mm Hg |
mWs | mmWs | atm | at | psi | |
| 1 Pascal = | 1 | 0,01 | 1,0000·10-5 | 0,007501 | 0,0001020 | 0,1020 | 9,8692·10-6 | 1,0197·10-5 | 0,0001450 |
| 1 Hektopascal = 1 Millibar = |
100 | 1 | 0,001 | 0,7501 | 0,0102 | 10,1972 | 0,0009869 | 0,00102 | 0,0145 |
| 1 bar = | 100.000 | 1.000 | 1 | 750,06 | 10,1972 | 10.197 | 0,9869 | 1,0197 | 14,5038 |
| 1 Torr = 1 mm mercury= |
133,32 | 1,3332 | 0,001333 | 1 | 0,01360 | 13,5951 | 0,001316 | 0,001360 | 0,01934 |
| 1 m water column = | 9.806,65 | 98,0665 | 0,09807 | 73,5559 | 1 | 1.000 | 0,09678 | 0,1 | 1,4223 |
| 1 mm water column = | 9,8067 | 0,09807 | 9,8067·10-5 | 0,07356 | 0,001 | 1 | 9,6784·10-5 | 1,0000·10-4 | 0,001422 |
| 1 physical atmosphere = | 101.325 | 1.013,25 | 1,0133 | 760 | 10,3323 | 10.332 | 1 | 1,0332 | 14,6960 |
| 1 technical atmosphere = | 98.067 | 980,67 | 0,9807 | 735,56 | 10 | 10.000 | 0,9678 | 1 | 14,2233 |
| 1 psi = pounds per sq inch |
6.894,76 | 68,9476 | 0,06895 | 51,7149 | 0,7031 | 703,07 | 0,06805 | 0,07031 | 1 |
Measures of pressure compare current pressure with reference pressure.
In pressure measurement engineering the following types of pressure are differentiated. They provide a statement about the relationship of measurement pressure to the reference pressure. Absolute pressure always refers to empty space of the universe (pressure zero).
Absolute pressure:
– Measured pressure above absolute zero
– Reference, ideal vakuum
– Measurement presure is always greater than reference pressure
Overpressure:
– Measured pressure above the barometric air pressure
– Reference ambient pressure
– Measured pressure always greater than reference pressure
Underpressure:
– Measured pressure below the baromatric air pressure
– Reference ambient pressure
– Measured pressure always lower than reference pressure
Differencial pressure:
– Measured pressure belog or above an arbitrary reference pressure
– Measurement pressure greater or lower reference pressure
Atmospherical pressure:
Atmospherical pressure is the most important pressure for life on earth. It arises due to the weight of the atmosphere that surrounds the earth. The atmosphere reaches up until about 500 km. Up until this heigth (absolute pressure pabs = zero) air pressure decreases constantly. Furthermore the atmospherical air pressure is influenced by weather-related variations. At sea level P amb is on average 1013,25hPa. At high pressure or low pressure conditions it could alternate up until ± 5 %.
Source: SI - Systeme