# What are the prefixes of pressure

The Pascal is a derived SI unit of pressure and stress in materials testing. It was named after Blaise Pascal. It is defined as

1 Pa = 1 kg / (m · s²) = 1 N / m².

One pascal is the pressure that a force of one newton exerts on an area of ​​one square meter.

### Prefixes

The air pressure is usually given in hectopascal (hPa) because on the one hand the SI-compliant unit Pascal can be used and on the other hand you have a numerical value that corresponds to the usual millibars (mbar).

In research, especially in vacuum technology, the millibar is often used as a unit. Instead of switching to Pascal, the complete abandonment of Torr is an issue.

The unit decapascal (daPa) is often used in ventilation technology, whereby one decapascal corresponds to 0.1 mbar.

• 100 Pa = 10 daPa = 1 hPa = 1 mbar
• 100,000 Pa = 0.1 MPa = 1 bar = 1000 mbar
• 1,000,000 Pa = 1 MPa = 10 bar = 1 N / mm²

The mean air pressure of the atmosphere at sea level and standard pressure or normal pressure is 101 325 Pascal = 1013.25 hPa or 101.325 kPa.

### Conversion of pressure units

Pascalbar technical atmosphere physical atmosphereTorrPounds per square inch
(Pa) (bar) (at) (atm) (torr) (psi)
≡ 1 N / m² ≡ 1 Mdyn / cm² ≡ 1 kp / cm² ≡ pSTP ≡ 1 mmEd ≡ 1 lbf / in.²
1 Pa 1 1,0000 · 10−5 1,0197 · 10−5 9,8692 · 10−6 7,5006 · 10−3 1,4504 · 10−4
1 bar 1,0000 · 105 1 1,0197 · 100 9,8692 · 10−1 7,5006 · 102 1,4504 · 101
1 at 9,8067 · 104 9,8067 · 10−1 1 9,6784 · 10−1 7,3556 · 102 1,4223 · 101
1 atm 1,0133 · 105 1,0133 · 100 1,0332 · 100 1 7,6000 · 102 1,4696 · 101
1 torr 1,3332 · 102 1,3332 · 10−3 1,3595 · 10−3 1,3158 · 10−3 1 1,9328 · 10−2
1 psi 6,8948 · 103 6,8948 · 10−2 7,0307 · 10−2 6,8046 · 10−2 5,1715 · 101 1

Exponential representation rounded to four places.

Category: SI unit