Pound-force per square inch
Encyclopedia : P : PO : POU : Pound-force per square inch
- The abbreviation psi has multiple meanings; see Psi for other possibilities.
The pound-force per square inch (symbol: lbf/in²) is a non-SI unit of pressure based on avoirdupois units. In casual English language use it is rendered as "pounds per square inch", abbreviated to psi with little distinction between "mass" and "force"
Definition
At 1 lbf/in², a force of one pound-force is applied to an area of one square inch.1 lbf/in² = 6,894.75729 pascals (Pa)
Other abbreviations are used that append a modifier to "psi". However, the National Institute of Standards and Technology recommends that, to avoid confusion, any modifiers be instead applied to the quantity being measured rather than the unit of measure[link] For example, "Pg = 100 psi" rather than "P = 100 psig".
- psia (pounds-force per square inch absolute) - gauge pressure plus local atmospheric pressure. Replace "x psia" with "Pa = x psi".
- psid (psi difference) - difference between two pressures. Replace "x psid" with "ΔP = x psi".
- psig (pounds-force per square inch gauge). Replace "x psig" with "Pg = x psi".
- psivg (psi vented gauge) - difference between the measuring point and the local pressure. Replace "x psivg" with "Pvg = x psi".
- psisg (psi sealed gauge) - difference between a chamber of air sealed at atmospheric pressure and the pressure at the measuring point. Replace "x psisg" with "Psg = x psi".
Context
- Atmospheric pressure at sea level: Pa = 14.7 psi
- Automobile tire: Pg = 32 psi
- Air brake reservoir: 90 psi ≤ Pg ≤ 120 psi
- Full scuba tank: Pg = 3,000 psi
| Pascal (Pa) | Bar (bar) | Technical atmosphere (at) | Atmosphere (atm) | Torr (mmHg) | Pound per square inch (psi) | |
|---|---|---|---|---|---|---|
| 1 Pa | N/m² | 10−5 | ||||
| 1 bar | 100 000 | 6 dyne>dyn/cm² | 1.0197 | 0.98692 | 750.06 | 14.504 |
| 1 at | 98 066.5 | 0.980665 | kgf/cm² | 0.96784 | 735.56 | 14.223 |
| 1 atm | 101 325 | 1.01325 | 1.0332 | Pa | 760 | 14.696 |
| 1 Torr | 133.322 | mmHg | ||||
| 1 psi | 6,894.76 | 51.715 | lbf/in² |
Example reading: 1 Pa = 1 N/m² = 10−5 bar = 10.197×10−6 at = 9.8692×10−6 atm ....etc.
Note: mmHg is an abbreviation for millimetres of mercury.
See also
External links
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