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Encyclopedia > Pound force per square inch

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" Cover of brochure The International System of Units. ... Pressure (symbol: p) is the force per unit area acting on a surface in a direction perpendicular to that surface. ... The avoirdupois system is a system of weights defining terms such as pound and ounce. ... Mass is a property of a physical object that quantifies the amount of matter it contains. ... In physics, a force is defined as the rate of change of momentum of that body. ...

## Contents

At 1 lbf/in², a force of one pound-force is applied to an area of one square inch. The pound-force is a non-SI unit of force or weight (properly abbreviated lbf or lbf). The pound-force is equal to a mass of one pound multiplied by the standard acceleration due to gravity on Earth (which is defined as exactly 9. ... A square inch is by definition the area enclosed by a square with sides each 1 inch long. ...

1 lbf/in² = 6 894.75729 pascals (Pa) The pascal (symbol: Pa) is the SI unit of pressure. ...

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 For example, "Pg = 100 psi" rather than "P = 100 psig". The National Institute of Standards and Technology (or NIST) formerly known as The National Bureau of Standards is a non regulatory agency of the United States Department of Commerceâ€™s Technology Administration. ...

• 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".

The ksi (kip, "kilo-pound per square inch") is defined as 1000 psi, combining the prefix kilo with the psi abbreviation. It is occasionally seen in materials science and mechanical engineering, where it is used to specify stress and Young's modulus. In the United States, a kip is sometimes a unit of mass that equals 1,000 avoirdupois pounds (used to compute shipping charges), or more often a unit of force that equals 1,000 pounds force (used to measure engineering loads). ... The Materials Science Tetrahedron, which often also includes Characterization at the center Materials science is the multidisciplinary field relating the performance and function of matter in any and all applications to its micro, nano, and atomic-structure, and vice versa. ... The W16 engine from a Bugatti Veyron Mechanical engineering is a very broad field of engineering that involves the application of physical principles for analysis, design, manufacturing, and maintenance of mechanical systems. ... Figure 1  Stress tensor In physics, stress is a measure of the internal distribution of force per unit area within a body that balances and reacts to the loads applied to it. ... In solid mechanics, Youngs modulus (also known as the modulus of elasticity, elastic modulus or tensile modulus) is a measure of the stiffness of a given material. ...

## 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
Pressure Units

Pascal
(Pa)

Bar
(bar)
Technical atmosphere
(at)

Atmosphere
(atm)

Torr
(mmHg)
Pound per
square inch

(psi)
1 Pa ≡ 1 N/m² 10−5 10.197×10−6 9.8692×10−6 7.5006×10−3 145.04×10−6
1 bar 100 000 ≡ 106 dyn/cm² 1.0197 0.98692 750.06 14.504
1 at 98 066.5 0.980665 ≡ 1 kgf/cm² 0.96784 735.56 14.223
1 atm 101 325 1.01325 1.0332 ≡ 101 325 Pa 760 14.696
1 Torr 133.322 1.3332×10−3 1.3595×10−3 1.3158×10−3 ≡ 1 mmHg 19.337×10−3
1 psi 6 894.76 68.948×10−3 70.307×10−3 68.046×10−3 51.715 ≡ 1 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. Air brake may refer to the following contexts: Air brake (aircraft) — In aeronautics these are a type of flight control system used on aircraft to reduce speed. ... SCUBA is an acronym for Self-Contained Underwater Breathing Apparatus. ... The pascal (symbol: Pa) is the SI unit of pressure. ... The bar (symbol bar) and the millibar (symbol mbar, also mb) are units of pressure. ... A technical atmosphere (symbol: at) is a non-SI unit of pressure equal to 1 kilogram-force per square centimeter, i. ... When expressed as a measurement, an atmosphere (symbol: atm) or standard atmosphere is a unit of pressure roughly equal to the average atmospheric pressure at sea level on Earth. ... The torr (symbol: Torr) or millimetre of mercury (mmHg) is a non-SI unit of pressure. ... The newton (symbol: N) is the SI unit of force. ... In physics, the dyne is a unit of force specified in the centimetre-gram-second (cgs) system of units, symbol dyn. One dyne is equal to exactly 10-5 newtons. ... The deprecated unit kilogram-force (kgf) or kilopond (kp) is the force exerted by one kilogram of mass in standard Earth gravity (defined as exactly 9. ... When expressed as a measurement, an atmosphere (symbol: atm) or standard atmosphere is a unit of pressure roughly equal to the average atmospheric pressure at sea level on Earth. ... The torr (symbol: Torr) or millimetre of mercury (mmHg) is a non-SI unit of pressure. ... The pound-force is a non-SI unit of force or weight (properly abbreviated lbf or lbf). The pound-force is equal to a mass of one pound multiplied by the standard acceleration due to gravity on Earth (which is defined as exactly 9. ...

This article lists conversion factors between a number of units of measurement. ... Pressure (symbol: p) is the force per unit area acting on a surface in a direction perpendicular to that surface. ...

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