Pound Force Per Square Inch

Information about Pound Force Per Square Inch

A pressure gauge reading in PSI (red scale) and kPa (black scale)

The pound per square inch or, more accurately, pound-force per square inch (symbol: psi or lbf/sq in) is a unit of pressure or of stress based on avoirdupois units. It is the pressure resulting from a force of one pound-force applied to an area of one square inch:

1 lbf/sq in ≈ 6,894.757 Pa (the SI unit of pressure).

Relation to other measures

Other abbreviations are used that append a modifier to "psi". However, the US 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[1] For example, "P_g = 100 psi" rather than "P = 100 psig".

psia (pounds-force per square inch absolute) - gauge pressure plus local atmospheric pressure. Replace "x psia" with "P_a = 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 "P_g = x psi".
psivg (psi vented gauge) - difference between the measuring point and the local pressure. Replace "x psivg" with "P_vg = 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 "P_sg = x psi".

psig

Psig (pound-force per square inch gauge) is a unit of pressure relative to atmospheric pressure at sea level. By contrast, psi measures pressure relative to a vacuum (such as that in space). Most pressure gauges, such as tire gauges, are calibrated to read zero at sea level, because most applications require the difference of pressure.

At sea level, Earth's atmosphere actually exerts a pressure of 14.695948804 psi (see below). Humans do not feel this pressure because internal pressure of liquid in their bodies matches the external pressure. If a pressure gauge is calibrated to read zero in space, then at sea level on Earth it would read 14.695948804 psi. Thus a reading of 30 psig on a tire gauge, represents an absolute pressure of 44.695948804 psi.

Psi is often used incorrectly instead of psig.^[1]

ksi and kip

The ksi (kip, "kilo-pound[-force] per square inch") is 1000 psi, combining the prefix kilo with the psi abbreviation. It is occasionally used in materials science and mechanical engineering to specify stress and Young's modulus.

Magnitude

Atmospheric pressure at sea level (standard): P_a = 14.695948804 psi
Automobile tire overpressure (common): P_g = 32 psi
Bike tire overpressure (common): P_g = 65 psi
Air brake reservoir overpressure (common): 90 psi ≤ P_g ≤ 120 psi
Ivan Drago's punch (fictional): P_g = 1850 psi
Full scuba tank overpressure (common): P_g = 3,000 psi

Conversions

**Pressure Units**
	pascal (Pa)	bar (bar)	technical atmosphere (at)	atmosphere (atm)	torr (mmHg)	pound-force per square inch (psi)
1 Pa	≡ 1 N/m²	10⁻⁵	1.019710⁻⁵	9.869210⁻⁶	7.500610⁻³	145.0410⁻⁶
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	≡ 1 atm	760	14.696
1 torr	133.322	1.333210⁻³	1.359510⁻³	1.315810⁻³	≡ 1 mmHg	19.33710⁻³
1 psi	6 894.76	68.94810⁻³	70.30710⁻³	68.04610⁻³	51.715	≡ 1 lbf/in²

Example reading: 1 Pa = 1 N/m² = 10⁻⁵ bar = 10.19710⁻⁶ at = 9.869210⁻⁶ atm, etc.
Note: mmHg is an abbreviation for millimetres of mercury.

Notes

1. ^ TurnFast Glossary www.turnfast.com/refc_glossary/glossary.shtml, psi and psig

change from (atm. presure at sea level (1 Pa = 14.5 psi) to (1 bar = 14.5 psi)

External links

Pressure (symbol: p) is the force per unit area applied on a surface in a direction perpendicular to that surface.

Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.
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Stress is a measure of force per unit area within a body. It is a body's internal distribution of force per area that reacts to external applied loads. Stress is often broken down into its shear and normal components as these have unique physical significance.
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The avoirdupois (IPA: /ˌævərdəˈpɔɪz/; French IPA: [avwɑrdypwɑ]
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A pound or pound-force (abbreviations: lb, lbf, or lb_f) is a unit of force. Pound is also the name of a unit of mass. One pound-force is approximately equal to the gravitational force exerted on a mass of one avoirdupois pound on the
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For other uses, see square.

A square inch (plural: square inches) is a unit of area, equal to the area of a square with sides of one inch.
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The pascal (symbol: Pa) is the SI derived unit of pressure or stress (also: Young's modulus and tensile strength). It is a measure of perpendicular force per unit area i.e. equivalent to one newton per square meter or one Joule per cubic meter.
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Si, si, or SI may refer to (all SI unless otherwise stated):

In language:

One of two Italian words:
sì (accented) for "yes"
si

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The National Institute of Standards and Technology (NIST), known between 1901–1988 as the National Bureau of Standards (NBS), is a non-regulatory agency of the United States Department of Commerce. The institute's mission is to promote U.S.
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This article or section relies largely or entirely upon a .
Please help [ improve this article] by introducing appropriate of additional sources. ()
This article has been tagged since December 2006.
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EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001. Their greatest hit, their debut single "time after time", peaked at #13 in the Oricon singles chart.
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atmosphere is a layer of gases that may surround a material body of sufficient mass.^[1] The gases are attracted by the gravity of the body, and are retained for a longer duration if gravity is high and the atmosphere's temperature is low.
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kip is a unit of force that equals 1,000 pounds-force, used primarily by architects and engineers to measure engineering loads. It is also used as a unit of weight to compute shipping charges. It is equivalent to one half of a U.S. ton.
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Materials science or materials engineering is an interdisciplinary field involving the properties of matter and its applications to various areas of science and engineering. This science investigates the relationship between the structure of materials and their properties.
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Mechanical Engineering is an engineering discipline that involves the application of principles of physics for analysis, design, manufacturing, and maintenance of mechanical systems.
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Young's modulus (E) is a measure of the stiffness of a given material. It is also known as the Young modulus, modulus of elasticity, elastic modulus or tensile modulus (the bulk modulus and shear modulus are different types of elastic modulus).
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Air brake may refer to the following contexts:

Air brake (aircraft), in aeronautics, a type of flight control system used on aircraft to reduce speed
Air brake (rail), a type of brake operated by compressed air and used on locomotives and railroad cars

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Ivan Drago

Statistics
Real name Ivan Drago
Nickname The Siberian Bull,
Death from Above,
The Siberian Express
Rated at Heavyweight
Nationality Soviet Russian
Birth date November 3 1963
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A scuba set is an independent breathing set that provides a scuba diver with the breathing gas necessary to breathe underwater during scuba diving. It is much used for sport diving and some sorts of work diving.
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The bar (symbol bar), decibar (symbol dbar) and the millibar (symbol mbar, also mb) are units of pressure. They are not SI units, but they are accepted for use with the SI.
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A technical atmosphere (symbol: at) is a non-SI unit of pressure equal to 1 kilogram-force per square centimeter, i.e. 98.0665 kilopascals (kPa) or about 0.967 84 standard atmospheres.
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Standard atmosphere is a pressure defined as 101 325 Pa and used as unit of pressure (symbol: atm). Standard atmosphere is a non-SI unit that is internationally recognized.
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torr (symbol: Torr) is a non-SI unit of pressure defined as 1/760 of an atmosphere. It was named after Evangelista Torricelli, an Italian physicist and mathematician who discovered the principle of the barometer in 1644.
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pound per square inch or, more accurately, pound-force per square inch (symbol: psi or lbf/sq in) is a unit of pressure or of stress based on avoirdupois units.
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The newton (symbol: N) is the SI derived unit of force, named after Sir Isaac Newton in recognition of his work on classical mechanics.

Definition

A newton
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Dynes redirects here. For the president of the University of California system, see Robert C. Dynes.

In physics, the dyne (symbol "dyn") is a unit of force specified in the centimeter-gram-second
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The unit kilogram-force (kgf, often just kg) or kilopond (kp) is defined as the force exerted by one kilogram of mass in standard Earth gravity.
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