Pound per square inch

The kilopound per square inch (ksi) is a scaled unit derived from psi, equivalent to a thousand psi (1000 lbf/in²).

ksi are not widely used for gas pressures. They are mostly used in materials science, where the tensile strength of a material is measured as a large number of psi.{{cite web |url=http://www.steelforge.com/literature/metal-tidbits/tensile-strength/ |title=Tensile Strength of Steel and Other Metals |date=18 April 2013 |publisher=All Metals & Forge Group |access-date=2016-07-26 |quote=A metal’s yield strength and ultimate tensile strength values are expressed in tons per square inch, pounds per square inch or thousand pounds (KSI) per square inch. For example, a tensile strength of a steel that can withstand 40,000 pounds of force per square inch may be expressed as 40,000 PSI or 40 KSI (with K being the denominator for thousands of pounds). The tensile strength of steel may also be shown in MPa, or megapascal.}}

The conversion in SI units is 1 ksi = 6.895 MPa, or 1 MPa = 0.145 ksi.

The megapound per square inch (Mpsi) is another multiple equal to a million psi. It is used in mechanics for the elastic modulus of materials, especially for metals.{{Cite web |url=http://www.eitexam.com/Search2/Mechanics/PropertiesEq.asp |title=An example of the use of Mpsi in mechanics for the elastic moduli of several materials |access-date=2015-06-06 |archive-date=2016-12-16 |archive-url=https://web.archive.org/web/20161216151259/http://www.eitexam.com/Search2/Mechanics/PropertiesEq.asp |url-status=dead }}

The conversion in SI units is 1 Mpsi = 6.895 GPa, or 1 GPa = 0.145 Mpsi.

{{main|Orders of magnitude (pressure)}}

• Inch of water: 0.036 psid
• Blood pressure – clinically normal human blood pressure (120/80 millimetre of mercury (mmHg): 2.32 psig/1.55 psig
• Natural gas residential piped in for consumer appliance; 4–6 psig.
• Boost pressure provided by an automotive turbocharger (common): 6–15 psig
• NFL football: 12.5–13.5 psig
• Atmospheric pressure at sea level (standard): 14.7 psia
• Automobile tire overpressure (common): 32 psig
• Bicycle tire overpressure (common): 65 psig
• Workshop or garage air tools: 90 psig
• Railway air brakes or road brakes reservoir overpressure (common): 90–120 psig
• Road racing bicycle tire overpressure: 120 psig
• Steam locomotive fire tube boiler (UK, 20th century): 150–280 psig
• Union Pacific Big Boy steam locomotive boiler: 300 psig
• US Navy steam boiler pressure: 800 psi
• Natural gas pipelines: 800–1,000 psig
• Full SCBA (self-contained breathing apparatus) for IDLH (non-fire) atmospheres: 2,216 psig
• Nuclear reactor primary loop: 2300 psi
• Full SCUBA (self-contained underwater breathing apparatus) tank overpressure (common): 3,000 psig
• Full SCBA (self-contained breathing apparatus) for interior firefighting operations: 4,500 psig
• Airbus A380 hydraulic system: 5,000 psig
• Land Rover Td5 diesel engine fuel injection pressure: 22,500 psi
• Ultimate tensile strength of ASTM A36 steel: 58,000 psi
• Water jet cutter: 40,000–100,000 psig

The conversions to and from SI are computed from exact definitions but result in a repeating decimal. {{Cite book |title=BS 350: Part 1: 1974 – Conversion factors and tables |date=1974 |publisher=British Standards Institution |isbn=0-580-08471-X |page=49 }}{{Cite book |url=https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication811e2008.pdf |title=NIST Special Publication 811 – Guide for the Use of the International System of Units (SI) |date=2008 |publisher=National Institute of Standards and Technology |page=66 }}

$$\backslash begin\{align\}$$

1 \, \mathrm{lbf / in ^ 2} & = \frac{(0.453\,592\,37 \, \mathrm{kg} \times 9.806\,65 \, \mathrm{m / s ^ 2}) / \mathrm{lbf}}{(0.0254 \, \mathrm{m / in}) ^ 2} \, \mathrm{lbf / in ^ 2} \\

& = \frac{8896\,443\,230\,521}{1290\,320\,000} \, \mathrm{Pa} \\

& \approx 6894.757 \, \mathrm{Pa} \\

1 \, \mathrm{Pa} & = \frac{1290\,320\,000}{8896\,443\,230\,521} \, \mathrm{lbf / in ^ 2} \\

& \approx 0.000\,145\,0377 \, \mathrm{lbf / in ^ 2} \\

1 \, \mathrm{kPa} & \approx 0.\,145\,0377 \, \mathrm{lbf / in ^ 2} \\

\end{align}

Approximate conversions (rounded to some arbitrary number of digits, except when denoted by "≡") are shown in the following table.

{{Pressure Units}}

• Conversion of units: Pressure or mechanical stress
• Pressure: Units

{{reflist}}

• [http://www.aeroconsystems.com/electronics/Pressure_transducer_basics/Transducer_primer.htm Pressure measurement primer]
• [http://www.imperialtometric.com/conversion_en.htm Online pressure conversions]

{{Imperial units}}

{{United States Customary Units}}

Category:Units of pressure

Category:Customary units of measurement in the United States

Category:Imperial units