Pounds per square inch

The pound per square inch or, more accurately,
pound-force per square inch 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: Using unit conversion:
1 psi=≈ 6894.757293168 N/m² Therefore, one pound per square inch is approximately
6894.757 Pa. Now converting the psi to standard atmospheres:
≈ 14.69594877551 psi/atm Therefore, 1 atmosphere is approximately 14.696
pounds per square inch. Pounds per square inch absolute is used to
make it clear that the pressure is relative to a vacuum rather than the ambient atmospheric
pressure. Since atmospheric pressure at sea level is around 14.7 psi, this will be added
to any pressure reading made in air at sea level. The converse is pounds per square inch
gauge or pounds per square inch gage, indicating that the pressure is relative to atmospheric
pressure. For example a bicycle tire pumped up to 65 psi above atmospheric pressure,
will have a pressure of 65 + 14.7=79.7 psia or 65 psig. ksi
The kilopound per square inch is a scaled unit derived from psi, equivalent to a thousand
psi. 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. Magnitude Inch of water: 0.036 psi
Blood pressure – clinically normal human blood pressure: 2.32 psi/1.55 psi
Boost pressure provided by an automotive turbocharger: Pg=6–15 psi
Atmospheric pressure at sea level: Pa=14.7 psi Automobile tyre overpressure: Pg=32 psi
Bicycle tyre overpressure: Pg=65 psi Workshop or garage air tools: Pg=90 psi
Air brake or air brake reservoir overpressure: 90 psi ≤ Pg ≤ 120 psi
Road racing bicycle tire overpressure: Pg=120 psi
Steam locomotive fire tube boiler: 150 psi ≤ Pg ≤ 280 psi
Union Pacific Big Boy steam locomotive boiler: 300 psi
Natural gas pipelines: 800 to 1000 psi Full SCBA for IDLH atmospheres: 2216 psi
Full SCBA for interior firefighting operations: 4500 psi
Full scuba tank overpressure: Pg=3000 psi Airbus A380 hydraulic system: 5000 psi
Ultimate strength of ASTM A36 steel: 58,000 psi Water jet cutter: 40,000–100,000 psi
Conversions See also
Conversion of units: Pressure or mechanical stress
Pressure: Units References External links
Pressure measurement primer Online pressure conversions

2 thoughts on “Pounds per square inch

  1. Is it possible to convert psi to pounds? I want to know in pounds how strong is 405 psi rope. As in if i was to hang weight on the rope how many pounds could it hold before snapping?

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