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The kilopound per square inch (ksi) is a scaled unit derived from psi, equivalent to a thousand psi (1000 lbf/in 2).. 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.
The SI unit for pressure is the pascal (Pa), equal to one newton per square metre (N/m 2, or kg·m −1 ·s −2). This name for the unit was added in 1971; [7] before that, pressure in SI was expressed in newtons per square metre. Other units of pressure, such as pounds per square inch (lbf/in 2) and bar, are also in common use.
The pascal (Pa) or kilopascal (kPa) as a unit of pressure measurement is widely used throughout the world and has largely replaced the pounds per square inch (psi) unit, except in some countries that still use the imperial measurement system or the US customary system, including the United States.
Units for other physical quantities are derived from this set as needed. In English Engineering Units, the pound-mass and the pound-force are distinct base units, and Newton's Second Law of Motion takes the form = where is the acceleration in ft/s 2 and g c = 32.174 lb·ft/(lbf·s 2).
In North America, air and other industrial gases are often measured in inches of water when at low pressure. This is in contrast to inches of mercury or pounds per square inch (psi, lbf/in 2) for larger pressures. One usage is in the measurement of air ("wind") that supplies a pipe organ and is referred simply as inches.
1.5 psi Pressure increase per meter of a water column [26] 10 kPa 1.5 psi Decrease in air pressure when going from Earth sea level to 1000 m elevation [citation needed] +13 kPa +1.9 psi High air pressure for human lung, measured for trumpet player making staccato high notes [48] < +16 kPa +2.3 psi
The pound per square inch (psi) is still in widespread use in the US and Canada, for measuring, for instance, tire pressure. A letter is often appended to the psi unit to indicate the measurement's zero reference; psia for absolute, psig for gauge, psid for differential, although this practice is discouraged by the NIST. [3]
Pound per square inch, unit of pressure; PSI (computational chemistry), software; J/psi meson, subatomic particle; Porous silicon; Water potential, denoted Ψ, in physical chemistry, the potential energy of a water solution relative to pure water; Wave function, denoted ψ, in quantum mechanics