Pound-force per square inch

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Physical unit
Unit name Pound-force per square inch
Unit symbol
Physical quantity (s) pressure
Formula symbol
system Anglo-American system of measurement
In SI units
Derived from Pound-force , square inch
Display on the round scale of a manometer with the units of measurement psi and k Pa

Pound-force per square inch , or pounds per square inch (" pounds per square inch "), is a unit of measurement commonly used in the United States for pressure . It is a unit of the Anglo-American system of measurement that does not belong to the international system of units (SI) . It is used in the USA for pressure specifications in everyday life. One example is tire pressure . The SI unit Pascal is mostly used in science .

Pound-force per square inch is defined as the pressure exerted by the weight of a mass of one Anglo-American pound (lb) at standard acceleration on an area of ​​one square inch. The designation of the unit is lb.p.sq.in., psi or psi for short . This is short for "pound-force per square inch".

Conversion into other units of the Anglo-American system of measurement:

1 lb.p.sq.in. = 1 psi = 144  lb.p.sq.ft = 1/2000  tn.sh. p.sq.in = 1/2240  tn. p.sq.in

With the standard acceleration of fall and the conversion of kg , the conversion factor from psi to the international system of units results:  

In the opposite direction, the conversion factor is:

Often the unit is specified even more precisely with psia (pounds-force per square inch absolute) for the absolute pressure or psig (pounds-force per square inch gauge) for the relative pressure (overpressure) To characterize the pressure measurement method, according to the - outdated - German terms ata and atü for atmosphere absolute or overpressure.

For larger pressures or tensions, the unit kilopound per square inch (ksi) (1 ksi = 1000 psi) is used in some cases .