Torr
Traditional unit of pressure / From Wikipedia, the free encyclopedia
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The torr (symbol: Torr) is a unit of pressure based on an absolute scale, defined as exactly 1/760 of a standard atmosphere (101325 Pa). Thus one torr is exactly 101325/760 pascals (≈ 133.32 Pa).
torr | |
---|---|
Unit of | pressure |
Symbol | Torr |
Named after | Evangelista Torricelli |
Definition | 1/760 atm |
Conversions | |
1 Torr in ... | ... is equal to ... |
SI derived units | 133.3224 Pa |
British Gravitational System | 0.01933677 psi |
Historically, one torr was intended to be the same as one "millimeter of mercury", but subsequent redefinitions of the two units made them slightly different (by less than 0.000015%). The torr is not part of the International System of Units (SI). Even so, it is often combined with the metric prefix milli to name one millitorr (mTorr) or 0.001 Torr.
The unit was named after Evangelista Torricelli, an Italian physicist and mathematician who discovered the principle of the barometer in 1644.[1]