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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). Historically, one torr was intended to be the same as one "millimeter of mercury", but subsequent redefinitions of the two units ...
Before 1918, many professionals and scientists using the metric system of units defined the standard reference conditions of temperature and pressure for expressing gas volumes as being 15 °C (288.15 K; 59.00 °F) and 101.325 kPa (1.00 atm; 760 Torr).
Atmospheric pressure, also known as air pressure or barometric pressure (after the barometer), is the pressure within the atmosphere of Earth.The standard atmosphere (symbol: atm) is a unit of pressure defined as 101,325 Pa (1,013.25 hPa), which is equivalent to 1,013.25 millibars, [1] 760 mm Hg, 29.9212 inches Hg, or 14.696 psi. [2]
Pressure units Pascal Bar Technical atmosphere Standard atmosphere Torr Pound per square inch (Pa) (bar) (at) (atm) (Torr) ... 760 14.695 948 775 5142:
The standard atmosphere was originally defined as the pressure exerted by a 760 mm column of mercury at 0 °C (32 °F) and standard gravity (g n = 9.806 65 m/s 2). [2] It was used as a reference condition for physical and chemical properties, and the definition of the centigrade temperature scale set 100 °C as the boiling point of water at this pressure.
Pressure may also be expressed in terms of standard atmospheric pressure; the unit atmosphere (atm) is equal to this pressure, and the torr is defined as 1 ⁄ 760 of this. Manometric units such as the centimetre of water , millimetre of mercury , and inch of mercury are used to express pressures in terms of the height of column of a particular ...
At the normal boiling point of a liquid, the vapor pressure is equal to the standard atmospheric pressure defined as 1 atmosphere, [1] 760 Torr, 101.325 kPa, or 14.69595 psi. For example, at any given temperature, methyl chloride has the highest vapor pressure of any of the liquids in the chart.
Pressure due to direct impact of a strong breeze (~28 mph or 45 km/h) [27] [28] [31] 120 Pa Pressure from the weight of a U.S. quarter lying flat [32] [33] 133 Pa 1 torr ≈ 1 mmHg [34] ±200 Pa ~140 dB: Threshold of pain pressure level for sound where prolonged exposure may lead to hearing loss [citation needed] ±300 Pa ±0.043 psi