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The unit, named after Blaise Pascal, is an SI coherent derived unit defined as one newton per square metre (N/m 2). [1] It is also equivalent to 10 barye (10 Ba) in the CGS system. Common multiple units of the pascal are the hectopascal (1 hPa = 100 Pa), which is equal to one millibar , and the kilopascal (1 kPa = 1000 Pa), which is equal to ...
1–10 kPa Typical explosion peak overpressure needed to break glass windows (approximate) [40] 2 kPa Pressure of popping popcorn (very approximate) [41] [42] 2.6 kPa 0.38 psi Pressure at which water boils at room temperature (22 °C) (20 mmHg) [43] 5 kPa 0.8 psi Blood pressure fluctuation (40 mmHg) between heartbeats for a typical healthy ...
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 ] The atm unit is roughly equivalent to the mean sea-level atmospheric pressure on Earth; that is, the Earth's atmospheric pressure at sea level is ...
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 was implicit in the definition of the Celsius temperature scale, which defined 100 °C (212 °F) as the boiling point of water at this pressure.
Since 1982, STP has been defined as a temperature of 273.15 K (0 °C, 32 °F) and an absolute pressure of exactly 10 5 Pa (100 kPa, 1 bar). NIST uses a temperature of 20 °C (293.15 K, 68 °F) and an absolute pressure of 1 atm (14.696 psi, 101.325 kPa). [3] This standard is also called normal temperature and pressure (abbreviated as NTP).
The reading of a mercury barometer (in mm of Hg, for example) can be converted into an absolute pressure using the above equations. If we had a column of mercury 767 mm high, we could calculate the atmospheric pressure as (767 mm)•(133 kN/m 3) = 102 kPa.
The atmospheric pressure is roughly equal to the sum of partial pressures of constituent gases – oxygen, nitrogen, argon, water vapor, carbon dioxide, etc.. In a mixture of gases, each constituent gas has a partial pressure which is the notional pressure of that constituent gas as if it alone occupied the entire volume of the original mixture at the same temperature. [1]
One pascal is one newton per square meter (N·m −2 or kg·m −1 ·s −2). Experimental measurement of vapor pressure is a simple procedure for common pressures between 1 and 200 kPa. [2] The most accurate results are obtained near the boiling point of the substance; measurements smaller than 1 kPa are subject to major errors. Procedures ...