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  2. Atmospheric pressure - Wikipedia

    en.wikipedia.org/wiki/Atmospheric_pressure

    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 ...

  3. International Standard Atmosphere - Wikipedia

    en.wikipedia.org/wiki/International_Standard...

    at each geopotential altitude, where g is the standard acceleration of gravity, and R specific is the specific gas constant for dry air (287.0528J⋅kg −1 ⋅K −1). The solution is given by the barometric formula. Air density must be calculated in order to solve for the pressure, and is used in calculating dynamic pressure for moving vehicles.

  4. Useful conversions and formulas for air dispersion modeling

    en.wikipedia.org/wiki/Useful_conversions_and...

    Atmospheric pollutant concentrations expressed as mass per unit volume of atmospheric air (e.g., mg/m 3, μg/m 3, etc.) at sea level will decrease with increasing altitude because the atmospheric pressure decreases with increasing altitude. The change of atmospheric pressure with altitude can be obtained from this equation: [2]

  5. Torr - Wikipedia

    en.wikipedia.org/wiki/Torr

    0.019 336 77 psi. 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 ...

  6. Building airtightness - Wikipedia

    en.wikipedia.org/wiki/Building_airtightness

    The relationship between pressure and leakage air flow rate is defined by the power law between the airflow rate and the pressure difference across the building envelope as follows: q L =C L ∆p n. where: q L is the volumetric leakage airflow rate expressed in m 3 h −1; C L is the air leakage coefficient expressed in m 3 h −1 Pa −n

  7. Psychrometrics - Wikipedia

    en.wikipedia.org/wiki/Psychrometrics

    Hygrometer. Dry / Wet-bulb temperature. v. t. e. Psychrometrics (or psychrometry, from Greek ψυχρόν (psuchron) 'cold' and μέτρον (metron) 'means of measurement'; [ 1][ 2] also called hygrometry) is the field of engineering concerned with the physical and thermodynamic properties of gas - vapor mixtures .

  8. Pressure measurement - Wikipedia

    en.wikipedia.org/wiki/Pressure_measurement

    Checking tire pressure with a spring and piston tire-pressure gauge. Pressure measurement is the measurement of an applied force by a fluid ( liquid or gas) on a surface. Pressure is typically measured in units of force per unit of surface area. Many techniques have been developed for the measurement of pressure and vacuum.

  9. Standard atmosphere (unit) - Wikipedia

    en.wikipedia.org/wiki/Standard_atmosphere_(unit)

    US customary units. 14.69595 psi. other metric units. 1.013250 bar. Aneroid barometer for household use from c. 1925. The standard atmosphere (symbol: atm) is a unit of pressure defined as 101 325 Pa. It is sometimes used as a reference pressure or standard pressure. It is approximately equal to Earth 's average atmospheric pressure at sea level.