Search results
Results from the WOW.Com Content Network
Inch of mercury (inHg and ″Hg) is a non-SI unit of measurement for pressure. It is used for barometric pressure in weather reports , refrigeration and aviation in the United States . It is the pressure exerted by a column of mercury 1 inch (25.4 mm) in height at the standard acceleration of gravity .
A millimetre of mercury is a manometric unit of pressure, formerly defined as the extra pressure generated by a column of mercury one millimetre high. Currently, it is defined as exactly 133.322 387 415 pascals, or approximately [a] 1 torr = 1 / 760 atmosphere = 101 325 / 760 pascals. [1] [2] It is denoted mmHg [3] or mm Hg. [4] [2]
The mercury barometer's design gives rise to the expression of atmospheric pressure in inches or millimeters of mercury (mmHg). A torr was originally defined as 1 mmHg. The pressure is quoted as the level of the mercury's height in the vertical column.
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]
When millimetres of mercury (or inches of mercury) are quoted today, these units are not based on a physical column of mercury; rather, they have been given precise definitions that can be expressed in terms of SI units. [9] One millimetre of mercury is approximately equal to one torr. The water-based units still depend on the density of water ...
millimetre of mercury: mmHg mmHg 1.0 mmHg (0.13 kPa) inch of mercury: inHg inHg 1.0 ...
centimetre of mercury: cmHg ... inch of mercury (conventional) inHg ... millimetre of mercury: mmHg: ≡ 13 595.1 kg/m 3 × 1 mm × g 0 ≈ 1 torr
The now-conventional inch of mercury is defined to as 25.4 mmHg, the same as the relationship between an inch and a millimeter (this isn't necessarily true when comparisions include either unit of pressure in an older version, and the relationship between the units of length has also varied over time and place).