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The distinction between gauge and absolute pressure is important for calculation of gas properties and pressure must be identified as either gauge or absolute. Gauge pressure in msw or fsw is converted to absolute pressure in bar or atm for decompression and gas consumption calculation, but decompression tables are usually provided ready for ...
[1] [2] By the barometric formula, 1 bar is roughly the atmospheric pressure on Earth at an altitude of 111 metres at 15 °C. The bar and the millibar were introduced by the Norwegian meteorologist Vilhelm Bjerknes, who was a founder of the modern practice of weather forecasting, with the bar defined as one mega dyne per square centimeter. [3]
Moderate vacuum pressure readings can be ambiguous without the proper context, as they may represent absolute pressure or gauge pressure without a negative sign. Thus a vacuum of 26 inHg gauge is equivalent to an absolute pressure of 4 inHg, calculated as 30 inHg (typical atmospheric pressure) − 26 inHg (gauge pressure).
It is defined as the pressure exerted by a column of water of 1 inch in height at defined conditions. At a temperature of 4 °C (39.2 °F) pure water has its highest density (1000 kg/m 3 ). At that temperature and assuming the standard acceleration of gravity , 1 inAq is approximately 249.082 pascals (0.0361263 psi ).
Air pressure in an automobile tire relative to atmosphere (gauge pressure) [citation needed] +210 to +900 kPa +30 to +130 psi Air pressure in a bicycle tire relative to atmosphere (gauge pressure) [57] 300 kPa 50 psi Water pressure of a garden hose [58] 300 to 700 kPa 50–100 psi Typical water pressure of a municipal water supply in the US [59]
For instance, an absolute pressure of 80 kPa may be described as a gauge pressure of −21 kPa (i.e., 21 kPa below an atmospheric pressure of 101 kPa). For example, abdominal decompression is an obstetric procedure during which negative gauge pressure is applied intermittently to a pregnant woman's abdomen. Negative absolute pressures are possible.
Since atmospheric pressure at sea level is around 14.7 psi (101 kilopascals), this will be added to any pressure reading made in air at sea level. The converse is pound per square inch gauge (psig), indicating that the pressure is relative to atmospheric pressure. For example, a bicycle tire pumped up to 65 psig in a local atmospheric pressure ...
A centimetre of water [1] is a unit of pressure. It may be defined as the pressure exerted by a column of water of 1 cm in height at 4 °C (temperature of maximum density) at the standard acceleration of gravity, so that 1 cmH 2 O (4°C) = 999.9720 kg/m 3 × 9.80665 m/s 2 × 1 cm = 98.063754138 Pa ≈ 98.0638 Pa, but conventionally a nominal maximum water density of 1000 kg/m 3 is used, giving ...