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In SI units, the unit is converted to the SI derived unit pascal (Pa), which is defined as one newton per square metre (N/m 2). A newton is equal to 1 kg⋅m/s 2, and a kilogram-force is 9.80665 N, [3] meaning that 1 kgf/cm 2 equals 98.0665 kilopascals (kPa).
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 ...
The table below lists units supported by {{convert}}. More complete lists are linked for each dimension. For a complete list of all dimensions, see full list of units. {{Convert}} uses unit-codes, which are similar to, but not necessarily exactly the same as, the usual written abbreviation for a given unit. These unit-codes are displayed in ...
The SI unit for pressure is the pascal (Pa), equal to one newton per square metre (N/m 2, or kg·m −1 ·s −2). This name for the unit was added in 1971; [7] before that, pressure in SI was expressed in newtons per square metre. Other units of pressure, such as pounds per square inch (lbf/in 2) and bar, are also in common use.
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.
The usage of the pre-SI units has only historic reasons and originates directly from Antoine's original publication. It is however easy to convert the parameters to different pressure and temperature units. For switching from degrees Celsius to kelvin it is sufficient to subtract 273.15 from the C parameter.
Convert mmHg to SI units as follows: 1 mmHg = 0.133 32 kPa. Hence the normal blood pressure in SI units is less than 16.0 kPa SBP and less than 10.7 kPa DBP. These values are similar to the pressure of water column of average human height; so pressure has to be measured on arm roughly at the level of the heart.
The saturated vapor pressure over water in the temperature range of −100 °C to −50 °C is only extrapolated [Translator's note: Supercooled liquid water is not known to exist below −42 °C]. The values have various units (Pa, hPa or bar), which must be considered when reading them.