Millibars (symbol: mb) are also commonly used when referencing atmospheric air pressure, where atmospheric pressure equals 1013.25 mbar (101.325 kPa). The International Bureau of Weights and Measures has specified the bar as a unit that authors should have the freedom to use but has chosen not to include the bar in the list of non-SI units accepted for use with SI. The term "bar" comes from the Greek word "baros," which means weight.Ĭurrent use: Although the bar is a metric unit of pressure, it is not accepted within the International System of Units (SI) and is even deprecated within certain fields. History/origin: The unit, bar, was introduced by Vilhelm Bjerknes, a Norwegian meteorologist who founded modern weather forecasting. It is equal to 0.987 atmospheres (101,325 Pa), the unit often used as a reference of standard pressure. Barĭefinition: A bar (symbol: bar) is a metric unit of pressure that is defined as exactly 100,000 pascals (symbol: Pa). This is true of most countries, including the United States. The kilopascal is more prevalent in scientific contexts such as material science, engineering, and geophysics. Exceptions include certain countries that use either the imperial or United States customary systems of measurement, such as the United States, in which the unit of pound per square inch is more commonly used. In 1971, at the 14 th General Conference on Weights and Measures, the pascal was adopted as an SI derived unit of pressure.Ĭurrent use: The kilopascal is widely used worldwide in countries that have adopted SI. The kilopascal is simply a multiple of the pascal, as is common within SI. History/origin: The unit, pascal, is named after Blaise Pascal, a French mathematician and physicist. ![]() A kilopascal is defined as 1,000 Pa, where 1 Pa is defined as the pressure exerted by a 1 newton force applied perpendicularly to an area of one square meter, expressed as 1 N/m 2 or 1 kg/m ĭensity of crude oil, Density of fuel oils, Density of lubricating oil and Density of jet fuel as function of temperature.Īs shown in the figures, the change in density is not linear with temperature - this means that the volumetric expansion coefficient for water is not constant over the temperature range.Definition: A kilopascal (symbol: kPa) is a multiple of the pascal (Pa), an SI (International System of Units) derived unit of pressure used to measure internal pressure, Young's modulus, stress, and ultimate tensile strength. įor other substances, see density and specific weight of acetone, air, ammonia, argon, benzene, butane, carbon dioxide, carbon monoxide, ethane, ethanol, ethylene, helium, hydrogen, methane, methanol, nitrogen, oxygen, pentane, propane and toluene. See also other properties of Water at varying temperature and pressure : Boiling points at high pressure, Boiling points at vacuum pressure, Dynamic and kinematic viscosity, Enthalpy and entropy, Heat of vaporization, Ionization Constant, pK w, of normal and heavy water, Melting points at high pressure, Prandtl number, Properties at Gas-Liquid Equilibrium Conditions, Saturation pressure, Specific gravity, Specific heat (heat capacity), Specific volume, Thermal conductivity, Thermal diffusivity and Vapour pressure at gas-liquid equilibrium. See Water and Heavy Water for thermodynamic properties at standard condtions. The density of water depends on temperature and pressure as shown below: Note! Temperature must be within the ranges 0-370 ☌, 32-700 ☏, 273-645 K and 492-1160 °R to get valid values. The output density is given as g/cm 3, kg/m 3, lb/ft 3, lb/gal(US liq) and sl/ft 3. The calculator below can be used to calculate the liquid water density at given temperatures. See more about the difference between mass and weight Online Water density Calculator The density of water is 1.940 sl/ft 3 at 39 ☏ (4 ☌), and the specific weight in Imperial units is In the Imperial system the mass unit is the slug, and is derived from the pound-force by defining it as the mass that will accelerate at 1 foot per square second when a 1 pound-force acts upon it :ġ = 1 * 1 and 1 = 1 /1 ![]() In the SI system, specific weight of water at 4☌ will be: G = acceleration due to gravity, units typically and value on Earth usually given as 9.80665 m/s 2 or 32.17405 ft/s 2 Specific weight is the ratio of the weight to the volume of a substance: Pure water has its highest density 1000 kg/m 3 or 1.940 slug/ft 3 at temperature 4☌ (=39.2☏). Density is the ratio of the mass to the volume of a substance:
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