Between 17, the word bar was used for a unit of weight in an early version of the metric system. The unit's official symbol is bar the earlier symbol b is now deprecated and conflicts with the use of b denoting the unit barn, but it is still encountered, especially as mb (rather than the proper mbar) to denote the millibar. The word bar has its origin in the Ancient Greek word βάρος ( baros), meaning weight. 1 millibar = 1 hectopascal (1 hPa = 100 Pa).1 millibar ( mbar) = 1 one-thousandth bar, or 1 ×10 −3 bar.1019.716 centimetres of water (cmH 2O) (1 bar approximately corresponds to the pressure of water at a depth of 10 meters).

The bar is defined using the SI derived unit, pascal: 1 bar ≡ 100,000 Pa ≡ 100,000 N/m 2. Units derived from the bar include the megabar (symbol: Mbar), kilobar (symbol: kbar), decibar (symbol: dbar), centibar (symbol: cbar), and millibar (symbol: mbar). The International Astronomical Union (IAU) also lists it under 'Non-SI units and symbols whose continued use is deprecated'. The US National Institute of Standards and Technology (NIST) deprecates its use except for 'limited use in meteorology' and lists it as one of several units that 'must not be introduced in fields where they are not presently used'. The bar has been legally recognised in countries of the European Union since 2004. The International System of Units, despite previously mentioning the bar, now omits any mention of it. The bar and the millibar were introduced by the Norwegian meteorologist Vilhelm Bjerknes, who was a founder of the modern practice of weather forecasting. By the barometric formula, 1 bar is roughly the atmospheric pressure on Earth at an altitude of 111 metres at 15 ☌. It is defined as exactly equal to 100,000 Pa (100 kPa), or slightly less than the current average atmospheric pressure on Earth at sea level (approximately 1.013 bar). The bar is a metric unit of pressure, but not part of the International System of Units (SI). Psi to Kilopascal Conversion Table Psi ġ5 psi = 15 × 6.8947572932 kPa = 103.A pressure of 700 bar flattened this length of aluminium tubing, which had a wall thickness of 5 millimetres (0.20 in). 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 Kilopascalĭefinition: 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. Although the pascal is more widely used in scientific contexts, psi is more often used in everyday contexts, particularly in countries like the United States as well as others under the US customary or imperial systems of units. As such, the prototype pound at the time was known as the avoirdupois wool pound.Ĭurrent use: The psi is fairly widely used to measure numerous pressures, such as tire pressure, scuba tank pressure, natural gas pipeline pressure, among others.

The system is believed to have come into use in England around 1300 and was used in the international wool trade. It is based on the avoirdupois system, a system that uses weights in terms of the avoirdupois pound, which was standardized in 1959. History/origin: Pound-force per square inch is a unit that originated in the imperial and US customary systems of units.

One psi is approximately 6,895 pascals (N/m 2). It is defined as the pressure that results when a force of one pound-force is applied to a one-square-inch area. Definition: A pound-force per square inch (symbol: psi) is an imperial and US customary unit of pressure based on avoirdupois units.

Psi to bar