Bars explained
The bar is a metric unit of pressure, defined as exactly 100,000 pascals. Although not part of the SI system, the bar is widely used in various scientific and industrial fields due to its convenient size, approximately equal to atmospheric pressure at sea level. This makes it particularly useful for applications where pressure measurements are close to atmospheric conditions.
Symbol
The official symbol for the bar is bar. The earlier symbol "b" is now deprecated due to potential confusion with other units such as the barn (a unit of area) or bit (a unit of information). Despite this, "b" is still occasionally encountered, especially in the form "mb" for millibar, though "mbar" is the preferred notation.
Comparison with Other Unit Systems
While the bar is not an SI unit, it is accepted for use with the SI system by organizations like the International Bureau of Weights and Measures (BIPM). The SI unit for pressure is the pascal (Pa), with 1 bar equaling 100,000 Pa. The bar is also approximately equal to 0.9869 atmospheres (atm), making it a convenient unit for expressing atmospheric pressure.
Applications and Fields of Use
The bar is utilized in various fields due to its practical size and ease of use:
- Meteorology: Atmospheric pressure is often measured in millibars (mbar), especially in weather forecasting.
- Oceanography: Pressure measurements in the ocean are commonly expressed in decibars (dbar).
- Engineering: Hydraulic and pneumatic systems frequently use bars to specify operating pressures.
- Automotive: Tire pressures are commonly indicated in bars.
- Beverage Industry: Carbonation levels in beverages are measured in bars.
Measurement Instruments
Instruments used to measure pressure in bars include:
- Barometer: Measures atmospheric pressure, typically in millibars.
- Manometer: Measures pressure of gases or liquids in a closed system.
- Pressure Gauge: Commonly used in industrial settings to measure system pressures.
Origin
The term "bar" originates from the Ancient Greek word βάρος (baros), meaning weight. The unit was introduced by British meteorologist Napier Shaw in 1909 to provide a convenient metric unit for atmospheric pressure measurements.
FAQs
What is the difference between bar and barg?
"Bar" refers to absolute pressure, measured relative to a perfect vacuum. "Barg" denotes gauge pressure, which is measured relative to ambient atmospheric pressure. For example, 1 barg equals 1 bar above atmospheric pressure.
Why is atmospheric pressure often given in millibars?
Millibars provide a convenient scale for atmospheric pressure measurements, with standard sea-level pressure defined as 1013.25 mbar. This unit is especially prevalent in meteorology.
What is the relationship between bar and depth in water?
In freshwater, pressure increases by approximately 1 bar for every 10 meters of depth. This means that at 10 meters underwater, the pressure is about 2 bars: 1 bar from the atmosphere and 1 bar from the water column. This relationship is crucial for divers and underwater operations.
How do I convert bars to other pressure units?
Use the links below for easy conversions from bars to other pressure units available on this website.
- Bars to pascals
- Bars to kilopascals
- Bars to joules per cubic meter
- Bars to newtons per square meter
- Bars to pounds per square inch
- Bars to kilopounds per square inch
- Bars to kilograms-force per square meter
- Bars to kilograms-force per square centimeter
- Bars to kilograms-force per square millimeter
- Bars to grams-force per square centimeter
- Bars to tons-force (short) per square foot
- Bars to tons-force (short) per square inch
- Bars to tons-force (long) per square foot
- Bars to tons force (long) per square inch
- Bars to kips-force per square inch
- Bars to pounds-force per square foot
- Bars to pounds-force per square inch
- Bars to poundals per square foot
- Bars to torrs
- Bars to standard atmosphere
- Bars to technical atmosphere
- Bars to newtons per square centimeter
- Bars to newtons per square millimeter
- Bars to kilonewtons per square meter
- Bars to dynes per square centimeter
- Bars to millibars
- Bars to microbars
- Bars to centimeters of water
- Bars to millimeters of water
- Bars to inches of water
- Bars to feet of water
- Bars to centimeters of mercury
- Bars to millimeters of mercury
- Bars to inches of mercury
- Bars to feet of mercury
- Bars to quettopascals
- Bars to ronnapascals
- Bars to yottapascals
- Bars to zettapascals
- Bars to exapascals
- Bars to petapascals
- Bars to terapascals
- Bars to gigapascals
- Bars to megapascals
- Bars to hectopascals
- Bars to dekapascals
- Bars to decipascals
- Bars to centipascals
- Bars to millipascals
- Bars to micropascals
- Bars to nanopascals
- Bars to picopascals
- Bars to femtopascals
- Bars to attopascals
- Bars to zeptopascals
- Bars to yoctopascals
- Bars to rontopascals
- Bars to quecpascals