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Encyclopedia > British thermal unit

The British thermal unit (BTU or Btu) is a unit of energy used in the Power, Steam Generation and Heating and Air Conditioning industry globally. Although it is in common use in these industries, in scientific use it has been replaced by the SI unit of energy, the joule (J). Look up si, Si, SI in Wiktionary, the free dictionary. ... The joule (IPA pronunciation: or ) (symbol: J) is the SI unit of energy. ...


In the United States, the term "Btu" is used to describe the heat value (energy content) of fuels, and also to describe the power of heating and cooling systems, such as furnaces, stoves, barbecue grills, and air conditioners. When used as a unit of power, Btu per hour (Btu/H) is understood, though this is often confusingly abbreviated to just "Btu". In the UK and other parts of the world it is notated as BTU. In physics, power (symbol: P) is the rate at which work is performed or energy is transferred. ...


The unit MBTU was defined as one thousand BTU presumably from the Roman numeral system where "M" stands for one thousand (1,000). There is currently a social push[citation needed] to redefine MBTU as one million (1,000,000) BTU, thus making the unit more intuitive with the number one million and the metric system that uses "M" to mean mega, or 106. To avoid confusion many companies and engineers use MMBTU to represent one million (1,000,000) BTU.

Contents

Definitions

A BTU is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. 143 BTU is required to melt a pound of ice. As is the case with the calorie, several different definitions of the BTU exist, which are ba sed on different water temperatures and therefore vary by up to 0.5%: The pound (abbreviations: lb or, sometimes in the United States, #) is a unit of mass in a number of different systems, including various systems of units of mass that formed part of English units, Imperial units, and United States customary units. ... Impact of a drop of water creating circular capillary waves. ... Fahrenheit is a temperature scale named after the German physicist Daniel Gabriel Fahrenheit (1686–1736), who proposed it in 1724. ... A calorie is a unit of measurement for energy. ...

Name Value (J) Notes
39 °F ≈ 1059.67 Uses the calorie value of water at its maximum density (4 °C)
Mean ≈ 1055.87 Uses a calorie averaged over water temperatures 0 °C to 100 °C
IT ≡ 1055.05585262 The most widespread Btu, uses the International [Steam] Table (IT) calorie, which was defined by the Fifth International Conference on the Properties of Steam (London, July 1956) to be exactly 4.1868 J
ISO ≡ 1055.056 International standard ISO 31-4 on Quantities and units – Part 4: Heat, Appendix A. This value uses the IT calorie and is rounded to a realistic accuracy
59 °F ≡ 1054.804 Chiefly American. Uses the 15 °C calorie, itself defined as exactly 4.1855 J (Comité international 1950; PV, 1950, 22, 79-80)
60 °F ≈ 1054.68 Chiefly Canadian
63 °F ≈ 1054.6
Thermochemical ≡ 1054.35026444 Uses the "thermochemical calorie" of exactly 4.184 J

A calorie is a unit of measurement for energy. ... This article is about the capital of England and the United Kingdom. ... 1956 (MCMLVI) was a leap year starting on Sunday of the Gregorian calendar. ... The International Organization for Standardization (ISO) is an international standard-setting body composed of representatives from national standards bodies. ... Standards are produced by many organizations, some for internal usage only, others for use by a groups of people, groups of companies, or a subsection of an industry. ... ISO 31-4 is the part of international standard ISO 31 that defines names and symbols for quantities and units related to heat. ... A calorie is a unit of measurement for energy. ...

Conversions

One BTU is approximately:

  • 1,054-1,060 joules
  • 252–253 cal (calories, small)
  • 0.252–0.253 kcal (kilocalories)
  • 778–782 ft·lbf (foot-pounds-force)

Other conversions: The joule (IPA pronunciation: or ) (symbol: J) is the SI unit of energy. ... A calorie is a unit of measurement for energy. ... In physics, a foot-pound (symbol ft·lbf or ft·lbf) is an Imperial and U.S. customary unit of mechanical work, or energy, although in scientific fields one commonly uses the equivalent metric unit of the joule (J). ...

  • In natural gas, by convention 1 MMBtu (1 million Btu, sometimes written "mmBTU") = 1.054615 GJ. Conversely, 1 gigajoule is equivalent to 26.8 m³ of natural gas at defined temperature and pressure.
  • 1 MMBtu = 1,000 cubic feet (Mcf) natural gas

Natural gas is gaseous fossil fuel consisting primarily of methane but including significant quantities of ethane, butane, propane, carbon dioxide, nitrogen, helium and hydrogen sulfide. ... Natural gas is gaseous fossil fuel consisting primarily of methane but including significant quantities of ethane, butane, propane, carbon dioxide, nitrogen, helium and hydrogen sulfide. ...

Associated units

The BTU per hour (BTU/h) is the unit of power most commonly associated with the BTU.

  • 1 watt is approximately 3.41 BTU/h
  • 1000 BTU/h is approximately 293 W
  • 1 horsepower is approximately 2540 BTU/h
  • 1 "ton of cooling", a common unit in North American refrigeration and air conditioning applications, is 12,000 BTU/h. It is the amount of power needed to melt one short ton of ice in 24 hours.
  • 1 therm is defined in the United States and European Union as 100,000 BTU – but the U.S. uses the BTU59 °F whilst the EU uses the BTUIT.
  • 1 quad (energy) (short for quadrillion BTU) is defined as 1015 BTU, which is about one exajoule (1.055×1018 J). Quads are occasionally used in the United States for representing the annual energy consumption of large economies: for example, the U.S. economy used 99.75 quads/year in 2005. [1].

The BTU should not be confused with the Board of Trade Unit (B.O.T.U.), which is a much larger quantity of energy (1 kWh, or about 3412 BTU). The watt (symbol: W) is the SI derived unit of power, equal to one joule per second. ... hp, see HP (disambiguation) The horsepower (hp) is the name of several non-metric units of power. ... Look up ton in Wiktionary, the free dictionary. ... The short ton is a unit of mass equal to 907. ... The therm (symbol thm) is a non-SI unit of heat energy. ... A typical chart using quads. ... The quadrillion is a large number which has one of two values depending on how or where it is being used. ... The Board of Trade Unit or B.O.T.U. is a non-SI unit of electrical energy, defined by a former department of the UK government. ...


See also

Conversion of units refers to conversion factors between different units of measurement for the same quantity. ... Metrication or metrification refers to the introduction of the SI metric system as the international standard for physical measurements—a long-term series of independent and systematic conversions from the various separate local systems of weights and measures. ...

External links

  • The Units of Measurement Regulations 1995
  • Natural Gas: A Primer

  Results from FactBites:
 
British thermal unit - Wikipedia, the free encyclopedia (529 words)
The British thermal unit (BTU or Btu) is a unit of energy used in the United States.
A Btu is defined as the amount of heat required to raise the temperature of one pound avoirdupois of water by one degree Fahrenheit.
The BTU is a unit of energy, and therefore not a unit of power, so while power can be measured in BTU-per-hour (BTU/h), it cannot be measured in BTU any more than it can be measured in milliseconds.
BTU - Basic Transmission Unit, British Thermal Unit (855 words)
British Thermal Unit—A measure of heat energy; the amount needed to raise the temperature of one pound of water by one degree Fahrenheit.
British Thermal Unit, the amount of energy required to raise one pound of water one degree Farenheit at 60°F, equivalent to 1055 joules or 252.1 calories.
A standard unit of measure equal to the quantity of heat required to raise the temperature of 1 pound of water by 1 degree Fahrenheit at or near 39.2 degrees Fahrenheit.
  More results at FactBites »

 
 

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