british thermal unit conversions

7/28/2019 British Thermal Unit Conversions

1/4

4/27/13 British thermal unit - Wikipedia, the free encyclopedia

en.wikipedia.org/wiki/British_thermal_unit

British thermal unitFrom Wikipedia, the free encyclopedia

The British thermal unit (symbol Btu or sometimes BTU) is a traditional unit of energy equal to about 1055

oules. It is the amount of energy needed to heat one pound of water by one degree Fahrenheit. In scientific

contexts the Btu has largely been replaced by the SI unit of energy, the joule.

The unit is most often used as a measure of power (as Btu/h) in the power, steam generation, heating and airconditioning industries, and also as a measure of agricultural energy production (Btu/kg). It is still used in metric

English-speaking countries (such as Canada), and remains the standard unit of classification for air conditioning uni

manufactured and sold in many non-English-speaking metric countries. In North America, the term "Btu" is used to

describe the heat value (energy content) of fuels.

Contents

1 Definitions2 Conversions

2.1 For natural gas

2.2 As a unit of power

3 Associated units

4 See also

5 References

6 External links

efinitions

A Btu is defined as amount of heat required to raise the temperature of 1 pound (0.454 kg) of liquid water by 1 F

(0.56 C) at a constant pressure of one atmosphere.[1] As is the case with the calorie, several different definitions

the Btu exist, which are based on different water temperatures and therefore vary by up to 0.5%. A Btu can be

approximated as the heat produced by burning a single wooden match[2] or as the amount of energy it would take

to lift a one-pound weight to a height of 778 feet (237 m).[3]
http://en.wikipedia.org/wiki/British_thermal_unit#Referenceshttp://en.wikipedia.org/wiki/British_thermal_unit#See_alsohttp://en.wikipedia.org/wiki/British_thermal_unit#Associated_unitshttp://en.wikipedia.org/wiki/British_thermal_unit#As_a_unit_of_powerhttp://en.wikipedia.org/wiki/British_thermal_unit#Conversionshttp://en.wikipedia.org/wiki/British_thermal_unit#Definitionshttp://en.wikipedia.org/wiki/Canadahttp://en.wikipedia.org/wiki/North_Americahttp://en.wikipedia.org/wiki/Air_conditioninghttp://en.wikipedia.org/wiki/Air_conditioninghttp://en.wikipedia.org/wiki/Air_conditioninghttp://en.wikipedia.org/wiki/Metric_systemhttp://en.wikipedia.org/wiki/Air_conditioninghttp://en.wikipedia.org/wiki/International_System_of_Unitshttp://en.wikipedia.org/wiki/Joulehttp://en.wikipedia.org/wiki/Joulehttp://en.wikipedia.org/wiki/British_thermal_unit#cite_note-3http://en.wikipedia.org/wiki/British_thermal_unit#cite_note-2http://en.wikipedia.org/wiki/Caloriehttp://en.wikipedia.org/wiki/British_thermal_unit#cite_note-1http://en.wikipedia.org/wiki/Atmosphere_(unit)http://en.wikipedia.org/wiki/British_thermal_unit#External_linkshttp://en.wikipedia.org/wiki/British_thermal_unit#Referenceshttp://en.wikipedia.org/wiki/British_thermal_unit#See_alsohttp://en.wikipedia.org/wiki/British_thermal_unit#Associated_unitshttp://en.wikipedia.org/wiki/British_thermal_unit#As_a_unit_of_powerhttp://en.wikipedia.org/wiki/British_thermal_unit#For_natural_gashttp://en.wikipedia.org/wiki/British_thermal_unit#Conversionshttp://en.wikipedia.org/wiki/British_thermal_unit#Definitionshttp://en.wikipedia.org/wiki/North_Americahttp://en.wikipedia.org/wiki/Canadahttp://en.wikipedia.org/wiki/Metric_systemhttp://en.wikipedia.org/wiki/Air_conditioninghttp://en.wikipedia.org/wiki/Heatinghttp://en.wikipedia.org/wiki/Steamhttp://en.wikipedia.org/wiki/Electrical_power_industryhttp://en.wikipedia.org/wiki/Joulehttp://en.wikipedia.org/wiki/International_System_of_Unitshttp://en.wikipedia.org/wiki/Joulehttp://en.wikipedia.org/wiki/Energy


2/4



Nominal

temperature

Btu equivalent in

joulesNotes

39 F (3.9 C) 1059.67Uses the calorie value of water at its maximum density (4 C or

39.2 F)

Mean 1055.87Uses a calorie averaged over water temperatures 0 to 100 C (32 to

212 F)

IT 1055.05585262The most widespread Btu, uses the International [Steam] Table (IT)calorie, which was defined by theFifth 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 unitsPart 4:

Heat,[4] Appendix A. This value uses the IT calorie and is rounded to a

realistic accuracy

59 F (15.0 C) 1054.804Chiefly American. Uses the 15 C calorie, itself now defined as exactly

4.1855 J (Comit international1950; PV, 1950, 22, 7980)

60 F (15.6 C) 1054.68 Chiefly Canadian63 F (17.2 C) 1054.6

Thermochemical 1054.35026444 Uses the "thermochemical calorie" of exactly 4.184 J

The unit MBtu was defined as one thousand Btu, presumably from the Roman numeral system where "M" stands

for one thousand (1,000). This is easily confused with the SI mega (M) prefix, which multiplies by a factor of one

million (1,000,000). To avoid confusion many companies and engineers use MMBtu to represent one million Btu

Alternatively a therm is used representing 100,000 or 105 Btu, and a quadas 1015 Btu. Some companies also us

BtuE6 in order to reduce confusion between a thousand Btu vs. a million Btu.[5]

Conversions

One Btu is approximately:

1.054 to 1.060 kJ (kilojoules)

0.293071 Wh (watt hours)

252 to 253 cal (calories, or "little calories")

0.25 kcal (kilocalories, "large calories," or "food calories")

25 031 to 25 160 ftpdl (foot-poundal)

778 to 782 ftlbf (foot-pounds-force)

5.40395 (lbf/in2)ft3

For natural gas

In natural gas, by convention 1 MMBtu (1 million Btu) = 1.054615 GJ. Conversely, 1 gigajoule is the

amount of energy in 26.8 m3 of natural gas at defined temperature and pressure. So, 1 MMBtu is the amoun

of energy in 28.263682 m3 (998.12 ft3) of natural gas at defined temperature and pressure.

1 standard cubic foot of natural gas yields 1030 Btu (between 1010 Btu and 1070 Btu, depending on
http://en.wikipedia.org/wiki/Natural_gashttp://en.wikipedia.org/wiki/Foot-poundhttp://en.wikipedia.org/wiki/Foot-poundalhttp://en.wikipedia.org/wiki/Caloriehttp://en.wikipedia.org/wiki/Watt_hourhttp://en.wikipedia.org/wiki/Joulehttp://en.wikipedia.org/wiki/British_thermal_unit#cite_note-5http://en.wikipedia.org/wiki/Quad_(energy)http://en.wikipedia.org/wiki/Thermhttp://en.wikipedia.org/wiki/Mega-http://en.wikipedia.org/wiki/Roman_numeralshttp://en.wikipedia.org/wiki/Caloriehttp://en.wikipedia.org/wiki/Canadahttp://en.wikipedia.org/wiki/United_Stateshttp://en.wikipedia.org/wiki/British_thermal_unit#cite_note-4http://en.wikipedia.org/wiki/ISO_31-4http://en.wikipedia.org/wiki/International_standardhttp://en.wikipedia.org/wiki/International_Organization_for_Standardizationhttp://en.wikipedia.org/wiki/Londonhttp://en.wikipedia.org/wiki/Calorie


3/4



quality, when burned)

As a coarse approximation, 1000 ft3 of natural gas yields 1 MMBtu 1 GJ

As a unit of power

When used as a unit of power for heating and cooling systems, Btuper hour(Btu/h) is the correct unit, though this

is often abbreviated to just "Btu"..

1 watt is approximately 3.41214 Btu/h[6]

1000 Btu/h is approximately 293.071 W

1 horsepower is approximately 2,544 Btu/h

Associated units

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 freeze one short ton of ice in 24 hours, and is

approximately 3.51 kW.

1 therm is defined in the United States and European Union as 100,000 Btubut the U.S. uses the Btu59 while the EU uses the BtuIT.

1 quad(short for quadrillion Btu) is defined as 1015 Btu, which is about one exajoule (1.055 1018 J).

Quads are used in the United States for representing the annual energy consumption of large economies: for

example, the U.S. economy used 99.75 quads in 2005.[7] One quad/year is about 33.43 gigawatts.

The Btu should not be confused with the Board of Trade Unit (B.O.T.U.), which is a much larger quantity of energ

(1 kWh, or about 3412 Btu).

The Btu is often used to express the conversion-efficiency of heat into electrical energy in power plants. Figures arquoted in terms of the quantity of heat in Btu required to generate 1 kWh of electrical energy. A typical coal-fired

power plant works at 10,500 Btu/kWh, an efficiency of 3233%.[8]

See also

Conversion of units

Latent heat

Metrication

Ton of refrigeration

References

1. ^ "What is British thermal unit (Btu)? definition and meaning"

(http://www.businessdictionary.com/definition/British-thermal-unit-Btu.html). Businessdictionary.com. Retrieved

2011-11-11.

2. ^ Energy and the Environment. Ristinen, Robert A. c.2006, pg 13

3. ^ Energy and the Environment. Ristinen, Robert A. c.2006, pg14

4. ^ International standard ISO 31-4:1992 Quantities and unitsPart 4: Heat
http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=3632http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=3632http://en.wikipedia.org/wiki/British_thermal_unit#cite_ref-4http://en.wikipedia.org/wiki/British_thermal_unit#cite_ref-3http://en.wikipedia.org/wiki/British_thermal_unit#cite_ref-2http://www.businessdictionary.com/definition/British-thermal-unit-Btu.htmlhttp://en.wikipedia.org/wiki/British_thermal_unit#cite_ref-1http://en.wikipedia.org/wiki/Ton_of_refrigerationhttp://en.wikipedia.org/wiki/Metricationhttp://en.wikipedia.org/wiki/Latent_heathttp://en.wikipedia.org/wiki/Conversion_of_unitshttp://en.wikipedia.org/wiki/British_thermal_unit#cite_note-8http://en.wikipedia.org/wiki/Board_of_Trade_Unithttp://en.wikipedia.org/wiki/British_thermal_unit#cite_note-7http://en.wikipedia.org/wiki/1,000,000,000,000,000http://en.wikipedia.org/wiki/Quad_(energy)http://en.wikipedia.org/wiki/Thermhttp://en.wikipedia.org/wiki/Short_tonhttp://en.wikipedia.org/wiki/Ton_of_refrigerationhttp://en.wikipedia.org/wiki/Horsepowerhttp://en.wikipedia.org/wiki/British_thermal_unit#cite_note-6http://en.wikipedia.org/wiki/Watt


4/4



(http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=3632)

5. ^ EIA (2012-09-17). "What are Mcf, Btu, and therms? How do I convert prices in Mcf to Btus and therms?"

(http://www.eia.gov/tools/faqs/faq.cfm?id=45&t=8). US Government.

6. ^ 2009 ASHRAE Handbook Fundamentals (I-P Edition) (http://knovel.com/web/portal/browse/display?

_EXT_KNOVEL_DISPLAY_bookid=2554&VerticalID=0). (pp: 38.2). American Society of Heating, Refrigerating

and Air-Conditioning Engineers, Inc

7. ^ Husher, John Durbin. Crises of the 21st Century: Start Drilling-The Year 2020 Is Coming Fast, iUniverse, 2009

Page 376.

8. ^ Electric Generation Efficiency, NPC Global Oil & Gas Study, 18 July 2007(http://www.npc.org/Study_Topic_Papers/4-DTG-ElectricEfficiency.pdf)

External links

The Units of Measurement Regulations 1995 (http://www.legislation.gov.uk/uksi/1995/1804)

Natural Gas: A Primer (http://www.nrcan.gc.ca/energy/sources/natural-gas/1233?

destination=node%2F1233)

Retrieved from "http://en.wikipedia.org/w/index.php?title=British_thermal_unit&oldid=551932259"

Categories: Units of energy Imperial units Customary units of measurement in the United States

This page was last modified on 24 April 2013 at 09:26.

Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply.

By using this site, you agree to the Terms of Use and Privacy Policy.

Wikipedia is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.
http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=3632http://www.wikimediafoundation.org/http://wikimediafoundation.org/wiki/Privacy_policyhttp://wikimediafoundation.org/wiki/Terms_of_Usehttp://en.wikipedia.org/wiki/Wikipedia:Text_of_Creative_Commons_Attribution-ShareAlike_3.0_Unported_Licensehttp://en.wikipedia.org/wiki/Help:Categorieshttp://en.wikipedia.org/w/index.php?title=British_thermal_unit&oldid=551932259http://www.nrcan.gc.ca/energy/sources/natural-gas/1233?destination=node%2F1233http://www.legislation.gov.uk/uksi/1995/1804http://www.npc.org/Study_Topic_Papers/4-DTG-ElectricEfficiency.pdfhttp://en.wikipedia.org/wiki/British_thermal_unit#cite_ref-8http://en.wikipedia.org/wiki/British_thermal_unit#cite_ref-7http://en.wikipedia.org/wiki/American_Society_of_Heating,_Refrigerating_and_Air-Conditioning_Engineershttp://knovel.com/web/portal/browse/display?_EXT_KNOVEL_DISPLAY_bookid=2554&VerticalID=0http://en.wikipedia.org/wiki/British_thermal_unit#cite_ref-6http://www.eia.gov/tools/faqs/faq.cfm?id=45&t=8http://en.wikipedia.org/wiki/British_thermal_unit#cite_ref-5http://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=3632http://en.wikipedia.org/wiki/Category:Customary_units_of_measurement_in_the_United_Stateshttp://en.wikipedia.org/wiki/Category:Imperial_unitshttp://en.wikipedia.org/wiki/Category:Units_of_energy

british thermal unit conversions

Documents