Liquified petroleum gas
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Liquified Petroleum Gas (also called Liquefied Petroleum Gas, Liquid Petroleum Gas, LPG, LP Gas, or autogas) is a mixture of hydrocarbon gases used as a fuel in heating appliances and vehicles, and increasingly replacing fluorocarbons as an aerosol propellant and a refrigerant to reduce damage to the ozone layer. Varieties of LPG bought and sold include mixes that are primarily propane, mixes that are primarily butanes, and mixes including both propane and butanes. Propylene and butylenes are usually also present in small concentration. A powerful odorant, ethanethiol, is added so that leaks can be detected easily. LPG is manufactured during the refining of crude oil, or extracted from oil or gas streams as they emerge from the ground.
At normal temperatures and pressures, LPG will evaporate. Because of this, LPG is supplied in pressurised steel bottles. In order to allow for thermal expansion of the contained liquid, these bottles should not be filled completely; typically, they are filled to between 80% and 85% of their capacity. The ratio between the volumes of the vaporised gas and the liquified gas varies depending on composition, pressure and temperature, but is typically around 250:1. The pressure at which LPG becomes liquid, called its vapor pressure, likewise varies depending on composition and temperature; for example, it is approximately 2.2 bar for pure butane at 20 °C, and approximately 22 bar for pure propane at 55 °C.
LPG was first produced in 1910 by Dr. Walter Snelling, and the first commercial products appeared in 1912. It currently provides about 3% of the energy consumed in the United States.
LPG is widely used as a "green" fuel for internal combustion engines as it decreases exhaust emissions. It has a RON that is between 90 and 110 and an energy content (HHV) that is between 25.5 megajoule/liter (for pure propane) and 28.7 megajoule/liter (for pure butane.) Toyota made a number of LPG engines in their 1970s M, R, and Y engine families.
Currently, a number of automobile manufacturers -Citroën, Daewoo, Fiat, Ford, Hyundai, Opel/Vauxhall, Peugeot, Renault, Saab and Volvo- have OEM bi-fuel models that will run equally well on both LPG and petrol.
LPG as cooking fuel
According to the 2004 Census of India, of Indian households or 70.0 million Indian households used LPG as cooking fuel in 2004. 76.64% of such households were from urban India making up 48% of urban Indian households as compared to a usage of 5.7% only in rural Indian households. LPG is subsidised by the government. Increase in LPG prices has been a politically sensitive matter in India as it potentially affects the urban middle class voting pattern.
LPG was once a popular cooking fuel in Hong Kong; however, the continued expansion of town gas to buildings has reduced LPG usage to less than 24% of residential units.
See also
External links
- About LPG (http://www.difflock.com/lpg/index.shtml)
- Autogas-India (http://www.autogas-india.com/fule.html)es:Gas licuado del petróleo
fr:Gaz de pétrole liquéfié id:Elpiji nl:LPG ja:液化石油ガス pl:LPG pt:GPL (combustível) zh:液化石油气