Liquified Petroleum Gas (LPG)

Liquefied petroleum gas is a mixture of hydrocarbon gases used as a fuel in heating appliances and vehicles, and it is increasingly replacing chlorofluorocarbons 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 butane, and the more common, mixes including both propane (60%) and butane (40%), depending on the season - in winter more propane, in summer more butane.   Propene and butene are usually also present in small concentration.   A powerful odorant, ethanethiol, is added so that leaks can be detected easily.   The international standard is EN 589. ^{Wiki n.p.}

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 are not 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 liquefied 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 220 kilopascals (2.2 bar) for pure butane at 20 °C (68 °F), and approximately 2.2 megapascals (22 bar) for pure propane at 55 °C (131 °F).   LPG is heavier than air, and thus will flow along floors and tend to settle in low spots, such as basements.   This can cause ignition or suffocation hazards if not dealt with. ^{Wiki n.p.}

LPG is synthesised by refining petroleum or natural gas.   it 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. ^{Wiki n.p.}

When LPG is used to fuel internal combustion engines, it is often referred to as autogas.   In some countries, it has been used since the 1940s as an alternative fuel for spark ignition engines.   More recently, it has also been used in diesel engines.   In highly purified form, various blends of the LPG constituents propane and iso-butane are used to make hydrocarbon refrigerants, which are increasingly being used in refrigeration and air conditioning systems including domestic refrigerators, building air conditioners and vehicle air conditioning.   This is partly because of concerns about the ozone depleting and greenhouse effects of the widely used HFC 134a.   Hydrocarbons are more energy efficient, run at the same or lower pressure and are generally cheaper than HFC 134a. ^{Wiki n.p.}

To 1859

1859-1869

1870-1879

1880-1889

1890-1899

1900-1909

1910-1919

1920-1929

1930-1939

1940-1949

1950-1959

1960-1969

1970-1979

1980-1989

1990-1999