Cryogenic Information Library
Liquified Natural Gas (LNG) - Cryogenic Fluids

Liquified Natural Gas (Liquid Methane) is made by cooling natural gas to a temperature of -260°F.  At that temperature, natural gas becomes a liquid and its volume is reduced 615 times.  (A car reduced 615 times would fit on your thumbnail.)  Liquified natural gas is easier to store than the gaseous form since it takes up much less space.  LNG is also easier to transport.  People can put LNG in special tanks and transport it on trucks or ships.  Today more than 100 LNG storage facilities are operating in the United States. Methane is a colorless, odorless gas with a wide distribution in nature.  It is the principal component of natural gas, a mixture containing about 75% CH4, 15% ethane (C2H6), and 5% other hydrocarbons, such as propane (C3H8) and butane (C4H10).  The "firedamp" of coal mines is chiefly methane.  Anaerobic bacterial decomposition of plant and animal matter, such as occurs under water, produces marsh gas, which is also methane. At room temperature, methane is a gas less dense than air.  It melts at -183°C and boils at -164°C.  It is not very soluble in water.  Methane is combustible, and mixtures of about 5 to 15 percent in air are explosive.  Methane is not toxic when inhaled, but it can produce suffocation by reducing the concentration of oxygen inhaled.  A trace amount of smelly organic sulfur compounds (tertiary-butyl mercaptan, (CH3)3CSH and dimethyl sulfide, (CH3)2S) is added to give commercial natural gas a detectable odor.  This is done to make gas leaks readily detectible.  An undetected gas leak could result in an explosion or asphyxiation. Methane is synthesized commercially by the distillation of bituminous coal and by heating a mixture of carbon and hydrogen.  It can be produced in the laboratory by heating sodium acetate (CH3COONa) with sodium hydroxide (NaOH) and by the reaction of aluminum carbide (Al4C3) with water. In the chemical industry, methane is a raw material for the manufacture of methanol (CH3OH), formaldehyde (CH2O), nitromethane (CH3NO2), chloroform (CH3Cl), carbon tetrachloride (CCl4), and some freons (compounds containing carbon and fluorine, and perhaps chlorine and hydrogen).  The reactions of methane with chlorine and fluorine are triggered by light.  When exposed to bright visible light, mixtures of methane with chlorine or fluorine react explosively. The principal use of methane is as a fuel.

Atomic Number 8 Atomic Weight 15.9994 Melting Point 54.36 K Heat of Vaporization 212.9 kj/kg K Specific Heat 1.70 kj/kg K Viscosity 188.0 kg/m-s X 106 Thermal Conductivity 151.4 mW/m-k Dielectric Constant 1.4837 Critical Temperature 154.576 K Critical Pressure 5.04 MPa Temperature at Triple Point 54.35 K Pressure at Triple Point .151 Mpa X 103 Density .001429 grams/cc Phase at Room Temperature Gas

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