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Natural Gas Information

What is Natural Gas?

Natural gas is a colourless, naturally occurring hydrocarbon gas mixture consisting primarily of methane, but commonly including varying amounts of other higher alkanes. Natural gas is a very clean burning source that is found underground and is most commonly used for heating or cooking. Rather than being supplied by a gas bottle (like LPG), your home or business is simply connected to the gas network. This means, similar to water and electricity, you have gas “on tap”.

Its properties and characteristics are as follows:

  • Natural gas is non-toxic before combustion, and the exhaust product from approved appliances is also non-toxic, provided equipment is properly maintained (see our appliance safety for more information).
  • Typically natural gas is comprised of 85%-90% methane, 5%-10% ethane, 2% carbon dioxide, 1%-2% nitrogen and 0.2% propane.
  • The natural gas flammability range – air/gas volume ratio – varies between 5:1 and 15:1. For stoichiometric combustion the air/gas volume is 9.91:1
  • Natural gas has an approximate auto-ignition temperature in air of 537oC – 680oC (dependent on air/gas composition and atmospheric pressure) and a flame speed of 0.4 metres per second. Natural gas has a relative density to air of 0.62.

Is Natural Gas Safe?

In Australia, the natural gas industry is highly regulated. Rigorous safety standards have been put in place to ensure safe distribution and gas quality. In the event of a gas leak, you would be able to smell the gas well in advance of it becoming dangerous. This is because an artificial “odorant” has been added to give natural gas a distinctive smell.

Flammability Limits

Not all air-gas mixtures are combustible. Air-gas mixtures will only burn or explode within certain known limits, known as the flammable (explosive) limits.

Explosive Limit Percent Gas to Air
Lower Explosive Limit (LEL) 5% gas to 95% air
Upper Explosive Limit (UEL) 14% gas to 86% air


The Gas Standards (Gas Supply and System Safety) Regulations 2000 specifies that all hydrocarbon gases have odour added before distribution to the customer and the amount of odorant required. Some compounds used to odorise gas may be different but their smell is similar. A common ingredient of odorants is Ethyl Mercaptan and it is very smelly.

Natural gas is odourless in low concentrations in air. Your distributor adds an odorant to its natural gas at the point prior to its distribution to allow for leakage detection.

The odorant blend is added to the gas to allow easy detection of the gas at one fifth of the lower explosive limit in air.