Natural gas contains 89 per cent methane CH4. Other components are small quantities of ethane, propane, butane, pentane and hexane and traces of water, sulphur, nitrogen and carbon dioxide.
The requirements applying to natural gas supplied to the Danish market are set by the Danish Safety Technology Authority and can be found in the Danish Gas Regulations, Section A, App. 1A. Natural gas received by, transported through and redelivered to the Danish natural gas system pursuant to a transport agreement must always comply with the Danish Gas Regulations and the quality specifications stipulated in Rules for Gas Transport.
Detailed information on the composition of natural gas and its burning behaviour can be found under the menu item system operation at www.energinet.dk.
Natural gas is non-toxic and, being lighter than air, usually ascends. However, leaking natural gas is ignitable and can cause fire. Natural gas is only inflammable in a specific mixing ratio with air.
Experience shows that such accidents are very infrequent, but in the event of an accident, a series of contingency plans prepared by Energinet.dk in cooperation with the police and the fire brigade will be implemented. The plans are tested at regular intervals.
Natural gas is in its natural state very clean and in itself an almost odourless gas without any toxic gases in harmful concentrations.
Therefore, for safety reasons, a very powerful and distinct smelling odorant is added so that any gas leaks can be detected swiftly by anybody in the vicinity.
For natural gas to burn, it must be mixed with air at a percentage of 5 – 15. If the percentage of gas in air is higher than 15, the gas will not burn – in daily terms, the mixture of gas and air is too rich.