FLAMMABLE MATERIAL PROPERTIES
Relative Density : The density of a gas or a vapour relative to the density of air. The result would be displayed in reference to air having a value equal to 1.
Flash Point : The minimum temperature at which a liquid give off sufficient vapour to form an explosive atmosphere when tested in a set of standard test apparatus.
Flammable Limits : The upper and lower percentages of gas / air mixture at normal atmospheric temperature and pressure which will burn if ignited.
The spark energy which will ignite the most easily ignited mixture of a test gas with air at atmospheric pressure in a set of standard test apparatus. The spark energy of the ignition is also related to the intensity of explosion, i.e. a highly flammable gas mixture can be ignited with a low energy spark to create a high intensity explosion. Ignition Temperature (Auto Ignition Temperature) Ignition temperature, or AIT as it is also known, is defined as the lowest temperature determined by a standardised method, at which the most explosive mixture of the given substance and air will automatically ignite when in contact with, or in the presence of, a heated surface. In this situation the flammable mixture spontaneous combustion will occur without the presence of an independent ignition source.
The Ignition Temperature of flammable materials (gases, vapours and liquids) is defined in IEC 60079, along with the corresponding gas group. Examples of ignition temperatures for commonly occurring flammable mixtures are town gas (surface methane)/air, which ignites at over 600ºC, and petrol/air which ignites at approximately 250ºC.