BS EN ISO 10093:1999 pdf free.Plastics – Fire tests – Standard ignition sources.
Introduction
Fires are caused by a wide range of possible ignition sources. Statistical analysis of fires has identified the main primary and secondary sources, especially for fires in buildings. The most frequent sources of fires have been found to be as follows:
a) cooking appliances;
b) space-heating appliances;
c) electric wiring, connectors and terminations;
d) other electrical appliances (such as washing machines, bedwarmers, televisions, water heaters);
e) cigarettes;
f) matches and smokers’ gas lighters;
g) blow-lamps, blow-torches and welding torches;
h) rubbish burning;
i) candles.
BS EN ISO 10093 describes and classifies a range of laboratory ignition sources for use in fire tests on plastics and products consisting substantially of plastics. These sources vary in intensity and area of impingement. They may be used to simulate the initial thermal abuse to which plastics may be exposed in certain actual fire risk scenarios.
4 Ignition processes
4.1 When plastics are exposed to thermal energy, flammable vapours may be generated from their surface. Under suitable conditions (especially high temperatures), a critical concentration of flammable vapour may form and spontaneous ignition will result. If a flame is present as the sole energy source, or as a supplementary source, the ignition process will be assisted; this mechanism is sometimes known as pilot ignition.
4.2 A specimen of plastic is regarded as ignited when flames appear on the surface of the plastic or when glowing combustion is evident.
4.3 After ignition has occurred, some burning plastics create additional fire hazards by forming flaming debris or drips. If this flaming debris falls on to combustible material, secondary ignition may occur and the fire will spread more rapidly.
4.4 The localized application of a heat source to some plastics results in glowing combustion. With some thermoplastic foams and foams from thermosetting materials the localized application of a heat source results in punking which produces a carbonaceous char.
5 Characteristics of ignition sources
5.1 The main characteristics of ignition sources and their relation to the test specimen may be defined by the following factors:
a) The intensity of the ignition source. This is a measure of the thermal load on the specimen resulting from the combined conduction, convection and radiation effects caused by the ignition source.
b) The area of impingement of the ignition source on the specimen.
c) The duration of exposure of the specimen and whether it is continuous or intermittent.BS EN ISO 10093 pdf download.