Standards Development

Scope

This document describes the test methods for determining whether a material exhibits properties to be considered to be combustible dust and for determining the characteristics of combustible dusts. This test method is applicable to the identification and classification of areas and for protection concepts where explosive dust atmospheres and combustible dust layers are present, in order to permit the proper assessment of potential equipment ignition sources that must be used in the construction and application of equipment for use in the presence of combustible dust.

This document describes the test methods for the determination of:

a)      explosion pressure characteristics of combustible dusts;

b)      lower flammable limit of combustible dust;

c)      limiting oxygen concentration.

d)      minimum ignition temperature of dust layer;

e)      minimum ignition temperature of dust cloud;

f)       minimum ignition energy to ignite a dust cloud;

g)      electrical resistivity of dust.

NOTE The upper flammable limit of combustible dust cannot be usefully or reliably determined. Explosions have been detected at a nominal concentration of 75 % dust

The standard atmospheric conditions for determination of characteristics of combustible dusts are:

–        temperature −20 °C to +60 °C,

–        pressure 80 kPa to 110 kPa and

–        air with normal oxygen content, typically 21 % v/v.

The test methods defined do not apply to:

–        recognized explosives, propellants (for example gunpowder, dynamite), or substances or mixtures of substances which can, under some circumstances, behave in a similar manner or

–        dusts of explosives and propellants that do not require atmospheric oxygen for combustion, or to pyrophoric substances.