As a rule, for explosions to happen in atmospheric
air, three factors have to be present at the same
time :
– flammable material
– oxygen (air)
– source of ignition
In production and work places, hazardous areas can
develop wherever the first two preconditions for an
explosion are fulfilled.
Typical hazardous areas form
in chemical factories, refineries, enamelling plants,
paint workshops, cleaning equipment, mills and
stores for milled products and other combustible
dusts, in tank facilities and loading areas for flammable gases, liquids and solids.
The first two preconditions - the flammable material and air - must be present in justified quantities
between LFL and UFL (Lower Flammable Limit
and Upper Flammable Limit) to form an explosive
atmosphere. The statutory definitions of explosion
protection - derived from the health and safety at
work regulations - are in relation to workplaces. For
this reason, explosion protection is generally limited
to description of reactions with oxygen in the air.
Oxidation reactions normally involve increasements
in heat and pressure and therefore fulfil the criteria
of an explosion.
