Determining the amount and likelihood of creating an
explosive atmosphere will depend upon the following:
➤ The presence of a fl ammable substance
➤ The degree of dispersion of the fl ammable substance
(this will vary dependent upon its state – dusts, gases,
vapours and mists)
➤ The concentration of the fl ammable substance in air
within the explosive range
Figure 7.26 The smaller a substance is divided the greater the surface area
Figure 7.27 Confi ned explosion within a tank
Burned
gas
Flame
Fuel/air
or
Fuel-oxidiser
Figure 7.28 Static discharge between an unearthed hopper
and an earthed vessel having the potential to ignite dust
Unearthed hopper
Non