Thirteen sources
- Hot surfaces
- Flames and hot gases
- Mechanically generated sparks
- Electrical apparatus
- Stray electric currents and cathodic corrosion protection
- Static electricity
- Lightning
- Electromagnetic fields
- Electromagnetic radiation
- Ionising radiation
- Ultrasonics
- Adiabatic compression and shock waves
- Exothermic reactions, including self-ignition of dust
Why each is written out
Assessments typically address the first four and skip the rest. Yet a large share of real explosions comes from the middle of the list: static electricity while emptying a sack, a conveyor bearing running dry (hot surface), a mechanical spark from aluminium against rust, dust self-heating after standing in a silo.
Three questions per source
- Is this source present in this zone?
- In which operating state does it appear — normal, fault, rare expected fault?
- By what measure is it rendered ineffective, and how is that measure verified?
Where those three answers are not written down, the source has not been assessed.
Why static needs its own heading
Static is generated everywhere in a plant for free: flowing liquid, falling dust, a moving belt, clothing. Controlling it is not a purchase but a regime — earthing and equipotential bonding, conductive hoses and containers, suitable clothing and footwear, flow rate limits, and measured verification of all of it.