Did you know that coal dust can lead to mine explosions? Dust is present in numerous industries with flour, sawdust and sugar potentially as explosive as coal dust. Vapours, mists and gases are also factors that may trigger explosions when exposed to spark ignition.
Oil and gas installations, petrochemical, chemical plants, grain storage, coal handling and refuelling areas often create hazardous areas resulting from flammable gases, vapours, mists and dusts which can produce explosive mixtures with air. The electrical, mechanical and instrumentation equipment installed in these potentially hazardous areas must be designed to provide protection against the possibility of gas or dust ignition. Solutions to these problems can be certified flameproof and intrinsically safe equipment.
Dusts are solid airborne particles, often created by operations such as grinding, crushing, milling and sanding. The size of the dust particles is important as there is a difference between inhalable and respirable dusts and the nature of the hazards they present.
Gases are formless fluids usually produced by chemical processes involving combustion or by the interaction of chemical substance. A gas will normally seek to fill the space completely into which it is liberated, for example, nitrogen gas widely used in vessels due to its chemically inert properties.
The four groups into which gases have been categorised are as follows:
Group 1: For mining applications specifically underground mining.
Test Gas – Methane
Group 2: For general industry
IIA Test Gas – Propane
IIB Test Gas – Ethylene
IIC Test Gas – Hydrogen
The likelihood of an ignition of gas occurring depends on the probability of an explosive mixture of gas being present at the same time as the electrical/mechanical apparatus produces an ignitable source (i.e. a spark or a hot surface).
Vapours are the gaseous form of a material normally encountered in a liquid or solid state at normal room temperature and pressure. Typical examples are solvents, for example, thinners that release vapours when the container is opened.
Mists are a state of matter with definite volume but no definite shape, like water. The routes of entry for liquids could be ingestion and skin contact. If finely dispersed, then they become a mist and therefore inhalable.
If you are interested in hazardous areas then perhaps you might like to attend or sponsor the upcoming:
Introduction to Hazardous Areas Workshop
Melbourne - 25th September 2018
7th Hazardous Areas Conference
Melbourne - 26th & 27th September 2018