Let’s start with…
What is ATEX?
The ATEX legislation is a European directive that requires all employers to check the risks relating to the explosion of some atmospheres. An assessment of the risk of explosion has to be made in the company to indicate all the places where explosive atmospheres may form and take the necessary steps to prevent explosions.
How to choose material suitable for an environment where there is the risk of explosion
ATEX environments are divided into three areas:
– Areas 0, 1 or 2 for gas,
– Areas 20, 21 or 22 for dust.
There are two large groups of materials:
– Group I: the specific case of mines (more restrictive),
– Group II: all other surface industries.
For Group II (surface industries): every ATEX area classification is connected to a specific category of equipment.
When may an explosion occur?
There is the risk of explosion when there are various elements – a combustible (the oxygen in the air and, for example, a combustible like gas or vapour such as hydrocarbons, solvents, paints, diluting agents, petrol, alcohol, colourants, perfumes, chemical products, manufacturing agents for plastics) and dust such as magnesium, aluminium, sulphur, cellulose, cereals, coal, wood, tin, resins, sugar, starch, polystyrene and fertilisers, an inflammation point or an ignition source. For example, when grain silos are filled, the concentration of dust is very high. Therefore, the atmosphere becomes dangerous and the increase in temperature or a simple spark can cause an explosion.
When there is the risk of explosion in an environment (gas or dust), a safety device is connected to it that requires the use of anti-explosive devices. These ensure various methods of protection intended to eliminate the risks of explosion.
|Classification of the area||ATEX classification of the equipment to use (for Group II – surface industries)|
|Area 0 (gas)/Area 20 (dust)/ PERMANENT RISK||Category 1/VERY HIGH LEVEL OF PROTECTION|
There is always the explosive mixture or it is present for long periods.
|Area 1 (gas)/Area 21 (dust) / FREQUENT RISK||Category 2/HIGH LEVEL OF PROTECTION|
The formation of an explosive mixture is likely during normal work.
|Area 2 (gas)/Area 22 (dust)/ OCCASIONAL RISK||Category 3/NORMAL LEVEL OF PROTECTION|
The formation of an explosive mixture is unlikely and, if it occurs, it will be for a short period.