Classification of areas where flammable gases or vapors are present
In these cases, explosive atmospheres can be formed at any time, for example explosive liquid transfer areas, paint booths, solvent storage areas, etc.
They are subdivided in turn according to the probability of presence of the explosive atmosphere in:
- Zone 0: permanent presence or for long periods of time.
- Zone 1: susceptible to formation under normal working conditions.
- Zone 2: unlikely presence and for short periods.
The safety principles to consider are:
- Areas of explosion hazard shall be as small as possible.
- The presence of electrical equipment will be minimized and will be protected according to the area.
Places with Diesel Fuel
As an example we can mention cereal silos, mills, coal treatment plants, fertilizer plants, etc.
Within this class is distinguished:
- Zone 20: It is one in which there is or may be combustible dust during normal operations of operation, start-up or cleaning, in sufficient quantity to produce an explosive atmosphere. Example: in pulverizadores mills.
- Zone 21: It is one in which the cloud or layer of dust is susceptible of being formed under normal working conditions.
- Zone 22: unlikely presence and for short periods.
The safety principles to consider are:
- Ventilation and dust removal will be avoided as far as possible.
- Maintenance of cleaning and collection of dust generated periodically.
- Electrical equipment shall be protected against the ingress of dust to the required degree:
- IP5x. Protection against harmful entry of dust.
- IP6x. Total protection against dust ingress.
- The maximum surface working temperatures of the equipment shall be limited to 2/3 of the TIN or to 745 ° C less of the TIC for 3 mm layers. If they are higher, the temperature must be lowered.