2. Zones Flashcards
Where are zones defined and marked?
On the Site Area Classification Drawings. The actual markings used may not be the same on all drawings. The drawing is to give details of the markings that are used.
What is a Zone 0?
A place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas, vapour or mist is present continuously or for long periods or frequently.
What is a Zone 1?
A place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas, vapour or mist is likely to occur in normal operation occassionally.
What is a Zone 2?
A place in which an explosive atmosphere of a mixture with air of flammable substances in the form of gas, vapour or mist is not likely to occur in normal operation, but if it does occur, persists for a short period only.
Comment on zone signs.
Where the presence of a sign indicating entry into a hazardous area, has been assessed as being required for safety, then the sign should be erected and comply with ATEX requirements. Many companies erect signs at each entry point into hazardous areas.
Triangle shape with black letters on yellow background. Yellow to be at least 50% of area.
Why zoning?
- Leak potential and presence of ignition sources.
- hazardous properties of hydrocarbons.
- safe selection & optimisation of electrical equipment.
- Worker safety (ATEX 137).
Comment on area classification diagrams.
Always refer to documentation for Zones.
