What are the three basic kinds of atmospheric hazards?

  • Oxygen (deficiency and enrichment)
  • Flammable gases and vapors
  • Toxic contaminants

We have three hazards could be occured in process plants
1- fire/flame
2- flammable gas
3- toxic gas


In oil & gas industry it is not practical to have 100% safe process areas. Usually these shall be rather precisely classified into Zones based on their leakage rates as defined below.

Zone 0

Zone 0 is an area in which an explosive atmosphere is present continuously for long periods of time or will frequently occur.

Zone 1

Zone 1 is an area in which an explosive atmosphere is likely to occur occasionally in normal operation. It may exist because of repair, maintenance operations, or leakage.

Zone 2

Zone 2 is a place in which an explosive atmosphere is not likely to occur in normal operation but, if it does occur, will persist for a short period only. These areas only become hazardous in case of an accident or some unusual operating condition.


@kumkir Excellent info. Thanks for sharing your knowledge.

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Simple and clear. Go a head for more detailed topics

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