- 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.
Simple and clear. Go a head for more detailed topics