The document defines three zones - red, yellow, and green - for areas with high, medium, and low toxic risk. It further defines three types of zones - zone 0 for areas with flammable gas continuously present over 1000 hours/year, zone 1 for areas where gas is likely present 10-1000 hours/year, and zone 2 for areas where gas would be present less than 10 hours/year. It identifies hazardous areas as those where flammable atmospheres may occur during normal operations or faults, and unclassified areas as those not defined as zones 0, 1, or 2 but still potentially unsafe.

1. ZONES:
 RED ZONE, High toxic risk will be undertaken with B.A.
 YELLOW ZONE, Medium toxic risk must available B.A.
 GREEN ZONE, Low toxic risk special precaution release from gas.
Type of Zones:
 Zone ,,0,, (High) An area which an explosive gas atmosphere continuously present for
long time(flammable gas available) typically more than 1000 hrs /year
 Zone ,,1,, (Medium) An area which an explosive gas atmospheres in likely occurin
normal operation (may be flammable gas) typically 10 to 1000 hrs / year
 Zone ,,2,, (Low) An area which an explosive gas atmospheres is not likely occurin
normal operation & if it does occuris likely to do so only infrequently and will exist for
a short period only.(any facility locate to near gas) Typically less than 10 hrs. / year
HAZARDOUS AREA:
 A hazardous area is the zone in which a flammable atmosphere may be present
during normal operation or under abnormal or fault condition.
Unclassified area:
 An area which is not classified as zone 0, 1, 2. Unclassified area may not necessary
be Considered as safe,
 Chalvyn valve used zone 1 area front of diesel entrance in vehicle or any diesel
tanker, color yellow which block the source when found any unsafe condition