Difference between hazardous area & restricted areas

Generally Hazardous area is an area where a hazard is present such as Explosive gas, chemicals, toxic gases etc. Natural gas stations, hydrogen cylinders, chemical storage etc are examples for hazardous areas.

Restricted areas are those which have restricted entry due to the nature of hazard and due to the conditions prevalent. High voltage switch yard and switchgear are restricted areas. Most of the restricted areas contain hazards while the remaining might be classified due to some other reasons.

In a plant,if any area is protected with fire protection system, it may become a restricted area to avoid personnel entry due to the hazard present there. Restricted areas are locked to control entry.