Explosion-hazardous areas, also known as Ex zones, refer to areas where flammable gases, vapours, or dust are present in the air in sufficient quantities to be explosive or combustible. In these areas, special precautions must be taken to prevent fires and explosions, as even a small spark or ignition source can cause a catastrophic event.
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The most common classification system used is the Zone system, which divides areas into four zones based on the likelihood and duration of the presence of hazardous materials.
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In explosion-hazardous areas, special care must be taken to ensure the safety of personnel and equipment. This may include the use of explosion-proof equipment, ventilation systems, and other safety measures.
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Zone 0:
- This is an area where hazardous materials are continuously present and are likely to ignite. It is the most hazardous area on a ship and refers to areas where flammable gases, vapours, or liquids are continuously present or may be present for long periods of time.
- Examples of Zone 0 areas on a ship include enclosed fuel tanks, engine crankcases, and fuel storage areas.
- Strict safety measures, such as explosion-proof equipment, ventilation, and regular gas testing, are required in Zone 0 areas to prevent ignition and explosion.
Zone 1:
- Zone 1 refers to areas where flammable gases, vapours, or liquids may occasionally be present during normal ship operations.
- Examples of Zone 1 areas on a ship include engine rooms, fuel transfer areas, and cargo holds.
- Safety measures in Zone 1 areas include the use of explosion-proof equipment, adequate ventilation, and regular gas monitoring to minimize the risk of ignition and explosion.
Zone 2:
- Zone 2 refers to areas where flammable gases, vapors, or liquids are unlikely to be present during normal ship operations, but may be present in abnormal situations.
- Examples of Zone 2 areas on a ship include accommodation spaces, corridors, and storage areas.
- Safety measures in Zone 2 areas include the use of intrinsically safe equipment and proper ventilation to minimize the risk of ignition and explosion.
Zone 3:
This is an area where hazardous materials are not likely to be present, but if they are, they will only be present for a short time.