Section 2 Extent of Hazardous Area

201. Application

For the purpose of machinery and electrical installations, hazardous areas are classified as in 202. to 204.. Hazardous areas not covered (such as, but not limited to, helicopter fuel storage areas, acetylene cylinder storage areas, battery rooms, paint lockers and flammable gas or vapour vents) in

202. to 204. are to be classified in accordance with section 102..

202. Hazardous areas Zone 0 Hazardous areas Zone 0 include ;

(1) The internal spaces of closed tanks and pipes for oil and gas products including escape gas out- let pipes.

(2) Outdoor location within 0.5 m from an opening to the hazardous areas defined in (1).

203. Hazardous areas Zone 1 Hazardous areas Zone 1 include ;

(1) Enclosed spaces containing tanks and pipes described in 202. (1)

(2) Enclosed spaces containing liquid or solid substances that are likely to emit flammable gases or vapors

(3) An enclosed space or semi-enclosed location:

(A) Having a direct access or opening into the hazardous areas defined in (1) or (2) or other

Zone 1 areas, through a door, a ventilation opening, etc.;

(B) Immediately adjacent to the closed tanks defined in 202. (1) or

(C) Containing pumps or piping used for conveying liquid described in 202. (1), except for all welded or continuous closed piping systems without valves, flanges or similar devices;

(4) Outdoor location within 1 m beyond the Zone 0 area defined in 202. (2).

(5) Outdoor location within 1.5 m from an opening to the hazardous areas defined in (1) to (3),

such as a door, a ventilation opening, a tank vent, etc;

(6) Outdoor or semi-enclosed locations within 1.5 m from any equipment, container, etc., stowed in

a designated open deck area, that are likely to emit flammable gases or vapors.

204. Hazardous areas Zone 2 Hazardous areas Zone 2 include;

(1) Outdoor location within 3 m from the boundaries of the closed tanks defined in 202. (1)

(2) Outdoor location within 1.5 m from pumps or piping used for conveying liquid described in

202. (1), except for all-welded or continuous closed piping systems without valves, flanges or

similar devices;

(3) Outdoor location within 1.5 m beyond the Zone 1 areas defined in 202. (4) and (5)

(4) Outdoor or semi-enclosed location within 1.5 m beyond the Zone 1 areas defined in 202. (6).

(5) Air locks between a Zone 1 and a non-hazardous area.

205. Openings, access and ventilation conditions affecting the extent of hazardous zones

1. Except for operational reasons access doors or other openings are not to be provided between the following spaces.

(1) A non-hazardous space and a hazardous zone

(2) A Zone 2 space and a Zone 1 space

2. Where such access doors or other openings are provided, any enclosed space not referred to under

202. or 203. and having a direct access to any Zone 1 location or Zone 2 location becomes the same zone as the location except that ;

(1) An enclosed space with direct access to any Zone 1 location can be considered as Zone 2 :

(A) The access is fitted with a gas-tight door opening into the Zone 2 space, and

(B) Ventilation is such that the air flow with the door open is from the Zone 2 space into the Zone 1 location, and

(C) Loss of ventilation is alarmed at a manned station.

(2) An enclosed space with direct access to any Zone 1 location is not considered hazardous if ;

(A) The access is fitted with a self-closing gas-tight door forming an air lock, and

(B) The space has ventilation overpressure in relation to the hazardous space, and

(C) Loss of ventilation overpressure is alarmed at a manned station.

(3) An enclosed space with direct access to any Zone 2 location is not considered hazardous if ;

(A) The access is fitted with a self-closing gas-tight door that opens into the non-hazardous lo- cation, and

(B) Ventilation is such that the air flow with the door open is from the non-hazardous space into the Zone 2 locations, and

(C) Loss of ventilation is alarmed at a manned station.

3. Where ventilation arrangements of the intended safe space are considered sufficient by the Society to prevent any ingress of gas from the Zone 1 location, the two self-closing doors forming an air lock may be replaced by a single self-closing gas-tight door which opens into the non-hazardous location and has no hold-back device.

4. Piping systems should be designed to preclude direct communication between hazardous areas of different classifications and between hazardous and nonhazardous areas.

5. Hold-back devices should not be used on self-closing gastight doors forming hazardous area boundaries.