AS/NZS 60079.2:2015 pdf free.AUSTRALIAN/NEW ZEAL AND STANDARD Explosive atmospheres.
5 Constructional requirements for pressurized enclosures
5.1 Enclosure
The pressurized enclosure shall have a degree of protection in accordance with Table 2.
For Level of Protection pxb with no internal components that exceed the marked temperature class and for Levels of Protection pyb and pzc. the tests for thermal endurance to heat and thermal endurance to cold for non-metallic enclosures and nonmetallic parts of enclosures of lEG 60079-0 need not be applied to the pressurized enclosure.
This is because degradation of the enclosure that results in increased leakage will result in alarm or removal of power to ignition capable circuits. Therefore, the pre-conditioning testing of non-metallic enclosures and non-metallic parts of enclosures is not considered necessary.
5.2 MaterIals
The materials used for the enclosure, ducts and connecting parts shall not be adversely affected by the specified protective gas.
5.3 Doors and covers
5.3.1 Group I pressurized enclosures Doors and covers shall either
— have special fasteners complying with IEC 60079-0; or
— be interlocked so that the electrical supply to equipment not providing an EPL as shown in 7.15 is disconnected automatically when they are opened and so that the supply cannot be restored until they are closed. The requirements of 7.7 shall also apply.
5.3.2 Group I pressurized enclosures with static pressurization Doors and covers shall have special fasteners complying with lEG 60079-0.
5.3.3 Group II and Group Ill pressurized enclosures The requirements for special fasteners in IEC 60079-0 do not apply.
For Level of Protection pxb”, doors and covers which can be opened without the use of a tool or key shall be interlocked so that the electrical supply to electrical equipment not identified in 7.15 is disconnected automatically when they are opened and so that the supply cannot be restored until they are closed.
For Level of Protection “pyb and Level of Protection pzc”. the use of a tool or key is not required.
Consideration should be given to the possibility that the internal pressure could cause a door or cover to open violently when the fastener is moved. The operator or maintenance personnel should be protected from injury by methods such as the following:
a) use multiple fasteners so that the enclosure will safely vent before all fasteners are released: or
b) use a two-position fastener to allow safe venting of the pressure when opening the enclosure; or
c) limit the maximum internal pressure to not greater than 2,5 kPa.AS/NZS 60079.2 pdf download.