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Installation of Flameproof
Installation and Operating
Installation of Flameproof Apparatus
Installation Area Flameproof apparatus may be installed, in accordance with
applicable gases, in a hazardous area in Zone 1 or 2, where the
specified gases are present. Those apparatus shall not be
installed in a hazardous area in Zone 0.
Hazardous areas are classified in zones based upon the fre-
quency of the appearance and the duration of an explosive gas
atmosphere as follows:
Zone 0: An area in which an explosive gas atmosphere is pres-
ent continuously or is present for long periods.
Zone 1: An area in which an explosive gas atmosphere is likely
to occur in normal operation.
Zone 2: An area in which an explosive gas atmosphere is not
likely to occur in normal operation and if it does occur it will exist
for a short period only.
Environmental
Conditions
The standard environmental condition for the installation of
flameproof apparatus is limited to an ambient temperature
range from –20 °C to +40 °C (for products certified under Tech-
nical Criteria). However, some field-mounted instruments may
be certified at an ambient temperature up to +60 °C as indi-
cated on the instrument nameplates. If the flameproof appara-
tus are exposed to direct sunshine or radiant heat from plant
facilities, appropriate thermal protection measures shall be
taken.
External Wiring for Flameproof Apparatus
Flameproof apparatus require cable wiring or flameproof metal conduits for their
electrical connections. For cable wiring, cable glands (cable entry devices for
flameproof type) to wiring connections shall be attached. For metal conduits, attach
sealing fittings as close to wiring connections as possible and completely seal the
apparatus. All non-live metal parts such as the enclosure shall be securely grounded.
For details, see the USER’S GUIDELINES for Electrical Installations for Explosive Gas
Atmospheres in General Industry, published in 1994.
Cable Wiring
❑ For cable wiring, cable glands (cable entry devices for flameproof type) specified
or supplied with the apparatus shall be directly attached to the wiring connections
to complete sealing of the apparatus.
❑ Screws that connect cable glands to the apparatus are those for G-type parallel
pipe threads (JIS B 0202) with no sealing property. To protect the apparatus from
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