Yokogawa ADMAG AXR Uživatelský manuál stáhnout pdf (Strana 191)

IM 01E30D01-01EN

(4) Path length of joint surface

On a joint surface, the length of the shortest path

hroughwhichameowsfromtheinsidetooutside

oftheameproofenclosure.Thisdenitioncannot

be applied to threaded joints.

(5) Gaps between joint surfaces

The physical distance between two mating surfaces,

or differences in diameters if the mating surfaces

are cylindrical.

Note: The permissible sizes of gaps between joint surfaces,

the path length of a joint surface and the number of joint

threads are determined by such factors as the enclosure’

s internal volume, joint and mating surface construction,

andtheexplosionclassicationofthespeciedgasesand

vapours.

4. Installation of Flameproof

Apparatus

(1) Installation Area

Flameproof apparatus may be installed, in

accordance with applicable gases, in a hazardous

reainZone1or2,wherethespeciedgasesare

present. Those apparatus shall not be installed in a

hazardous area in Zone 0.

Note: Hazardousareasareclassiedinzonesbasedupon

the frequency of the appearance and the duration of an

explosive gas atmosphere as follows:

Zone 0: An area in which an explosive gas atmosphere

is present 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.

(2) Environmental Conditions

The standard environmental condition for the

nstallationofameproofapparatusislimitedtoan

ambient temperature range from –20°C to +40°C

(forproductscertiedunderTechnicalCriteria).

However,someeld-mountedinstrumentsmay

becertiedatanambienttemperatureupto+60

°C as indicated on the instrument nameplates. If

theameproofapparatusareexposedtodirect

sunshine or radiant heat from plant facilities,

appropriate thermal protection measures shall be

taken.

5. External Wiring for

Flameproof Apparatus

Flameproof apparatus require cable wiring or

ameproofmetalconduitsfortheirelectrical

connections. For cable wiring, cable glands

(cableentrydevicesforameprooftype)towiring

connections shall be attached. For metal conduits,

attachsealingttings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.

(1) Cable Wiring

• For cable wiring, cable glands (cable entry

devicesforameprooftype)speciedor

supplied with the apparatus shall be directly

attached to the wiring connections to complete

sealing of the apparatus.

• S

crews 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 corrosive gases

or moisture, apply nonhardening sealant

such as liquid gaskets to those threads for

waterproong.

• Speciccablesshallbeusedasrecommended

by the “USER’S GUIDELINES for Electrical

Installations for Explosive Gas Atmospheres in

General Industry,” published in 1994.

• In necessary, appropriate protective pipes

(conduitorexiblepipes),ductsortraysshall

be used for preventing the cable run (outside

the cable glands) from damage.

• To prevent explosive atmosphere from being

propagated form Zone 1 or 2 hazardous

location to any different location or non-

hazardous location through the protective pipe

or duct, apply sealing of the protective pipes in

thevicinityofindividualboundaries,orllthe

ducts with sand appropriately.

• When branch connections of cables, or cable

connections with insulated cables inside

theconduitpipesaremade,aameproofor

increased-safety connection box shall be used.

Inthiscase,ameprooforincreased-safety

cable glands meeting the type of connection

box must be used for cable connections to the

box.

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