Yokogawa YTA320 - Manual (Page 42)

<Installation and Operating Precautions for TIIS Flameproof Equipment>

EX-B03E
Installation and Operating Precautions for TIIS Flameproof Equipment
Apparatus Certified Under Technical Criteria (IEC-compatible Standards)
. General
The following describes precautions on electrical apparatus of
flameproof construction (hereinafter referred to as flameproof
apparatus) in explosion-protected apparatus.
Following the Labour Safety and Health Laws of Japan,
flameproof apparatus is subjected to type tests to meet either
the technical criteria for explosionproof electrical machinery and
equipment (standards notification no. 556 from the Japanese
Ministry of Labour) (hereinafter referred to as technical criteria),
in conformity with the IEC Standards, or the “Recommended
Practice for Explosion-Protected Electrical Installations in
General Industries,” published in 1979. These certified apparatus
can be used in hazardous locations where explosive or
inflammable gases or vapours may be present.
Certified apparatus includes a certification label and an
equipment nameplate with the specifications necessary for
explosion requirements as well as precautions on explosion
protection. Please confirm these precautionary items and use
them to meet specification requirements.
For electrical wiring and maintenance servicing, please refer
to “Internal Wiring Rules” in the Electrical Installation Technical
Standards as well as “USER’S GUIDELINES for Electrical
Installations for Explosive Gas Atmospheres in General
Industry,” published in 1994.
To meet flameproof requirements, equipment that can be termed
“flameproof” must:
(1) Be certified by a Japanese public authority in accordance
with the Labour Safety and Health Laws of Japan and have
a certification label in an appropriate location on its case,
and
(2) Be used in compliance with the specifications marked on its
certification label, equipment nameplate and precautionary
information furnished.
2. Electrical Apparatus of Flameproof Type of
Explosion-Protected Construction
Electrical apparatus which is of flameproof construction is
subjected to a type test and certified by the Japanese Ministry
of Labour aiming at preventing explosion caused by electrical
apparatus in a factory or any location where inflammable gases
or vapours may be present. The flameproof construction is
of completely enclosed type and its enclosure shall endure
explosive pressures in cases where explosive gases or
vapours entering the enclosure cause explosion. In addition,
the enclosure construction shall be such that flame caused
by explosion does not ignite gases or vapours outside the
enclosure.
In this manual, the word "flameproof" is applied to the flameproof
equipment combined with the types of protection "e", "o", "i", and
"d" as well as flameproof equipment.
3. Terminology
() Enclosure
An outer shell of an electrical apparatus, which encloses live
parts and thus is needed to configure explosion-protected
construction.
(2) Shroud
A component part which is so designed that the fastening of joint
surfaces cannot be loosened unless a special tool is used.
(3) Enclosure internal volume
This is indicated by:— the total internal volume of the flameproof
enclosure minus the volume of the internal components essential
to equipment functions.
(4) Path length of joint surface
On a joint surface, the length of the shortest path through
which flame flows from the inside to outside of the flameproof
enclosure. This definition 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
classification of the specified gases and vapours.
4. 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.
Note: Hazardous areas are classified 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 installation of
flameproof apparatus is limited to an ambient temperature range
from –20°C to +40°C (for products certified under Technical
Criteria). However, some field-mounted instruments may be
certified at an ambient temperature up to +60°C as indicated
on the instrument nameplates. If the flameproof 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 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 corrosive gases
or moisture, apply non-hardening sealant such as liquid
gaskets to those threads for waterproofing.