Yokogawa digitalYEWFLO (DY) - Manual (Page 167)

<INSTALLATION AND OPERATING PRECAUTIONS FOR TIIS FLAMEPROOF EQUIPMENT>
1
IM 01F06A00-01EN
INSTALLATION AND OPERATING
PRECAUTIONS FOR TIIS FLAMEPROOF
EQUIPMENT
Apparatus Certifi ed Under Technical Criteria (IEC-compatible Standards)
1. General
The following describes precautions on electrical
apparatus of fl ameproof construction (hereinafter
referred to as fl ameproof apparatus) in explosion-
protected apparatus.
Following the Labour Safety and Health Laws
of Japan, fl ameproof apparatus is subjected to
type tests to meet either the technical criteria for
explosionproof electrical machinery and equipment
(standards notifi cation 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
certifi ed apparatus can be used in hazardous
locations where explosive or infl ammable gases or
vapours may be present.
Certifi ed apparatus includes a certifi cation label and
an equipment nameplate with the specifi cations
necessary for explosion requirements as well as
precautions on explosion protection. Please confi rm
these precautionary items and use them to meet
specifi cation 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 fl ameproof requirements, equipment that
can be termed “fl ameproof” must:
(1)
Be certifi ed by a Japanese public authority in
accordance with the Labour Safety and Health
Laws of Japan and have a certifi cation label in
an appropriate location on its case, and
(2) Be used in compliance with the specifi cations
marked on its certifi cation label, equipment
name plate and precautionary information
furnished.
2. Electrical Apparatus of Flameproof Type
of Explosion-Protected Construction
Electrical apparatus which is of fl ameproof
construction is subjected to a type test and certifi ed
by the Japanese Ministry of Labour aiming at
preventing explosion caused by electrical apparatus
in a factory or any location where infl ammable
gases or vapours may be present. The fl ameproof
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 fl ame
caused by explosion does not ignite gases or
vapours outside the enclosure.
In this manual, the word "fl ameproof" is applied
to the fl ameproof equipment combined with the
types of protection "e", "o", "i", and "d" as well as
fl ameproof equipment.
3. Terminology
(1) Enclosure
An outer shell of an electrical apparatus, which
encloses live parts and thus is needed to confi gure
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 fl ameproof 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 fl ame fl ows from the inside to outside
of the fl ameproof enclosure. This defi nition cannot
be applied to threaded joints.