Table of Contents
Advertisement
11 - SPECIAL INFORMATION FOR ATEX ZONES
11.3.1 - Exchanger coils:
■ The temperature of the fluids circulating in the coils must not exceed the value given on the unit's name plate.
■ It must be below the surface temperature limit (or temperature class) corresponding to the ATEX atmosphere for which the unit is
certified (see § 11.2 Marking).
11.3.2 - Fan motor assembly section:
■ Follow the recommendations from the manufacturers of the motors and fan motor assemblies in the manuals included with the
ATEX file.
■ For belt pulley systems, the belt tension must be regularly adjusted and checked. A slack belt can slip and reach high temperatures.
The frequency for these checks is once a week. This frequency must be adapted to the observations made during previous checks
(condition of the belt, stability of the settings) and the ATEX risk.
■ Only use non-flammable, antistatic electrically conductive belts adapted to the unit's ATEX atmosphere.
11.3.3 - Air filter:
■ For ATEX units (in categories 2 - zone 1 - and 3 – zone 2 or 22 -), only use ATEX-certified antistatic filters, compatible with the zone
and the gas and/or dust group.
■ To limit the deposits of dust in the units installed in zone 22, you must:
- Replace the filters once they are moderately fouled,
- When replacing filters, clean the unit fully using a vacuum cleaner, in particular any components subject to high temperatures
(exchanger coils, fan motor assembly, etc.),
- Ensure that the ground straps for the filter cells are reconnected, and check that they are in good condition before restarting.
11.3.4 - Electrical connections:
■ All electrical connections must be performed by qualified, ATEX-approved personnel. Under no circumstances may the manufacturer
be held liable for the performance of these connections, which are outside the scope of its services.
11.3.5 - Prevention of corrosion:
■ If any rust appears, sand the corroded surface with an emery cloth, clean, then protect with rustproof, anti-electrostatic paint.
11.4 - Using tools in an explosive atmosphere
■ The operating managers for the installations and processes which include explosive atmospheres must provide all persons working
on a site with information relating to using manual tools in complete safety. There are two different types to be taken into consideration:
- Type A: Tools liable to only produce single sparks when used, such as screwdrivers, spanners or impact wrenches, for example,
- Type B: Tools that generate a plume of sparks, which may be used during grinding or sawing operations.
■ In zones 1 and 2 (or 22), only type A tools are permitted; use of type B tools can only be authorised if no dangerous explosive
atmosphere is present within the working area.
■ In zone 1, and in the presence of substances belonging to group IIC (acetylene, carbon disulphide, hydrogen) and hydrogen sulphide,
ethylene oxide, carbon monoxide, if there is a risk of explosion due to the presence of these substances, the use of steel tools is
prohibited unless it can be assured that no dangerous explosive atmosphere remains in the place of work whilst these tools are
being used.
■ Type A steel tools can be authorised in zone 22; type B steel tools can only be used if the place of work is separated and protected
from the remaining zone 22 locations and if the following additional measures are taken:
- Either any dust deposits have been removed from the working area,
- Or there is sufficient moisture in the working area to prevent dust from being dispersed into the air and the development of
smouldering fires.
■ During grinding or sawing operations in zone 22 or close to such a zone, it is possible that any sparks produced could be projected
large distances and thereby form glowing particles. For this reason, the other zones around the place of work must also be included
in the protective measures mentioned above.
■ The use of tools in zones 1, 2 and 22 must be subject to the "work permit" system.
■ All other types of tools or equipment required for maintenance operations (vacuum cleaners, etc.) must be compatible with use in
the ATEX zone in question. Otherwise, it must be ensured that, prior to and for the duration of any maintenance operation, the place
of work is sufficiently ventilated to prevent the presence or formation of an explosive atmosphere.
72
Advertisement
Table of Contents
