MEDC DB3 Manuel Technique page 3

English
1.0 INTRODUCTION
This range of light weight all GRP, flameproof sounders is intended for use in potentially explosive gas and dust
atmospheres and has been designed with high ingress protection to cope with the harsh environmental conditions
found offshore and onshore in the oil, gas and petrochemical industries.
The flamepaths, flare and body are manufactured completely from a UV stable glass reinforced polyester. Stainless
steel screws and sinter are incorporated thus ensuring a corrosion free product. A tapered Flamepath is used to
overcome the problems of assembly of parallel spigot flamepaths.
An Optional Exe terminal chamber is available
An uncertified version is available for use in non-explosive atmospheres.
2.0 INSTALLATION
General
When installing and operating explosion-protected equipment, requirements for selection, installation and
operation should be referred to e.g. IEE Wiring Regulations and the 'National Electrical Code' in North America.
Additional national and/or local requirements may apply.
Ensure that all nuts, bolts and fixings are secure.
Ensure that only the correct listed or certified stopping plugs are used to blank off unused gland entry points and
that the NEMA/IP rating of the unit is maintained. MEDC recommend the use of a sealing compound such as
HYLOMAR PL32 on the threads of glands and stopping plugs in order to maintain the IP rating of the unit.
The unit mounts via 2 off 9mm mounting holes in the 'U' shaped stirrup / mounting bracket. The holes have been
designed to accept an M8 screw or bolt. If required the unit can be initially placed using the 13mm central hole in
the mounting bracket. The unit can then be rotated into the correct orientation and fixed via the other two holes.
When the unit is fixed in the required position, its alignment can be adjusted by loosening the two M6 screws which
fasten the mounting bracket to the speaker. The speaker can then be adjusted to the required position and the
screws tightened. The unit should be positioned such that dust/debris or water cannot settle in the re-entrant horn
MEDC recommend the use of stainless steel screws.
Cable Termination
CAUTION: Before removing the cover assembly, ensure that the power to the unit is isolated.
On Exd versions, the cover is secured with 6 off M5 cover screws (4.0mm A/F hexagon key). Once the cover
fixings are unscrewed, twist the cover assembly gently clockwise and anti-clockwise, whilst pulling it away from the
base. Remove to gain access to the interior.
On Exde versions the removable cover is secured using 2 off M5 cover screws (4.0mm A/F hexagon key). Once
the cover fixings are unscrewed, the cover can be lifted away from the enclosure to gain access to the interior.
Ensure all non-captive fixings are kept in a safe accessible location during cable termination.
Cable termination should be in accordance with specifications applying to the required application. MEDC
recommends that all cables and cores should be correctly identified. Please refer to the wiring diagram provided
with the product.
Ensure that only the correct listed or certified cable glands are used and that the assembly is shrouded and correctly
earthed.
All cable glands should be of an equivalent NEMA/IP rating to that of the speaker and integrated with the unit such
that this rating is maintained.
The internal earth terminal, where fitted, must be used for the equipment grounding connection and the external
terminal is for a supplementary bonding connection where local codes or authorities permit or require such a
connection.
Once termination is complete, carefully replace the cover assembly back onto the body, avoiding damage to the
mating surfaces. Replace the cover screws into the holes in the cover assembly and tighten evenly. Ensure the O-
ring is seated correctly on the cover during re-assembly. On Exd certified versions, ensure the required maximum
gap of 0.15mm is maintained between the cover and the base once assembled.
© MEDC 2014 07/14