MEDC HORN DB3 Technical Manual Download

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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 sounder. The sounder 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

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.

sounder

ENGLISH

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