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The horn – DB3B UL
TM261 April 2020 www.eaton.com
The horn – DB3B UL
English
1.0 Introduction
This range of horns, suitable for fire alarm or general use,
is intended for use in potentially explosive gas (G) or gas
and dust (GD) atmospheres.
The enclosure is manufactured from a UV stable glass
reinforced polyester with a rugged thermoplastic flare.
Stainless steel mounting bracket, cover screws and
fixings are incorporated throughout thus ensuring a
corrosion free product.
A UL ordinary locations listed version is also available for
use in non-explosive atmospheres.
2.0 General safety messages and
warnings
All instructions and safety messages in this manual must
be followed to allow safe installation of the device. The
device must only be installed and maintained by correctly
trained site personnel/installers.
I. To reduce the risk of ignition of hazardous
atmospheres and shock, do not apply power to the
device until installation has been completed and the
device is fully sealed and secured.
II. To reduce the risk of ignition of hazardous
atmospheres and shock, keep device tightly closed
when the circuit is energised.
III. Before removing the cover for installation or
maintenance, ensure that the power to the device
is isolated.
IV. Following installation, test the device to ensure
correct operation.
V. Following installation ensure a copy of this manual
is made available to all operating personnel.
VI. When installing the device, 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 also apply.
VII. Cable termination should be in accordance with the
specification applying to the required application.
MEDC recommends that all cables and cores should
be correctly identified. Please refer to the wiring
diagram in this manual (or separate diagram provided
with the unit).
VIII. This is an Ex d product, correctly listed or certified
explosion proof cable glands and stopping plugs must
be used.
IX. 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.
X. MEDC recommend the use of a sealing compound
such as HYLOMAR PL32 on the threads of all glands
and stopping plugs and/or a suitable sealing washer
in order to maintain the IP rating of the unit.
XI. The internal earth terminal
must be used for
protective earthing when required. Do not remove
the internal ground strap from the earth terminal
where fitted.
For units with metric entries; gland continuity and
earthing my be achieved with an optional external
earth plate. If the external plate is fitted, a thread
sealing compound such as HYLOMAR PL32 must be
employed to maintain the IP rating of the unit.
XII. When installing the device, MEDC recommends the
use of stainless steel fasteners. Ensure that all nuts,
bolts and fixings are secure.
XIII. The unit should be positioned such that debris, dust
or water cannot settle in the re-entrant horn.
XIV. The unit should be positioned such that any solid
object, not part of the equipment, is a minimum of
40mm from the Ex d flamepath joint.
3.0 Installation
The unit is mounted via 2 off Ø23/64” (Ø9mm) fixing
holes in the U-shaped stirrup/mounting bracket. If
required, the unit can be initially placed via the Ø33/64”
(Ø13mm) central hole in the stirrup. The unit can then
be rotated to the required position and fixed via the
other holes.
If ordered with the unit, a swivel mounting bracket option
is available to allow further rotational adjustment to
the unit.
The fixing holes have been designed to accept an Ø5/16”
(M8) screw or bolt.
Access to terminals
The cover is secured with 6 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. The cover fixings
are captive and will remain in the cover.
Once termination is complete, carefully replace the
cover assembly back onto the body, avoiding damage to
the mating surfaces. Tighten the cover screws evenly.
Ensure the O-ring is seated correctly on the cover during
reassembly. Ensure the required maximum gap of
0.0015” (0.038mm) is maintained between the cover and
the enclosure body once assembled.
