MEDC DB3B - Manuel (Page 3)

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
Note:
(G) unit has nominally 6dB higher output than (GD) unit
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. Ensure that only the correct listed or certified cable glands are used and that the assembly is shrouded and
correctly earthed.
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, where fitted, must be used for the equipment grounding and the external
terminal, if available, is for a supplementary bonding connection where local codes or authorities permit or
require such a connection.
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 Ш23/64” (Ш9mm) fixing holes in the U-shaped stirrup/mounting bracket. If required,
the unit can be initially placed via the Ш33/64” (Ш13mm) 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.
© MEDC 2015 02/15