MEDC DB3B - Manual (Page 3)

1.0 INTRODUCTION
This range of sounders, intended for use in potentially explosive gas and dust atmospheres, is available in versions
suitable for use in the following gas/dust groups:
The range is available in versions suitable for use in either gas (G) or gas and dust (GD) groups.
Note: (G) unit has nominally 6dB higher output than (GD) unit
The Ex 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.
An optional Ex e terminal chamber is available (see certification section for further details).
An uncertified version is 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. On Exde units, a suitable sealing washer must be fitted to all glands and stopping plugs fitted into the Exe
enclosure.
xii. 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.
xiii. When installing the device, MEDC recommends the use of stainless steel fasteners. Ensure that all nuts,
bolts and fixings are secure.
xiv. The unit should be positioned such that debris, dust or water cannot settle in the re-entrant horn.
xv. 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 Ø9mm fixing holes in the U-shaped stirrup/mounting bracket. If required, the unit can
be initially placed via the 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 M8 screw or bolt.
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© MEDC 2014 07/14