MEDC DB18 User manual
Technical Manual for the
Speaker – DB18
Please note that every care has been taken to ensure the accuracy of our
technical manual. We do not, however, accept responsibility for damage,
loss or expense resulting from any error or omission. We reserve the right
to make alterations in line with technical advances and industry standards.
© MEDC 2002 04/02
04/02 © MEDC 2002
1. INTRODUCTION
This loudspeaker, intended for use in potentially explosive gas atmos-
pheres, has a power rating of up to 15 watts and is suitable for use in all
gas groups including hydrogen.
2. INSTALLATION
General
When installing and operating explosion-protected equipment, require-
ments for selection, installation and operation should be referred to eg.
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.
The DB18 is mounted via 2 off Ø7 mm (Ø0.28”) fixing holes in the ‘U’
shaped stirrup/mounting bracket. If required, the unit can be initially
placed via the Ø13mm (Ø0.51”) central hole in the stirrup. The unit can
be rotated to the required position and fixed via the two other holes.
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.
Unscrew and remove the 2 off screws holding the cover assembly to the
base. Keep in a safe, accessible location.
Remove cover to gain access to the interior.
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
© MEDC 2002 04/02
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 push the cover assembly back
onto the base, avoiding damage to the mating surfaces. Please Note: The
cover should be fitted in the orientation as supplied by MEDC to avoid the
cover fouling on the internal components. Replace the 2 off screws into the
holes in the cover assembly and tighten evenly.
3. OPERATION
The operating voltage of the unit is stated on the unit label.
The speaker is available as a 15W version only.
Different sound levels can be obtained by selecting the transformer tap-
pings in the unit (see table below)
TRANSFORMER POWER
TAPPINGS 15W
1:2 15
2:3 7.5
3:4 5
1:3 4
2:4 2
1:4 0.8
4. MAINTENANCE
During the working life of the unit, it should require little or no mainte-
nance. However, if abnormal or unusual environmental conditions occur
due to plant damage or accident etc., then visual inspection is recom-
mended.
If a unit fault should occur, then the unit can be repaired by MEDC. All
parts of the unit are replaceable.
MEDC Ltd, Colliery Road, Pinxton, Nottingham NG16 6JF, UK.
Tel: +44 (0)1773 864100 Fax: +44 (0)1773 582800
Sales Enq. Fax: +44 (0)1773 582830 Sales Orders Fax: +44 (0)1773 582832 MEDC Stock No.
If you acquired a significant quantity of units, then it is recommended that
spares are also made available. Please discuss your requirements with the
Technical Sales Engineers at MEDC.
5. CONFORMITY
Tested to EN50014:1997, EN50021:1999
EEx nA II T135°C (-55°C Tamb +55°C) T4.
The Declaration of Conformity and the product label carry the ATEX
group and category marking:- II 3 GD
Where signifies compliance with ATEX
II signifies suitability for use in surface industries
3 signifies suitability for use in Zone 2
G signifies suitability for use in the presence of gases
D signifies suitability for use in dust atmospheres
6. AMBIENT TEMPERATURE
-55°C to +55°C.
GENERAL ARRANGEMENT
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