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Hazardous Area Operation
Service Replacement Items
conduit. To maintain the purge integrity of the RMS enclosure, the
conduit is internally sealed. Due to the complexity of isolating all the
signal and power lines to the RMS enclosure, in the event of loss of
purge (ATEX, IECEx and X-Purge systems) power to the whole
instrument is switched off.
The purge requirements for these two cases are different and are also
different to the standard (local RMS) case. Details of the purge
"Purge Operation
parameters are given earlier in
Requirements".
The previous section
("RMS and Instrument in Hazardous
Area") is
also valid for the purge arrangement of a dual RMS Sentinel PRO
Ex. A dual RMS Prima PRO Ex is not an allowable configuration
due to the difficulty of handling the gas line from the second, remote
RMS within the purged enclosure.
Sample Pump
The pump in Sentinel PRO applications is powered independently of
(Sentinel PRO
the instrument and will, in general, require 3-phase power. The pump
will need to be hazardous area protected in its own right. Note that
Applications)
the pump might be exposed to explosive gases via both the external
atmosphere and the internal flow path. The requirements in the case
of the latter will vary depending on the local regulations in force and
the area classification.
Fibre Optic
Note that systems using fibre optic require a different ATEX/IECEx
Communications
certification code compared to the standard systems (see
Figure A–2
through
Figure
A–9). Adding fibre optics might therefore require a
change to the instrument label. Only fibre optic converters supplied
from the factory should be used.
Information on the type of fibre optic cable allowed and how to
connect is given in
Chapter 3: Site Requirements
and
Chapter 5:
Installation &
Interconnection.
Service
In order to maintain the system safe for hazardous area use and to
Replacement
maintain its certification, it is essential to replace any faulty item
Items
with an identical model, part, etc. Similar versions might possess
subtle differences that could adversely affect safe operation. If in
doubt, consult the factory.
A number of items, such as turbo molecular pump electronics,
Penning gauge, RMS stepper motor, and signal amplifier have been
adapted to ensure internal volumes are purged by means of suction
"Leakage
from a vacuum ejector (see
Handling"). In the case of third
party supplied components, these have not been physically modified
but have had fixing screws, or similar, replaced with a special hollow
adapters to allow for connection to the ejector circuit.
Thermo Fisher Scientific
Prima PRO & Sentinel PRO Mass Spectrometers User Guide
A-21
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