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...1.4 Installation
Environmental Protection – The approval permits
installation below ground level where provision has
been made to prevent flooding. However to
accommodate accidental flooding (e.g. following a
pump failure) or if moisture ingress is possible, the
sensor connection box must be potted as soon as
connections are completed. Potting is supplied.
For a dry location with no possibility of flooding, it
is recommended that the unit is not potted.
Information. Certification does not apply to
submerged or buried sensors.
…1 CENELEC/ATEX APPROVED FLOWMETERS
1.4.1 Sensor Box Wiring
The wiring details (see below) are, in general, the
same as the standard (non-Hazardous Area)
remote version. However since the safety of the
system depends upon reliable connections, the
following points must be observed:
• Prepare cables with care as shown in the
installation manual except that bared cable
ends must be 10mm long, and not 5mm as for
the standard version.
• Remove all wire cuttings.
• Note routing of outer screen earth drain wire
(see illustration below).
• Sleeve all exposed conductors.
• Fully insert wires into terminal blocks up to the
insulation.
• Ensure that terminals, cable clamps, glands
etc. are fully tightened.
Caution. The sensor connection box
contains low value fuses. Under no
circumstances should low impedance
voltage be applied or electrode cleaning be
attempted.
CD1
CD2
SIG GND
DS1
SIG1
SIG2
DS2
CD1
CD2
–––
SIG GND
DS1
SIG1
SIG2
DS2
1.5 Safety of Pressurised Flowlines
If the flowmeter is to operate at significantly more
than one bar, see the following EECS Newsletter
extract.
The extract applies to any electromagnetic
flowmeter operated above atmospheric pressure.
It is not a limitation on the use of the equipment so
much as a limitation of the approval standards, If
the plant is deemed unconditionally safe by the
following criteria then the contents of the
newsletter do not apply.
System is Unconditionally Safe if:
• Operation is nominally 1 bar.
• Pipeline is operated with no explosive gas
mixture.
• Pipeline is full of liquid, at any rated pressure.
• Pipeline is reduced to atmospheric pressure
before being allowed to drain.
• Pipeline is vented or depressurised, whether
empty, full or partly full.
• Transmitter is working normally.
• Transmitter is switched off.
Recommendation – Mount sensor in a low part of
pipe run, i.e. pipe normally full.
Fig. 1.1 Sensor Box Wiring
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