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Series RMI
2.6
Special requirements for ex-
plosion protection
If the units are used in potentially explosive areas, the
measures and notes in Sections 2.6.1 to 2.6.9 are
imperative to guarantee the explosion protection.
2.6.1 Filling the unit
During pump operation the wetted interior of
the pump must always be filled with the liquid
medium.
This prevents any explosive atmosphere and the risk
of dry-running.
If the customer cannot ensure this, we rec-
ommend that appropriate monitoring facilities
be provided.
All auxiliary, heating and cooling systems
must also be carefully filled.
2.6.2 Special operating conditions
In the standard design the can chamber and the plain
bearings are cooled and lubricated by a flushing flow.
Owing to properties of the medium (e.g. sticking due
to inadmissible solids entrainment, clogging, gas en-
trainment etc.) the cooling flow can be interrupted
and, as a result, an inadmissible temperature rise may
occur. Provide appropriate monitoring facilities. See
Section 5.6.
For safe pump operation, we recommend a flow rate
of 0.3 to 1.1 Q
. If the pump is operated outside this
opt
range, it must be ensured that the max. admissible
flow rate according to the pump characteristic curve is
not exceeded and that the max. admissible operating
temperature according to Section 2.6.7 is observed.
If the flow rate is too high, the differential pressure
upstream and downstream of the plain bearings could
fall so much that a lack of lubrication or dry-running
may occur.
If the flow rate is too low, the medium may heat up so
much owing to the fluid friction that the max.
admissible surface temperature of the relevant
temperature class is exceeded.
Overloading, overheating, non-observance of the
design data or the incorrect selection of the magnetic
drive can lead to the decoupling of the inner and outer
magnet assemblies. As a result, eddy currents may be
induced on the inner and outer magnet assemblies
and an inadmissible temperature rise may occur.
The situation is to be remedied by providing appropri-
ate monitoring facilities. See Section 5.6.
9430-050-en
Revision 00
TM 9886
Edition 03/2018
The plant NPSH value (NPSHA) should be minimum
0.5 m higher than the NPSH value of the pump
(NPSHR) to prevent a lack of lubrication or dry-
running of the plain bearings.
2.6.3 Chargeable liquids
For
operation
with
chargeable
conductivity < 10
S/m inert gas must be used for
-8
flushing during drain. See also Section 6.3.
2.6.4 Identification
The ex identification on the pump relates to
the pump section. A separate declaration of
conformity must be provided for the shaft
coupling and motor and for other attach-
ments as well as corresponding identifica-
tion.
Example of the identification of the pump section:
II2GD IIC TX X.
For assembling the pump with components which are
not explosion-protected (e.g. motor, shaft coupling), it
is recommended to mask or remove the "potentially
explosive" identification from the pump component
and, if necessary, from other accessories.
In this case the declaration of conformity applies with-
out ATEX identification.
At surface temperatures which depend primarily on
operating conditions, DIN EN 13463-1 Chapter 9.3
allows no temperature class or temperature to be indi-
cated.
The temperature class must be determined by the
operator in accordance with Section 2.6.7 "Tempera-
ture Limits".
2.6.5 Check of the direction of rotation
If there is also a risk of explosion during the
installation phase, the check of the direction
of rotation must under no circumstances be
conducted by briefly switching on the unfilled
pump in order to prevent an inadmissible rise
in temperature at the plain bearings.
We recommend you to only perform a check
of the direction of rotation with the coupling
disengaged
or
instrument. See also Section 6.1.2.
2.6.6 Mode of operation of the pump
The pump may only be started with the suction side
shut-off element fully opened and the discharge side
shut-off element slightly opened. Start-up against a
closed check valve is also possible. The discharge
side shut-off element is to be regulated to the
operating design point directly after run-up.
See also Section 5.4.1.
Page 7
liquids
with
with
a
rotating
field
a
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