Series RMI-B
close-coupled design
Page
7
9430-005-en
Revision 03
TM 10456
Edition 06/2022
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 recom-
mend that appropriate monitoring facilities be
provided.
Also carefully fill auxiliary, heating and
cooling systems.
2.6.2 Special operating conditions
In the standard design the can chamber
and the plain bearings are cooled and lubri-
cated by a flushing flow.
Owing to properties of the medium (e.g. sticking due to
inadmissible solids entrainment, clogging, gas entrain-
ment 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
opt
. If the pump is operated outside this
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
.
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 liquids with a
conductivity < 10
-8
S/m inert gas must be used for
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:
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.
For surface temperatures that mainly depend on the
operating conditions of the pump, DIN EN ISO 80079-
36 Chapter 11.2 f) and g) state that no temperature
class or temperature may be specified. In this case, the
identification must include temperature range identifi-
cation (e.g. T4 ... T3 for gas or for dust D135 ° C ...
T200 ° C).
The temperature class must be determined by the op-
erator in accordance with
Section 2.6.7
“Temperature
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 un-
filled pump in order to prevent an inadmis-
sible rise in temperature at the plain bear-
ings.
We recommend you to only perform a check of the
direction of rotation with with filled pump and with a
rotating field 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.
Operation with closed shut-off elements in the suc-
tion and/or discharge lines is not permitted!
There is a risk that even after a short time
high surface temperatures on the pump
housing may occur owing to rapid heating
of the liquid in the pump interior.
