Series MNKA,
acc. to ASME
Page 7
9250-050-en
Revision 11
TM 7903
Edition 07/2010
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 are
induced on the inner and outer magnet assemblies
and an inadmissible rise in temperature may occur.
The situation is to be remedied by providing
appropriate monitoring facilities. See
Section 5.6
.
The plant NPSH value (NPSHA) should be 1.64 ft
(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 evacuation if the lining of the pump is
non-conductive. See
Section 6.3
.
2.6.4 Identification
The 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 attachments as well as corresponding
identification.
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
without 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
indicated.
The temperature class must be determined by the
operated 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 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 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
suction and/or discharge lines is not permitted!
There is a risk that even after a short time
high surface temperatures on the pump
housing (casing) may occur owing to rapid
heating of the liquid in the pump interior.
A rapid rise in the pressure inside the pump
involves the risk of overloading to the point of
bursting.
The pump must not be in operation in the
unfilled or partially filled state (dry
running). This results in serious damage to
the pump and additional risks to the environment
can arise.
Dry-running cannot only occur with an
insufficiently filled interior but also in the event
of high gas contents in the fluid.
Operation of the pump outside the admissible
operating range may also lead to dry-running (e.g.
due to evaporation in the interior).
2.6.7 Temperature limits
In the normal operating condition the highest
temperatures are to be expected at the
contact point shaft seal/shaft, on the inner
races of the rolling bearings and, at high medium
temperatures, on surface of the pump housing.
In the case of fluids > 104 °F (40°C) the surface
temperature of the pump housing (casing) is generally
lower than the temperature of the liquid as the lining
has an insulating effect.
If the pump is heated (e.g. heating jacket), it
must be ensured that the temperature classes
prescribed in the annex are observed.
The not heated pump surface must have free contact
with the environment.
