Series MNKA,
acc. to ASME
Page 15
9250-050-en
Revision 11
TM 7903
Edition 07/2010
6.3 Shutdown
Close discharge valve down to the position
"minimum flow rate"
Switch motor off.
Close discharge valve completely.
Only close the suction line if the pump is to be
evacuated or dismantled.
For all work on the machine, make sure that
the motor cannot be inadvertently switched
on.
If the pump is to be evacuated or flushed,
observe the local regulations.
If the pump has been operated with a
chargeable liquid, it must be filled with inert
gas (e.g. nitrogen) to prevent an explosive
atmosphere.
It is recommended to wait one hour before the pump
is dismantled from the plant to permit static peak
charges to be eliminated.
These measures are not necessary with pumps with a
conductive plastic lining.
If the pump is returned to the manufacturer's, clean
the pump very thoroughly.
See also
Section 3.1
.
6.4 Restarting
When the pump is restarted, it must be ensured that
all the relative steps as described in
Section 6.1
are
repeated, depending on the progress of the shutdown
operation.
6.5 Improper operations and their
consequences (examples)
Inadmissible modes of operation, even for a short
time, can result in serious damage to the unit.
In connection with explosion protection,
potential sources of ignition (overheating,
electrostatic and induced charges, mechanical and
electric sparks) may result from these inadmissible
modes of operation; their occurrence can only be
prevented by adhering to the intended use.
Pump is started up without medium :
The plain bearings in the pump may be destroyed.
Other pump components may be destroyed due to
overheating.
Operation with magnetic drive stopped :
If no heat is dissipated, damage to the inner and
drive magnet assemblies may occur.
Suction line not opened or not opened fully :
Pump suffers cavitation – material damage.
Pump does not achieve the necessary head or
flow rate.
Pump may be destroyed due to overheating.
Discharge valve closed too much:
Pump may be destroyed due to overheating.
Axial thrust too great.
Discharge valve opened too much:
Pump can cavitate. Particularly severe with an
empty discharge line.
Risk of pressure surge.
Possible damage to the plain bearings.
Magnetic drive may stop.
Motor may be overloaded.
Suction valve and discharge valve closed:
Destruction due to rapid overheating and sharp
rise in pressure.
Control of the pump with the suction valve
Cavitation – the flow is only to be regulated on the
discharge side.
Overrun of the admissible gas content:
The flow may stop.
Switch pump and vent off for renewed
conveyance.
Make sure that the gas content is not exceeded, as
described in the intended use.
