Richter MNK Series - Manual (Page 15)

Series MNK
Page 15
9230-050-en Revision 11
TM 7903 Edition 07/2010
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 volume may only 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.
7 Maintenance
7.1 Screw connections of the
housing
After initial loading by the operating pressure and
operating temperature the tightening torques of all
connection screws must be checked at the following
points:
housing flange
suction flange
discharge flange
See also Section 6.1.1, para. 1 .
Other inspections are to be performed regularly,
depending on the operating requirements.
7.2 Bearing pedestal
The temperature of the bearing pedestal is
not to exceed more than 70 °C and under no
circumstances 80 °C.
If higher temperatures do occur, call in qualified staff
without delay. If this is not possible, the pump must be
shut down and taken out of service.
In many cases a vibration measurement is
recommended to detect bearing wear in good time.
7.2.1 Long life grease lubrication
Grease fill bearings of the series 2RS are installed as
standard features. The grease is lithium-saponified.
The admissible temperature range is – 30 °C to
+ 110 °C.
The rolling bearings are designed for an L10 service
life of >17,500 hours.
The service life of the grease
filling guaranteed by the bearing manufacturers is
given in the following table.
Size Bearing size > Service life
Group 1.1 6206-2RS / 15000 hr*
Group 1.2 6308-2RS / 15000 hr*
Group 1.3 6308-2RS / 15000 hr*
Group 2 6211-2RS / 15000 hr*
* at bearing temperature <50 °C
at bearing temperature 70 °C approx. 7500 hr
If the pump is serviced, it is recommended to also
replace the bearings as a precaution.
In potentially explosive works it is
advisable to monitor the condition of
the rolling bearings
7.2.2 Oil bath lubrication
We recommend a mineral oil with the following
characteristics for an expected bearing temperature of
about 70 °C:
Viscosity index :
85 . appr
Kinematic viscosity at 40 °C :
s
2
mm 40 . appr
A fully synthetic gear oil to ISO VG 220 is to be used
for temperatures below – 20
Replacing the bearings: The ball bearings are
designed for an L
10
service life of >17,500 hours.
We recommend 17.500 working hours respectively
every 3 years a change of bearing should be made.
Oil changes: 1x per year at bearing temperatures of
about 50 °C.
Every 6 months at bearing temperatures of about
70 °C.
At higher temperatures more frequently in accordance
with the regulations.