Maintenance And Service; Pump Construction; Cleaning The Pump; Contaminated Pumps - Grundfos Unilift AP12 Installation And Operating Instructions Manual

10. Maintenance and service

Warning
Before starting work on the pump,
make sure that the power supply to the
pump has been switched off and that it
cannot be accidentally switched on.
During dismantling, caution should be
exercised as there will be access to
sharp edges, etc. which may cut.
Warning
Before carrying out maintenance and
service, make sure that the pump has
been thoroughly flushed with clean
water. Rinse the pump parts in water
after dismantling.

10.1 Pump construction

The main components of the pump appear from the
table below and figures A, B and C on page 26.
Pos. Description
6 Pump housing
37a O-ring
49 Impeller
55 Pump sleeve with motor
66 Washer
67 Lock nut
84 Suction strainer
105 Shaft seal
182 Float switch
188a Screws
193 Screws
The position numbers are referred to in the following
cleaning instructions.

10.2 Cleaning the pump

If the pump does not deliver a sufficient quantity of
water because of sediment, dismantle and clean the
pump.
To dismantle the pump, follow this procedure:
1. Disconnect the power supply.
2. Allow the pump to drain.
3. Carefully loosen the suction strainer (pos. 84) by
inserting a screwdriver through one of the holes
of the strainer and press it downwards (towards
bottom). Repeat the procedure until the strainer is
free and can be removed.
4. Remove the suction stainer, clean, and refit it.
5. Connect the power supply and start the pump.
8
If the pump still does not deliver sufficient water,
dismantle the pump:
1. Disconnect the power supply.
2. Allow the pump to drain.
3. Carefully loosen the suction strainer (pos. 84) by
inserting a screwdriver through one of the holes
of the strainer and press it downwards (towards
bottom). Repeat the procedure until the strainer is
free and can be removed.
4. Remove the suction stainer and clean it.
5. Unscrew the six screws (pos. 188a) close to the
edge of the pump sleeve (pos. 55) and lift the
pump housing (pos. 6) out of the pump sleeve.
6. Clean the pump housing, the pump, and the
impeller (pos. 49).
7. Check to make sure the impeller can rotate freely.
If not, remove the impeller:
– Hold the impeller in place with a screwdriver
while loosening and removing the lock nut (pos.
67) on the motor shaft.
– Clean the impeller and around the shaft.
8. Check the impeller and around the shaft. If the
impeller is worn or defective, replace it.
9. Assemble the pump in reverse order of
dismantling:
– Fit the impeller (pos. 49) with the washer and
lock nut (pos. 67). Make sure the impeller
engages with the shaft.
– Position the O-ring (pos. 37a) in the pump
sleeve and lower the pump into the pump
housing.
– Fit the six screws (pos. 188a) with gaskets in
the pump housing (pos. 6) and tighten securely.

10.3 Contaminated pumps

Any application for service (no matter to whom it may
be made) must include details about the pumped
liquid.
Warning
If a pump has been used for a liquid
which is injurious to health or toxic, the
pump will be classified as
contaminated.
If Grundfos is requested to service the pump,
Grundfos must be contacted with details about the
pumped liquid, etc. before the pump is returned for
service. Otherwise Grundfos can refuse to accept
the pump for service.
Possible costs of returning the pump are paid by the
customer.

10.4 Replacement of parts

The impeller assembly and power cable can be
replaced. The part numbers and the components
included in the service kits can be found on
WebCAPS (www.grundfos.com). Alternatively,
contact your local Grundfos dealer.