Checking The Direction Of Rotation; Maintenance And Service; Maintenance Schedule - Grundfos DWK Installation And Operating Instructions Manual

6.3 Checking the direction of rotation

Check the direction of rotation every time the pump is
connected to a new installation.
1. Remove the pump from the system.
2. Let the pump hang from a lifting device such as
the chain used for lowering the pump into the pit.
3. Start and stop the pump while observing the
movement (jerk) of the pump.
4. If connected correctly, the pump jerks
counterclockwise.
5. If the direction of rotation is wrong, interchange
two phases in the power cable.
DANGER
Crushing of hands
Death or serious personal injury
‐
Do not touch the pump when starting it
up.
Without being submerged in the pumped
liquid, start the pump and let it run for
maximum 5 seconds to check the direction
of rotation.
Before startup, make sure that the bottom
of the pit is clean to avoid material or
objects being sucked into the impeller.
Related information
6. Preparations before startup
9. Fault finding
18

7. Maintenance and service

7.1 Maintenance schedule

Under normal operating conditions, remove the pump
from the pit and inspect it once a year.
Under severe operating conditions, including when
the liquid contains sand, fibrous matter and solids,
inspect the pump once a month.
DANGER
Electric shock
Death or serious personal injury
‐
Before working on the pump, make
sure that the main switch is switched
off and locked in position 0. Make sure
that the power supply is switched off
and it cannot be switched on
unintentionally.
Measure insulation resistance once a
month.
Measure outlet pressure and flow rate
once a month if a flowmeter is available.
Ball bearings require no maintenance and
are lubricated for life.
Check the current and voltage
Check the pump current and voltage. If the value
measured by the ammeter deviates from the rated
value, it indicates a problem. The voltage must be
stable (within ± 5 %) throughout the operational
period.
Check the insulation resistance
If the insulation resistance has significantly declined
since the previous reading, it may indicate an
impending insulation failure. The pump must be
scheduled for service even if the insulation resistance
is still over 10 MΩ.
Check the outlet pressure and flow rate
Declining performance may indicate the need for an
overhaul. Regardless of performance, the pressure
and flow rate must be stable, and rapidly changing
pressure or flow rate indicate system problems on the
inlet or outlet side.
Check impeller clearence
Check the clearance between the impeller and the
wear plate. The recommended clearance is 0.3 - 0.5
mm. Replace or repair it as necessary.