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8. Check all controls for proper operation. If the pump
is controlled by a pressure switch, check and adjust
the cut-in and cut-out pressures. If low-water-level
controls are used, be sure the low-water-level switch is
properly adjusted so the pump cannot run if the pump
should break suction.
Operation and maintenance
Operation
When Grundfos HS centrifugal pumps are installed in
accordance with these instructions and sized for correct
performance, they will operate efficiently and provide
years of service. The pumps are water lubricated and do not
require any external lubrication or inspection. The motors
may require periodic lubrication as noted in the following
maintenance information.
Under no circumstances should the pump be operated for
any prolonged periods of time without flow through the
pump.
This can result in motor and pump damage due to over-
heating. A properly sized relief valve or bypass line should
be installed to allow sufficient water to circulate through
the pump to provide adequate cooling and lubrication of
the pump bearings and seals.
Pump cycling should be checked to ensure the pump is not
starting more than 20 times per hour on 1⁄2 HP to 5 HP mod-
els or 15 times per hour on 7 1⁄2 HP models. Rapid cycling is
a major cause of premature motor failure due to increased
heat build-up in the motor. If necessary, adjust controls to
reduce the frequency of starts and stops.
Freeze protection
If the pump is installed in an area where freezing could
occur, the pump and system should be drained during
freezing temperatures to avoid damage. To drain the pump,
close the isolation valves and remove the drain/vent plugs
at both the top and bottom of the pump volute. DO NOT
replace the plugs until the pump is to be used again.
Maintenance
Motor lubrication
Electric motors are pre-lubricated at the factory and do not
require additional lubrication at start-up. Motors without
external grease fittings have sealed bearings that cannot
be re-lubricated. Motors with grease fittings should only
be lubricated with approved types of grease. Do not over-
grease the bearings. Over greasing will cause increased
bearing heat and can result in bearing/motor failure. Do
not mix petroleum grease and silicon grease in motor bear-
ings.
Bearing grease will lose its lubricating ability over time,
not suddenly. The lubricating ability of a grease (over
6
time) depends primarily on the type of grease, the size of
the bearings, the speed at which the bearings operate and
the severity of the operating conditions. Good results can
be obtained if the following recommendations are used in
your maintenance program.
Severity
Ambient
of
Temperature
Service
(Maximum)
Standard
+104°F (+40°C)
Clean, little corrosion
Severe
+122°F (+50°C)
Moderate dirt, corrosion
Extreme
>+122°F (+50°C)
Severe dirt, abrasive
or Class H insulation
dust, corrosion
Motor lubrication schedule
NEMA Frame Size 56 to 210
Severity
Interval
of
(Hours)
Grease to Add
Service
Standard
5500
Severe
2750
Extreme
550
Preventative maintenance
At regular intervals, depending on the conditions and time
of operation, the following checks should be made:
1. Pump meets required performance and is operating
smoothly and quietly.
2. There are no leaks, particularly at the shaft seal.
3. The motor is not overheating.
4. Remove and clean all strainers or filters in the system.
5. Verify the tripping of the motor overload protection.
6. Check the operation of all controls. Check until control
cycling twice and adjust if necessary.
7. If the pump is not operated for unusually long periods,
the unit should be maintained in accordance with
these instructions. In addition, if the pump is not
drained, the pump shaft should be manually rotated or
run for short periods of time at monthly intervals.
If the pump fails to operate or there is a loss of perform-
ance, refer to pages 11 - 13, "Troubleshooting."
Motor replacement
If the motor is damaged as a result of bearing failure,
burning, or electrical failure, the following instructions
detail how to remove the motor for replacement. It must be
emphasized that motors used on HS pumps are specifically
selected to our rigid specifications. Replacement motors
must be of the same NEMA C frame size and have the same
service factor.
Failure to follow these recommendations may result in
premature motor failure.
Environment
Approved
Types
of Grease
See motor
nameplate for
grease type or
compatible
equivalent type
of grease
Weight of
Volume of
Grease to Add
(oz)
(in
3
/tspn)
0.3
0.6/2
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