VARISCO J2 180 - Troubleshooting

12 Troubleshooting
WARNING
In the event of a malfunction or abnormal operation, shut off the pump or pump unit
immediately to prevent a dangerous situation and/or damage (possibly severe) to the
pump or pump unit.
Inform to responsible persons. Determine the cause of the malfunction. Resolve the
problem before restarting the pump
Problem
Possible cause
Verifications and solutions
Pump does not prime
Delivery pipe under pressure
Bleed delivery pipe.
Impeller may be worn or broken
Disassemble pump casing and check
impeller for wear
Suction strainer, where applicable,
may be clogged
Remove obstructions
Excessive suction lift
Reduce suction lift
Air entering through seal
Disassemble seal and clean it
Impeller clogged by foreign matter
Disassemble casing and remove
foreign matter
Pump does not deliver
liquid
Head required by the system is
greater than the rated head of the
pump
Revise system design or select a
different pump
Excessive flow resistance along
suction line
Revise distribution of elbows, valves,
constrictions etc.; where necessary,
increase diameter of pipework
Impeller clogged by foreign matter
Disassemble casing and remove
foreign matter
Suction/delivery pipes may be
obstructed or clogged
Locate the obstructed or clogged
area and clean
Pump does not deliver
enough liquid
Air leaks in suction line.
Check joints are airtight and inspect
suction pipe.
Impeller and/or wear plate may be
worn.
Replace them by disassembling the
pump
Diameter of the suction pipe too
small
Replace suction pipe.
Pump does not
provide enough
pressure
Viscosity of the liquid is higher than
expected
Contact the pump manufacturer once
you have measured the viscosity of
the liquid.
Viscosity for centrifugal pumps
should not exceed 50 cSt
Pump absorbs too
much power
Pump operates under conditions
that are different from those
specified in the contract
Check operating conditions of pump
and compare them to those on the
pump’s nameplate
Density of the liquid is higher than
planned
Measure density of the liquid and
compare it with the agreed value
Incorrect unit alignment
Check unit is correctly aligned
There may be friction inside the
pump between rotating and non-
rotating components
Disassemble pump casing and check
for scratches on surfaces