Mas Grup
10
11. POSSIBLE FAILURES, CAUSES, SOLUTIONS
Possible failures and solution strategies are listed in the table below. Please apply to the Customers’ Service Department of our company when a
generic solution is not found to your problem.
While the failures are repaired the pump must always be dry and un-pressurized.
POSSIBLE FAILURE
CAUSES
SOLUTIONS
The pump delivers insufficient
capacity
Discharge head too high
Very high counter pressure
Pump and/or pipe cannot discharge air, cannot suck
Occurrence of air pockets inside the pipe
NPSH is too low
Readjust the operating point
See if there is any undesired material inside
the pipe
Vent completely the pump and the pipe
Change the piping configuration
Increase the liquid level
Motor overload
System pressure is lower than the requested pressure level
Speed too high
Liquid pumped of different specific gravity and viscosity than
that for which pump is rated
Engine works at two phases
Adjust the operating pressure to the label
value
Decrease the speed
Increase the engine power
Replace the fuse and control the electrical
connections
Pump head is too high
System pressure is higher than the requested pressure level
Set the operating pressure to the label value.
Bearing temperatures are high
Too much, too little or improper lubrication
Increase in axial forcing
Change the oil, decrease or increase its
quantity
Clean the balance holes on the impeller disc
Excessive leakage from the
stuffing box
Worn out gland
Loose gland.
Use brand new gland
Change the stuffing bush
Tighten the gland nuts
Noisy operation
Worn out motor or pump ball bearings
Cavitation
Worn out or misaligned coupling
Operation in the far left or right of the performance curve
Replace
Close the delivery partially in order to reduce
the capacity.
Replace the coupling or align it
Operate the pump at its label setting
Excessive increase in pump
temperature
Pump and/or pipe can neither discharge, nor aspirate air
Too low capacity
Bleed completely the pump and the pipe
Open more the valve
Vibration
Pump and/or pipe can neither discharge, nor aspirate air
NPSH is too low
Internal components of the pump are worn out
System pressure is lower than the requested pressure level
Coupling is misaligned
Too much, too little or improper lubrication
Rotor unbalanced
Improper bearings
Bleed completely the pump and the pipe
Increase the liquid level
Replace the worn out components
Adjust the operating pressure to the label
value
In case of continuous overload, decrease
the impeller diameter
Align the coupling
Change the oil, decrease or increase its
quantity
Balance the impeller again
Use new bearings
Table 3 -
Possible Failures, Causes, Solutions
