KSB WKT - 8. Troubleshooting

WKT
25
8. Troubleshooting
Pump delivers insufficient flow rate Motor is overloaded Excessive pump discharge pressure Increase in bearing temperature Leakage at the pump Excessive leakage at the shaft seal Vibration during pump operation
E
xcess
i
ve r
i
se o
f
temperature inside the
pump
Cause Remedy
1)

The pump generates an excessively high
differential pressure.
Open discharge valve further until the duty
point conditions have been attained.

Excessively high back pressure.
Fit larger impeller (s)
Increase speed (applies to turbine driven or
I.C Engine driven pumps)
  
The pump or piping are incompletely vented
or primed.
Vent or prime the pump and piping
completely.

Suction line or impeller (s) clogged.
Remove deposits in the pump and/or piping.

Formation of air pockets in the piping.
Alter piping layout.
If necessary fit a vent valve.
  
The pump is warped.
Check piping connections and pump fixing
bolts.
  
NPSH available is too low (on positive
suction head installations).
Check liquid level in suction vessel.
Open isolating valve in suction line fully.
Alter suction line if necessary, if the friction
losses in the suction line are excessive.
Check suction line strainer.
Make sure that the permissible rate of
pressure decrease is not exceeded.

Increased axial thrust.
2)
Clean out balance holes in impeller.
Fit new casing wear rings.

Air intake at the shaft seal. Fit new shaft seal.

Reverse rotation
Interchange two of the phases of the power
supply cable.
 
Motor is running on two phases only.
Replace the defective fuse.
Check electric connections.

Rotational speed is too low.
2)
Increase speed.
Increase voltage.

Defective bearings. Fit new bearings.
  
Insufficient rate of flow. Increase the minimum rate of flow.
 
Excessive wear of the pump internals. Replace worn components by new ones.
 
Pump back pressure is lower than specified
in the purchase order.
Adjust duty point accurately by means of the
isolating valve in the discharge line.
In case of persistent overloading, trim the
impeller (s) if necessary
2)

Specific gravity or viscosity of the fluid
pumped is higher than that specified in the
purchase order.
2)
 
Use of unsuitable materials. Change the Material combination.

Excessive rotational speed.
Reduce speed (applies to turbine driven or
I.C. engine driven pump).
2) 3)

The connection bolts are slack. Tighten the bolts. /Fit new gaskets

Worn shaft seal.
Check condition of shaft seal and renew it if
necessary.
Check flushing liquid or sealing liquid
pressure
 
Grooving, score marks or roughness or shaft
sleeve surface.
Fit new shaft sleeve.

Lack of cooling liquid or fouled and clogged
cooling liquid compartment.
Increase the flow of cooling liquid.
Clean out the cooling compartment.
Clean the cooling liquid.

Vibrations during pump operation.
Improve suction conditions. /Re-align the
pump. /Re-balance the impeller. /Increase
the pressure at the pump suction nozzle.
  
Pump set is misaligned.
Check alignment at coupling and realign the
set if necessary.

Too much, too little, or unsuitable lubricant
quality.
Reduce quantity of or top up lubricant or
change lubricant quality.

The specified coupling gap has not been
maintained.
Restore correct coupling gap in accordance
with the data on the installation plan.

Operating voltage is too low. Increase the voltage.

Rotor is out of balance .
Clean the rotor.
Rebalance the rotor dynamically.
1)
Pump pressure must be released before attempting to remedy faults on parts which are subjected to pressure.
2)
Request particulars.