Faults, Causes And Remedies - Samson NESE Manuel D'installation Et Mise En Service

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10 FAULTS, CAUSES AND REMEDIES
Fault
The pump is
not producing
the rated flow
or head
Pump does not
prime
continuously
Pump leaks
Temperature of
bearing bracket
increases
Pump runs
noisily
Motor
protection
switches off
Cause
‐ Discharge pressure is too high
‐ Pump or piping is not completely vented or
filled
‐ No water inlet or water inlet flow is to low
‐ Impeller laminating surfaces are worn
‐ Wrong direction of rotation
‐ Leakage on pump casing gaskets, on shaft
sealing
‐ Inlet pressure too low
‐ Loose or jammed part in the pump
‐ Casing seal leaks
‐ Mechanical seal leaks
‐ Not enough grease in the ball bearing
‐ Coupling not properly aligned
‐ Carbide shaft sleeve or carbide bushing is
damaged
‐ Pump or motor ball bearing is worn
‐ Suction pressure is too low
‐ NPSH available is too low
‐ Pump is not properly leveled or base plate is
distorted. Excessive forces applied on flanges
‐ Foreign material in the pump
‐ Current leakage
‐ Protection fuses not calibrated properly
‐ Pump runs right of curve or out of
application limits
‐ Foreign matter remains inside the pump
casing
Remedy
Open and clean discharge pipe work
Check pump duty point
Vent pump casing
Fill completely suction pipe with liquid
Check that both suction and discharge isolating
valves are open
Clean filters
Replace impeller – Check wear in the casing
Change two phases in motor junction box
Check the tightening of the casing cover fastening
nuts
Replace casing seal
Replace mechanical seal
Check that static pressure is sufficient regarding
pumping temperature
Remove the back pull out assembly and clean the
inside of pump
Check the tightening of the casing cover fastening
nuts
Check the state of the casing seal
Check the state of the mechanical seal faces and
O'Ring
Check proper venting of mechanical seal housing
Proceed with replacement of the mechanical seal
if required
Add grease in the ball bearing
Check for a proper coupling alignment
Check static pressure and correct venting of the
loop
Replace the sleeve and the bushing
Identify and replace worn ball bearing
Vent pump casing and suction line
Check static pressure in the loop
Check that isolating valve on suction line is opened
Clean the filter
Check that available NPSH of the process is higher
than the pump required NPSH
Check pump installation and coupling alignment
Remove back pull out assembly and clean the
inside of pump casing
Check earthing of motor
Find out the origin of current leakage : damaged
cables, fluid leakage on electrical components, ...
Check motor current and select motor protection
accordingly
Measure pump duty point and check pump runs in
authorized application limits
Remove back pull out assembly and clean the
inside of pump casing
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