7
LOCATING OPERATING DIFFICULTIES
In the majority of cases, operating difficulties are external to the pump and the following causes should be
carefully investigated before undertaking repairs:
No W
ater Delivered
Pump not primed
indicated by no pressure on discharge.
Speed too low
indicated by low pressure on discharge.
Valve closed
indicated by high discharge head.
Impeller completely plugged up
indicated by low discharge pressure.
Abno
rmally Small Quantities Delivered
Air leaks in suction pipe or stuffing boxes.
Speed too low.
Discharge head higher than anticipated.
Impeller partially plugged up.
Obstruction in suction line.
Mechanical defects: casing rings worn, impeller damaged
, casing or seal defective.
Insufficient Pressure
Speed too low. Might be caused by low voltage or current characteristics different from
nameplate reading on the motor.
Air in water will cause the pump to make a cracking noise.
Mechanical defects: w
orn casing rings, damaged impeller, defective casing or seal.
Intermittent Operation
Leaky suction line.
Water seal plugged (hence, a leaky stuffing box).
Suction lift too high.
Air, gas or vapor in liquid.
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