Flowserve Pump Division - 26
SECTION VI: Locating Trouble
Common troubles that may occur with your pump and potential causes are listed below. The operator
can often avoid unnecessary expenses by careful consideration of the points below.
FAILURE TO DELIVER FLUID OR INSUFFICIENT CAPACITY
1. Pump not primed
2. Liquid level is too low in the wet pit
3. Speed is too low; check voltage and current of each phase of the motor
4. Discharge pressure required by the system is greater than design pressure
5. Waterways of impeller, casing and /or piping are partially clogged
6. Wrong direction of rotation
7. Valves not open
8. Insufficient net positive suction head
9. Excess amount of gas or air in the liquid
10. Mechanical defects: impeller damage, wearing ring gap worn excessively
INSUFFICIENT DISCHARGE PRESSURE
1. Speed is too low
2. Excessive amount of air or gases in liquid
3. Discharge pressure required by the system is greater than the design pressure
4. Liquid viscosity is higher than that for which the pump was designed
5. Waterway of impeller, casing and/or piping are partially clogged
6. Wrong direction of rotation
7. Mechanical defects: impeller damaged, wearing ring gap worn excessively
PUMP POWER CONSUMPTION TOO HIGH
1. Speed is too high
2. The liquid being pumped is of a higher specific gravity or viscosity than that for which the
pump was designed.
3. Mechanical damage
4. Excessive solid concentration is causing binding at the wearing ring gap area
5. Bearings are over-greased
6. Pump capacity exceeds design capacity (system head is lower than design head)
7. Motor temperature exceeds design temperature
PUMP VIBRATES
1. Foundation not sufficiently rigid or foundation bolts loose
2. Impeller partially clogged, causing imbalance
3. Mechanical defects
- Bent shaft
- Rotating element rubbing on stationary part
- Worn bearings
- Impeller or driver rotor out of balance
- Loose impeller nut
4. The critical frequency of the system including pump, piping and foundation is being
excited
5. The pump is being operated too far away from capacities for which it was designed
6. Insufficient net positive suction head
7. Inadequate piping support
8. Pump is not properly seated on the discharge elbow (wet pit applications)
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