MIL-HDBK-1164
Table 12 (Continued)
Symptom
Possible Cause
Failure to provide cooling liquid to water-cooled
stuffing boxes.
Excessive clearance at bottom of stuffing box
between shaft and casing, causing packing to be
forced into pump interior.
Dirt or grit in sealing liquid, leading to scoring of
shaft or shaft sleeve.
Pump vibrates or is noisy.
Pump or suction pipe not completely filled with
water.
Suction lift too high.
Foot valve too small.
Foot valve partially clogged.
Inlet of suction pipe insufficiently submerged.
Operation at very low capacity.
Foreign matter in impeller.
Misalignment.
Foundations not rigid.
Shaft bent.
Rotating part rubbing on stationary part.
Bearings worn.
Impeller damaged.
Shaft running off center because of worn bearings
or misalignment.
Rotor out of balance, resulting in vibration.
Dirt or grit in sealing liquid, leading to scoring of
shaft or shaft sleeve.
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