MIL-HDBK-1164
Procedures may vary for different pump types and pump applications. Know what to
expect when the equipment starts.
6.4.2
Troubleshooting Centrifugal Pumps. Symptoms and possible causes of
operating difficulties are listed in Table 12. For more troubleshooting help, see
par. 2.1.4.
See also Table 19, a troubleshooting checklist for vertical turbine well
pumps, which are a class of centrifugal pump.
6.4.2.1
Cavitation Problems. Cavitation is one of the most serious operational
problems with centrifugal pumps. Cavitation occurs when cavities or bubbles of vapor
form in the liquid. The bubbles collapse against the impeller, making a sound as
though there were rocks in the pump. If left uncorrected, cavitation will seriously
damage the pump.
6.4.2.2
Causes of Cavitation. Conditions that typically cause cavitation include
operating the pump with too great a suction lift or an insufficiently submerged suction
inlet. Cavitation develops when normal pump operating conditions have been
exceeded. Noise, vibration, impeller erosion, and reduction in total head and efficiency
result from cavitation. Cavitation in a centrifugal pump may be caused by any of the
following:
a)
The impeller vane is traveling at higher revolutions per minutes
(rpm) than the liquid.
b)
Suction is restricted.
Note: Do not throttle the suction of a centrifugal pump.
c)
The required net positive suction head (NPSH) is equal to or
greater than the available NPSH.
d)
The specific pump speed is too high for the operating conditions.
e)
The liquid temperature is too high for the suction conditions.
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