Centrifugal Pumps Design and Application 2nd ed - Val S. Lobanoff, Robert R. Ross (Butterworth-Heinemann, 1992)

Vibration and Noise in Pumps 471
Figure 18-28. Pump shaft stress with variable frequency drive motor.
housing. These systems are satisfactory for pumps with rolling element
bearings, because the bearings transmit the rotor forces directly to the
case. However, additional instrumentation is often required to define difficult
problems. For pumps with oil film bearings, it is desirable to have
two proximity probes 90° apart near each bearing and an axial probe.
Accelerometers and velocity probes attached to the bearing housings or
case are often used to measure pump vibration; however, if the proximity
probes are not installed, the data will be limited and may be a detriment
to the diagnosis of some types of problems. A pressure transducer is vital
to diagnostic work for measuring dynamic pulsations in the piping, impeller
eye, diffuser, and across flow meters. Accurate flow measurements
are necessary to define the pump vibration characteristics as a
function of its location on the head-flow performance map.
Accelerometers or velocity transducers can be used to determine frequencies
and amplitudes of the pump case or support structure during
normal operation [45]. Two accelerometers and a dual channel oscilloscope
displaying their complex vibration waveforms can be used to de-