Page 44 - Rotating Machinery Pratical Solutions to Unbalance and Misalignment

Rotating Machinery: Practical Solutions

Thus the force generated by this vibration is almost three
times the weight of the shaft. Using the vibration severity table at
the end of Chapter 3, a velocity reading of .401 inches per second
rates as rough, and some action should be taken.

Example 2.3:
A centrifugal pump operating at 3,450 rpm shows a filter
in vibration of .114 inches per second at operating speed. What is
the peak-to-peak displacement? If the impeller and shaft weigh 40
pounds, what is the force produced?

Using Equation 2.15
D = 60000 × . 114/(3.14159 × 3450) = .63 mils peak-to-peak
The mass of the rotating element is 40/32.2 = 1.24 pounds
mass.

Using Equation 2.33
G = 3450 x . 114/3689.8484201 = .1066

F = 386.4 × G = 368.4 × . 1066 = 41.19 pounds force.