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STEP 3 - Vibration Quiz #1

Vibration Quiz #1

1) Which parameter is best for evaluating a problem causing vibration at afrequency of 600,000 CPM (10,000 Hz)?

a) Velocity

b) Acceleration

c) Displacement

2) What would be the Period (sec/cycle) for a frequency of 1,200 CPM (20

Hz)?

a) 0.05 sec/cycleb) 0.50 sec/cycle

c) 5.0 sec/cycle

3) Vibration Phase can best be described as:

a) An amplitude measurement.

b) The motion of the shaft at a particular location.

c) Measure of the vibration motion at one location relative to the vibration motionat another location at a particular frequency.

4) What is the phase difference between signals A & B?

a) 180

b) 90

c) 0

5) Which is not an example of a forcing frequency?

a) A structural natural frequency

b) Blade pass frequency

c) Gear mesh frequency

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6) On a belt-driven fan, a phase difference of 180 or 0 between the

horizontal and the vertical directions on the fan bearing cap would likelyindicate:

a) Couple unbalance

b) Misalignment

c) An eccentric pulley

7) What is the blade pass frequency (BPF) of a direct coupled horizontal

centrifugal pump with rolling element bearings and a 5 blade impeller? Theoperating speed is 1749 RPM and the nameplate speed is 1780 RPM.

a) 8900 CPM (148.3 Hz)

b) 8745 CPM (145.8 Hz)

c) 7425 CPM (123.8 Hz)

8) Which accelerometer mounting method gives the widest frequency

response?

a) Magnet mount

b) Stud mount

c) Quick connect

9) Resonance is shown by:

a) A 180 phase change at the point where the forcing frequency coincides with anatural frequency, and approaches a full 360 phase change when the machine

passes through the natural frequency (depending on the amount of damping present)

b) A 90 phase change at the point where the forcing frequency coincides with anatural frequency, and approaches a full 180 phase change when the machine

passes through the natural frequency (depending on the amount of damping present)

c) A 180 phase change at the point where the forcing frequency coincides with anatural frequency, and an additional 90 phase change when the machine passes

through the natural frequency (depending on the amount of damping present)

10) Parallel (offset) misalignment will usually show:

a) 180 radial phase difference across the coupling of a direct coupled machine

b) A higher than normal 2X operating speed peak in the FFT spectrum

c) All of the above