Shaft misalignment, vibrational analysis type multiple choice

1. The rotational speed of a pump shaft is 19.5 Hz. The frequency spectrum of
accelerometers placed on inboard and outboard bearings in the vertical
direction generally indicate shaft imbalance at a frequency of
A. 19.5 Hz. B. 39 Hz. C. 9.75 Hz. D. Always a sub-synchronous value of shaft
speed.

2. A ceiling fan has a rotational speed of 600 RPM and has five blades. The
blade pass frequency at this speed is
A. 60 Hz. B. 50 Hz. C. 30 Hz. D. 10 Hz.

3. The oil whirl phenomenon in a sleeve bearing (journal bearing), with a shaft
frequency of fr , occurs approximately at the following frequency.
A. 0.45 x fr. B. 1 x fr. C. 2 x fr. D. 2.45 x fr.

4. Which one of the following is not a condition-based (predictive maintenance)
technology?
A. Lubrication oil analysis
B. Vibration monitoring
C. Periodic replacement of pump seals
D. Ultrasonic testing for flaw detection
E. Thermography for inspecting hot spots on equipment

5. The coherence function between two detector signals is given by

A. 1/10. B. ½. C. 0.0 D. infinity.

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