Assignment:
Question 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.
Question 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.
Question 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.
Question 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
Question 5. The coherence function between two detector signals is given by
A. 1/10.
B. ½.
C. 0.0
D. infinity.