Where should vibration readings be taken?

• A. On the shaft, in or near the bearings
• B. At the discharge elbow
• C. On the exterior surface of the casing
• D. In the control room

Answer: (A)

Vibration readings are most informative when taken as close to the source of the rotating motion as possible—on the shaft, in or near the bearings. This location directly captures the rotor dynamics that reveal issues like imbalance, misalignment, bearing wear, or looseness, providing a clear picture of the machine’s mechanical health. Placing a sensor on the discharge elbow or on the exterior casing can pick up general vibrations from piping or the structure, but those signals are not as diagnostic for bearing or rotor faults and can mask the specific problems. Reading in the control room wouldn’t reflect the machine’s actual vibration behavior in real time.