Which factors can only be determined by a human operator in plant operations?

• A. Sight, sound, or smell
• B. Temperature and humidity
• C. Flow rate and pressure
• D. Electrical consumption

Answer: (A)

The correct answer is based on the inherent qualities of the factors involved in plant operations. Sight, sound, and smell are sensory observations that rely on human perception. These senses enable operators to detect unusual conditions or changes in the environment that may not be measurable quantitatively by instruments.

For instance, an operator might notice an unusual odor indicating a chemical leak or hear abnormal noises that suggest equipment malfunctions. These human observations can provide immediate alerts to potential issues that automated systems may not identify, highlighting the importance of human judgment and experience in plant operations.

In contrast, the other options—temperature, humidity, flow rate, pressure, and electrical consumption—are typically measured by instruments that provide quantifiable and objective data. Instruments can accurately gauge these parameters without the need for human interpretation, which is why they differ from the subjective nature of sensory observations.