Velocity may be sensed in which ways?

• A. Electrically
• B. Hydraulically
• C. All of the above
• D. Mechanically

Answer: (C)

Velocity can be sensed through electrical, hydraulic, or mechanical means. Electrical sensing turns motion into an electrical signal; meters with rotating elements or ultrasonic transducers produce pulses or signals that grow with flow velocity, giving you a velocity reading electronically. Hydraulic sensing uses the relationship between velocity and pressure in a flowing fluid; by measuring pressure differences across a restriction or using differential-pressure meters, you can deduce velocity from the hydraulic conditions. Mechanical sensing relies on a moving part driven by the flow, such as a paddlewheel or turbine; the rotation rate is directly proportional to the fluid’s velocity. Since velocity information can be captured by all these approaches, “all of the above” is the most complete answer.