Instrument inserted into a flowing fluid to measure velocity pressure, commonly used to measure flow?

Instrument inserted into a flowing fluid to measure velocity pressure, commonly used to measure flow?

• A. Gate Valve
• B. Water Main
• C. Pitot Tube
• D. Cavitation

Answer: (C)

A Pitot tube is an instrument designed to measure velocity pressure by capturing stagnation pressure from the flowing fluid and comparing it to the static pressure. The difference between these pressures gives dynamic (velocity) pressure, which is related to flow velocity by the equation v = sqrt(2ΔP/ρ). This setup is specifically used to determine flow rate in many applications, including fire protection testing, where it helps estimate how much water is moving through a line. The other options don’t fit because a gate valve is a device used to start, stop, or regulate flow rather than measure it; a water main is simply the large pipe that carries water, not a measuring instrument; and cavitation is a fluid phenomenon that occurs when local pressures drop below the fluid’s vapor pressure, not a measurement device.

A Pitot tube is an instrument designed to measure velocity pressure by capturing stagnation pressure from the flowing fluid and comparing it to the static pressure. The difference between these pressures gives dynamic (velocity) pressure, which is related to flow velocity by the equation v = sqrt(2ΔP/ρ). This setup is specifically used to determine flow rate in many applications, including fire protection testing, where it helps estimate how much water is moving through a line.

The other options don’t fit because a gate valve is a device used to start, stop, or regulate flow rather than measure it; a water main is simply the large pipe that carries water, not a measuring instrument; and cavitation is a fluid phenomenon that occurs when local pressures drop below the fluid’s vapor pressure, not a measurement device.