Which device is used to measure velocity pressure inside a duct?

Which device is used to measure velocity pressure inside a duct?

• A. Pitot tube
• B. Manometer
• C. Thermistor
• D. Thermometer

Answer: (A)

Velocity pressure is the dynamic part of air pressure caused by motion. In a duct, the Pitot tube faces into the airflow to measure stagnation (total) pressure. By also measuring static pressure from a separate port, you can take the difference between total and static pressure to obtain velocity pressure. This dynamic pressure is what relates directly to the airflow speed in the duct. A thermometer or thermistor measures temperature, not pressure. A manometer measures pressure generally, but it isn’t by itself the device that determines velocity pressure unless used in a Pitot-static setup. So the Pitot tube is the device used to measure velocity pressure inside a duct.

Velocity pressure is the dynamic part of air pressure caused by motion. In a duct, the Pitot tube faces into the airflow to measure stagnation (total) pressure. By also measuring static pressure from a separate port, you can take the difference between total and static pressure to obtain velocity pressure. This dynamic pressure is what relates directly to the airflow speed in the duct. A thermometer or thermistor measures temperature, not pressure. A manometer measures pressure generally, but it isn’t by itself the device that determines velocity pressure unless used in a Pitot-static setup. So the Pitot tube is the device used to measure velocity pressure inside a duct.