Which device is commonly used to measure air pressure differences in ducts?

The manometer is the device that is most commonly used to measure air pressure differences in ducts. It operates based on the principle of balancing the weight of a column of liquid against the pressure of the air or gas being measured. Manometers can be simple U-tube types or more complex digital versions that provide precise readings. They are essential in HVAC applications for ensuring that ducts are balanced and functioning properly, as pressure differences can indicate issues such as leaks or blockages.

While pressure gauges can also measure air pressure, they often measure absolute pressure rather than the differences between two points, which is crucial in ductwork to assess system performance. Thermometers measure temperature and barometers measure atmospheric pressure, neither of which provide the specific information about pressure differences needed in duct systems.