Which tool is used to measure air pressure in ducts?

The manometer is specifically designed to measure air pressure within ducts and is an essential tool in HVAC applications. It operates by comparing the pressure of the air in the duct to a reference pressure, generally atmospheric pressure, allowing for accurate measurements in various duct conditions. This is crucial for maintaining proper airflow and system efficiency, as precise pressure readings can help diagnose issues within the HVAC system.

Other tools mentioned serve different purposes: an altimeter measures altitude based on atmospheric pressure changes, a pressure gauge is a broader term that may not provide the precision needed for duct measurements specifically, and a voltmeter is used to measure electrical potential difference. Each has its function in their respective fields, but for measuring air pressure in ducts, the manometer is the most appropriate and effective choice.