What is a Manometer used for?

• A. Liquid-filled tube used to measure pressure.
• B. An electrical device that measures temperature.
• C. A sensor that detects flow rate.
• D. A device to regulate valve position.

Answer: (A)

A manometer measures pressure by using a liquid-filled tube whose fluid column shifts height in response to pressure differences. When one side is connected to a pressure source and the other side to a reference (often atmospheric pressure), the liquid rises on the side with lower pressure and falls on the side with higher pressure. The pressure difference is read from the height difference: ΔP = ρ g Δh, where ρ is the liquid density and g is gravity. This direct relationship lets you determine pressure from how far the liquid moves. Different designs exist (like U-tube or inclined or differential manometers) and liquids such as mercury or water are chosen based on the pressure range. Devices that measure temperature, flow rate, or regulate valve position serve different purposes and don’t rely on a liquid column to indicate pressure.