A device used to measure fluid pressure is known as?

A manometer is a device specifically designed to measure fluid pressure. It operates by balancing the pressure of the fluid against a column of liquid, typically mercury or another fluid, thereby providing a visual measure of pressure in various applications, including medical, HVAC, and process industries.

In contrast, a capnometer measures the concentration of carbon dioxide in exhaled air, which is important for monitoring respiratory function but does not relate to fluid pressure. A spirometer is used to measure the volume of air inhaled and exhaled by the lungs, which also does not pertain to pressure measurement but rather to lung function. A thermometer measures temperature, not pressure, and is used in various settings, from clinical to environmental.

Therefore, the term manometer is the correct choice for evaluating fluid pressure, highlighting its specific application in measuring and assessing pressure levels across different systems.