What does a rotameter measure?

A rotameter is specifically designed to measure the flow rate of liquids or gases. It operates based on the principle of variable area flow measurement, where a float within a tapered tube rises or falls in response to the flow rate. As the flow rate increases, the float moves to a higher position in the tube, indicating a higher flow rate, and vice versa.

This device is commonly used in various applications across industries, such as chemical processing, water treatment, and pharmaceuticals, due to its simplicity and reliability. By determining the position of the float, users can easily read and monitor the flow rate, making it an invaluable tool for managing fluid dynamics in various systems.

Other options, while they may pertain to fluid or gas characteristics, do not accurately describe the primary function of a rotameter. The device does not measure temperature, concentration, or viscosity, which are distinct properties requiring different measuring instruments. This specificity makes the rotameter a unique and essential tool for directly assessing flow rates.