Which device is primarily used to measure flow?

The Venturi Tube is specifically designed to measure flow rates of fluids. It operates on the principle of fluid dynamics, utilizing the Venturi effect, which states that when a fluid flows through a constricted section of pipe, its velocity increases while the pressure decreases. This change in pressure can be accurately measured, allowing for the calculation of the flow rate.

In practical applications, the Venturi Tube has a distinct shape that constricts at the center, facilitating this measurement. It’s typically employed in various industrial processes to monitor and control the flow of liquids and gases, making it an essential instrument in fluid dynamics.

The other devices listed serve different purposes. The Bourdon Tube is primarily used for measuring pressure, the Sight Glass provides a visual indication of liquid levels rather than flow rates, and the Pressure Gauge measures the pressure within a system, not the flow. Thus, when it comes to directly measuring flow, the Venturi Tube is the optimal choice.