What is the main advantage of using a venturi tube for flow measurement compared to an orifice plate?

The main advantage of using a venturi tube for flow measurement compared to an orifice plate is that a venturi tube produces less permanent pressure drop. This characteristic is particularly important in applications where maintaining pressure is essential for system efficiency and performance.

A venturi tube is designed with a gradual, smooth convergence and divergence in its shape, allowing for a more efficient flow of fluid. This construction minimizes turbulence and energy losses, consequently maintaining more of the inlet pressure. In contrast, an orifice plate has a more abrupt change in cross-sectional area, which leads to a higher velocity and greater turbulence as the fluid passes through. This higher turbulence tends to create a more significant pressure drop that can affect the overall efficiency of the system.

While there are other considerations such as installation costs, the number of pressure taps, and the physical space required for the devices, the reduced permanent pressure drop of a venturi tube is a critical advantage, making it more suited for applications where fluid dynamics and pressure considerations are of high importance.