What type of flow measurement instrument is a Venturi Tube?

A Venturi Tube is fundamentally a device used for measuring the flow rate of a fluid. It operates based on the principle of conservation of energy and Bernoulli's equation, which relates the velocity of a fluid to its pressure. As fluid flows through the tube, it encounters a constriction that causes the fluid velocity to increase and the pressure to decrease according to Bernoulli's principle. The relationship between the change in pressure and the fluid's velocity allows for the calculation of volumetric flow rate.

This characteristic makes the Venturi Tube primarily a velocity instrument. It is designed to measure how fast the fluid is moving, rather than measuring the total pressure or mass directly. This is why it is categorized under velocity measurement instruments.