Venturi tube flowmeters are frequently used in applications involving higher TurnDown Rates or lower pressure drops, particularly in areas where orifice plates fails to perform.

Use of venturi tubes involves a lot of savings in installation and operating and maintenance costs.

Venturi tubes are resistant to corrosion, erosion, and internal scale build up, owing to their contoured nature, pooled with the self- scouring action of the flow through the tube.

Unlike orifice plates, venturi tubes are almost insensitive to velocity profile effects and consequently call for less straight pipe run than an orifice.

Since, the early cost of a venturi tube is quite high, it is mainly engaged on larger flows and in more complicated or challenging flow applications.

A venturi tube can pass 25 to 50% extra flow than that of an orifice plate keeping the same drop in pressure.

Essential upstream pipe length of a venturi tube is 5 to 20 diameters.

In venturi tubes, pressure recovery is more compared to other flow measuring devices.Venturi tubes are appropriate for clean, dirty and viscous liquid and few slurry services as well.Pressure recovery for venturi tubes is a better than that of the orifice meter.This pressure difference is used to calculate the rate flow of a fluid flowing through a pipe.The pressure difference at the two section can be seen in the manometer attached at both the section.And at the section 2 (at the throat) the velocity of the fluid is maximum and the pressure is minimum. at the inlet) the pressure of the fluid is maximum and the velocity is minimum. Now there is a pressure difference of the fluid at the two sections.As the water enters in the throat its velocity gets increases and due to increase in the velocity the pressure drops to the minimum. The throat has the uniform cross section area and least cross section area in the venturimeter.in the converging part it converges and reaches to the throat.

As the water enters at the inlet section i.e.

The difference in the pressure heads of these two sections is used to calculate the rate of flow through venturimeter. Here we have considered two cross section, first at the inlet and the second one is at the throat.Lets understand how it does this measurement step by step. The venturimeter is used to measure the rate of flow of a fluid flowing through the pipes.

Venturi pipe dd15