A Venturi tube is a device which consists of a convergent inlet connected to a cylindrical throat which is in turn connected to a conical expanding section called the “divergent” exit
The principle of the method of measurement is based on the installation of a Venturi tube into a pipeline in which a fluid is running full. In a Venturi tube a static pressure difference exists between the upstream section and the throat section of the device. Whenever the device is geometrically similar to one on which direct calibration has been made, the conditions of use being the same, the flowrate can be determined from the measured value of this pressure difference and from a knowledge of the fluid conditions.

Mass flow rate calculations can be found in various industry publications. The computation includes variables including the pipe and throat internal diameters and differential pressure measurements obtained using secondary flow instruments. The measured values must be corrected for possible expansion or contraction of the primary device and the pipe due to the values of the temperature and pressure of the fluid during the measurement. It is necessary to know the density and the viscosity of the fluid at working conditions. In the case of a compressible fluid, it is also necessary to know the isentropic exponent of the fluid at working conditions.

Triad Measurement & Equipment, Inc. engineers can provide detailed information regarding the manufacture and design of venturi tube flow meters. Please contact us for further information.

48" Insert Venturi Tube	36" Venturi	Multiple Venturi's	52" Insert Venturi Tube
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Twin 81" Venturi Tubes