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1、 Principle of Insertion Venturi Tube Measurement
The measurement principle of this product is similar to that of a pitot tube, which involves combining two different sized Venturi tubes in a reasonable manner to amplify the differential pressure signal twice, thereby improving measurement accuracy. Please refer to the structural diagram for details.
After fixing the dual Venturi structure, the differential pressure values at various flow velocities were measured in wind tunnel tests to obtain the relationship between flow velocity and differential pressure, thereby obtaining the "flow coefficient" of the dual Venturi.
The positive pressure pipe of the outlet pipe is installed outside the foreign dome, and the full pressure is introduced. The negative pressure tube of the outlet pipe is taken from the throat of the inner cavity, and through the contraction effect of the flow velocity of the inner and outer Venturi, the static pressure at the throat rapidly decreases with the increase of flow velocity, thereby obtaining a differential pressure signal that is more than four times larger than that of throttling elements such as pitot tubes, Annubar, and wings. In addition, due to the suction effect of the foreign Qiuli on the inner Venturi, the turbulent airflow at the inner Qiuli outlet can be rectified, making the characteristics of the dual Venturi relatively stable.
2、 Installation and use of plug-in Venturi tube
1. Dual Venturi is used to measure media such as flue gas, air, and air volume. It has almost no resistance loss and has the advantages of large differential pressure signal, high sensitivity, stable performance, reliable operation, simple structure, and easy maintenance. It is suitable for flow measurement of large flow rates, large pipe diameters, especially rectangular pipes. It is currently an ideal device for low flow rate and high flow rate air volume measurement in China.
2. When installing the double Venturi tube, check the tag number on the product to ensure it matches the installation tag number on the process pipeline; The flow direction on the product is consistent with the flow direction of the medium in the process pipeline.
When installing the double Venturi on a horizontal pipeline, it can be installed vertically from top to bottom or vertically from bottom to top. For media containing dust or large solid particles, it is best to install them in vertical pipes from bottom to top. When the inner diameter of the pipeline is less than 700mm, the misalignment between the double Venturi and the pipeline shall not exceed 5mm.
4. The process pipeline for installing dual Venturi should have a straight pipe section length, and it is recommended to consider the first 5D and the second 2D.
5. To ensure accurate transmission of differential pressure signals, the signal pipeline should be regularly purged to maintain smoothness.
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