The Venturi nozzle is mainly suitable for gas flow measurement, transfer of flow standards, and limitation of maximum flow rate in flow systems. Originally applied in the aerospace industry, it is widely used in various industries such as automobiles, energy, and metrology. The Venturi nozzle is designed with reasonable geometric surface parameters based on the principle of Bobolic gravity, which can form a large flow cycle and have jet holes to prevent blockage. When high-speed liquid passes through the nozzle, it drives the surrounding liquid into the jet to form a circulation The mixture of liquid and the solution produced by the pump increases the total amount of solution, and the nozzle can produce a 4:1 flow ratio. Therefore, a small pump with a mixing nozzle can be used for large volume fluid circulation, thereby saving various energy consumption. The principle of the throttling device is that in the throttling device where the fluid filled with the pipeline flows through the pipeline, the flow beam will form local contraction at the throttling point, thereby increasing the flow rate, reducing the static pressure, and generating a static pressure difference before and after throttling, The throttling flowmeter is a typical differential pressure flowmeter Due to its simple structure, convenient installation, reliable use, and wide application range, it is one of the main instruments for measuring flow in industrial automation control processes. The throttling device mainly includes orifice plates, ASME nozzles, and Venturi tubes.
The selection of throttling devices, such as orifice plates, ASME nozzles, and Venturi tubes, should follow the following principles:
1. Orifice plates, ASME nozzles, and Venturi nozzles are generally used in pipelines with a diameter of 50 millimeters or greater.
2. The Venturi tube is only suitable for measuring the flow rate of low pressure fluid media, measuring the flow rate of high-temperature and high-pressure media, using orifice plates and ASME nozzles, such as orifice plates or nozzles, to measure steam flow rate;
3. The use of ASME nozzles or Venturi tubes requires that the pressure loss generated by the throttling device is relatively small.
When measuring the flow rate of some dirty or corrosive media, the nozzle is better.
5. The nozzle has high measurement accuracy and short requirements for straight pipe sections.
During processing, manufacturing, and installation, Venturi tubes are relatively complex, with relatively simple orifice requirements, followed by ASME nozzles.
