Inventory of common knowledge about Venturi flowmeter

 　　Venturi flowmeter is also called classic Venturi tube, classical Venturi tube, customarily called Venturi tube, standard Venturi tube. It is a kind of economical flow sensor developed based on the Venturi effect, and is a standard economical device. In the range of 50-1200mm, it does not require real flow calibration. Because of its high accuracy, small pressure loss, and not easy to wear, it is often used as a transaction settlement flow meter for accurate measurement of steam, natural gas, and petrochemical media. Its design and production are designed and manufactured according to the national standard GB/T2624-93 or ISO5167, and verified according to the national standard JJG640-94. It is used to measure the flow of single-phase stable fluid in a closed pipeline, and is often used to measure the flow of fluids such as air, natural gas, coal gas, and water. In the standard economical device, it requires the shortest upstream and downstream straight pipe sections, the smallest long-term pressure loss, stable performance, and convenient maintenance. Because of its accurate calculation and low energy consumption, it has been widely used in petroleum, chemical, electric power, and metallurgical industries.

2. Classification of Venturi flowmeters:
 　　Venturi flowmeters are divided into pipeline Venturi flowmeters and insertion Venturi flowmeters according to their different installation methods. Pipeline Venturi flowmeters can be divided into standard Venturi flowmeters (general pipelines) and rectangular Venturi flowmeters. Rectangular Venturi flowmeters are built-in Venturi tubes. They are mainly used for flow measurement of various gases with large diameters, low flow rates and large flows in industrial enterprises. They have a unique structural design and are calibrated in real flow in national large-scale key wind tunnel laboratories. They can be widely used in the control and measurement of large-diameter fluids in industries such as petroleum, chemical industry, metallurgy, and electric power. Insertion Venturi flowmeters are mainly used in fields with large diameters, short installation straight pipelines, or limited installation locations, and low requirements for flow measurement accuracy. They have the characteristics of convenient equipment debugging, no need to cut pipe sections, and low cost. They are currently often used to replace rectangular Venturi and wing wind measurement equipment for wind flow measurement.
　　According to the different processing and manufacturing methods, it can be divided into standard Venturi flowmeter with rough cast shortening section, Venturi flowmeter with machined shortening section, and Venturi flowmeter with rough welded iron plate shortening section.

3. The main features of Venturi flowmeter:
　　1. Simple structure, durable, stable performance, not easy to block.
　　2. Small pressure loss, saving the power required for flow transmission, can be used for two-phase flow, mixed phase flow, low flow rate, large diameter, special-shaped pipe and other complex flow measurement.
　　3. High accuracy, good repeatability, small pressure loss, and short straight pipe required.
　　3. Within the range of 50-1200 diameter, no real flow calibration is required. Beyond this range, it can be manufactured by reference design. When higher accuracy is required, real flow calibration can be performed.
　　4. The main equipment size is large. For large-diameter surfaces, it is not convenient to transport equipment. You can consider using standard orifice plates or insertion double Venturi flowmeters.