Lining material selection for liquid turbine flowmeters and straight pipe section requirements during installation

Liquid turbine flowmeter has many characteristics such as simple structure, few processed parts, light weight, easy maintenance, large flow capacity and adaptability to high parameters. It is mainly used to measure the flow of fluid materials. It can be used to measure the flow and total amount of liquids when matched with corresponding flow totalizers. Liquid turbine flowmeters have been widely used in metering control systems in petrochemical, metallurgical, scientific research and other fields. Products equipped with sanitary joints can be used in food and pharmaceutical industries. According to the characteristics of corrosiveness, abrasiveness, temperature and condensation of the measured substances, flowmeters with different lining materials should be selected. Runzhong Instrument Technology Co., Ltd. is an enterprise specializing in the production and manufacturing of gas-to-liquid turbine flowmeters. Over the years, the company's technical personnel have accumulated certain technical experience to improve the success rate of installation and commissioning of liquid turbine flowmeters in industrial pipeline control systems, and provide practical experience for a higher degree of integration and automation of industrial pipeline control systems. This article is written specifically for the selection of lining materials for liquid turbine flowmeters and the requirements for installation of straight pipe sections.
 
       

     Common lining materials include fluoroplastics, polyurethane rubber, chloroprene rubber and ceramics. Fluoroplastics include polytetrafluoroethylene, perfluoroethylene propylene, tetrafluoroethylene and ethylene copolymers, and perfluoroalkyl vinyl ether copolymers. FRP is used as a lining, and some are made into measuring tubes alone. This year, high-purity alumina ceramics are used to make Chenli, but only small and medium-caliber sensors are limited. Chloroprene rubber and FRP are used for non-corrosive or weakly corrosive liquids, such as industrial water, waste water, and acids and alkalis, and are the cheapest. Fluoroplastics have excellent resistance to chemically corrosive liquids. The earliest fluoroplastic was polytetrafluoroethylene, which was only pressed against the measuring tube without adhesion, and injection molding was achieved. It has a strong bonding force with the measuring tube and can be used for negative pressure. The    
 
       installation method of liquid turbine flowmeter is generally flange-type, and the pipeline can be connected using the matching flange. Before installation, ensure that the purge and pressure test of the pipeline have been completed. Through the application of liquid turbine flowmeter in industrial pipeline control systems, the selection of instruments, adjustment of installation processes, and testing are summarized.
 
       Intelligent turbine flowmeters are not sensitive to the upstream and downstream piping layout, and it is generally believed that there is no requirement for the length of upstream and downstream straight pipe sections. The draft international standard ISO/DIS 11451 believes that flow measurement is not affected by rotational flow and flow velocity profile distortion. However, BS 7405 believes that the length of the upstream and downstream straight pipe sections can be as short as 2d. Placing a metal (or plastic) mesh at the inlet end can effectively improve the velocity distribution distortion and obtain a uniformly distributed airflow. It is necessary to prevent the sudden expansion from a small diameter into a larger diameter instrument and to transition slowly. The front straight pipe section of the intelligent turbine flowmeter and the flow sensor with a measuring tube require a certain length of front straight pipe section. There is no specific regulation for this, but the value recommended by the manufacturer is used. It is recommended that for the hot wire flow meter inserted in the pipeline, an upstream straight pipe section of (8~10)d and a downstream straight pipe section of (3~5)d are required. The length of the upper straight pipe section specified for the intelligent turbine flowmeter with measuring tube; if one or two porous plate flow conditioners are installed at its inlet end, its length can be greatly shortened. The upstream straight pipe section length requirements of the insertion-type intelligent turbine flowmeter with only one set of temperature detection points are similar to those of the intelligent turbine flowmeter with measuring tube;    
 
     In summary, in order to ensure the measurement accuracy and service life of the intelligent turbine flowmeter, we must ensure the correct installation of the instrument and the installation requirements of the straight pipe section in industrial installation. For example, when it uses detection rods with multiple sets of detection points or multiple detection rods, the length of the straight pipe section can be shortened a lot. Usually the manufacturer will provide suggestions