How to choose a correct electromagnetic flowmeter?

　　Electromagnetic flowmeter selection needs to consider the measurement requirements, media characteristics, flowmeter type, installation conditions, output signal, economy and maintenance, a comprehensive assessment of the most suitable for the application of the product selected.

　　There are several factors to consider when choosing a correct electromagnetic flow meter, here are some key steps and points to consider:

　　First, clear measurement requirements

　　Measurement medium: electromagnetic flowmeter can only measure conductive liquids, the measured medium conductivity usually needs to be greater than 5μS/cm, such as ordinary tap water conductivity between 200 ~ 500μS/cm. At the same time, you need to consider the corrosiveness of the medium, temperature, pressure and other characteristics (such as whether it contains solid particles, fibrous material or easy to precipitate, scaling, etc.), which will be related to the choice of electrodes and lining.

　　Measurement range and accuracy: According to the actual process requirements to determine the maximum flow rate and minimum flow rate measurement, to ensure that the measurement range of the selected flowmeter can cover the actual flow rate changes. At the same time, according to the production process on the flow measurement accuracy requirements, select the appropriate accuracy level of electromagnetic flowmeter.

　　Second, understand the type of flowmeter

　　Electromagnetic flowmeter has a variety of types, including general-purpose, explosion-proof, hygienic, anti-submerged, submersible, pipeline, insertion, flange, clamping type, sanitary clamp type, threaded connection type. In addition, there are one-piece and split-type, four-wire and two-wire, DC excitation and AC excitation and other classifications. The choice needs to be determined according to the actual installation environment and measurement needs.

　　Third, consider the installation conditions

　　Pipeline conditions: specify the nominal diameter of the pipe, material, wall thickness and other parameters, select the calibre of the flowmeter to match the pipeline and installation.

　　Installation location: Determine the length of the instrument before and after the installation of the straight section, generally require the flow meter before the straight section of 5 times the diameter, after the straight section of 2 times the diameter. At the same time, to avoid installation near the regulating valve and half-open valve after the installation, to prevent unstable fluid flow affects the measurement accuracy.

　　Working environment: consider the ambient temperature and electromagnetic interference. If there is a strong source of electromagnetic interference at the scene, you should choose the electromagnetic flowmeter with good anti-interference capability.

　　Fourth, determine the output signal and communication mode

　　According to the requirements of the connection with the control system, select the appropriate type of output signal, such as common 4 ~ 20mA current signal, pulse signal, etc.. May also be required to choose with RS-485, Modbus and other communication protocols flowmeter, remote monitoring and data transmission.

　　Fifth, consider the economy and maintenance

　　Under the premise of meeting the measurement requirements, the comprehensive consideration of the purchase cost of the flowmeter, installation costs, operating costs and maintenance costs, choose cost-effective products. At the same time, to choose a simple structure, easy to maintain and repair electromagnetic flowmeter, and consider the manufacturer's after-sales service and technical support capabilities.

　　In summary, choosing a correct electromagnetic flowmeter requires comprehensive consideration of a number of factors, including measurement requirements, flowmeter type, installation conditions, output signals and communication methods, as well as economy and maintenance. By carefully evaluating and comparing different options, you can find the electromagnetic flowmeter that best suits your application.