How to select an electromagnetic flow meter?

Electromagnetic flow meter is a widely used instrument for liquid and gas flow measurement, with high measurement accuracy, good stability, fast response speed, long service life and other characteristics. In industrial production, environmental monitoring, medical and other fields are widely used. However, different application scenarios on the electromagnetic flowmeterperformance and parameter requirements are different, so the selection of the right type directly affects the use of the flowmeter effect!

• Caliber and flow: electromagnetic flowmeter caliber and flow range is one of the key factors in the selection. Need to choose the appropriate caliber and flow range according to the actual flow size and pipe size. At the same time, you need to pay attention to the electromagnetic flowmeter flow range and the actual flow rate is matched to ensure the accuracy of measurement.

• Fluid medium: consider the nature of the measured medium, including the type of fluid (liquid or gas), temperature, pressure, density, viscosity, etc., for corrosive media, the selection of corrosion-resistant materials manufactured sensors and electrodes; for high-viscosity media, you need to choose a larger aperture and special structure of the sensor. Select the appropriate electromagnetic flowmeter materials and models.

•  Accuracy requirements: measurement accuracy is one of the important performance indicators of electromagnetic flowmeter. According to the measurement of the accuracy requirements to choose the appropriate flowmeter model, usually expressed as a percentage or specific flow rate value.

• Installation conditions and environmental factors: electromagnetic flowmeter installation conditions and environmental factors will also affect its measurement effect and service life. Consider the temperature, humidity, air pressure and other conditions of the installation environment, choose high temperature, corrosion, explosion-proof and other characteristics of the flowmeter model. Consider the installation space, pipe diameter, pipe materials and other factors, choose the appropriate flowmeter structure and installation.

• Output requirements: according to the actual demand to choose the appropriate output signal type, such as analog signal (4-20mA, 0-10V), digital signal (RS485, HART, etc.) or pulse signal.

Electromagnetic flow meterselection for its use and service life has an important impact. In the selection process need to consider the measurement medium, measurement accuracy, caliber and flow rate, working pressure and temperature, electrode material and wear resistance, as well as installation conditions and environmental factors and other factors.

Selection of Flowmeter Electromagnetic

Instrument selection is very important, flowmeter electromagnetic in the actual application of 2 / 3 of the failure of the instrument selection error or improper use of the cause, therefore, in determining the selection of electromagnetic flowmeter, should also be based on different processes, environment, measurement, media and other comprehensive consideration.

1. Selection of the caliber

According to the sewage treatment plant to provide the process pipe diameter, pipe pressure and sewage flow rate, select the caliber D = 600mm electromagnetic flowmeter, the site does not need to shrink and expand the pipe.

2. Selection of liner and electrode materials

Electromagnetic flowmeter is mainly used to measure the conductivity ≥ 5 μS / cm of the fluid flow, should be measured according to the corrosive nature of the material, abrasive, temperature and condensation and other characteristics and price affordability, should be selected from different lining, electrode materials. Electromagnetic flowmeter lining materials are: medium corrosion resistance, general low concentration of acid, alkali, salt neoprene materials, strong wear resistance and corrosion resistance of general polyurethane rubber, strong corrosion resistance and suitable for high temperature polytetrafluoroethylene, chemically equivalent to polytetrafluoroethylene, tensile, compression polyperfluoroethylene propylene, resistance to dilute acids, alkalis, salts, the temperature of <60 ℃ polyethylene and the temperature of <100 ℃ of the Polyphenylene sulfide, etc.

Electrode material mounted on the inner wall of its pipeline, and the measured substance is in direct contact, so it should be selected according to the corrosiveness of the measured substance. Electromagnetic flowmeter electrode materials are: salt and less than 50% concentration of alkali solution titanium (Ti) electrode, acid and salt-resistant tantalum (Ta) electrode, corrosion-resistant precious metal platinum electrode, not suitable for hydrochloric acid Hastelloy C electrode and nitric acid Hastelloy B electrode, corrosion-resistant ability of the general, but the price of low-priced stainless steel 316L and so on. According to the wastewater treatment plant mainly treats domestic wastewater and industrial wastewater, and considering the price acceptable to the user, the neoprene liner and stainless steel 316L material electrode are selected.

3. Selection of protection level

The sensor is available in IP65 water spray type and IP68 submersible type, according to the user's actual installation location in the low borehole, so the sensor selected IP68 dust submersible type.

4. Selection of additional functions

(1) For the selected basic type, flowmeter electromagnetic with LCD display, 4 ~ 20mA current output and 0 ~ 1KHz frequency output, according to the requirements of the flowmeter and computer communication, the need to increase the RS-485 communication port function.

( 2 ) For the sensor installed below the ground, should choose the split type.