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Advantages and Disadvantages of Electromagnetic Flow Meter

Electromagnetic Flow meters are widely used in process control, as China some instruments factories have now obtained mature technology of magnetic flow meters, we now can purchase cheap mag meters with stable performance.
Here we list some magnetic flow meters advantages and disadvantages for you .

Electromagnetic Flow meters
1, Advantages
(1) Electromagnetic flow meters can be used to measure industrial conductive liquids or Slurry.
(2) No pressure loss.
(3) The measuring range is large, and the diameter of the electromagnetic flow transmitter is from 2.5mm to 2.6m.
(4) The electromagnetic flow meter measures the volume flow rate of the fluid under test, and the influence of temperature, pressure, density and viscosity of the fluid is not involved in the measurement principle.

2, Disadvantages
(1) The application of electromagnetic flow meter has certain limitations. It can only measure the liquid flow of conductive medium, and can not measure the flow of non-conductive medium, such as gas and water for better heat treatment. In addition, the lining needs to be considered under high temperature conditions.
(2) The electromagnetic flow meter determines the volume flow rate in the working state by measuring the speed of the conductive liquid. According to the measurement requirements, for liquid media, mass flow should be measured. The flow rate of the medium should be related to the density of the fluid. Different fluid media have different densities and vary with temperature. If the electromagnetic flow meter converter does not consider the fluid density, it is not appropriate to give only the volume flow at normal temperature.
(3) The installation and commissioning of the electromagnetic flow meter is more complicated than other flow meters, and the requirements are more stringent. The transmitter and converter must be used together and cannot be used with two different types of instruments. When installing the transmitter, the selection from the installation site to the specific installation and commissioning must be carried out in strict accordance with the product specifications. The installation site must be free from vibration and strong magnetic fields. The transmitter and piping must be in good contact and well grounded during installation. The potential of the transmitter is equipotential to the fluid being measured. When using, the gas remaining in the measuring tube must be drained, otherwise it will cause a large measurement error.
(4) When the electromagnetic flow meter is used to measure the viscous liquid with dirt, the sticky substance or sediment adheres to the inner wall or the electrode of the measuring tube, so that the output potential of the transmitter changes, which brings measurement error, and the dirt on the electrode reaches a certain level. Thickness may cause the meter to be unmeasured.
(5) The scaling or wear of the water supply pipe changes the inner diameter size, which will affect the original flow value and cause measurement error. If the inner diameter of the 100mm diameter meter changes by 1mm, it will bring about 2% additional error.
(6) The measurement signal of the transmitter is a small millivolt potential signal. In addition to the flow signal, it also contains some signals that are independent of the flow, such as phase voltage, quadrature voltage and common mode voltage. In order to accurately measure the flow rate, various interference signals must be eliminated to effectively amplify the flow signal. The performance of the flow converter should be improved. It is best to use a microprocessor type converter to control the excitation voltage. The excitation mode and frequency can be selected according to the nature of the fluid to be tested, and the in-phase interference and quadrature interference can be eliminated. However, the improved instrument structure is complicated and the cost is high.
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