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Five Factors Directly Lead to Measurement Errors of Electromagnetic Flow Meter

Five Factors Directly Lead to Measurement Errors of Electromagnetic Flow Meter

Views: Release Time:2019-08-14

Electromagnetic flow meter is developed by the Faraday’s law of electromagnetic induction, it has inherited advantages. But it also has the disadvantage as that it will be affected by external electromagnetic interferences. During installation, if we don’t effectively deal with these external factors, it will easily lead to the measurement of errors.

 

Please find bellow tips summarizing the five main factors affecting the measurement of electromagnetic flow meter:

 

1. The fluids are not fully filled the pipe

This is mainly due to the insufficient back pressure in the pipeline or the inappropriate installation of the sensor. It will result to different errors according to how much the pipes are not fully filled.

(1) A small amount of gas in the pipeline could lead to stratified flow or wavy flow, thus, the measurement results will be inconsistent with the actual flow data;

(2) When the fluid is bubbly flow or plug flow, in addition to the inconsistence of the measurement results, there also could be fluctuations of the readings due the surface of the electrodes could be covered by the bubbles momently when the fluid flows through the flow sensor.

(3) When the area of the flow section of the fluid in the pipeline increases, it means that the unfilled tube state of the liquid also increases, and it could lead to the fluctuation of the measurement data;

(4) When the pipeline is seriously unfilled, and the surface of the fluid is lower than the electrodes of the flow sensor, the reading of the measurement may appear larger than the full scale value of the meter. This normally happens due to the inappropriate estimation of the working flow range for model selection.

 

2. Fluids with solid mixed in the medium

When there are solids such as powders, particles, or other fibers in liquids, the following failures could happen:

(1) Noise appears in the flow meter;

(2) Surface of the electrodes get stained by the impurities;

(3) The surface of the electrodes and the lining inside the meter are covered by conductive or insulation deposit;

(4) The abrasion of the lining or the deposition in the measuring tube lead to the increase or decrease of the area of the cross-section of the measuring tube.

 

3. Liquids that easy to crystalize

For the liquid that easy to crystallize, when in right temperature, it can be measured by electromagnetic flow meter, but only under the premise that the pipeline has a good heat traceability. Meanwhile, in most of the cases, it’s hard to hold the temperature of the measuring tube of the flow sensor as still, and once the temperature falls down, the liquid will crystalize over the inner surface of the measuring tube and lead to failure.

 

4. The material of the earth rings selected is not right

For such fault, please consult the electromagnetic flow meter manufacturer for suitable material according to the actual measuring conditions, and make sure the grounding is reliable.

 

5. The conductivity of the liquid does not meet the requirement

Because the working principle of electromagnetic flow meter is Ferrari’s law of electromagnetic induction, the medium of the flow should retain at least a minimum conductivity larger than 5μs/cm. When the conductivity of the medium is below this minimum value, it will lead to fluctuations of the flow data.

 

For above analysis, we may find out that most of the faults can be solved effectively during model selection and installation. Thus, after purchasing the instrument, we suggest all users take some time to read through the sections in the manual on installation and operation of the instrument, so as to avoid improper installation and failure, which may seriously damage the flow meter.


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Kaifeng Instrument Co., Ltd., set up in 1958, is the leading flow measuring instrument manufacture in China. Our main products include: Electromagnetic flowmeter, Insertion electromagnetic flow meter, Electromagnetic velocity meter, Ultrasonic flow meter, Battery power electromagnetic flow meter, GPRS/GSM electromagnetic flow meter, Electromagnetic BTU meter, Turbine flow meter, Variable area flowmeter, Sliding Vane flowmeter, Birotary flowmeter, Roots flow meter, Vortex flow meter, Gas mass flow meter, Movable pipe prover, and complete water calibration rigs. Need more info contact us at: Email: info@kyflowmeter.com  Tel: 008637122950908





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