Flow Mesurement Knowledge

Causes and solutions of abnormal zero point of electromagnetic flow meter

Views:1     Author:Site Editor     Publish Time: 2021-08-26      Origin:Site

1.The pipeline is not filled with liquid or the liquid contains bubbles

Solution: A. If the liquid in the pipeline is not full, the magnetic flow sensor should be changed to a position where it can be fully filled when installed horizontally; when the flow sensor is installed vertically,the liquid flow should be from bottom to top.

B.If there are bubbles in the pipeline, install a getter or automatic exhaust valve upstream of the sensor.

2.The unstable zero point of magnetic meter is caused by the tiny flow in the pipeline

The shut-off valve of the pipeline has poor airtight performance,and misunderstands the small leakage measured by the electromagnetic flow meter as zero point instability of flow meter (a. The valve is used for a long time or the liquid is dirty, which makes the valve has poor airtight performance; b.In addition to the main pipeline, there are several branch pipes, forget to close the valve of the branch)

3.External interference such as stray current causes abnormal zero point.

a.Eliminating external interference such as stray current in the pipeline mainly depends on good grounding protection of the electromagnetic flow meter. Generally, the grounding resistance is required to be less than 10Ω.Importantly ,it should not be grounded together with other electrical appliances.

b.When the flow sensor is installed on plastic pipes, pipes with insulating coatings, paints or insulating linings.It is necessary to install grounding rings at both ends of the sensor to ensure that there is sufficient electrical contact  between the measured medium flowing in the main pipe and the sensor housing. And guarantee that the electromagnetic flow meter works normally.

c.The sensor should be far away from the motor, engine and other devices that may cause interference.

4.Unstable zero point of flow sensor is caused by changing or uneven liquid conductivity in the pipe.

Install the flow sensor to a place where the conductivity is constant or uniform, and avoid the adjacent dosing point and also avoid to place the flow meter in the downstream of the pipeline, where there is inadequate chemical reaction.

5.low conductivity of medium cause the zero cause the magnetic meter zero point sway

6.Contaminated electrode and inner tube deposit of the mag meter lead to jumping zero-point

the oil on the electrode surface and measuring tube of mag flow sensor destroy the balance of the initial zero setting of the electromagnetic flow meter 

Solution: Eliminate dirt, scale deposits

7.The reduced insulation of the instrument signal lines

Signal line insulation and its terminal is reduced due to damp, water,moisture acid fog, etc.

ARTANG flowmeter
Hangzhou City, Zhejiang
About ARTang
ARTang is the flow & level measurement manufacturer in China, specialied in electromagnetic flowmeter, liquid analysis, vortex flowmeter, level meter, widely used in water/sewage flow measurement, chemical process flow measurement, food process flow measurement, flow measurement of solid liquid, steam delivery flow measurement.
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