1. Electromagnetic flowmeter measuring tube liquid is not filled:
In fact, non-full tube measurement is almost inaccurate for most types of measuring instruments. For example, due to the insufficient back pressure of the ultrasonic flowmeter or the poor installation position of the flow sensor, the measuring tube of the electromagnetic flowmeter cannot be filled with liquid, and the fault phenomenon varies according to the degree of non-filling and flow conditions. If a small amount of gas is stratified flow or waveform flow in the water pipe, the fault phenomenon is shown as an increase in error, that is, the measured flow value is inconsistent with the actual value. If the gas phase part of the cross section of the flow area in the stratified flow of the horizontal pipe increases, that is, the degree of liquid filling the pipe increases, the output will also wobble. If the situation of liquid filling the pipe is serious, so that the liquid level is below the electrode, the output overfull phenomenon will occur, resulting in the measurement work cannot be carried out.
2. Electromagnetic flowmeter to measure liquid containing solid phase:
The liquid contains solids such as powders, particles or fibers, and faults may occur: slurry noise, electrode surface contamination. Conductive or insulating deposits cover the electrode or lining, and the electrode does not work. The lining is covered by wear or sediment, and the circulation cross-sectional area is reduced.
3. The measuring medium contains components that are easy to crystallize:
Electromagnetic flowmeters must be used with caution to measure liquids that may crystallize. Some chemical materials that are easy to crystallize can also be measured with an electromagnetic flowmeter at normal temperatures, but because the pipe transporting the fluid has good heat tracing and insulation, it will not crystallize in the heat preservation work. However, the measuring tube of electromagnetic flow sensor is difficult to implement heat tracing and insulation. Therefore, when the fluid flows through the measuring tube, it is easy to cause a solid layer on the inner wall due to cooling. The main function of the electromagnetic flowmeter lining is to protect the electrode, the electrode insulation is low, the flowmeter will appear various phenomena, the flowmeter shows the flow value fluctuates, is unstable, the error is large, and the measurement data has no reference value.
