Customers often call to consult us and ask why is the electromagnetic flow meter inaccurate or drifting? When this situation happens, we will analyze and explain for customers from the following points:
In general, the zero point instability of the electromagnetic flow meter can be summarized as five reasons:
(1) The measuring pipe is not filled with liquid, or the liquid contains air bubbles.
(2) The liquid has a small flow. In fact, this is a misunderstanding of the liquid flow since it is not an electromagnetic flow meter fault.
(3) The sensor grounding is not perfect due to external interference such as stray current.
(4) Liquid causes (such as the uniformity of the liquid conductivity).
(5) The insulation of the signal circuit decreases.
(1) The pipe is not filled with liquid or the liquid contains bubbles are mainly caused by poor design of pipe network engineering or imperfect related equipment.
(2) There is a trace flow in the pipe. In fact, the trace flow is in the electromagnetic flow meter sensor. The main reason for this type of failure is the poor airtightness of the stop valve of the pipe. The small leakage detected by the electromagnetic flow meter is mistaken for zero variation or zero instability.
Cases such as the valve is used for a long time or the incomplete valve caused by dirty liquid are often encountered, especially for large valves. Another common reason is forgetting to close branch valves outside the main pipe. Sometimes, it is difficult to confirm the absence of flow on site.
(3) Observe for leakage.
(4) The influence of external interference such as imperfect grounding and stray pipeline current mainly depends on the good grounding protection of the electromagnetic flow meter. In general, the grounding resistance is required to be less than 10Ω, and it is necessary to ensure that it does not share the grounding with other motors and appliances. If a good environment cannot be ensured, the meter will have faults. And it is a trouble stuff to check it again at this time.