During commissioning period of electromagnetic flowmeter failure analysis
In this article, we mainly is about the electromagnetic flowmeter debugging period of fault, fault is mainly divided into three aspects: installation, environment, fluid.
1) installation of
In the process of electromagnetic flowmeter installation, is usually caused by electromagnetic flow sensor installation position is not correct fault, common such as sensor installed on the easy accumulation of gas piping peak; Or installed on the top-down vertical tube, may appear empty; Or sensors after no back pressure, fluid directly discharged into the atmosphere to form the measuring tube not full package.
2) fluid
Electromagnetic flowmeter in fluid is mainly refers to the uniform distribution of tiny air bubbles in the liquid to be measured is usually does not affect the normal work of the electromagnetic flowmeter, but with the increase of air bubbles, the volatility meter output signal, if the bubble is big enough to cover the entire electrode surface, as the bubble through the electrodes can make electrode circuit instantaneous trip and make the output signals appear larger fluctuation.
3) environmental aspects
Environment usually in pipeline stray current interference, space is strong electromagnetic interference, large motor magnetic field interference, etc. Pipeline stray current interference usually take good separate grounding protection can obtain satisfactory results, but if strong stray current (such as electrolytic workshop pipeline, sometimes in two electrode induction ac peak potential Vpp can be as high as 1 v), still need to take other measures and flow sensor and pipe insulation, etc. Generally by the signal cable into space electromagnetic interference, usually adopts single layer or multi-layer shielding protected.
Low frequency square wave excitation of electromagnetic flowmeter measurement too solid content in slurry, slurry noise will be generated, the output signal wave.
Measurement of mixed media, if before not mixing into the flow sensor measurements, will also make the output signal wave.
If the electrode materials and matching properly measured medium, will also be due to the chemistry or the polarization phenomenon affects normal measurement. Should be according to the electromagnetic flow meter and related manual correct matching electrode materials.