Electromagnetic flowmeter using the common faults

Electromagnetic flowmeter using the common faults, have a plenty of due to damage caused by the instrument itself components fault, have a plenty of due to improper selection, installation wrong, environmental conditions, and fluid characteristics in the fault of the factors, such as showing fluctuation, precision instrument down even damage etc. It generally can be divided into two types: the fault occurred when installation (commissioning phase fault) and normal operation failures (running period of fault).
(1) commissioning phase fault fault generally appear to debug in instrument installation commissioning phase, once ruled out, in the later will generally not under the same conditions again. Common commissioning phase fault general by installation wrong, environmental interference and fluid characteristics such as influence of causes.
1) is usually the installation of electromagnetic flow sensor installation position incorrect fault caused, common such as sensors installed in easy accumulative gas pipe to high; Or installed in top-down vertical tube, may appear empty; Or sensors without back pressure after, fluid straight into the atmosphere and the formation of the full measure tube tube.
2) the environment is often the main pipe stray current interference, space powerful electromagnetic wave interference, large motor magnetic field interference, etc. Pipe stray current interference usually taken good separate grounding protection can be obtained satisfactory results, but such as the powerful stray current (such as electrolysis workshop, sometimes two electrodes in pipeline on induction of communication Vpp peak electric potential can be as high as 1 V), still need to take additional measures and flow sensor and pipe insulation, etc. Space interference by the electromagnetic wave general introduction signal cable, usually the single or multiple shield to protect it.
3) fluid aspects measured liquid contains uniform distribution of small bubbles usually does not affect the normal work of the electromagnetic flowmeter, but along with the increase of bubbles, and the instrument signal output volatility, if the bubble is big enough to cover the whole electrode surface, the air bubbles flow through electrode can make electrode circuit breaker and make the output signal instantly appear more volatility.
The low frequency electromagnetic flowmeter measurement of square wave excitation solid content slurry too much, there will also be a slurry noise, to make the output signal wave.
Measuring mixed media, if not even before in mixed into the flow sensor measuring, also make the output signal wave.
Electrode materials and tested medium improper matching, will also because chemistry or the polarization phenomenon and affect the normal measurement. Should choose the manual or according to the instrument correctly matching electrode materials.
(2) running period of fault operation period the fault is electromagnetic flowmeter by commissioning and normal operation appears after a period of fault, common operation period by flow sensor fault general inner layer, lightning strike attachment and environment conditions caused by change and other factors.
1) sensor attached to the wall of commonly used to measure because electromagnetic flowmeter smudgy fluid, run after period of time, often in the sensor attached layer and produce wall accumulation fault. The fault is often the result of conductivity attached layer is too big or too small causes. If attached objects for insulating layer, the electrode circuit breakers will appear, and the instrument can not work normally; If attached layer conductivity significantly higher than fluid conductivity, the electrode loop will appear short circuit, instrument and can't work normally. So, should keep clear of electromagnetic flowmeter measurement tube attachment of scaling layer.
2) lightning hit by lightning in instrument circuit to a high voltage induction and surge current, makes the gauge damage. It is mainly through the power cord or excitation coil or sensors and switches the flow line between the way such as introducing, especially from the control room the power cord into account for most part.
3) environmental changes during commissioning, due to the environmental condition is good (such as there is no interference source), flowmeter normal work, now often easily negligence installation conditions (for example grounding is not how good). In this case, once the environmental changes, there is a new during a run interference sources (as in near the pipe welding flowmeter, installed near large transformer on, you can interfere with the normal work of the instrument, the output of the flowmeter output signal there will be fluctuations.