Do magnetostrictive level gauges always undergo sudden restart self-checks?
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The material present on site is ethylene oxide. The magnetostrictive level gauge used on site was originally from WIKA. Over the past couple of years, there has been a problem: it would suddenly fluctuate and give an overestimated reading, reaching 21 mA. The gauge would then restart its self-check; sometimes it would return to normal after just such a fluctuation, while other times it took several minutes to do so. On the DCS, the trend display showed an initial overestimated reading, followed by a drop in the reading, before it returned to normal. Later, we switched to a domestic brand, but it didn’t work either after being used for some time; similar issues occurred again – the level gauge displayed NOFLOAT and kept giving incorrect readings (it seems this is what happens when the connection is broken). Has anyone encountered similar problems? How is it usually handled?
Based on what you’ve described, it seems it might be related to the condition of the medium. Ethylene oxide is a low-boiling-point medium that is highly sensitive to environmental temperature and pressure within the container. If the container does not have adequate temperature control measures, the float of the level gauge may be affected by false indications resulting from changes in the state of the medium caused by fluctuations in temperature and pressure. The poster should check the temperature and pressure of the medium at the time when the abnormal signal occurred. If it is a persistent fault with the level gauge, it will not recover or reset on its own in a short time.
It is recommended to check the stability of the power supply: if the supply voltage is below 21.6VDC, the instrument will restart due to under-voltage； If there is a momentary power loss due to poor contact in the loop supply, it will trigger \"Wire Break → NOFLOAT → High/Low Alarm\".
No, we measured that the normal operating voltage is 20.7V, while the faulty one reads 20.8V; it’s not likely to be a voltage deficiency issue. There’s no need to restart by turning off the power – it keeps undergoing self-checks