Double-flange level gauge
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The Yokogawa dual-flange level gauge installed on the new storage tank does not give readings that match those of the magnetic flap level indicator; both are at the same height. Initially, the transmitter indicated a value below zero. Upon on-site inspection, it was found that the range setting was incorrect. After making the adjustment, the gauge started to give readings, but they were almost half higher than those of the magnetic flap indicator. The magnetic flap indicator functioned properly without any issues, and it responded sensitively to changes in liquid level. The transmitter also had a good sensitivity curve. Any suggestions?
It’s necessary to share your specific data in order to conduct an analysis – such as the density of the light medium, the density of the heavy medium, the measurement range, operating conditions, and so on
Light phase: 1001; heavy phase: 1232. The specification sheet indicates a pressure range of 5.5 kPa and a height of 2.5 meters. I’m sorry, but I’m not very familiar with the operating conditions yet :(. I’ve adjusted the values related to the capillary section – the density has been set at 0.96, with a height of 2.5 meters
Based on the density you provided, the migration value is 1.0045 kPa; the range is 1.0045 to 6.5045. You can give it a try, and please feel free to point out any mistakes
The magnetic flip plate is installed on the side, just short of the top; the same goes for the bottom. The light phase material is 1001, while the heavy phase material is 1232. The distance between the two flanges is two and a half meters. To be honest, I’m not confident about the installation location – it seems like there will be a lot of maintenance work required in the future :(
There is no window on the tank,,,,:((
Most of these problems are related to the gauge range – whether the migration was done correctly and whether the range is accurate; nothing else really
The rank panel indeed isn’t inserted in the exact highest position; it feels a bit off； This double-flange type device wasn’t calibrated by filling it with light or heavy media; the values were simply entered after some calculations, and the silicone oil component was removed. It’s the first time I’ve used an Yokogawa device – I’ve always used FOXBORO instruments before. The flanges for positive and negative pressure are mounted directly on the horizontal tank, at an angle of about 45 degrees, and there’s no valve either. In my opinion, this setup isn’t very reliable…… I doubt I’ll use this kind of device often in the future
The range and drift have been checked; there should be no issues, as everything follows the specifications. It seems that there is a slight change in the density of the process medium, and we are checking on that.
It’s just my personal opinion; there’s nothing wrong with the range specified in the technical specifications. I suspect the issue lies in the amount of migration that occurs. The amount of migration should equal the density of the silicone oil inside the capillary (0.96) multiplied by g, multiplied by the distance between the flanges (2.5 meters). The resulting value should be -24 KPa; in other words, after migration, the range should be from -24 KPa to -18.5 KPa. Additionally, it is important to note that if the density of the medium under actual operating conditions differs from the densities specified in the manual (1001 for the light phase and 1232 for the heavy phase), it will result in inaccurate level measurement by the dual-float gauge.
Mm-hmm, that makes sense. Thanks for the advice! :)