Yokogawa model 118: the liquid level deviation when heated on one side is quite large
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Yokogawa 118 double flanges: when heated on both sides, the deviation is small; but when heated on only one side, the level deviation is 6% – is this normal?
Of course it’s not normal. The positive and negative pressure chambers of the differential pressure transmitter must be used at an equal temperature. Moreover, the type 118 is a double-flange capillary differential pressure transmitter, with the diaphragm box in direct contact with the medium, which makes it more sensitive to temperature and thus leads to the level difference you mentioned. Excessively high temperatures can easily damage the transmitter.
Abnormal. Logically, the silicone oil filled in the diaphragm box should not expand due to heat. This situation must be caused by air inside the diaphragm box.
“Logically, the silicone oil filled in the diaphragm box shouldn’t expand when heated. Bullshit! Thermal expansion and contraction are inherent properties of matter. A substance that does not expand when heated has not yet been created by God. Silicone oil filled under vacuum conditions cannot be completely free of air. Whether it is silicone oil expansion or gas compression, sensor manufacturing technology relies on temperature compensation methods to reduce and mitigate temperature drift. Can’t even understand basic common sense – ugh!
It’s clearly because the warming and tonifying techniques aren’t robust enough, resulting in a weak compensatory ability. Stop talking nonsense. If we keep talking, it will be the New Year already~~~ Happy New Year!
The double flange is a low-precision, rough-measurement instrument — I’ve said it for ages; I mentioned it back at least in 1999. As of today, that’s already 20 years ago, and I’ve said it over and over again~~~
However, there are some situations that do exist in reality. A typical example is a reaction vessel with flanges at the top and bottom, used to hold ordinary liquids; the high-pressure flange is located within the medium. If the temperature of that medium is 150 degrees, wouldn’t that affect its performance? There are also issues with temperature compensation; the temperature sensor for this purpose must be installed within the main unit’s sensors. If the capillary is 5 meters long, the flange can reach a temperature of 150 degrees, while the main unit remains exposed to cold winds. In such conditions, will the machine’s temperature compensation function still work?
1. For warm supplementation, it is not necessarily necessary to use a temperature sensor; other mechanisms can be employed. 2. For warm supplementation, when using temperature sensors, where should the temperature measurement points be placed? How many points are needed for measurement? There are many considerations involved in this......
That’s where the problem with the selection arises.
So I think for transmitters with diaphragm remote transmission, the impact of temperature compensation is very small