Seeking help with fluctuations in differential pressure level gauges
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For the differential diaphragm level gauge, the liquid level rises during hot days and drops at night. Please, experts, analyze what could be the reason for this； The operating conditions remain unchanged; the medium in the tank is acetic acid and water
Are you using a single-flange sealed tank?
Capillaries are not suitable when the height difference between the two flanges is too small
316L may not be suitable for your operating conditions, as the medium is acidic; it would be better to use a different type of Hastelloy or tantalum alloy. It seems that there’s no visible issue with the transmitter diaphragm, but it might already be leaking. If there are spare parts, it’s best to replace it. The one that was replaced was sent back to the factory for inspection; the diaphragm had a leak, which is impossible to detect with the naked eye – I’ve encountered this before.
The bilateral capillaries are bundled together to provide insulation; electric or hot water heating is used to maintain a constant temperature.
Check whether the diaphragm has suffered oxidation or corrosion. Additionally, with many domestic low-brand or imported single-flange products that are not manufactured by the original manufacturer but are processed by other factories, the phenomenon you described – higher pressure during the day and lower pressure at night – can occur; I have seen this phenomenon in person