Capillary level measurement

So we just had to replace a capillary on one of our vessels no big deal. Well the thing is a have 32” tap to tap my capillary is silicone 704 with an sg of 1.07 all of this means I should show roughly -34” of differential while mounted and vented.

For whatever reason we only have -17.53” H2O. So we told the day techs to get the pipe guys to remove it lay the cells flat and attempt a pressure zero trim.

Rather than doing that the day tech decided to just shift the span across the 0 margin. Making the span -18”H2O to +3”.

I see how theoretically this works but it does not sit well lol. We are going to attempt the original plan tonight just looking for any input on the functionality of the their fix. Also process she is.662

This technique is used by everyone to adjust the transmitter range in order to get the required PV.

Yes, I understand the premise of setting the level up for a suppressed 0 or, negative span. However, outside of a process fluid that has a greater SG than my fill fluid I have never heard of crossing the 0 threshold. For example going -18 to +3. To me if that isn’t correct.

Make sure you transmitter is not located too high, not to draw full vacuum on its HP side (in such a case it would give a wrong reading)>.

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