3051C with 199 seals, thoughts about "seal effect"

We measure the level in a small propylene vessel using a 3051C with 1199 capillary seals.  It is a balanced system.  During warm weather, we experience a positive zero shift in the measurement.  The transmitter is only spanned from 0 - 13 inH2O, and the vessel is normally only vapor - think of it as a knock out drum.  And our installation isn't ideal since the capillaries are probably much longer than necessary to reach the process nozzles.

I just re-read the Emerson white paper that discusses tuned systems vs. balanced systems, and I believe I understand what is going on.  I'm sure a tuned system with an appropriate length low side capillary would perform better than what we have.  But I'm curious if just raising the transmitter would cancel out the change in density to the point where the error is cancelled out?  If so, what would the right elevation be?  Even with the top tap, centered between the taps?

Thanks for your thoughts,

Kevin Schroeder

  • How do I use the Emerson's HART communicator 475 to zero trim a Yokogawa YTA temperature transmitter.

  • In reply to kevwe ujevs:

    Hello

    You will need to consult the YTA product manual for the instructions on how to do the zero trim.  Below is a ink to a manual (I am not sure if this is the latest version).  

    https://web-material3.yokogawa.com/IM01C50T01-01EN.pdf

    Page 3-4 lists the menu tree with the corresponding HART communicator buttons for the various commands.  These should be applicable for a 475 communicator. 

    Thank you,

    Michael

  • Hi Kevin,

    Raising your transmitter will not cancel out the change in density. Though, years ago it was thought that using a balanced system and mounting the transmitter between the two taps would eliminate the density error. This is not because head effect is still based on vertical distance between the taps.

    Feel free to reach out to our specialist and we can help evaluate your specific application. rmt-na.specialistremoteseals@emerson.com

    Thanks,

    Nicole