Zero Trimming DP and P and Multivarible Transmitters

C

Thread Starter

chillwin

How would I go about zero trimming a DP and P on a multivarible transmitter? Would I do a high static zero for the DP or would I open the equaliser manifold valve and open up to atmosphere?
 
Answer - get the manual, software and modem needed to talk to the multivariable.

Several years ago, I checked a DP measurement on a multivariable to see if it needed trim. I recall that I needed the mfg software and modem, but it was straightforward - open ports for zero, applying span pressure to the high side. It turns out it needed no 'trim', it was dead nuts on.

The static pressure P might be absolute pressure. Note that in the latest Rosemount 3051S Multivariable manual,
http://tinyurl.com/ngpufhr
it distinguishes between a zero trim (gauge sensor) or a lower sensor trim (absolute sensor) (pg 103 pdf).

"The lower sensor trim function provides an offset correction similar to the zero trim function, but it does not require a zero-based input", which infers that a vacuum pump might not be needed for a P trim. If your model has an absolute pressure sensor, then you'd need an absolute pressure reference to trim against.

In any case, it takes software.
 
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