Pressure Transmitter Calibration Upgrade

Hello Team,
I was given Rosemount 3051L to calibrat and install to measure the pressure.
The range of this diaphragm pressure transmitter is 0 - 250 kPa.
Span is 60 - 80 kPa.

This was what I did:

  1. Re-range using HART communicator (Beamax). I set URV= 80 kPa & LRV=60 kPa
  2. Error set to 1.5 % of Span.

The calibration passed. However, I was not satisfied about this result as this I think will definitely have a great impact on production…but this was what the guys here have been using… The turn down ration of this transmitter is 10:1 that makes the minimum span to be 25kPa, where as the span of this measurement is 20kPa.

I therefore would like to change out the existing installation and change with a different one that will be more suitable to the process.
Anybody having any idea as to what I will need to do?
Has anyone ever come across this issue before?

Thank you for your time.

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Hi,
Yes, there will be an impact on the measurement, if your process needs exact control of the pressure in their system then it is better to take some action on it.

If your process is okay with a measurement error of 1 to 2 % of span then you can ignore it. It entirely depends on process application. But as a matter of fact, you are 100% correct on the impact of the turndown ratio.

You can replace the existing pressure transmitter ( 0 to 250 kPa) to lower range PT.

Consider a diaphragm pressure transmitter with 0 - 100 kPa.range.

(also consider max pressure of the process in the selection of the PT range)

Or

Re-range the existing LRV and URV values of the Pressure Transmitter.

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Hello John,

The application for this installation is to measure the bed pressure of slurry(gold ) in the counter current decantation circuit in gold process plant. The PT goes under the cone where the underflow goes to NCA ( Neutralisation, Cyanidation and Absorbation) circuit.

I will embark on liaising with Rosemount and order in a diaphragm PT with 0-150 kPa if any. I am sure the process pressure would be around 100 kPa.

Thank you for your insight. Really appreciate it.

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When you’re talking kPa and such us simple American folks get confused lol. But, if you go to the Emerson website you can build a PT to your specifications using their program and call your rep with the appropriate model number.

Also consider that your diaphragm rating for range is not the same as the pressure rating of the instrument. Generally speaking all of our transmitters have a pressure rating of 3000 PSI but may only have a measurable range of 0-30 PSI.

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