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Repeatibility and Linearity in 5081-A Transmitter

Hi

I want to use 5081-A Transmitter along with 499ATrDO Dissolved oxygen sensor.

Our required calibrated range is 0-20 ppb.

In the transmitter 5081 datasheet (LIQ_PDS_5081/Rev.R Page#6) under the heading of General Specifications for 5081-A, it is defined as following:

Repeatibility (Input) = 0.1% of range

Linearity (input)= 0.3% of range

and above some input ranges are given in current units.

Now, we know that the sensor 499ATrDO has the range of 0.1 to 20 ppm (i.e. 20,000 ppb), so does it meant that the repeatability of the transmitter will be 0.1% of 20,000 ppb? and similarly linearity will be 0.3% of 20,000 ppb? This will result in a very high values for repeatability and linearity as our working range is only 20 ppb. Can you please explain this doubt?

Regards

• amperometric sensor
• dissolved oxygen
• 499ATrDO
• 5081

farzan

• 18 Jul 2023 10:42 PM
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2 Replies

• Jacalyn Saint Rudolph

  

  • 26 Jul 2023 9:31 PM

  The 499ATRDO sensor PDS dated 2019 has the following specifications (see pages 3-4):
  
  Rosemount 499ATrDO (emerson.com)
  
  The repeatability is 2% of reading at constant temp, and linearity is either 5% of reading or 3ppb, whichever is greater.
  
  The 5081-A PDS, to the best of my understanding, refers to the full range. So even if you say you will calibrate to 20 ppb, it is declared as 0.1% of the transmitter range. Furthermore, it seems to have been written such that it applies to any amperometric sensor, whereas the specifications above is intended specifically for 499ATRDO.

  Jacalyn Saint Rudolph (she/her/hers) | Global Product Manager | Rosemount Analytical
  Emerson Automation Solutions | 6021 Innovation Blvd | Shakopee | MN | 55379 | USA

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• farzan

  

  • 27 Jul 2023 1:58 AM

  In reply to Jacalyn Saint Rudolph:

  HI Jacalyn
  
  Thanks for the response.
  
  What i understand that we need to consider the repeatability and linearity of transmitter and sensor both. in this case, if your point is take that Repeatibility is 0.1% of Range (which is 20,000 ppb) then the value comes out to be 20 ppb which is an extremely high value for a calibrated span of 20 ppb.
  
  What would you suggest that the customer should consider this much error in the reading if he keeps the span to 0 to 20 ppb?
  
  Regards

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