A Practical Solution to Using Temperature Data to Compensate Conductivity

Greetings! Pete Anson here. I’m a Senior Product Manager here at Emerson Process Management and responsible for all liquid analytical instrumentation. A customer recently came to me asking how he could use the temperature data from an installed Rosemount 644 temperature transmitter for compensation of conductivity on a boiler feed water application. The customer really trusts the reliability and accuracy of the Rosemount transmitter and wants to integrate the output to support a liquid analytical measurement.  

Nice concept but the only thing that makes it practical is if you have the ability to receive and algorithmically integrate the temperature data for compensation of the conductivity measurement.    

Fortunately, Rosemount Analytical does have a solution for this “out-of-the-box” scenario. Using the Model 1056 installed with a current input signal board, any 4-20mA signal from any device can be received, integrated as compensation data for conductivity, and displayed locally. The user simply selects the programming option to use the 4-20mA data as temperature for conductivity measurement with the installed Model 400 Endurance line contacting conductivity sensor. The input of temperature data from the 644 transmitter is received at 1/second to provide immediate determination of conductivity, which is highly affected by temperature.

Further, the Model 1056 can power the transmitter (up to 36 volts DC) to avoid additional DC loop power leads of the temperature device. The temperature data and the measured conductivity can be output to a PLC or DCS if wired to the 4-20mA output. HART configurations of Model 1056 can report all live variables and diagnostics associated with the conductivity loop to the DCS including the temperature data converted from degrees to 4-20mA readings.

Using the versatile 4-20mA input capability of the Model 1056, many other inputs can be accepted and displayed.  Variables such as atmospheric pressure can be input to compensate dissolved oxygen measurement for partial pressure.  And, almost any type of measurement can be input and displayed for the convenience of field technicians and I&E. This is especially useful in the field if the 4-20mA device does not have a local display, aka “blind transmitter.”  

The Model 1056 offers an innovative solution for this unconventional but reasonable request.  The solution described using the Model 1056 with the current input board will elevate the customer’s confidence in the process measurement, allow real-time local display and reporting of live temperature readings from the adjacent transmitter, and potentially save wiring of leads to power the temperature transmitter.

Please feel free to check out our Model 1056 page for more information, including product data, features and benefits.

4 Comments

  1. Dr. Martin Pernigotti says:

    The report was very interesting and opened my mind respect the relation betwen Tº and conductivity.I think Thanks!!

  2. pete anson says:

    Dr. Pernigotti,
    Exactly our intent at Analytical. We hope to catalize thoughts about innovative solutions and encourage discussions on any topic of interest within our scope. Please feel free to correspond with me directly or pose any questions/issue, etc.
    Pete Anson

  3. Abdelrahman says:

    we can use also a conductivity transmitter and some conductivity cell with built in temperature sensor, then we can activate the temperature compensation facility inside the transmitter(ex. 5081 model).

  4. Adriel says:

    Pete, is possible use this input board in the 1056 analyzer to receive a 4-20mA signal from a silica analyzer and relay as a Profibus DP signal to the PLC?

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