Precision Temperature Measurement

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Discussion Overview

The discussion centers on the most precise methods for logging temperature in laboratory settings, focusing specifically on resolution and precision rather than accuracy. Participants explore various measurement techniques, particularly in the context of aqueous solutions and contact versus non-contact methods.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Fritz expresses a need for temperature measurement with a resolution of 0.01 deg C, indicating dissatisfaction with the performance of RTDs.
  • One participant inquires about the specifics of the measurement context, including whether the measurement is contact or non-contact, and the thermal properties of the probe.
  • Fritz clarifies that he typically measures the temperature of aqueous solutions below 100 deg C and prefers contact methods for their presumed accuracy.
  • Fritz notes that temperature changes in large volumes of liquid are slow, often occurring in a constant temperature bath, and discusses the challenges posed by probe thermal properties.
  • A suggestion is made regarding literature on precision temperature measurement techniques, specifically recommending "Measurement Systems, Application and Design" by Ernest O. Doebelin and "Applied Measurement Engineering" by Charles P. Wright.

Areas of Agreement / Disagreement

Participants have not reached a consensus on the best method for precise temperature measurement, and multiple viewpoints regarding techniques and challenges remain present.

Contextual Notes

Participants have not fully addressed the assumptions regarding the specific measurement environment or the limitations of different measurement techniques. The discussion includes unresolved questions about the impact of probe thermal properties on measurements.

fsonnichsen
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What is the most precise way to log temperature in the laboratory? I am concerned with resolution and precision here, not accuracy.
RTDs don't seem to cut it. Almost all that I have looked at and tried only have a resolution of around 0.1 deg C. I was hoping for 10X better than that-
Thanks
Fritz
 
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What is the substance/object you are trying to measure? Is this a contact temperature measurement, or non-contact? If it is a contact measurement, how do you keep the thermal properties of the probe from altering the temperature of the subject?

What is the environment? How quickly can the temperature of the subject change?
 
I am trying to keep this somewhat open but usually I am measuring the temperature of aqueous solutions at under 100 deg.

Any method is OK but I assume contact methods would be more accurate.

The temperature changes rather slowly in a large volume of liquid-in most cases it is in a constant temperature bath.
Regarding the probe thermal properties is always problematic and I have even seen RTDs carry heat down their wiring. However if the probe circuit is itself reasonably temperature stabilized this can be minimized. Again I am mainly interested in changes (resolution, precision) and not calibrated accuracy.

Thanks for the good questions
Fritz
 
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There is a good discussion of precision temperature measurement techniques in Measurement Systems, Application and Design, 4th Edition, by Ernest O. Doebelin. I see that Amazon has a 6th Edition of this book for the dirt cheap price of $28.00 (International Edition). It's a bargain at five times that price.

Another good book with information on temperature measurement is Applied Measurement Engineering, by Charles P. Wright.

Both of these books would be good additions to your library. Doebelin has more information relevant to your specific application, so get it first. Wright complements Doebelin, and should be in the library of anybody making precise measurements.
 
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Thank you for the book suggestions. I will certainly order Doebelin.
 

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