Precision Temperature Measurement

[fsonnichsen]

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

 

[berkeman]

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?

 

[fsonnichsen]

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

 

[jrmichler]

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.

 

[fsonnichsen]

Thank you for the book suggestions. I will certainly order Doebelin.