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High Accuracy Temperature Indicator

09/18/2017 11:15 AM

I need high accuracy temperature indication for water at ambient temperature... range 0 - 50 deg C

The combined accuracy needed including sensor inaccuracy and indicator inaccuracy is better than 0.1 deg C and resolution 0.01 deg C

The sensor should be PT 100 (3 wire) , which can be integral or remote.

Can anyone suggest the supplier ? Fluke makes it which is very costly... almost $1000.

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#1

Re: High Accuracy Temperature Indicator

09/18/2017 11:21 AM

Google, "High Accuracy Temperature Indicator."

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#2

Re: High Accuracy Temperature Indicator

09/18/2017 11:35 AM

You might a consider Pt 1000 sensor with appropriate instrumentation.

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#3

Re: High Accuracy Temperature Indicator

09/18/2017 12:01 PM

$1000 seems reasonable to me. Particularly if you want real credibility in the data you are taking.

Wait a minute, three wire measurements assume identical errors on the other leg. I guess you don't really want high accuracy then. You only want better accuracy than a two wire measurement.

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#4

Re: High Accuracy Temperature Indicator

09/18/2017 12:03 PM

1. Those kind of specs warrant a true 4 wire RTD.

2. 'high accuracy' and 'too costly' tend to be mutually exclusive.

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#5

Re: High Accuracy Temperature Indicator

09/18/2017 1:19 PM

For highest accuracy, you would need a good calibrator for the triple point of water, or solute-free freeze point, and solute-free boiling point at sea level.

You could go with a thermistor (cheaper), but you will sacrifice some accuracy.

If you cannot procure a good calibrator, you will need a thermometer that is certified to a defined standard. In the United States of America, I think we still use NIST traceable ones. At least I do when calibrating other temperature measurements against this secondary standard, such as wastewater measurement.

Pt1000 will offer you more measurement accuracy in the temperature range you are interested in, IMHO.

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#6

Re: High Accuracy Temperature Indicator

09/19/2017 2:57 AM

Why?

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#7

Re: High Accuracy Temperature Indicator

09/19/2017 7:49 AM

One should question whether the temperature in a liquid is anywhere the same within 0.01degC. Convection currents and evaporation render the measurement criterion dubious.

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#8
In reply to #7

Re: High Accuracy Temperature Indicator

09/19/2017 9:49 AM

What you are saying is true while the water is far from equilibrium (i.e.- being rapidly and locally heated, wherein convection, and conduction might not be keeping up with heat input, and evaporation is not able to restore a set temperature related to pressure.

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#9
In reply to #8

Re: High Accuracy Temperature Indicator

09/19/2017 10:32 AM

Exactly. That is why the question stands as to the need for such a remarkable device in the first place. The original poster has withheld that detail from the forum.

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#10

Re: High Accuracy Temperature Indicator

09/19/2017 11:23 AM

A resolution of .01 and accuracy of .1 seems a bit pointless. Usually in measuring applications the desired accuracy of the measurement is 1/10th that of the desired measurement resolution.

Why would you want a reading of 23.04 if it could actually range from 22.99 to 23.09 and you don't know where in the range it actually is? In actual use, you would want a resolved reading of 23.04 that could range from 23.039 to 23.041.

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#11
In reply to #10

Re: High Accuracy Temperature Indicator

09/19/2017 11:53 AM

Absolutely true, but sometimes we play trickery, and average a lot of numbers to arrive at central tendency? Yes? No?

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#12
In reply to #11

Re: High Accuracy Temperature Indicator

09/19/2017 12:16 PM

Sounds like a reason to fudge temperature numbers...where have we seen that before?

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#13
In reply to #12

Re: High Accuracy Temperature Indicator

09/19/2017 12:20 PM

Algore Industries?

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