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Manager   •   over 7 years ago

Updates to SRD60 JSON Files

Hi everyone, an astute participant in the Reference Data Challenge found three errors in the JSON files for NIST SRD 60 (ITS-90 Thermocouple Database). Our expert Don Burgess has reviewed the SRD60 JSON files line by line and corrected these errors as well as an additional one that was found on closer inspection. For details you can read below. If you have any followup questions, post them here. Our apologies for the inconvenience and huge thanks for the careful review by our challenge participant!

Specifically, the errors were reported as described below.

REPORT
Data discrepancy in the json files of srd60 reference functions of types R and S, and inverse function of type R

In file srd60_type_r_coefficients.json, the polynomial for domain T=[1664.5,1768.1] is missing.
In file srd60_type_s_coefficients.json, the polynomial for domain T=[1664.5,1768.1] is missing.
In file srd60_type_r_coefficients_inverse.json, in the polynomial for domain T=[1064,1664.5], Emin should be 11.361 instead of 1.361.

RESPONSE
We have gone through all of the files line by line and checked for any other errors.

We corrected the errors in the three files.
srd60_type_r_coefficients.json
srd60_type_s_coefficients.json
srd60_type_r_coefficients_inverse.json

We also corrected an error in srd60_type_k_coefficients.json for Type K.

Type K thermocouples have two equations for EMF - one below T=0°C and one above T=0°C. The equation below 0°C is the same as all the other thermocouple types, but above 0°C there is an addditional ("exponential") term

We corrected the error in srd60_type_k_coefficients.json as follows.

CHANGED
"equation": "EMF = sum(i=0 to n) c_i t^i",

TO
"equation": {
"Tlo": "EMF = sum(i=0 to n) c_i t^i (t<0°C)",
"Thi": "EMF = sum(i=0 to n) c_i t^i + a0 exp(a1 (t - a2)^2) (t>0°C)",
},

Please note that when you generated the thermoelectric voltages using the equations and coefficients, you can double the values with the tables found on the website at
http://srdata.nist.gov/its90/main/
http://srdata.nist.gov/its90/download/download.html
http://srdata.nist.gov/its90/download/all.tab

  • 2 comments

  •   •   over 7 years ago

    Dear Mdm,

    Thank you for the update. I just tested the new json files and discovered a very small syntax error. In the change made to the srd60_type_k_coefficients.json file, the comma at the end of the following line is redundant:

    "Thi": "EMF = sum(i=0 to n) c_i t^i + a0 exp(a1 (t - a2)^2) (t>0°C)",

    While this extra comma is a very tiny syntax error, it unfortunately has caused failure in 3 out of 4 JSON parsers, including one in Python, one in C, and one in Java. Therefore, I thought it worthwhile bringing this small error to your attention.

    Thank you.

  • Manager   •   over 7 years ago

    Thanks for letting us know! We are working to get the changes implemented. They should be updated this morning. We appreciate your careful review of these files and do apologize for the inconvenience.

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