How do I calculate the accuracy of a thermometer?

C

calib_eng

#1
pls help me,
i have one dig thermo meter (UUT), i applied standard values from a primary standard digital. temperature calibrator and found the following results.

applied(C) 30 60 100
found(C) 31 62 102


kindly tell me how to calculate the accuracy of the unit under test (digital thermo meter ETI)
thanks
 
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Hershal

Metrologist-Auditor
Staff member
Super Moderator
#2
If you can adjust the digital then you can make them match, but either way you need to calculate the measurement uncertainty.

You have the Type A uncertainties, your actual readings. You should have 3 or more at each reading, take the standard deviation of each set of readings, divide by square root of n, now you have Type A.

Take the Type B uncertainties and include them. They include but may not be limited to: the difference of each set of readings compared to your standard; the potential variance of your baths or similar medium; the calibration uncertainty of the digital standard; and the resolution error of each digital (one half of the least significant digit). Calibration uncertainty is divided by 2, other Type B influences are divided by square root of 3 (1.732).

Take each resulting Type A and B number, square the number, add all them together, take the square root of the total, then multiply by 2. This is expanded uncertainty and will tell you what you need. The true value of a measurement then is the observed value plus or minus the uncertainty value, with 95% confidence.

Hope this helps.

Hershal
 
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