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I did it today in excel, and the matlab equation I wrote for it last week gave me the same answer. According to the lab handouts, the error should only be +/- 0.05 C.

Thanks for any help!

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- #1

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I did it today in excel, and the matlab equation I wrote for it last week gave me the same answer. According to the lab handouts, the error should only be +/- 0.05 C.

Thanks for any help!

- #2

FredGarvin

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- #3

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Type K thermocouples (given by profs)

Here is the equation

T = 0.0 + 2.508355e-2*v + 7.860106e–8*v^2 + –2.503131e–10*v^3 + 8.315270e–14*v^4 + –1.228034e–17*v^5 + 9.804036e–22*v^6 + –4.413030e–26*v^7 + 1.057734e–30*v^8 + –1.052755e–35*v^9

Again v is in microvolts, and T is in celsius.

Because I am just a few degrees off, I am wondering if the polynomial is right, ie do we have the right thermocouple type.

- #4

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I have checked this in matlab, and with other people, getting the same answer.

but the LabVIEW VI software in the lab gives us the right answer

- #5

FredGarvin

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I pulled mine from National Instruments documentation on thermocouples, but I will be interested to see yours.

- #7

FredGarvin

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Without running some numbers I can't say if this will fix your offset, but I did forget that there are two exponential corrections for the first two terms. Take a look at the attached page.

Also note the reference temperature of 0°

Ref. ASTM Manual on the use of thermocouples in temperature measurement, 4th edition.

Also note the reference temperature of 0°

Ref. ASTM Manual on the use of thermocouples in temperature measurement, 4th edition.

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- #9

FredGarvin

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All right. Let me see what else I can dig up.

- #10

FredGarvin

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OK. Try this one. Hopefully this one will help. This is from NIST. It is a typical K type TC table, however at the very end there is a section for the inverse function of temp and emf. Give that a look see and maybe that will hlp you out.

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