Formula to correct SG for temp

Wally · Post by **Wally** » Friday Jul 07, 2006 2:33 pm

I am looking for the formula to correct the SG for temperature variations. It needs to be for a hydrometer which has been calibrated at 20 deg C. It can be complicated since I will be using it in a spreadsheet. At this point I could only get one that corrects for a calibration temp of 60 deg F.

Wally

TommyH · Post by **TommyH** » Friday Jul 07, 2006 2:58 pm

Courtesy of Oliver

Posted: Friday Apr 01, 2005 12:58 am Post subject:

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The corrections should have come with the hydrometer.

Here are the corrections for a hydrometer calibrated to 20C:
Code:

Temp(C) Correction
4-10 -2
11-17 -1
18-22 0
23-26 +1
27-29 +2
30-32 +3
33-35 +4
36-38 +5
49-41 +6

So let's say that your wort was 27C when you took the reading of 1035/36. Therefore, the corrected reading is 1037/38.

Cheers,

Oliver

DJ · Post by DJ » Friday Jul 07, 2006 2:58 pm

someone had a link on here to a speadsheet that had it..

Ill have a search..

Wally · Post by **Wally** » Friday Jul 07, 2006 4:27 pm

Thanks for the quick replies, but I am looking for the mathematical formula to enable me to use it in a spreadsheet.

Ed · Post by Ed » Friday Jul 07, 2006 5:46 pm

This should be right, I use it in my spreadsheet. I just set up a conversion in another column to take the recorded temp in *C to *F to allow the formula to work.

To conver *C to *F
*F=(DC*1.8 )+32

Where DC is temp *C

Correction
Correction=(1.313454 - 0.132674*T + 0.002057793*T*T - 0.000002627634*T*T*T)/1000

Where T is temperature in *F

The resulting figure is the correction. Add that to the recorded gravity.

Cheers, Ed