From the HBD Archive
From: ephram@violet.Berkeley.EDU
Subject: Re: Homebrew Digest #242 (August 31, 1989)
Date: 1989-09-01 13:01:35 GMT

~sSG temperature correction formula

As previouseley noted

>and on Doug Roberts (HBD #236)
>
> (T x 1.449E-4 - 0.009) + SG(uncorrected) = SG(corrected)

This formula does not hold true for 60 degrees F. For 60 F I get a correction
factor of -0.000306, decidedly not 0 as it should be for a hydrometer
calibrated to read acurateley @ 60. I plotted the function using data
points that I got out of the back of Byron Burch's Brewing quality Beers.
The function that I was looking at was decidedly _not_ linear.

Here are the data points that I got from the book (reprinted without
authorization)
Degrees F Correction
32 -1.6
41 -1.3
50 -0.8
60 0.0
68 1.0
77 2.2
86 3.5
95 5.0
104 6.8
etc.

The point is that one of the two are wrong, the table or the formula. I too
would like to see a formula for SG correction, but, I would like it to agree
with a little more of the published (alright I only looked at 1 source) data.


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