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Old 02-24-2011, 07:37 PM   #11
passedpawn
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I think the only thing that might be affected is how well the hop acids are liberated from the hops.

Here, I plotted that formula from above.

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Old 02-24-2011, 08:58 PM   #12
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According to this, the above chart could accurately be written as hop utilization vs boil temperature.

 
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Old 02-24-2011, 09:02 PM   #13
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Quote:
Originally Posted by passedpawn View Post
I think the only thing that might be affected is how well the hop acids are liberated from the hops.

Here, I plotted that formula from above.
I must say, seeing that graphically is a little discouraging. That indicates that I'm only getting about 80% utilization since I'm at 6000 ft. If that's the case, then I would theoretically need to increase my 60 min additions 25% to get the expected IBUs. However, my brews come out pretty good so I probably won't change my additions.

And for the record, water/wort at my house boils at ~202 F. I typically boil off 1 gallon per hour. If I kept my burner cranked, I'd probably boil off twice that amount.
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Old 02-25-2011, 12:00 AM   #14
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boil_temp_vs_abs_barometric_pressure
y (boil temp deg.f)=49.161 * ln (x barometric pressure inches mercury) + 44.932

Equations - Air Density and Density Altitude


Also:

p = 101325 (1 - 2.25577 10^-5 h)^5.25588
where
p = air pressure (Pa)
h = altitude above sea level (m)

 
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