Ss Brewing Technologies Giveaway!

Home Brew Forums > Home Brewing Beer > Brew Science > What's the % ABV?
Reply
 
LinkBack Thread Tools
Old 10-24-2011, 04:10 PM   #1
Beervana
Feedback Score: 0 reviews
Recipes 
 
Join Date: Oct 2008
Location: Portland, Oregon
Posts: 17
Default What's the % ABV?

I made a very strong beer with 12.2% ABV. I decided to tame it down so I made another beer with 4.2% ABV and blended the two in a 50/50 blend by volume. So equal parts of each beer. I want to determine the % ABV of the blended result - short of a lab analysis. I know it's not a simple linear dilution (meaning the average of the two) and everything I've come across for dilution assumes diluting with water. Does anyone know how to calculate the resulting ABV of the blend?

__________________
Beervana is offline
 
Reply With Quote Quick reply to this message
Old 10-24-2011, 04:37 PM   #2
Brewkowski
HBT_SUPPORTER.png
Feedback Score: 0 reviews
 
Brewkowski's Avatar
Recipes 
 
Join Date: Aug 2008
Location: Chicago area
Posts: 1,370
Liked 24 Times on 23 Posts
Likes Given: 24

Default

http://winemaking.jackkeller.net/blending.asp

a couple of calculators I think the easier one is the second one down, basically ABV of each and then put in the quantity of your 12.2% and change the amount of the Fortifier (4%) until you reach the ABV desired. From what I ran with 5 gal of 12%, if you add 2 gal of 4% you'll be at around 9.7%.
__________________
Brewkowski is offline
 
Reply With Quote Quick reply to this message
Old 10-24-2011, 07:03 PM   #3
pickles
HBT_SUPPORTER.png
Feedback Score: 0 reviews
 
pickles's Avatar
Recipes 
 
Join Date: Feb 2008
Location: Columbus
Posts: 1,985
Liked 48 Times on 40 Posts
Likes Given: 23

Default

If the volumes were equal it should be an average of the two.

__________________
Gaptooth Brewhouse
pickles is offline
 
Reply With Quote Quick reply to this message
Old 10-24-2011, 07:23 PM   #4
solbes
Feedback Score: 0 reviews
Recipes 
 
Join Date: Jul 2011
Location: Ramsey & Akeley, Mn
Posts: 2,342
Liked 147 Times on 139 Posts
Likes Given: 53

Default

+1, I was thinking the same thing. Why wouldn't it be a straight linear dilution?

5 gallons * 0.122 = 0.61 gallons of ethanol
5 gallons * 0.042 = 0.21 gallons of ethanol

Upon blending you have 0.82 gallons of ethanol in 10 gallons total, or 8.2%. Unless I'm somehow under thinking this.

__________________
Primary #1: Empty #2: Black Currant Wine
Secondary #1
: Berry Rhubarb Wine #2: Empty
Kegged
: Cascadian Dark Ale
Bottles
: Spruced Winter Warmer, Surly Bender clone, Big 50 Barleywine, Framboise Lambic, Dark Belgian Strong, Kicked by a Moose Scotch Ale, Russian Imperial Stout, Sparkling Elderflower Wine, Barolo Wine, On Deck: Orange Pale Ale IV, Hidden Lake Nut Brown, 2H IPA III
solbes is offline
 
Reply With Quote Quick reply to this message
Old 10-24-2011, 09:38 PM   #5
ajdelange
Senior Member
HBT_LIFETIMESUPPORTER.png
Feedback Score: 0 reviews
Recipes 
 
Join Date: Aug 2010
Location: McLean/Ogden, Virginia/Quebec
Posts: 5,959
Liked 591 Times on 488 Posts
Likes Given: 16

Default

Quote:
Why wouldn't it be a straight linear dilution?
Because volume isn't conserved but mass is so the first thing to do is convert the ABVs of each beer to ABW's by

ABW = ABV*0.791/SG

where SG is the specific gravity of the beer. Now calculate the weight of each volume of beer by W = Vol*SG*.998203. Multiply by the ABWs to find the weight of alcohol in each. Add the weights of alcohol and divide by the sum of the weights of the 2 beers to find the ABW of the mix. Now convert back to ABV. To do that you need the SG of the mixture so measure it or estimated it by a weighted average of the "points" i.e. 40% 1.030 beer with 60% 1.070 beer will probably have an SG of around 1 + .4*30 + .6*70. Now compute the new ABV from ABV = SG*ABW/0.791
__________________
ajdelange is offline
 
Reply With Quote Quick reply to this message
Old 11-24-2011, 09:23 PM   #6
doomedplanet
Feedback Score: 0 reviews
Recipes 
 
Join Date: Aug 2008
Posts: 18
Default

I'm trying to calculate a similar thing for a big Belgian I made, wondering how I would know the final ABV with this scenario:

9 gals in fermenter of 1.110

at high krauesen I added 3 gallons of 1.065 sugars

FG = 1.012

I guessed this was around 15%.

__________________
doomedplanet is offline
 
Reply With Quote Quick reply to this message
Old 11-24-2011, 09:58 PM   #7
ajdelange
Senior Member
HBT_LIFETIMESUPPORTER.png
Feedback Score: 0 reviews
Recipes 
 
Join Date: Aug 2010
Location: McLean/Ogden, Virginia/Quebec
Posts: 5,959
Liked 591 Times on 488 Posts
Likes Given: 16

Default

Same technique - conservation of mass. Find density of each liquid by multiplying SG of each by 0.998203 (the density of water). Find the mass of each liquid. Convert the SG's to °P and calculate the mass of extract in each from the °P (mass_extract = mass_liquid*°P/100). Calculate the mass of the water in each by subtracting the extract mass from the total mass of each. Sum the masses of the water and of the extract. Divide the sum of the masses of the extracts by the total mass of water plus extract and multiply by 100. This is the effective OG in °P for the mix. Apply the expected RDF or ADF to calculate the apparent or true extract. Subtract from the OG and multiply by the proper Balling factor for the OG. This is the ABW. Divide by 0.791 and multiply by the specific gravity of the finished beer (as obtained from the AE estimate if you estimating before the beer finishes). There will be some error from the water lost to evaporation during the fermentation.

__________________
ajdelange is offline
 
Reply With Quote Quick reply to this message
Old 11-25-2011, 06:57 AM   #8
doomedplanet
Feedback Score: 0 reviews
Recipes 
 
Join Date: Aug 2008
Posts: 18
Default

Whew, more complex than expected, thanks, I'll have to print that out and try to figure it. Any water loss was fairly minimal because I got 11 gallons out of the 12, which is typical with my fermenter.

__________________
doomedplanet is offline
 
Reply With Quote Quick reply to this message
Old 11-25-2011, 12:39 PM   #9
ajdelange
Senior Member
HBT_LIFETIMESUPPORTER.png
Feedback Score: 0 reviews
Recipes 
 
Join Date: Aug 2010
Location: McLean/Ogden, Virginia/Quebec
Posts: 5,959
Liked 591 Times on 488 Posts
Likes Given: 16

Default

If you go and plug it into a spreadsheet you will probably find it's not as bad as it looks and once it's in the spreadsheet then you don't have to worry about the complexity any more.

Also, if you know that you are losing a gallon to evaporation you can account for that by subtracting 3.78 kg from the total water mass.

__________________
ajdelange is offline
 
Reply With Quote Quick reply to this message
Old 11-25-2011, 12:50 PM   #10
Brewskii
Feedback Score: 0 reviews
Recipes 
 
Join Date: May 2011
Location: Williamsburg, Va
Posts: 1,154
Liked 113 Times on 64 Posts

Default

Quote:
Originally Posted by ajdelange
Same technique - conservation of mass. Find density of each liquid by multiplying SG of each by 0.998203 (the density of water). Find the mass of each liquid. Convert the SG's to °P and calculate the mass of extract in each from the °P (mass_extract = mass_liquid*°P/100). Calculate the mass of the water in each by subtracting the extract mass from the total mass of each. Sum the masses of the water and of the extract. Divide the sum of the masses of the extracts by the total mass of water plus extract and multiply by 100. This is the effective OG in °P for the mix. Apply the expected RDF or ADF to calculate the apparent or true extract. Subtract from the OG and multiply by the proper Balling factor for the OG. This is the ABW. Divide by 0.791 and multiply by the specific gravity of the finished beer (as obtained from the AE estimate if you estimating before the beer finishes). There will be some error from the water lost to evaporation during the fermentation.
I can not imagine a scenario where this info would be that important to me.
Good luck though.
__________________
Brewskii is offline
 
Reply With Quote Quick reply to this message
Reply



Quick Reply
Message:
Options
Thread Tools