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new2brew1221 08-17-2012 10:57 PM

Alcohol content
 
If I let a glass of beer warm to room temp, and the use the hydrometer will it tell me what % the beer is? I had someone ask me after I gave them a bottle.

bleme 08-17-2012 11:05 PM

Nope. For that they would have to take a gravity reading before fermentation as well.

kh54s10 08-17-2012 11:11 PM

The alcohol scale on a hydrometer is for "potential alcohol" and does not equal the actual alcohol level in a beer.

To calculate the alcohol by volume of a beer is an equation using the Original Gravity and Final Gravity. I do not know what the equation is, I just plug the numbers into an online calculator.

Without the OG or sophisticated lab equipment you can not tell.

unionrdr 08-17-2012 11:14 PM

Here's the Cooper's formula I use; (OG-FG)/7.46 +.5= ABV%. If you kept notes,you can quickly figure it out with the windows calculator.

Revvy 08-17-2012 11:22 PM

og-fg x 131

unionrdr 08-17-2012 11:27 PM

Not tryin to stir things up again from last year,but the beer/kummel/buttershots demands it. :drunk: I noticed some 8 different formulas that all give different results. I guess a brewer should use the one his buzzed nurons say is right...:tank:

BrewKnurd 08-17-2012 11:41 PM

Quote:

Originally Posted by new2brew1221 (Post 4340214)
If I let a glass of beer warm to room temp, and the use the hydrometer will it tell me what % the beer is? I had someone ask me after I gave them a bottle.

So the best you could do would be to assume a middle of the road attenuation like maybe 72% and use that to estimate what the OG and therefore the alcohol was. But that would be a very rough estimate. Better than a total guess, but still could be well off.

For instance, a beer that finished at 1.012, if you assume 72% attenuation, OG would be 1.043, for an ABV of 4. But if the attenuation was really 65%, then OG is 1.034 and ABV is 2.9. On the other hand, if the attenuation was 80%, then OG was 1.060 and ABV was 6.3%.

Now, get yourself a liquid cromatograph or something like that and you'll be in business. ;)

bleme 08-17-2012 11:42 PM

Revvy's is the formula I have always seen.

The Coopers formula makes everything 5% or more. Take 1.000 water, ferment and it is still 1.000 water. Divide by 7 and it is still zero. Then add .5. That doesn't make any sense.

unionrdr 08-17-2012 11:46 PM

Not in my experience. I've used their formula & got 4.5% as well.

BrewKnurd 08-18-2012 12:00 AM

Quote:

Originally Posted by bleme (Post 4340314)
Revvy's is the formula I have always seen.

The Coopers formula makes everything 5% or more. Take 1.000 water, ferment and it is still 1.000 water. Divide by 7 and it is still zero. Then add .5. That doesn't make any sense.

Well, really it makes it 0.5% or more. I agree the result you get from water makes no sense, but not quite as badly as you have indicated. :D


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