Specific Gravity & Alc %

[knightt]

I purchased one of the specific gravity floats (for light fluids) and another for heavy. It does not have the % Alc on it. It measures in specific gravity.

How do I do the calculation to give me the % Alc? After I have distilled my batch?

On a personal note, I am really looking forward to my first batch. I just picked up a bunch of supplies to make a still. I am making the tubeing modular so depending on the tube you attach it moves from being a pot/reflux/fractionating. One could also put a jar in the middle for botanicals. I am making the reflux attachment first.

Thanks

Brendan

[pHneutral]

This table is a bit small, but it has what you need on it. Zoom in on it and you should be all set. It goes all the way from 1.00 to 0.793

http://journeytoforever.org/biofuel_lib ... fig5-3.jpg" onclick="window.open(this.href);return false;" rel="nofollow

and the correction table for temp is here

http://journeytoforever.org/biofuel_lib ... fig5-4.jpg" onclick="window.open(this.href);return false;" rel="nofollow

[rad14701]

Modified versions of those tables can be found elsewhere here in these forums... Someone went to the trouble of recreating them from scratch... Perhaps they will post internal links here...

[SuperDavid]

according to my beer brewing handbook......you find the difference between your sg and your fg and divide it by 7.36.

[HookLine]

Modified versions of those tables can be found elsewhere here in these forums... Someone went to the trouble of recreating them from scratch... Perhaps they will post internal links here...

I did one of them a while back, just a straight copy in larger text.

Specific Gravity of ethanol at 60ºF (15.55ºC).png

[Husker]

according to my beer brewing handbook......you find the difference between your sg and your fg and divide it by 7.36.

This is how you determine the ABV of a wash/mash. The other spreadsheet of numbers simply tells you the % ABV of a mix of pure water and pure EtOH.

There are different hydrometers which measure each of these types of problems. The one that SD mentions, is used to compute ABV of a beer/wine to determine how much sugar has been converted into EtOH. The other links provide (and sheet inline uploaded), are of the same 'scale' as a alcoholmeter is set to test. In that form, you are only able to test a distilled spirit which has had no other things, such as sugars or juices added.

Since knightt originally asked this question:

How do I do the calculation to give me the % Alc? After I have distilled my batch?

it is obvious that a simple alcoholmeter is the proper tool (that along with a thermometer). However, if he has hydrometers that are simply calibrated in SG readings (SG of distilled water being 1.00), then he can obtain the actual SG reading (and temp), and use a lookup table (along with correction for temp), and come up with the same result as an alcoholmeter would give. The only thing an alcoholometer is, different than a hydro, is that it has a 'scale' that has 0 ABV at the bottom, and 96 ABV at the top (or possibly some other smaller range for more accurate units).

H.

[SuperDavid]

oops...must have been half a sleep when I read the question.

[knightt]

Thanks.

The chart really helps!

Brendan

[knightt]

Figured out the formula.

So, Water at 20 degrees is .99823 ethanol is .78934

A mixture of 1part water and 99parts ethanol would look like (.99823/100*1+.78934/100*99) = .7914289

hmmmm. Now to figure the formula to a start with a sp and "know" the alc %. ok.

Got mathematically inclined a friend to help me.

Water% = (SG - 0.78934)/0.20889

I think I might be able to make a single formula to figure alc %.... Maybe not.

One could probably drop a couple of the decimal points and still come up with an accurate number.

These numbers are calibrated at 20 degrees.