Tool to measure abv?

[Smiling Frog]

See previous post.

You're previous post only talks about refractometer readings, not specific gravity readings, as quoted in post #47.

 

[rushpapers]

That's why I stated a % calculation.
Measure the volume (weighing) would be more accurate.
Take original % BY VOLUME, and calculate the change.
ABV is % alcohol diluted in beer. As you take it away density changes, but so does volume. Calculate the % loss.

But frankly it's going to be so small it's negligible.

 

[Birrofilo]

...and we know the effects of sugar and alcohol on the density of liquids. If we have our numbers we can calculate changes.

If you want to bang your heads against the wall, by all means.

You take alcohol away, you then have a new FG to calculate with.

It's that simple.

I could understand this being difficult if the OG was unknown.

And a refractometer would work as well.

Man, you should listen, and you don't listen. Stop a moment to think what we are saying.

One of the many formulas to derive alcohol from density is this:

% ABV = [(OGp - FGp) / 7,46]

The reason why the formula uses OG - FG is that it is sugar missing which lets you derive alcohol produced by that sugar.

If you take alcohol away, and your density rises, applying this formula your ABV goes down but that doesn't mean that this formula tells you the actual alcohol present. The (OGp - FGp) part has not any more the same significance, it will not tell you anymore the sugar consumed during the original fermentation.

 

[rushpapers]

No, as @Vale explained pretty clearly in post #52.

 

[Birrofilo]

That's why I stated a % calculation.
Measure the volume (weighing) would be more accurate.
Take original % BY VOLUME, and calculate the change.
ABV is % alcohol diluted in beer. As you take it away density changes, but so does volume. Calculate the % loss.

But frankly it's going to be so small it's negligible.

If the part which is subtracted by beer is collectible, and the relative percentage of alcohol and water is measurable in the subtracted part, then yes I do agree it could be possible to make some equation that calculates the alcohol present in the beer.

But you cannot eliminate alcohol without eliminating water as well if you use heat, therefore you cannot derive the ABV remaining in the kettle if you don't calculate the ABV of the evaporation (the product of the distiller).

But it's not easy method, one cannot simply take the FG and apply the old same formula.

 

[Birrofilo]

[Graph connecting the deviation alcohol creates in a sugar solution density measured by refraction index]

This is actually interesting and, thinking about it, it might be possible to:

a) Measure the density by the hydrometer;
b) Measure the density by the refractometer;
c) Knowing the real density, and observing the deviation between refractomer and hydrometer, one can infer how much alcohol there is because the deviation is due to the alcohol, and the more the deviation, the more the alcohol.

This might be the right solution to the OP problem. Actually I think it really is, and it's not that complicated after all. It will not be extremely precise because there is the old usual imprecision given by the fact that wort is not a real sucrose solution, but it should give a result which is only a few percentage points wrong.

 

[Smiling Frog]

{attachment removed}

rushpapers, where did this graph come from? Is there a way I can get the original paper?

 

[Birrofilo]

rushpapers, where did this graph come from? Is there a way I can get the original paper?

I found it here: EtOH to Brix and Measurement of %ABV

 

[Birrofilo]

The simple method should be:

Get the post-dealcoholization gravity of the beer with a hydrometer. Let's say it is 3,5 °Brix.
Get the post-dealcoholization gravity of the beer with a refractometer. Let's say it is 4,5° Brix.

Draw a line in the graph starting from 3,5 and keeping the line parallel with the other lines in the graph.
Draw an horizontal line in the graph starting from 4,5.
Where the two lines cross, the value on the abscissa gives the ABV in %.

Should be easy-peasy.

 

[VikeMan]

"attachment"

I see the three lines on that graph all have different slopes, which does not support the use of standard refractometer formulae to determine ABV after alcohol removal. How would you determine a slope to use for a particular beer? And even if that were easy, the refractometer ABV formulae wouldn't accommodate that anyway.

When you remove alcohol (and change nothing else), the refractometer reading decreases. Just as it would if some more extract had been removed, along with an increase in alcohol. The refractometer ABV formulae solve for the latter and not the former.

 

[Birrofilo]

The "method" outlined in my post #69 is not correct because the graph tells me the "added" alcohol by the refractometer, not the "added density". Should work more on it. It's possibly the right direction of investigation, though.

 

[Smiling Frog]

This is actually interesting and, thinking about it, it might be possible to:

a) Measure the density by the hydrometer;
b) Measure the density by the refractometer;
c) Knowing the real density, and observing the deviation between refractomer and hydrometer, one can infer how much alcohol there is because the deviation is due to the alcohol, and the more the deviation, the more the alcohol.

This might be the right solution to the OP problem.

This is likely to the way to a better determination of the alcohol content (likely better than the [OG-FG] method). A couple of problems, however. One, in step b), remember that the refractometer does not measure density. You cannot "measure the density by the refractometer."

One of my major complaints about the cheap hand-held Brix refractometers on the market is not that they are of poor quality or that they are not accurate, but they do not give you a reading of the property they are measuring. They measure the refractive index but give you a reading of % sucrose (or even more egregiously, a density reading). While (as best as I can determine) these values are correct when dealing with pure sucrose and water solutions, things change when you get to the real world.

I would change/redefine your method to:

a) Measure the density of the beer with the hydrometer to get an estimate of the % sugars present in the final beer
b) Measure the refractive index of the beer
c) Assuming the two major factors that affect the refractive index of the beer are the sugar content and the alcohol content, if the sugar content is known, the alcohol content should be able to be estimated.

 

[rushpapers]

This is actually interesting and, thinking about it, it might be possible to:

This is what I am looking for. Thanks.
I may not be completely right in my method, but am right that there is a simple method that can be done on paper.

I don't have the time to work it out for you in text, but it's not that hard.

You need to realize these are calculations, laws and constants. You can do this.

You don't need a fancy $2000 tool.

 

[Birrofilo]

This is likely to the way to a better determination of the alcohol content (likely better than the [OG-FG] method). A couple of problems, however. One, in step b), remember that the refractometer does not measure density. You cannot "measure the density by the refractometer."

I know. It should have read as "read the apparent density by the refractometer". The refractometer applies an internal look-up table to convert RI to the density of a syrup.

One of my major complaints about the cheap hand-held Brix refractometers on the market is not that they are of poor quality or that they are not accurate, but they do not give you a reading of the property they are measuring. They measure the refractive index but give you a reading of % sucrose (or even more egregiously, a density reading).

You can determine the RI by using the look-up table in the other direction.

I would change/redefine your method to:

a) Measure the density of the beer with the hydrometer to get an estimate of the % sugars present in the final beer
b) Measure the refractive index of the beer
c) Assuming the two major factors that affect the refractive index of the beer are the sugar content and the alcohol content, if the sugar content is known, the alcohol content should be able to be estimated.

Besides the "recalling" of my method, I think a) has a problem, that the % sugars present in the final beer is not entirely knowable even by a hydrometer reading, because the alcohol present is skewing (lowering) the density thus bringing to an underestimation of the sugar in the beer.

 

[Birrofilo]

I don't have the time to work it out for you in text, but it's not that hard.

You need to realize these are calculations, laws and constants. You can do this.

You don't need a fancy $2000 tool.

I agree it is probably possible to make an equation, but I don't agree that it is easy. This is a problem akin to the estimation of density of a beer with a refractometer with alcohol present. Proper mathematics might require an iterative calculation, or some very complicated equation.

 

[rushpapers]

As the percent alcohol in a solution is reduced, the volume, mass and therefore density will change accordingly. Ethanol has a constant density, which can be calculated into percentage loss.

 

[bracconiere]

well i see i must have been set to ignore....lol


but anyway....i just weighed out a known amount of 65% alcohol, with wood sugar and all in it.....added it to known amount of water....measured it BOTH with a hydrometer, AND refractometer....and the calculator to compare the two was pretty much spot on to what it should be.....


so YES, alcohol increases a refractometer, AND lowers a hydrometer...thus comparing the two, you can calculate ABV....assuming you're not trying to drink acetone or something, as long as it's just water, sugar, and ethanol....(i think anyway, just got my refrac, and having fun with it!)

 

[bobtheUKbrewer2]

Both hydrometers and refractometers are inaccurate for FG readings. But what does it matter ? It is consistently inaccurate. I aim to make 3.8% SMASH beers. Maybe they are REALLY 3.6% or maybe they are REALLY 4.2%. I have my recipe, I have my methodology, I like the end result.

The only way to determine ABV is in an accredited laboratory. In the UK breweries have to have their ABVs calculated accurately once a year. And it is not unknown for breweries to declare lower ABVs to pay less duty but supply beers that are 0.5% higher.

There are more things to worry about than the accuracy of measured ABV for home brewers.

Just get some nice beers brewed (make beer before the sun shines) because barbecue season starts in 21 days in southern UK.

 

[Vale71]

Both hydrometers and refractometers are inaccurate for FG readings. But what does it matter ?

To the OP it matters a lot since he plans to de-alcoholize his beers and needs a way to determine wether he was succesful or not. The fact that you don't care about ABV does not really help him.

 

[bobtheUKbrewer2]

ok - I personally do not know how to remove 100% alcohol, but I do know where to find out how much alcohol is left in the equilibrium solution. Will follow this thread carefully.

 

[bracconiere]

well i just performed an experiement....i poured a glasses worth of beer in a sauce pot and put it in the oven for 45 minutes at 170f....

it was a known beer of OG 1.066, FG of 1.003....Brix for it before the oven 7 or so....brix after then oven 6...and the hydrometer reading after the oven was 1.012....so 45 minutes in the oven took it from a bit over 8% to about 4%......

 

[VikeMan]

well i just performed an experiement....i poured a glasses worth of beer in a sauce pot and put it in the oven for 45 minutes at 170f....

it was a known beer of OG 1.066, FG of 1.003....Brix for it before the oven 7 or so....brix after then oven 6...and the hydrometer reading after the oven was 1.012....so 45 minutes in the oven took it from a bit over 8% to about 4%......

What formula did you use to determine this? As far as I know, nobody has derived one yet. And the standard hydrometer/refractometer formulae will not work for this, for reasons already discussed ad nauseum.

 

[bracconiere]

What formula did you use to determine this? As far as I know, nobody has derived one yet. And the standard hydrometer/refractometer formulae will not work for this, for reasons already discussed ad nauseum.

i used the one in beersmith....Tools/Refractometer/Original Gravity.....


it worked for a beer i double checked it with....and when i diluted a know amount of known 65% whisky in a measured amount of water...i think it works pretty good....


so far within a half percent right? i'll keep f'n around with it, it's really the only reason i got a refractometer.....

edit: i'm not talking about the correction FOR FG using a refractometer....i'm talk about the one to figure alcohol content? i may be wrong, but like i said so far it's a pretty cool trick....

 

[VikeMan]

i used the one in beersmith....Tools/Refractometer/Original Gravity.....

That won't work. The reasons are in the thread.

it worked for a beer i double checked it with....and when i diluted a know amount of known 65% whisky in a measured amount of water...i think it works pretty good....

That's a different problem, uncomplicated by the presence of unfermented dextrins/sugars that the standard formulae work for in a normal fermentation, but not when alcohol is removed without replacing extract.

 

[bracconiere]

That's a different problem, uncomplicated by the presence of unfermented dextrins/sugars that the standard formulae work for in a normal fermentation, but not when alcohol is removed without replacing extract.

but then why after i left the beer in the oven at 170f for 45minutes, did the brix go down 1 on the refractometer, and the hydrometer went from 1.003 to 1.012? seems pretty solid?

it resulted in the calc saying it went from 8 something percent to 4 or so...which i find believable?

 

[bracconiere]

well i want know FOR SURE....so like should i add whiskey to water....compare then add sugar and check if it's the same ABV calculated?


because i know my proof trales hydro doesn't work once it's aged on wood for a while....

 

[VikeMan]

@bracconiere, sorry I don't know how to explain it other than what I wrote in posts 59 and 70. But to try to summarize one last time... the hydrometer and refractometer ABV formulae both rely on the estimated relationship between sugar lost (fermented) and ethanol gained. If you increase or decrease ethanol without decreasing/increasing the corresponding (exact) amounts of sugars, the relationship falls apart, which makes the answer meaningless.

 

[bracconiere]

well @VikeMan , i just tried it with 84 grams of my known 65% 18 year old brandy....added water up to 250grams..... got 6 brix and well i'm guesstimating around .970 hydro reading told me 15% alcohol by weight, which is pretty accurate.....and then i dumped a bit out so i could fill it with an extra ounce of sucrose.....and then i got a hydro of 1.009 or so, and a brix of 14.....which gives me about 13% by weight which is good enough for my uses.....figureing into account the loss for what i dumped and all...

edit: i did put my proof trales hydro in it, and it read 40 proof....so that kinda confirm my guess at my other hydro that only goes down to .990......because it was lower....

(i am trusting this to my waist line, so don't want to gain a 100 pounds because it doesn't work? lol but so far i'm satisfied it does )

 

[bracconiere]

When you remove alcohol (and change nothing else), the refractometer reading decreases.

i just looked at your post #59 and #70.....read this but as the refractometer goes down due to less alcohol...the hydrometer goes up, thus comparing the two and using the calc works? because as the refrac goes down, the hydro goes up?

 

[bracconiere]