Want to borrow refrac

[n87]

Hey guys,

I am planning an eis-bock in the coming months (have the dublebock lagering now), and would like to borrow a refrac when its finished so I can determine the final % (comparing refrac and hydro values).
This would likely be next weekend~ish, and it would be awesome to have someone local that could lend it to me..

Let me know if you can help me out, thanks
~n87

 

[Pnutapper]

If you have any problems getting hold of one locally mate, give me a whistle, I will mail mine to you with a return satchel.

 

[evoo4u]

The presence of alcohol in the liquid being tested will distort the results. There is a formula which can be applied to a refrac reading, but it requires an initial (unfermented) refrac reading.

EDIT: Unless I've misunderstood what you want it for...

 

[n87]

The presence of alcohol in the liquid being tested will distort the results. There is a formula which can be applied to a refrac reading, but it requires an initial (unfermented) refrac reading.

EDIT: Unless I've misunderstood what you want it for...

From my understanding, comparing the hydro and refrac results (and doing fancy maths stuff) you are able to work out the current ABV.
Considering I would have taken a qty of water and other substances (including some alc by all reports) I dont know the adjusted OG and therefore ABV

If you have any problems getting hold of one locally mate, give me a whistle, I will mail mine to you with a return satchel.

Thanks heaps, I know a couple of locals have them, but will keep you in mind.

 

[mr_wibble]

You're welcome to borrow mine, but it will be a 45 minute drive.
We come down to Tuggerah occasionally, so we could meet somewhere too.

If I understand your problem correctly, you should only need a the hydrometer for this.
The OG remains constant, and post-fermentation freezing & ice-removal becomes an alcohol concentration process.
However it's still only adjusting the water/sugar/alcohol mix, and thus changing gravity of the final product.

So it's still just FG, and the hydrometer can handle it.

 

[n87]

You're welcome to borrow mine, but it will be a 45 minute drive.
We come down to Tuggerah occasionally, so we could meet somewhere too.

If I understand your problem correctly, you should only need a the hydrometer for this.
The OG remains constant, and post-fermentation freezing & ice-removal becomes an alcohol concentration process.
However it's still only adjusting the water/sugar/alcohol mix, and thus changing gravity of the final product.

So it's still just FG.

Thanks. Will see if I am in the area any time soon.

By removing the ice, the ABV changes, and while the OG technically does not change, you are unable to use the measured OG to work out the new ABV with a hydro.
My reading also indicates that the ice does not include only water, so a simple calculation on the amount removed doesnt help either.
This is mainly for curiosity and completeness, I know the ABV will be in the 9-15% range, but it would be good to know what i did end up with.

 

[Lyrebird_Cycles]

From my understanding, comparing the hydro and refrac results (and doing fancy maths stuff) you are able to work out the current ABV.

None of the published algorithms work well because they do not take into account the changing ratio of refractive index to density with the average molecular weight of the remnant wort solids (from about 104% with an average unfermented wort to around 95% for an average fermented wort).

The other problem you will have is that the precision available from an ordinary refractometer / hydrometer combination is only sufficient to get you to about +/- 1% ABV. With a good digital refrac with 0.1 oP precision and a density meter or precision hydrometer* you can get +/- 0.5% ABV.

To get better precision you'll need a refractometer capable of reading to the equivalent to 0.02 or 0.01 oP, a density meter with similar precision and an updated algorithm.


* Lab grade hydrometers are much larger than the standard sort, generally about 300mm long and will come with a calibration certificate and a substantial price tag.

 

[Lyrebird_Cycles]

The OG remains constant, and post-fermentation freezing & ice-removal becomes an alcohol concentration process.

That would be true if and only if the ice removed was pure water. Unfortunately this isn't possible in practice, what you will be able to separate is a slush with higher water content than the parent but with some alcohol and dissolved solids still present.

 

[n87]

Thanks LB.

Any measurement would be better than a guess anyway, its not like I am going to have to pay excise on every drop of alc. A +-1% measurement would be better than a +- 5% guess

I did just buy myself a lab grade (Brennan) 1.000-1.100 hydro tho

 

[Lyrebird_Cycles]

From my understanding, comparing the hydro and refrac results (and doing fancy maths stuff).

Within the limits noted above, the maths involved are not fancy.

(oP(refrac) - oP(hydro)) * 1.36 is as good as anything available.

I am currently trying to get hold of a refrac capable of 0.01 oP precision. When I do I will repeat the lab work I did at Hawker's last year comparing a range of algorithms against the values generated by an Anton Paar alcoliser and see if we can get better precision.

 

[n87]

Within the limits noted above, the maths involved are not fancy.

(oP(refrac) - oP(hydro)) * 1.36 is as good as anything available.

I am currently trying to get hold of a refrac capable of 0.01 oP precision. When I do I will repeat the lab work I did at Hawker's last year comparing a range of algorithms against the values generated by their Anton Paar alcoliser and see if we can get better precision.

Shhhh.... if you let them know the maths is easy everyone will do it!

Will be curious to see your results when you get a chance to do the experiment.

 

[Lyrebird_Cycles]

With the last lot using the best algorithm I developed we got an error range of +/- 0.2% ABV and an average of 0.1%.

I am slightly suspicious of this result: it may simply be the case that I shaped the algorithm to the available data, given that the precision of the refrac is only +/- 0.1 oP (the densitometer is +/- 0.01 oP) and the algorithm relies on the difference between two values so relative errors are increased.

More research needed.

 

[gone brewing]

If you take the ice that you remove and let it melt then check the SG, would that tell you how pure the water is? If you have pure water, or close to it, could you then make an adjustment to your OG, so that the measured OG is adjusted to account for that amount of water not being in the wort at the start of fermentation? This adjusted OG, with your FG, could then be used to calculate the alcohol concentration.

It'd be ballpark.

 

[Lyrebird_Cycles]

No, because you won't know how much alcohol is in the meltwater. If you could measure that the whole procedure would be unecessary.

 

[Lyrebird_Cycles]

Or you could distill the original beer, make the distillate back up to correct volume with distilled water and measure its gravity. (That's the ASBC reference method for alcohol BTW)

 

[gone brewing]

Or you could distill the original beer, make the distillate back up to correct volume with distilled water and measure its gravity. (That's the ASBC reference method for alcohol BTW)

Absolutely! But you need a really special (precise) set of hydrometers to do that accurately. I was just suggesting something a bit rough and ready with a solution that I would expect to be fairly low in alcohol. Unfortunately n87 only mentions having a hydrometer with a 1.000-1.100 range (maybe he has simplified this comment a little and it might go a bit lower, like my Big W hydrometer does).

I'm just keen to see how much, if any, alcohol gets frozen in the ice.

 

[barls]

Or you could distill the original beer, make the distillate back up to correct volume with distilled water and measure its gravity. (That's the ASBC reference method for alcohol BTW)

we don't talk about this on here. last comment about it.

 

[Lyrebird_Cycles]

I'm just keen to see how much, if any, alcohol gets frozen in the ice.

The alcohol itself doesn't get frozen but the ice that is removed is slush which contains a lot of liquid which contains alcohol and dissolved solids.

FWIW I once spent a lot of time and money on developing an alcohol concentration system using a freeze thaw process because it is less energy intensive than distillation (the entropy of vaporisation is much higher than the entropy of solidification). It was designed around a very expensive piece of gear that produced high purity ice but carryover of alcohol into the solids removal stream was still a problem.

There is no way you will get anything close to quantitative recovery using a home system and without quantitative recovery you can't trust any measurement derived so the scheme is useless..

 

[Lyrebird_Cycles]

we don't talk about this on here. last comment about it.

I have no idea what that means.

 

[barls]

as per the forum rules we don't talk distillation. any further will be removed and points awarded.