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ABV' changes during run

ABV' changes during run

Postby bigfoot » Mon Jun 22, 2015 6:49 pm

Hi,
Just had a rather strange experience.
I ran a feints(collected heads and tails) run thru the reflux (essencia).
The wash was 40% and 25 litres.

When I started running, I threw 50mls foreshots and collected heads. I tested abv and it was as per normal, around 88%. I though damn, I turned up water flow to increase reflux and as expected, it jumper to 91% but the rate it was coming out was too slow. So I dialled back the water and got a steady stream at 86-88%. I thought, stuff it - ill run it at that.
Collected another 600ml and then took abv...weird, it jumped to 90%.
A litre later - it was at my highest ever - 93/94% abv at a very good stream. I was fascinated.
It stayed here for over an hour and did not drop off for several more litres. Even after I'd collected some 5+ litres, it had only dropped to 89% - I was amazed. Normally - my abv is highest in the first 1 litre and then slowly drops, this was low, then crept up, stayed up and ever so slowly dropped off.
So my question - with reflux runs, at what point of collection is generally the highest abv point? Or are all stills different in this regard?
Bf.
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Re: ABV' changes during run

Postby JayD » Mon Jun 22, 2015 7:05 pm

Don't forget your starting abv was 40% so you are going to stay in the vinegar stroke for much longer than usual...so at 40% abv should have collected 40% of your total charge including fores,heads hearts and tails... :handgestures-thumbupright: if your charge was 50 ltrs at 40% you should get just under half your charge back overall.
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Re: ABV' changes during run

Postby Maheel » Mon Jun 22, 2015 8:51 pm

what was your time line like ? how many mins in complete reflux or did you just adjust water flow and then begin measuring % etc

your ABV may go "up" if you slow down your off take and allow more reflux.
especially if to begin you were not getting a lot of reflux going on

I reckon this has happened here
your still has been "equilizing" as it has been running and the ABV has increased due to reflux action
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Re: ABV' changes during run

Postby bigfoot » Mon Jun 22, 2015 9:35 pm

Hi MH, I didnt put it into full reflux, it's a CM style, super reflux...(yes, I know - it's being replaced soon)
It took 5.5 hours not inc warm up.
Once I had a decent stream flowing(toothpick), and it was at 88 - I left it alone for the entire run.
That's why it was so surprising to reach the highest abv, some 2 hours into a run...
Bit weird to be honest. Perhaps a colder water came through the tap...I dunno
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Re: ABV' changes during run

Postby kimbodious » Wed Jun 24, 2015 12:33 am

How long should we keep the column in complete reflux Maheel? I take it we need to do that to compress the heads? So you are suggesting Cousin Bigfoot was still in Heads with the 88% ABV when he thought he should have been in the Hearts, and that is because the Heads had not been compressed by having the column in complete reflux?
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Re: ABV' changes during run

Postby Maheel » Wed Jun 24, 2015 4:53 pm

i am not certain but i thought it might have started to reflux "more" over time and push up the % offtake like has been described

maybe the high low wines 40% may have alowed this to happen ?

it's my only explanation without actually seeing happen hands on :?

with my VM and past BOKA's i would always fully reflux for 30mins or so to compress heads somewhat.
some say they go longer full reflux but each to their own i reckon (and whatever works for you)
i strip then do spirit runs mostly with TPW
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and associated shed filling stuff......
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Re: ABV' changes during run

Postby kimbodious » Wed Jun 24, 2015 10:03 pm

Thanks Maheel, I'll give 30 mins of full reflux a crack next run.
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