science question here about drop in proof

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science question here about drop in proof

Postby jon1163 » Mon May 14, 2018 9:59 pm

I've noticed it in every single one of my runs regardless of what I'm running, neutral, All Grain, sugar head, Etc, that my proof starts off in the first jar just a hair lower then my early heads then I get the typical drop-in proof over the duration of the run.

Here's a typical strip run example for me:
jar#-ABV
1-64
2-65
3-63
4-62
5-60
6-60
7-59
8-55
9-50
10-48
11-45
12-40
13-35
14-30
15-22
16-15

Why is the initial jar almost always a hair lower than my early heads?
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Re: science question here about drop in proof

Postby der wo » Tue May 15, 2018 1:08 am

Did you correct the temperature? Normally the first jar is much colder, because probably the condenser is oversized for such a slow distillate flow. If you have 15 instead of 20°C, your 64% are in reality 66%.
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Re: science question here about drop in proof

Postby bilgriss » Tue May 15, 2018 2:49 am

Is the first jar cloudy?
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Re: science question here about drop in proof

Postby jon1163 » Tue May 15, 2018 7:01 am

bilgriss wrote:Is the first jar cloudy?
no. clear as day
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Re: science question here about drop in proof

Postby jon1163 » Tue May 15, 2018 7:01 am

der wo wrote:Did you correct the temperature? Normally the first jar is much colder, because probably the condenser is oversized for such a slow distillate flow. If you have 15 instead of 20°C, your 64% are in reality 66%.
no I didn't. I'll drop a thermometer in next time. thanks
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Re: science question here about drop in proof

Postby bilgriss » Sat May 19, 2018 9:36 am

If it's clear, I second der wo's answer. It's temperature related.
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Re: science question here about drop in proof

Postby JellybeanCorncob » Sat May 19, 2018 10:21 am

There is an app for that! :roll:
It’s called “Whiskey Systems”.
At least on the IPhone. Plug in the ABV and temp. Boom! Correct proof!
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Re: science question here about drop in proof

Postby zapata » Sat May 19, 2018 11:36 pm

Or theres enough non ethanol non water stuff in the first jar to depress it?
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Re: science question here about drop in proof

Postby Kareltje » Sun May 20, 2018 2:23 pm

I observed the same effect. Not always, but regularly. Didn't pay much attention, though.
Some causes I pondered:
- a rest of tails in the condenser
- some light substances in the fores
- I also saw sometimes some cool vapour coming fron the condenser, far before the run started

Now you mentioned it, I thought about it again.
- It can not be caused by differences in temperature: today I stripped a rum wash with my thumper and measured the samples after standing side by side for 3 hours on my table: 73, 74.5, 70 %ABV.
- It can not be the nasties in the fores, as their sg is about 0.8 to 0.9 kg/l

I think it might be caused by the speed.
I have a riser of only 13 mm ID, which of course is thin and causes a relatively high vapour speed. In heating up I use full power, which in my case is about 1.3 kW. During running I can only use about 0.6 kW, as I have a air-cooled condenser.
I think that, when I don't slow down soon enough, the vapour rushes through the riser, arm and condenser without much time to deposit some condense. While it is subject to (passive) reflux when I run slow/with low energy.
This passive reflux can be caused by running slow, but also by a boiler that has a lot of free space or is not insulated.

So I guess it is a matter of behaviour. I plan to run two runs the next two days and try this idea.
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Re: science question here about drop in proof

Postby der wo » Mon May 21, 2018 1:48 am

Does anyone using a thermometer in the vapor path recognizing this too?

I never measure the abv of my fractions, at least not at the beginning of the run. I never saw a drop of the temperature at the beginning of the run. So I always thought, the abv is dropping constantly.

The "nasty" ethylacetate has a SG of 0.894. In theory it could be the reason for this bahaviour, because ethanol has 0.789. But in practice I think the amount of ethylacetate is not enough.

Acetaldehyde is a bit lighter (0.784). Perhaps this is the cause of your vapor? It has a boiling point of only 20°C. Once unleashed from the wash, this low boiling point should have the effect, that it is very difficult to condense again. The vapor should smell like apples, if it's acetaldehyde.
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Re: science question here about drop in proof

Postby Kareltje » Mon May 21, 2018 2:04 pm

I agree with your judgment that the nasties are only present in too small amounts to cause this effect.
I did not smell the nothot vapour coming from the condenser, but it reminded me of something I also observed: when heating a pan of water to about 60 dg C there is not much vapour coming from it. But when I turn down the heat, the vapour suddenly rises. There must be a good explanation, but I don't know it.

Today I reproduced the effect mentioned in the OP. I had 4 ltrs of 34 %ABV in a 10 L boiler, used a very long, thin riser (13 mm ID, 300 cm long) and slowed the heating down when the vapour reached the top. Took samples of 100 ml and measured: 85.5, 91.5 and 93 %ABV.

I was planning to do a comparing run tomorrow, but a friend swallowed some needles of Taxus, so I may have to look after her dogs.

Some people just can not keep their mouths shut! :evil:
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Re: science question here about drop in proof

Postby der wo » Tue May 22, 2018 1:14 am

Kareltje wrote: when heating a pan of water to about 60 dg C there is not much vapour coming from it. But when I turn down the heat, the vapour suddenly rises. There must be a good explanation, but I don't know it.
Perhaps because there doesn't rise hot air from the hotplate or burner anymore, the vapor condenses?

Today I reproduced the effect mentioned in the OP. I had 4 ltrs of 34 %ABV in a 10 L boiler, used a very long, thin riser (13 mm ID, 300 cm long) and slowed the heating down when the vapour reached the top. Took samples of 100 ml and measured: 85.5, 91.5 and 93 %ABV. No measurements with a vapor thermometer?
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Re: science question here about drop in proof

Postby Kareltje » Tue May 22, 2018 4:36 pm

der wo wrote:
Kareltje wrote: when heating a pan of water to about 60 dg C there is not much vapour coming from it. But when I turn down the heat, the vapour suddenly rises. There must be a good explanation, but I don't know it.
Perhaps because there doesn't rise hot air from the hotplate or burner anymore, the vapor condenses?
Good point. But the pan is much larger than the burner. Both in horizotal and in vertical size.

Today I reproduced the effect mentioned in the OP. I had 4 ltrs of 34 %ABV in a 10 L boiler, used a very long, thin riser (13 mm ID, 300 cm long) and slowed the heating down when the vapour reached the top. Took samples of 100 ml and measured: 85.5, 91.5 and 93 %ABV. No measurements with a vapor thermometer?
Yes, 83, 81.5 and 81 dgr C, on top of the still and taking into account, that this thermometer points about 2.5 dgr too high. So the real temperatures would be 80.5, 79.0 and 78.5 dgr C.

But that is all peanuts: I easily reproduced the obervation of topic starter.
Which is: the %ABV of my first sample is lower than the %ABV of my next sample.
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Re: science question here about drop in proof

Postby der wo » Wed May 23, 2018 2:02 am

Ok, when at the same time the abv rises and the temp drops, it's probably reflux. When using a reflux still, there is always this effect, that at first the temp jumps to 80°C for example and then slowly drops down.
My potstill has a very short riser. So I have almost no reflux. Probably this is why I don't know this.
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Re: science question here about drop in proof

Postby butterpants » Wed May 23, 2018 9:34 am

der wo wrote:Did you correct the temperature? Normally the first jar is much colder, because probably the condenser is oversized for such a slow distillate flow. If you have 15 instead of 20°C, your 64% are in reality 66%.
This.
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Re: science question here about drop in proof

Postby Kareltje » Sat May 26, 2018 12:51 pm

Yesterday I ran another spirit run. After a slow start I by accident added too much gas, so I made a rather fast start, but I kept it steady this time.
I meaured today, so all the samples had the same temperature. The samples of about 100 ml showed: 86 %, 87++ %, 87+ %.
I noticed that the first drop came when 3.5 windings of my 9-wind air condenser were hot, when I took the first sample 7.667 windings and when I took the second sample more than 9 windings were hot. So during the first sample the vapour was still crawling forward and only after the second or third sample the cooling capacity was used fully.

I will try to make an even slower run.
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Re: science question here about drop in proof

Postby jon1163 » Sat May 26, 2018 5:08 pm

I appreciate the work in trying to figure this out. I'm perplexed.
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Re: science question here about drop in proof

Postby still_stirrin » Sat May 26, 2018 8:18 pm

jon1163 wrote:I appreciate the work in trying to figure this out. I'm perplexed.

It is not so perplexing really.

At the start of your reflux run, you’ll get some foreshots, components with a high volatility (higher than ethanol). Those constituents include acetone (784 kg/m3), acetaldehyde (788 kg/m3), and ethyl acetate (902 kg/m3), among others.

And with ethyl alcohol (789 kg/m3), you can see that the “potential” exists for the heads to actually have a slightly higher density than your “pure” ethanol hearts. And in certain washes, the proportion of ethyl acetate (fingernail polish remover) is high, making the hydrometer (Proof & Traille) rise slightly at the start when the heads are coming out, and then sink as you get to the lighter (less dense, not less volatile) constituents.

I have experienced this phenomenon when running neutral spirits with very high proof off still. The foreshots (the real stinky fingernail polish remover stuff) often measures a “lower proof” than the next jars as I progress into the heads, late heads, and into the early hearts. The measured proof will rise after the initial foreshots jar is pulled. I’ve measured fores at 92%ABV and 93%ABV only to have the following jars measure up to 96%ABV, with all of the jars temperature corrected and stabilized.

There...an explaination for you.
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Re: science question here about drop in proof

Postby der wo » Sun May 27, 2018 12:04 am

still_stirrin wrote:At the start of your reflux run, you’ll get some foreshots, components with a high volatility (higher than ethanol). Those constituents include acetone (784 kg/m3), acetaldehyde (788 kg/m3), and ethyl acetate (902 kg/m3), among others.

And with ethyl alcohol (789 kg/m3), you can see that the “potential” exists for the heads to actually have a slightly higher density than your “pure” ethanol hearts. And in certain washes, the proportion of ethyl acetate (fingernail polish remover) is high, making the hydrometer (Proof & Traille) rise slightly at the start when the heads are coming out, and then sink as you get to the lighter (less dense, not less volatile) constituents.

Sounds plausible. But Kareltje also measured the same behaviour with his vapor thermometer. He measured a higher temp at the foreshots. With a long riser. This sounds more like a rectification effect.
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Re: science question here about drop in proof

Postby Kareltje » Sun May 27, 2018 1:55 am

Yes, indeed: it sounds plausible. And maybe the condenser is not entirely dry when you start, so a bit of tails from the previous run might be involved. That is why I never thought about it.
But now I think there is a bit more to it.

Test temperatuur.jpg

At the lowest energy the vapour did not rise, so at 15:10 I speeded it a bit up. (More than I intended, but next time I will be more cautious!)
At 15:25 the vapour reached the thermometer. The degrees are dgr Kareltje, i.e. about 2 dgr C higher than the real temperature! But the point is the comparison!
The thermometer is at the top of the still, so before it the condens will flow backwards towards te boiler and after it the condens flows forward towards the receptacle. Each winding of the condenser is 85 cm long and its volume is 113 ml. When the front of the vapour reached the outlet, I had to cool the last two windings with a damp cloth.
Of course a reading of .3 in the temperature or % is not exact, but as I said: the point is the comparison of successive samples.
Oh, by the way: the first samples did not smell very terrible, so the amount of nasties was not very high.
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Re: science question here about drop in proof

Postby der wo » Sun May 27, 2018 2:04 am

Last time you had 83---81.5---81°C, the temp went down.
This time 83.5---84---84---84.3°C, the temp went up.
But both times rise in abv.
:think:
Do you have an idea, why?
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Re: science question here about drop in proof

Postby Kareltje » Sun May 27, 2018 3:51 pm

der wo wrote:Last time you had 83---81.5---81°C, the temp went down.
This time 83.5---84---84---84.3°C, the temp went up.
But both times rise in abv.
:think:
Do you have an idea, why?

First time I tried to start fast and then slow down, in which I succeeded. Just like someone heating up his mash and then, after reaching the boiling temperature, slowing down to distilling pace.
Second time I tried to start slow, but the heat was not enough to fill the riser, so I stepped it up. A bit too much, but I decided to keep it steady.
No, I have not really a solid idea. While collecting the first and second sample, the hot vapour kept on filling the volume of the condenser.
There is something about vapour speed and temperature and vaporizing speed, but I am still trying to get my head around it.

Something I noticed, that might be related: when I put wet rags on the first windings of my cooler, the temperature on the top seems to diminish a bit. As if the forced cooling some 50 cm downflow from the thermometer lowers the temperature on the top. But I can not measure temp and %ABV on that scale. :evil:
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Re: science question here about drop in proof

Postby Antler24 » Sun May 27, 2018 7:26 pm

I've noticed this on most of my runs as well. I also don't think it's temp related at I sometimes didn't check the ABV of the jars until I did the cuts a few days later. These days I only check ABV after cuts blending.
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Re: science question here about drop in proof

Postby Kareltje » Sat Jun 02, 2018 3:40 pm

Another run: 5.5 l of about 6 % ABV in a 10 L boiler, about 20 cm pipe of 13 mm ID to the thermometer and then 13 mm ID lynearm and my aircoolerd condenser.
I ran at lowest possible energy and from start of boiling (judging by tinkling of the copper boiling stones) to 78 dg it took 15 minutes. Then 10 min later I got the first drops, while almost 3 windings @ 85 cm of the cooler were hot and the thermometer showed 88.5 dg. (Degrees Kareltje2, not any known scale!) From that moment on the temperature slowly rose, while the hot stretch of the cooler was extendend to about 3.75 to 4 windings.
First 2 samples were less than 50 ml, so I had to dilute them to measure the %, but it seemed the first samples were 41, 47 and 48.5 %. At about 100 ml in 20 minutes.

I think another observation may be related. When running a boiler and a thumper I found that the temperature from boiler to thumper could get as high as 102 dg C, even when there had to be some alcohol in the vapour. After turning the heat down the temperature would diminish to about 100 dg C. The level of the fluid in the thumper was not more than 20 cm, i.e. 0.002 bar.

And another observation: a droplet of sweat from a coupling before the surrounding pipes were hot! So far before any hot vapour reached it.
(By the way: these sweats contain hardly any alcohol!!)

I can not get my head around the problem, but running very slowly does not seem to diminish the problem.
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Re: science question here about drop in proof

Postby Kareltje » Sun Jun 10, 2018 3:25 pm

It seems to me that the speed of the vapour and the amount of cooling are dominant factors.
When you bring a 10 %ABV wash to the boil, the vapour is about 54 %ABV. This vapour rises from the surface, meets cooler things and starts to condens. The first drops of condens are not 54 %, but only 10 %! Leaving a stronger vapour in the air.

Now if this condens flows back to the boiler or forward to the outlet will make a difference to the product.

I have a still with 13 mm ID pipes all the way from lid to outlet. I can change the highest point back and forward.
When the lid is hot, I set the fire on minimum and leave it there. The front of the vapour then slowly crawls upward. Of course: when this front hits the thermometer on the top, the temperature goes whoosh from 30 dg C to over 80 or so. The front of heath then moves on, until it reaches a steady position. The condens follows some minutes later.
It seems to me, that the lowest %ABV of the condens is collected when the vapourfront reaches the top. Then, as long as the vapour front is moving forward, the collected %ABV is rising.

For example: I had a pot still setup, so very soon the vapour reached the top, started to condens and it took 3 samples to both reach the farthest point of the vapourborder and the highest %ABV.
Next run with my longneck of 3 m: took some half hour to reach the top and already the second sample had a higher ABV.

But I see no explanation: only 13 mm inner diameter. And about 100 ml condensate per 10 minutes.
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Re: science question here about drop in proof

Postby Kareltje » Sat Aug 18, 2018 12:43 pm

Still chewing on the question.
Yesterday and today I tested two versions of my 1 L ginbox: one empty, which means it forms a layer of fluid on the bottom, almost 1 cm high and one with a small cup placed upside down over the entrance, making it a small inline thumper. Height of the fluid was about 2 cm.
In both cases I am not really sure the condenser was dry before I started: some tails of the former run might linger inside.
Started fast at start up, at first drops minimizing to running as slow as I can: 379 W, about 100 ml per quarter of an hour.
Samples of about 100 ml:
run 1: 65.5 %, 67 % and 66.5 %
run 2: 65 %, 67.3 % and 68 %. Judging by the sound between sample 2 and 3 the thumperfunction started.

So this made me pose a hypothesis:
The first amount of vapour flows fast without condensing unto the condenser.
Later amounts partly condense on their way up, and as the condense is of low %, the remaining vapour has a higher % than the vapour leaving the boiler. This effect is enhanced by the thumper effect, small as it may be.

Can anybody test this? Or device a test.
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Re: science question here about drop in proof

Postby LWTCS » Sun Aug 19, 2018 4:10 am

What are your typical cooling medium temps for this behavior?
And are your flow rates consistent?
Also how close is your temp probe positioned to the RC?

Oh wait,,pot stilling or column?

Edit: ah, after re reading I see the OP pulled ABVs on liquid product.
My question was more in line with the reference to vapor temps.
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Re: science question here about drop in proof

Postby Kareltje » Sun Aug 19, 2018 5:16 am

LWTCS wrote:What are your typical cooling medium temps for this behavior?
And are your flow rates consistent?
Also how close is your temp probe positioned to the RC?

Oh wait,,pot stilling or column?

Edit: ah, after re reading I see the OP pulled ABVs on liquid product.
My question was more in line with the reference to vapor temps.

Good questions!
I cool with air, so it depends on the weather, but at least fairly constant during a run. Problem might be the long cooling coil of about 8 m length. This causes some delay and maybe smearing during condensing, cooling and take-off. And maybe drops of the last tails.
I try to set my valve way before the first drop. Only the first of the two runs it took me by surprise, so I copied my behaviour in the second run.
My temp probes are several meat thermometers, which are all off about 1 or 2 dg C plus or minus. But I do not use them for decisions.

Several. I made a series with different columns: 3 m, 2 m and 20 cm. The last one making it (almost) a pot still. Only the pot still showed the highest % in the first sample, the other showed the highest % in the second sample.

Do not really have a solid idea about this effect, but I see it a lot of times.
Chewing long enough will give the answer, I guess.
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Re: science question here about drop in proof

Postby LWTCS » Sun Aug 19, 2018 10:16 am

Ah ok. It doesn't sound like what I was initially thinking.

And that was that if coolant temps (or perhaps flow) were too,,,cool, it is possible to knock vapor down so rapidly that it causes a vacuum and temps will drop in and around where the vacuum is initiated. You've probably seen that demonstration on YouTube?

Well to continue, if your temp probe is located too close to this vacuum occurrence, the vacuum created can distort temp/abv relationship if you see my meaning? Temps drop but ABV remains unchanged. So the temp read by its self, on it's own accord creates the illusion of higher abv.
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Re: science question here about drop in proof

Postby Kareltje » Sun Aug 19, 2018 1:46 pm

In doing normal runs I use copper equipment and I do not take the temperature readings all too serious. Not in relation with abv anyway! I measure the ABV. I do not correct for temperature, but I measure all samples at the same temperature.

I have seen some fluctuations in temperature in the top of a glass still.
It seemed the temperature rose slowly and then suddenly there seemed to be a breaking of condens, accompanied by a sudden drop in temperature. More pronounced when a drop of condens too dropped from the tip of the thermometer. (Like the drip from the top of the witch into the soup!) Then again the temperature rose slowly.
I concluded that the condensing of a tiny bit of vapour freed some heat and then, if the condens had accumulated and dropped, fresh vapour was introduced. But of course that was just an interpretation of which I have no proof.

Strange things seem to happen inside the tubes. I noticed a slow rising in my 3 m long riser of 13 mm ID. The temperature on the top showed a rise from 40 to 55 dg C, then back to 45, the rising again to 65, then back to 55, etc. All without external changes.
I guess it has to do with the traveling speed of the vapour in the pipes, combined with the speed of heat transfer and the changes in %abv of vapour and fluid.
Even when you keep the flow of heat into the system constant, each of these processes take time and oscillations may occur, I guess.

I have not seen the demonstration on Youtube. Do you have a link?
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