Bain marie affected by barometric pressure?

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Alchemist75
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Bain marie affected by barometric pressure?

Post by Alchemist75 »

While new mexico is not officially in its winter the temps have dropped quite a bit. Typically lower temps are associated with higher barometric pressure.
I've recently noticed a new issue with my brain marie set up. Usually I don't have a hard time making a stripping run go into deep tails but the last couple batches have become an uphill battle just past mid run. I've actually had the still grind to a halt at early tails even though it's still heating and boiling away. Could it be that the increased barometric pressure is making it harder to run off the more watery part of the distillation? The lyne arm used when stripping is relatively narrow, short and downward angle so the vapor doesn't have far to travel to get to the condenser.
Any thoughts?
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NZChris
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Re: Bain marie affected by barometric pressure?

Post by NZChris »

The pressure should affect the boiling point of the charge about the same amount. At colder ambient temperatures, passive reflux will stop it earlier. Insulating exposed boiler and riser surfaces should help squeeze a bit more out of it.
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Re: Bain marie affected by barometric pressure?

Post by Alchemist75 »

Yeah, I had a feeling it might be the colder temps. Thanks for the tip, I think I know what I'll have to do going forward.
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Re: Bain marie affected by barometric pressure?

Post by Kareltje »

Alchemist75 wrote: I've recently noticed a new issue with my brain marie set up.

Any thoughts?
Mistyping of course, but funny one nonetheless. :ebiggrin:

As NZChris said: barometric pressure influences boiling temperature of bain marie and boiler contents in the same direction, be it maybe not in the same amount.
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Re: Bain marie affected by barometric pressure?

Post by Alchemist75 »

Damn auto correct lol.
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Re: Bain marie affected by barometric pressure?

Post by bluefish_dist »

I have only noticed that atmospheric pressure changes the boiling point. It can change by +/-.5-1 deg or so. This happens all year round depending on the weather. I have considered plotting boiling point vs pressure, but am not sure what good it would do. I first noticed it during vodka spirit runs where I hold azeo. One day the still would do 163.5, then next 164.3. Both temps are azeo on a specific day. Now I just see what the temp is for that day and roll with it.

I have never noticed that it changes anything else in the process. Otherwise we would have issues if we changed altitude as that has a bigger effect on pressure than the weather.
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Re: Bain marie affected by barometric pressure?

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I'm having a hard time understanding why this has been an issue only in the last month or so. The only thing that has changed is the sharp temperature drop within the last 4 weeks. My wash is the same, I let it go to dryness which is to say it's about 11% abv. My fill in the boiler is the same it usually is ie 3/4 full though I'm wondering if I shouldn't fill it a bit higher in the colder months. If it's not barometric pressure increase then perhaps it's just the lower atmospheric temp making it harder for the spirit to get past the head space without refluxing. A bit higher fill and insulation around the head space is what I'm going try and see what that does. Previous years were run without a bain marie set up so this specific phenomena is new to me. There were no problems of this sort two months ago so something has changed. Again, it ONLY poses a problem with my stripping runs, not the spirit run.
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Re: Bain marie affected by barometric pressure?

Post by OtisT »

Those symptoms sound like you just ran out of alcohol. Are you sure about this washes’ ABV?
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Re: Bain marie affected by barometric pressure?

Post by NZChris »

My stripping runs go to within 0.5C of the boiling point of water, so with a bain Marie charged with plain water there would be so little heat transfer happening that I doubt it would strip as low as I want.
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Re: Bain marie affected by barometric pressure?

Post by Alchemist75 »

OtisT wrote:Those symptoms sound like you just ran out of alcohol. Are you sure about this washes’ ABV?
Pretty sure +/- .05%
The thing is that they have been done the same for years and give consistent results if allowed to go to dryness. Very clockwork as a general rule. If there's no variance in the general wash composition, no variance in the equipment but variance is noted with the changing of seasons then my eyebrows go up. There must be a rational explanation. Winter translates into slower ferments probably because of ambient temp drops and possibly less sunlight (my ferments are often more vigorous during the day). I can only assume temp/pressure must play some role though I could be wrong.....
The bain marie is definitely a fussy set up, I've half a mind to start packing the double boiler with copper shot rather than using water. Expensive set up but no more hassle
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Re: Bain marie affected by barometric pressure?

Post by Alchemist75 »

After this holiday has passed I'm going to be investing in some new equipment that will eliminate the need for bain marie set ups. I'm making more and more over the course of time so bigger and better is where it's heading.
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Re: Bain marie affected by barometric pressure?

Post by shadylane »

NZChris wrote:Insulating exposed boiler and riser surfaces should help squeeze a bit more out of it.
Good advice :thumbup:
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Re: Bain marie affected by barometric pressure?

Post by Alchemist75 »

So yesterday I tried a higher fill level and it appeared to help the situation. I collected a bit more of course because I added more though I also observed that I was able to take it below the 40% mark which was hardly possible before. I think the spirit was just struggling to get past the head/lyne arm as the volume in the boiler fell.
The irony here is that I don't typically collect below 40% but it shouldn't take an hour longer to climb past mid run to get to that point. Hopefully this fixes the issue for good.
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Re: Bain marie affected by barometric pressure?

Post by DAD300 »

I'm at 2,000ft and distillery running 40-50 deg F.

I only fill the ban marie with enough water to cover the elements plus what I expect to loose to and evaporation, so about half full.

I have a 5psi pressure release, a 0-30 pressure gauge and a second vent with a swinging check valve on the boiler jacket as a Vacuum Release Valve.

At 0psi I can get 210F, 1psi 220F and about 230F at 2psi in the boiler.

Just 1psi gets me to 10% abv and that's more than I can justify time wise.
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