VM Head

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Skookum
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VM Head

Post by Skookum »

Hey all,

Looking for thoughts/opinions on my 2” VM setup. I’m new to this so if you figure that I’m completely off track then let me know!
I’ve got this head sitting on top of about 52” of copper mesh packed column. My 59L keg is heated with a 5500w element with an SCR control and readout.
A22338FA-AF1A-404F-850C-1D93133A9DD1.jpeg
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BDB65048-7F34-43F1-8CE5-3416E579F2D0.jpeg
Some background on what led me to this setup... I wanted to go VM and when looking for valves I stumbled onto this 2” tri-clamp ball with PTFE seats. I know that generally a smaller valve is recommended, but so far I have pretty fine control of take off rates (in my opinion anyways). However, I had become convinced, based on how my first few runs went, that I had some smearing issues. So, I tapped a hole in the body of the valve and sure enough, I could drain about an ounce out of the valve body between jars. So... instead of constantly (manually) draining hot distillate after every jar, I decided to route the drain down into the packing (the 3/8” tube extends just into the main column).
This gives me a bit of extra reflux from my takeoff vapour and hopefully keeps the valve body from getting any kind of pooling.
I haven’t seen anyone doing a setup quite like this so hoping for some feedback. This whole deal has me thinking of CCVM but I haven’t run this configuration yet, so we’ll see how this works on some Birdwatchers and go from there.

Cheers!
S
OtisT
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Re: VM Head

Post by OtisT »

Hi skookem. I think you will be challenged by that big ball valve trying to fraction on a 2” column. My 2” has a 3/4” gate valve, and VM adjustments during a run are measured in 1/4 turn increments (8 full turns to go from closed to full open). I rarely open the valve more than a single turn during a fractioning run. The adjustments needs are for very small increments, and you will likely get frustrated by over/undershooting your mark.

The drain is a good solution to your pooling issue. If you insulate the upper section from the column to PC, you will generate less liquid to begin with by keeping that valve hot.

Your 5500 watts potential will help you heat up quickly but when fractioning you will need to reduce power to somewhere near 1500w at the max because the column is only 2” diameter. By the time you are refluxing, maybe 8:1, that takeoff rate will be quite slow. Think 12+ hour spirit runs. I was in your exact situation a few years back when I upgraded to a 5500w boiler. I was able to keep using my 2” VM head and double my production rate by simply swapping out the packed column section under the head with a 3” packed column. That Required a 2” to 3” reducer plate, and of course a 3” packed column section. Well worth the investment IMHO.

Best of luck to you.
Otis
Last edited by OtisT on Wed Feb 03, 2021 3:22 pm, edited 1 time in total.
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Yummyrum
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Re: VM Head

Post by Yummyrum »

+1 what Otis said .
I have an equal size Ball valve and it is indeed very touchy with only a 1-2 degrees turn of the handle between no output and drips for heads take off .

Not impossible to use but you won’t be grabbing the handle and turning it .... more like a gentle tap.
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MartinCash
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Re: VM Head

Post by MartinCash »

I would have imagined more smearing issues from the lack of fine control over vapour flow than from the ounce or so that collects in the valve, but every improvement should help.
4'' SS modular CCVM on gas-fired 50L keg.
OtisT
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Re: VM Head

Post by OtisT »

I think a person could learn how to make it work with a ball valve. The problem with a 1 oz pool is that the first oz is gonna be concentrated foreshots, acetone, and those are sitting in a air cooled mass of steel. I think they would drag well into the run. Otis
Otis’ Pot and Thumper, Dimroth Condenser: Pot-n-Thumper/Dimroth
Learning to Toast: Toasting Wood
Polishing Spirits with Fruitwood: Fruitwood
Badmotivator’s Barrels: Badmo Barrels
Skookum
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Re: VM Head

Post by Skookum »

Yummyrum wrote: Wed Feb 03, 2021 11:49 am +1 what Otis said .
I have an equal size Ball valve and it is indeed very touchy with only a 1-2 degrees turn of the handle between no output and drips for heads take off .

Not impossible to use but you won’t be grabbing the handle and turning it .... more like a gentle tap.
Yeah, that’s what I’ve been finding. Adjustments definitely take a certain amount of feel.

Have you ever heard of someone putting an orifice plate before or after the valve to slow things down? I’m not sure if that would give more or less control...

Something like this downstream of the valve:
https://www.rodem.com/manufacturers/rub ... te-gaskets
Skookum
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Re: VM Head

Post by Skookum »

OtisT wrote: Wed Feb 03, 2021 6:05 pm I think a person could learn how to make it work with a ball valve. The problem with a 1 oz pool is that the first oz is gonna be concentrated foreshots, acetone, and those are sitting in a air cooled mass of steel. I think they would drag well into the run. Otis
Hey Otis. I was thinking that the more volatile compounds would tend to make it through the air cooled heat sink of the valve due to their lower boiling points, and less volatile compounds in the vapour stream would have a greater tendency to condense and run through the drain, returning to the column? I was hoping it would act kind of like additional passive reflux acting just on what I’m taking off?
Setsumi
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Re: VM Head

Post by Setsumi »

you could mount the valve at an up hill angle. or just leave it completely off. look into CCVM
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