Pros and cons - VM head design

VM CM LM Flutes Plate

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Pros and cons - VM head design

Postby equilibrium » Wed Feb 13, 2019 11:30 am

Hi all.

As per today, I have a VM still similar to the picture called "todays design". Will I get any sort of benefit from changing design to one similar to the other picture?
No real reason for asking, just curious. I am actually real happy with the performance of the still I have. Output speed is great, heads come out at a rate around 1,9 liter per hour as a azeotrop (2" insulated still and boiler, 135 cm of SPP and powered by 2 kW). And I like the principle that the still will not be able to run dry due to need of different density between alcohol vapor and air density.

More of an aesthetically thing. Like the design of a proportional vapor splitting head. So is there any point of changing out the design?
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vapor-management-reflux-still-design-VM.png
Proportional vapor splitting
Princip_-_Vapor_management.jpg
Todays design
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Re: Pros and cons - VM head design

Postby Yummyrum » Wed Feb 13, 2019 11:05 pm

When I think of a proportional vapour splitting head I think of the one Harry made that had two gate valves back to back so when you opened one , it closed the other .
Edit: took me a while to find but I snatched it off Modern Distiller Forum as I could ‘t find it here .This was built by another member following Harry’s design
8E163170-C43B-485E-8A14-8C7FBFAC7BDC.jpeg



Your first pic is just an offset version of the yours .
The only thing is the offset one has a gate valve the same diameter as the port to the reflux condenser . This would mean when the gate was fully open you could get a 1:1 split in vapour whereas your still has a smaller gate diameter relative to the column diameter ..... so when you fully open your valve you are probably getting at best 4:1 ratio of vapour going up and refluxing to vapour eing taken off .

Does it matter ?
Well only if you want to use your still for stripping . If your sole purpose is just to make high proof clean spirit then it won’t matter a dam..... infact the larger gate valve will be touchier to control than the smaller diameter one like you have . In reality you will be running that still with around 10:1 and up to 20:1 refux ratio so having a larger diameter gate is pointless
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Re: Pros and cons - VM head design

Postby equilibrium » Thu Feb 14, 2019 12:35 am

I am clearly misusing the term proportional splitting :)
Then I do not really see any real point of playing around with the VM head design. That being said, my still is modular (tri clamps all the way), so I will probably end up trying it out around with different designs anyway.
When it comes to stripping I just convert the whole rig into a pot still.

Thanks for the clarifications!
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Re: Pros and cons - VM head design

Postby Yummyrum » Thu Feb 14, 2019 12:53 am

equilibrium wrote:I am clearly misusing the term proportional splitting :)
.....
Thanks for the clarifications!


No , I was being pedantic and splitting hairs . :oops:

You are correct . A VM still proportions the vapour .... thats how it works .

In identally , heres another wacky build viewtopic.php?f=17&t=40063
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Re: Pros and cons - VM head design

Postby equilibrium » Thu Feb 14, 2019 1:16 am

Holy.. People are creative. Really liked the design on that hybrid still. I have seen other variants of LM/VM, cannot recall ever seeing one with a pot mode as well. This was a clever build.
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Re: Pros and cons - VM head design

Postby bluefish_dist » Thu Feb 14, 2019 1:18 pm

I run a design like your first one with the T at the top. I like it and have made 100’s of runs with it. The advantage I see is that it has an external return so the takeoff can’t have any condensate splashing out. It is also easier to get the valve the same size as the Rc side. I use a 2” T on a 4” column and a 4” T on my 6” column.
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