LM v. VM

Wed Feb 08, 2006 1:28 pm

This might be a dumb question. Bear with me.

What are the benifits / drawbacks of VM as opposed to LM?

I have a general idea of how the VM systems work. It would help if I could find more detailed info on them. I have searched a few sites and search engines. I'm getting vauge discriptions and references. From my understanding, a vm has a condenser at the top of the column. That condenser's soul purpose is for reflux. A valved vapor out take is placed somewhere below that condenser near the top of the column. The vapor from this out take is then passed through a second condenser for collection. Reflux is controlled by opening or closing the valve that controls the out take volume.
Am I even close?

TEC · Post by **TEC** » Wed Feb 08, 2006 2:42 pm

LHCB,

Have you read this thread?

http://homedistiller.org/forum/viewtopic.php?t=994

Wed Feb 08, 2006 3:05 pm

That's the info I've been looking for. Thanks so much, and I appologize for bringing up old news. I know that can be annoying.

TEC · Post by **TEC** » Wed Feb 08, 2006 3:11 pm

Doesn't bother me any, I know what it is like to look for something that you just can't seem to find.

Good Luck with your project.

linw · Post by **linw** » Thu Feb 09, 2006 1:24 am

You won't regret it if you go for VM. Easy and cheap to make and very simple to control your run. No pesky needle valves to fiddle with!

LeftLaneCruiser · Post by **LeftLaneCruiser** » Mon Feb 13, 2006 1:10 pm

linw wrote:You won't regret it if you go for VM. Easy and cheap to make and very simple to control your run. No pesky needle valves to fiddle with!

Second that

KJH

agl · Post by **agl** » Mon Feb 13, 2006 3:42 pm

I will be building my next still with vapor management, and I was wondering, besides a permenant restriction to balance flow (a number of people described in the previous thread just mentioned by TEC)- has anyone out there put a variable valve below the reflux coil in order to shut down reflux altogether?
It is probably totally unecessary, but I was curious if it has been done, and if so what if any use it was.

knuklehead · Post by **knuklehead** » Mon Feb 13, 2006 3:49 pm

linw wrote:You won't regret it if you go for VM. Easy and cheap to make and very simple to control your run. No pesky needle valves to fiddle with!

You have no needle valves but you have a valve or valves none the less, right?

I use LM and I like it a lot. I love the needle valves. I like the fact that if I do a maximum output test I can do it then close the output and dump the test portion back down the condenser and it flows back down the column. I have never used VM but I understand it and I think both systems are great.

Tue Feb 14, 2006 12:17 am

This is my design concept, so far. I am going with a vapor management set-up. Please excuse the crappy photo of the crappy draft. No scanner access.

The column will attach to the bottom of this head so that the packing highth is ~ 40". The thermometer nipple is placed so the probe will be at the very top of the packing and out of the way of the returning reflux condensate. The valve to the right is the vapor take off. This connects to a 90 degree elbow in the downward direction. A liebig condenser is then connected to this. The bottom 1" x 1/2" reducer has the stop grinded out so as to let the 1/2" pipe pass through it. The piece that is marked with a star (its below the top gate valve) is that 1/2" tube. It's purpose is to direct the returning condensate to (relatively) the center of the packing. The valve that is in line with the column is for better control of the reflux ("reflux valve"). With both valves open, its 50-50 or 1:1, theoreticly. Leaving the top valve wide open and adjusting the take off valve the range of reflux is 50%-100%. By adjusting the reflux valve with the take off valve wide open, the range of reflux is 0% - 50%. The benifit of the extra "reflux valve" is that after the still stops producing once the 40%-45% abv mark is met, the valve can then be closed to continue collecting tails. This valve would also allow the still to be ran in a" virtual pot mode" with varying degrees of reflux for stripping runs and flavored spirits.
Anybody have any suggestions/comments/criticizims, other than I should get a scanner and learn how to draft?
BTW the thing on the left middle that is most hard to see is the scale. It says 1 square = 1/4".

agl · Post by **agl** » Tue Feb 14, 2006 3:15 am

That arrangement of valves is exactly what I was thinking of. I can't see why it wouldn't work wel, but then I have not yet built or run a VM still, I have only read about them. That looks like a good idea, having the 1/2" pipe protrude down into the 1.5" reducer so that refluxed liquid is delivered to the middle of the packing. Hopefully someone out there has done this before and can enlighten us on the details/practicality.

TEC · Post by **TEC** » Tue Feb 14, 2006 6:23 am

The only problem I see with having the two valves is that you can close off the column completly and build up pressure.

agl · Post by **agl** » Tue Feb 14, 2006 8:02 am

Oh, yeah I hate explosions !
My boiler has an over pressure vent, but perhaps a crude preventative measure would be to drill a small hole in the reflux control valve's gate, that wouldn't allow a 0% reflux but still very close to it, and it would be impossible to accidentally build a huge pressure.

Guest · Post by **Guest** » Tue Feb 14, 2006 9:07 am

I have thought about the possibility of accidently closing both valves, but if the thermometer probe is installed with a loose fitting cork and wrapped with teflon tape to seal, it should blow first. That is how my pot still is set up. Maybe I'll go with 1/2" for the thermometer and a bigger cork, Or install a safety release valve, like on an air compresser. This whole thing is conceptual right now. I have not yet built a reflux still of any kind. I don't know if any of these things will work.

Looking at it today, I'm wondering if the take off placement is wrong. The pressure increase in the reducers might push vapor through the take off and effect the natural flow through the liebig off the side. My thought is that the increase in pressure would continue to push the vapor down the condenser even after the vapor density reached equillibrium with the atmospheric pressure. Now that I think about it, moving the take off to the bottom sleave of the 2"x1" reducer and packing to just below that might be the way to go.

Tue Feb 14, 2006 9:10 am

oops, that was me.

Nevermind the repositioning of the valve. I had just woke up and hadn't had my coffee yet.

knuklehead · Post by **knuklehead** » Tue Feb 14, 2006 3:24 pm

Don't forget about implossion. A blow off cork or pressure release valve won't help with that.

Tue Feb 14, 2006 5:18 pm

Here's version 2. It's a hybrid VM/LM.

It's basically Bokakob's Mini, scaled to a 2" column, with the addition of a vapor take off below the plates. Thats a needle valve on top and a gate valve under it. Needle valve closed = VM, the gate valve closed = LM. both closed = 100% reflux. Completely open column. No pressure worries. Tails can still be ran with the turn of a valve. I really like this one, but I would like to here the groups opinion before committing to the design.

linw · Post by **linw** » Tue Feb 14, 2006 6:04 pm

Why not keep it simple and safe by chopping out the top valve? You could build it so you could add it in later if you thought it desirable. I think the fiddling with reflux ratio ranges would look better on paper than in actuality!

As for converting to a pot still, all you need to do is lift out the reflux coil and put a bung in the top. This also provides a safety blow hole if the outlet valve gets shutoff. But note KH's warning re implosion.

I wrote the above before seeing your next try on page 2! I like the open column change - this is just sensible because if we rely on humans to do everything right we will get stuffed sooner or later! And there is no compelling reason to take extra risks.

Now, you seem to have abandoned the pot still concept and gone for two systems that will produce the same results. Confused? I am! Getting good results is reliant on several things but one of those is getting to know how your still works. If you make it needlessly complicated, or have two stills in one, you will take much longer to learn your still.

My sincere advice is to choose LM or VM and get on and do it. When you master either and get good product, you won't need to come here for advice about changes as you will know what to do yourself.

BTW, LM stills don't run the distillate into another condenser as per your diag. It is already condensed so goes straight into the bottle.

TEC · Post by **TEC** » Tue Feb 14, 2006 7:02 pm

I like it

Having the valved output go to the condenser adds extra support to both.

You could also add a coil just below the VM offtake in the main column and have a CM still.

A LM/VM/CM Hybrid...

Tue Feb 14, 2006 7:07 pm

LINW,
My intention is to simplify, not complicate. I feel that closing a valve and opening another would be more simple and tidy than lifting out the condenser and plugging the top. Also I would like to hard pipe the cooling system with 1/4" copper and have the input and output for the cooling water at the base of the column (not through the column or even touching it, just attached and permenent). I don't like seeing all of those plastic tubes wrapping around and hanging. I do have an idea for mounting the top condenser, I haven't drawn it out yet, though. It connects with compression fittings so it can be removed during clean up, but it would be tricky to remove it in the middle of a run.

I do know that the LM output doesn't need to go through the side condenser. I drew it there just because that output route is already there. I saw no reason to have two routes. It's just to get the condensate from point A to point B, not to cool the condensate further or anything like that.

This design doesn't seem much more complicated to me. It's a VM with an extra valve and small piece of tube. I thought it was pretty simple, actually. The extra valve just allows me to get the reflux down to 0 without removing the coil in the middle of the run. Just shut the gate and open the needle.

My head has been full of ideas and it has been alot of fun just thinking about different things. I do want to make something simple and functional and something I can be proud of. I hope that helps you understand where I'm comming from with this thing. Thanks for your input.

Wed Feb 15, 2006 12:09 am

TEC,
I think CM is out of the reach of my capabilities right now. I don't have a very good understanding of it at the moment. Maybe (with some more research) something for me to think about in the future. I mean, hey man, I'm working on getting my first reflux still together.
I have a pump and barrel for recirculating water. From my limited understanding, this would make cooling management almost impossible, besides, I don't exactly know how it works. If you have any interesting links on hand, I would love to check them out.

TEC · Post by **TEC** » Wed Feb 15, 2006 12:51 am

I like it the way you have it designed now and did not mean to throw more at you with the CM.
I am currently running an similar design that uses the elliptical plates and I agree that both plates need to be cut and welded into the column to insure that the reflux does not have a chance to run down the sides of the column. The designs that have the upper plate attached to the coil are lacking IMHO.
I mean, as long as you are cutting and welding one plate in, why get lazy there?

OldStormy · Post by **OldStormy** » Wed Feb 15, 2006 2:19 am

Hi Tec,
I don't think it is a case of 'lazy'. By having the plate attached to the bottom of the coil and not protruding past the coil diameter, the vapour can more easily travel up all around the coil. The condensate will run down the coil and off the top plate onto the catchment plate. I could be wrong but that seems to me to be the logic. It also makes cleaning a fair bit easier which I would imagine is somewhat difficult with both plates welded into the column.
Cheers,
OldStormy

Swag · Post by **Swag** » Mon Feb 20, 2006 3:14 pm

On your first design it seems to me that you could control the amount of reflux by adjusting the flow of water to the reflux condenser. Then you wouldn't need the valve.

linw · Post by **linw** » Tue Feb 21, 2006 2:06 am

Swag wrote:On your first design it seems to me that you could control the amount of reflux by adjusting the flow of water to the reflux condenser. Then you wouldn't need the valve.

So where would the vapour go that didn't get condensed?

Tue Feb 21, 2006 7:46 am

Swag wrote:
On your first design it seems to me that you could control the amount of reflux by adjusting the flow of water to the reflux condenser. Then you wouldn't need the valve.

Linw wrote:
So where would the vapour go that didn't get condensed?

The vapor would escape out the top of the column.

Here is a picture from the homedistiller site. This is almost exactly what I was getting at with the first design. Journeyman Vapor Management Still Head by Nixon/McCaw

In the description it mentions a safety bypass (not pictured) on the back of the head...???...Two way safety pressure release valve, maybe?

Swag · Post by **Swag** » Tue Feb 21, 2006 11:34 am

linw wrote:
Swag wrote:On your first design it seems to me that you could control the amount of reflux by adjusting the flow of water to the reflux condenser. Then you wouldn't need the valve.
So where would the vapour go that didn't get condensed?

The whole idea behind equalizing a column is to be ably to put it into full reflux. If you have maximum water flow going to your reflux condenser and you are still getting excess vapor, you need to turn the heat down.

Tue Feb 21, 2006 5:33 pm

Swag wrote:On your first design it seems to me that you could control the amount of reflux by adjusting the flow of water to the reflux condenser. Then you wouldn't need the valve.

This is a VM design. The vapor has two paths to chose. Each path has its own condeser, one on top for reflux and one off the side for product. The amount of condensate returned and the amount collected is in purportion to the size of the openings to each of these paths, and the density of the vapor comming off the boiler. The flow of water to the top condenser has nothing to do with it. It has to knock down all the vapor that reaches it or vapor will be lost out the top. All of the condensate from this condenser is returned back down the column and into the boiler. The valve is to limit the amount of vapor that reaches the top condenser.

Swag · Post by **Swag** » Tue Feb 21, 2006 6:31 pm

Longhairedcountryboy wrote:
Swag wrote:On your first design it seems to me that you could control the amount of reflux by adjusting the flow of water to the reflux condenser. Then you wouldn't need the valve.
This is a VM design. The vapor has two paths to chose. Each path has its own condeser, one on top for reflux and one off the side for product. The amount of condensate returned and the amount collected is in purportion to the size of the openings to each of these paths, and the density of the vapor comming off the boiler. The flow of water to the top condenser has nothing to do with it. It has to knock down all the vapor that reaches it or vapor will be lost out the top. All of the condensate from this condenser is returned back down the column and into the boiler. The valve is to limit the amount of vapor that reaches the top condenser.

If you capped the top of the reflux condenser you wouldn't have to worry about any vapor escaping. Then you could control the amount of reflux with your water flow.
Just an alternative, either way will work.

Tue Feb 21, 2006 6:39 pm

O.K. I see where you're comming from now. My first thought with the design had the condensers in a series but after thinking about it I think running them in parallel would be better for exactly that purpose. You could valve the flow to the top condenser. Capping the top would still leave the pressure issue. That is where I got stuck on this thing.

Swag · Post by **Swag** » Wed Feb 22, 2006 11:15 am

Longhairedcountryboy wrote:O.K. I see where you're comming from now. My first thought with the design had the condensers in a series but after thinking about it I think running them in parallel would be better for exactly that purpose. You could valve the flow to the top condenser. Capping the top would still leave the pressure issue. That is where I got stuck on this thing.

You could solve that by drilling a 1/2" hole somewhere and putting a cork in it.