I've got a question about the bokakob still head design. I'm admiring the head in this thread. It looks like the simplest head design I've seen, as long as you can get those crazy looking plates into place. Reading through that thread, I came across this diagram of the still head:
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I noticed that this diagram has an extra hole in the side under the thermometer insert labled as "B- Vapor Takeoff". It looks like the still head in the pics for that thread doesn't have that hole there, and I'm not really clear what that hole would do other than give vapors a path out of the still head that doesn't go past the condenser coil (and probably mess with the temperature reading of the thermometer immediately above that hole). So what is that hole for and is in needed for operation?
The other question I had was about the top of the head where the coil goes in. It looks like the condenser coil in the pic (which looks really nice) goes through a cap at the top. Is there any danger with pressure build-up in the head, as the top of the still head isn't exactly open to the atmosphere? Where does excess pressure go?
That particular image is a modified modular dual slant plate design very much like the Bokakob design... The difference is that the "B" port allows Vapor Management take off and the "D" port allows Liquid Management take off... It's a dual design reflux head... The Bokakob dual slant plate column is an LM design... Several members have modified their Bokakob's to be a dual mode column...
Also, there should be a vent hole in the cap.
The idea behind this modification is to draw the foreshots and heads through the LM port, then switch to the VM port for the hearts.
It is the very things that we think we know, that keep us from learning what we should know.
Valved Reflux, 3"x54" Bok 'mini', 2 liebig based pots and the 'Blockhead' 60K btu propane heat
1. The slip joints above and below the plate section are optional.Sealing them up is a bit of a pain. Probably better not to have them, just have unbroken column.
2. The vapour port is too small. Go to at least 1".
Thanks, now I understand the purpose of the vapor takeoff in that diagram, and why I haven't been seeing it in some of the pics on this forum.
If you used a 2 foot piece of 2 inch copper tubing, and put the plates roughly at the 1/2 way point, would a foot of packing give you any benefits rather than operating the head like a pot still without any packing or extra space below the plates'? I don't have much vertical space right now, but was thinking of using male and female threaded joints on my boiler lid and the still head, so I could potentially add a more adequate reflux column when I get the opportunity, joining the 3 parts together with threaded joints. Would there be any use in stuffing the lower half of the head with packing material, or is one foot just not enough to gain any benefits from? I know that this is a pretty sad height/width ratio of 6:1 rather than 24:1 or more that I see recommended.
You are on exactly the right track, Mr Lewis. Having a detachable head/removable column gives you a lot of flexibility.
The 1' packing section is not a waste. You can get quite a bit of benefit from it. Varying the amount of packing in the column will vary the amount of reflux, and this can be used to fine tune it as a pot still for use with different flavoured spirits.
My 3" version has a slip joint below the plates, and another at the base of the column. I use a few wraps of teflon tape to seal things up. Never had a problem with leakage. For those that are anal retentive, cotton strips with flour paste would also make a propper seal.
It is the very things that we think we know, that keep us from learning what we should know.
Valved Reflux, 3"x54" Bok 'mini', 2 liebig based pots and the 'Blockhead' 60K btu propane heat
Hey guys thanks for the help with the bokakob design.
To convert the head to VM, you'd drill that extra hole in the diagram, attach a gate valve, and run a 2nd condenser pointing downward to collect the distillate. Is that correct?
If you were to do this modification, would you need the plates and liquid take-off at all?
carl1078lewis wrote:Hey guys thanks for the help with the bokakob design.
To convert the head to VM, you'd drill that extra hole in the diagram, attach a gate valve, and run a 2nd condenser pointing downward to collect the distillate. Is that correct?
Correct.
If you were to do this modification, would you need the plates and liquid take-off at all?
No, it is not needed. Straight VMs are about the best design we have for a basic reflux column and are pretty popular here. You won't go wrong with them (or a good LM). One advantage of having the combined LM/VM head is that you can do stripping or pot still runs with the head more easily (using the LM part). You can do it with a plain VM, but it is a bit more stuffing around, you have to plug the top of the column (and do it safely). I have a plain VM column, and a separate pot column. Works well.
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