Alembic head design considerations?

[Steve Broady]

If the answer to my question is out there, I am too dumb to find it, or I gave up too soon. I’m looking for any information about the factors that go into designing an alembic dome, onion head, or anything similar. Volume, surface area, vapor speed, cross section, anything. All I’ve been able to find are pictures, some comments about how much of a difference they’ve made , some saying they’re old fashioned and not useful, and plenty of companies selling them. What I can’t find is any information on designing and building my own. Can anyone help, please? I’m not asking anyone to do my homework for me. I’m trying to do it myself. I just need a hint on how to get started.

[acfixer69]

In the many years I've been around these forums I have been humored by the way the word design is abused. What you want is to copy a design not redesign it. Volume, surface area, vapor speed, cross section are not that important in the simple home distiller size still. You are not going to find a geometric floor plan for a homie cause scaled down it is meaningless. Put a larger diameter riser above the boiler and reduce back to whatever your condenser can handle and be happy. Its just a pot still.

[6 Row Joe]

If the answer to my question is out there, I am too dumb to find it, or I gave up too soon. I’m looking for any information about the factors that go into designing an alembic dome, onion head, or anything similar. Volume, surface area, vapor speed, cross section, anything. All I’ve been able to find are pictures, some comments about how much of a difference they’ve made , some saying they’re old fashioned and not useful, and plenty of companies selling them. What I can’t find is any information on designing and building my own. Can anyone help, please? I’m not asking anyone to do my homework for me. I’m trying to do it myself. I just need a hint on how to get started.

Get on the internet and look at commercial distilleries and pot stills. Most have a onion head. They must work or provide a benefit.

[Steve Broady]

What you want is to copy a design not redesign it.

With the utmost respect, that may indeed be what I need, but what I WANT is to get a better understanding of why something that works is designed the way it is. I have no desire to reinvent the wheel. I just want to understand what works and doesn’t work, and hopefully why. If all I do is copy someone else’s design and use it, it’s not really my still, and it is probably not ideal for me. Since I have the luxury of a lot of down time for reading and research, but very little for building or distilling, I try to make sure that I use what little time I have as efficiently as possible, mainly by doing as much research as I can.

[Saltbush Bill]

At hobby level you will battle to tell the difference between a normal everyday keg boiler with a simple pot still on top and a fancy looking onion head or alembic.
Every man and his dog seems to be using the "Alembic" terminology at the moment in a bid to sell stills.

[dunluce]

I might be wrong here, but I think what acfixer69 means is that with the small design of most home stills, fancy things like alembic heads, onions, whiskey helmets and such really don't make a lot of difference (feel free to correct me if I am putting words into your mouth).

Sure, they look nice, but for us it is a lot more function over form. I too, wanted a whiskey helmet when I started out, but upon doing research I realized that while it would look awesome, that piece of eye candy wouldn't really affect my end product enough for me to notice. The large diameter scale riser referred to should serve to function just as well, and will cut down your limited building time a you mentioned.

Edit: And SBB beat me to the punch.

[6 Row Joe]

If the answer to my question is out there, I am too dumb to find it, or I gave up too soon. I’m looking for any information about the factors that go into designing an alembic dome, onion head, or anything similar. Volume, surface area, vapor speed, cross section, anything. All I’ve been able to find are pictures, some comments about how much of a difference they’ve made , some saying they’re old fashioned and not useful, and plenty of companies selling them. What I can’t find is any information on designing and building my own. Can anyone help, please? I’m not asking anyone to do my homework for me. I’m trying to do it myself. I just need a hint on how to get started.

Here is a interesting discussion about it.

http://www.coppercustomstillcomponents. ... php?t=2677

[Stilljoy McFlavour]

I have a helmet that, in all honesty, I bought mostly for aesthetics. Secondary reason; it puts a bit of extra copper in the vapor path.
As for sizes and content I can offer you only that it has 4" tri clamp connectors and 12 liter volume.
Larger connectors generally seem to have larger volumes and vice versa. I have no information regarding vapor speeds, calculating useful sizes or dimensions.

As for actual usefulness to me?
- Fantastic foam collapsar when stripping sugar or rum - I can almost strip at full power now without having to bork around with oil or butter or whathaveyou. In hindsight this is by far the greatest benefit - much greater than anything else and I am very happy with it
- Flavors? Mouthfeel? Quality? No improvement that I can detect.
- Passive reflux due to cooling? Negligible unless I direct a fan at it.
- Reflux due to pressure drop; a sight glass mounted under the helmet shows no drops falling, once the helmet has warmed up
- When bubbling I have no benefit and it may even be slightly counterproductive. I see no reason in putting theoretical extra reflux under the column, and above the column the deflag is already doing more than the helmet ever can.
- Aesthetics? I think it made my nightly quality time in the bathroom when doing runs approximately 14.8% more enjoyable and gives me on average 1.6 "ahh, pretty.." moments - which is sufficient for me to mount it when potting

[SDEngr1]

I purchased one made in Ukraine. Very heavy copper and have no idea how they made it. Also very expensive. Not sure of the effects, time will tell, but does seem to reduce the tails slightly.

[SDEngr1]

I added in another topic you can easily hand a botanical bag within the dome creating a gin basket effect.