Brass should be kept to a minimum is a still.
It leaches zinc which gives an off flavor.
And only food grade should be used ie. No leaded brass.Fulmen - 8-2-2015 at 11:34
Did you look at the vid? It's a copper tube with an outer brass cooler. macckone - 8-2-2015 at 16:02
No I didn't watch the video before posting.
Thanks for correcting me.
Of course the standard copper outer shell is going to be cheaper.
I use a pvc outer shell myself.Zombie - 8-2-2015 at 16:16
Brass should be kept to a minimum is a still.
It leaches zinc which gives an off flavor.
And only food grade should be used ie. No leaded brass.
In this case the brass is not in contact with the ETOH. Just the cooling water for the condenser.
Also brass does not impart a taste but the real concern was in Lead in the brass leeching into ETOH Vapor.
That is a non issue today, as modern Brass is lead free.macckone - 8-2-2015 at 16:23
All brass is definitely not lead free.
Food grade brass is.
Other brass may not be especially imported brass.Zombie - 8-2-2015 at 16:29
As of Jan. 4, 2014, ALL brass sold in the US for potable water must be lead free,.
This applies to all imported brass as well.
Granted if you dug thru some old bits... Yes you could find lead contaminated brass.
I said food grade is lead free.
Brass used for boilers, boat fittings, industrial machinery
Can still contain lead and is easily mistaken for
Food grade.violet sin - 8-2-2015 at 19:16
I noticed here about a year and a half ago in california, there were hardware stores all over the place with a TON of brass fittings for super cheap.
I bought a bunch because I was tired of the 5$ each. found out later it was lead stock sell off, that they totally didn't mention in any way shape or
form... I wanted mine for various tinkering projects or to melt, so not too offended at being offered lead heavy stuff right before they legally
couldn't sell it. but still seems underhanded.
the condenser is fairly cool, but I prefer mine: https://www.youtube.com/watch?v=kPdcWWZ4Piw
information section has a lot of details on how to and a bunch of "don't sue me" crap. I was concerned at the time, about people getting hurt. but
realized I should have to shoulder the responsibility of their safety. enjoy, or not, it works great with MeOH, Isoproply and acetone just fine.
these days I have it rigged to an aluminum water bottle with a rubber bung. this is put in a small styro-ice chest, through a hole cut in the top.
put a garbage can liner in it, ice and an aquarium pump, and you have your receiving flask and water supply for the condenser. used it for extracts
from plants, and reused the solvents. plenty of good smells and colors had cheaply when I was getting back into chem.
-VSFulmen - 23-2-2015 at 12:40
Speaking of stills and choice of metals: Any thoughts on copper and brass for distilled water? I need to assemble a small still for things like DW and
perhaps separation of some solvents. A simple pot still should suffice, it might look crude but it should get the job done for a minimal cost. Pot
(and if needed, the column) will be made from stainless, but I'm seriously considering a copper/brass air condenser for maximum flexibility. I just
did some quick calculations and there is no practical way to make a working air condenser capable of dissipating 1 kW out of stainless, the thermal
conductivity is just too low.
I'm just worried about copper contamination, I will use this for anything from analysis to chlorate production and battery maintenance. Maybe I'm
overly cautious, but it's much simpler to get things right than to fix poor designs later on. Zombie - 23-2-2015 at 12:55
You're correct about the air condenser, It just wont work. The simplest condenser is a water jacketed Liebig.
To save some grey matter there is a calculator here...
Now on to the still...
For plain distilled water Stainless is best. You can use Silicone to seal bits or make quick connects.
For Chlorates one of the real chemists here should help you. I could look it up but I'd rather you get the correct information.
Depending on the size of the unit, simple hardware store items can be used to assemble something. How large / small are you thinking?
I can help with a parts list if you like. Fulmen - 23-2-2015 at 13:24
I can make it myself, don't worry about that. I'm thinking a 2-3 liter pot, interchangeable column (just a straight piece of insulated tube for DW to
avoid carry over), and a suitable condenser. I rechecked my math and found I had swapped a few numbers, the difference in conductivity is
insignificant. 1 meter of 10mm tube and forced air can perhaps dissipate a few hundred watts at best.
But that still doesn't solve all my problems, I'm having trouble finding suitable SS tubing. Best I can find is 90/10 copper/nickel brake line tubing.
Zombie - 23-2-2015 at 13:49
Even Home Depot type stores. Re purpose a Towel rack or something similar.
For things like a water jacket you can use copper adapters / reducers, and silver solder them to stainless with a plain Mapp torch.
For the column (if you want a full reflux column) I use Stainless Scrubbies like you use in the kitchen for packing, and a simple reflux coil made
from stainless Natural Gas line in the top of the column.
Here's a copper "cold finger" condenser. it's much easier to build with the corrugated stainless.
Fulmen - 23-2-2015 at 14:05
Ordering from the US isn't really an option for me, but I still have a few possible sources to check out. We'll se what turns up, if not I might make
one out of Cu/Ni ant just take my chances.Zombie - 23-2-2015 at 15:04
Try Marine supply sources. Items like bow rails... That tubing is usually from 15mm on up.
Also for a column / water jacket, try Auto exhaust shops. They could even make the bends, and reduce the sizes or flare ends.
Sanitary clamps, and PTFE gaskets are easy to find.
I forgot you were not in the US.
[Edited on 2-23-2015 by Zombie]Fulmen - 23-2-2015 at 15:13
I was planning on using thin tube to make a coil placed in a bigger tube, but a simple cooling jacket would be acceptable and easier to source
materials for. I'll figure it out, don't worry. Luckily I have access to both a lathe and a mill, and I can get things welded if I really need to.
Still would like to know more about the suitability of copper, but I don't rally have any hope of it being a good solution. Zombie - 23-2-2015 at 16:11
Stainless is very easy to silver solder if you electro plate it with copper first. Copper Sulfate I think, and a battery charger.
