US source for Dufton, Bruun or Pear bulb columns?

Part numbers for Quickfit Dufton columns
https://www.scilabware.com/en/quickfit-fractionating-columns...
... good luck keeping the helix in one piece

I'm not registered with scilabware so can't buy direct.

For the other rarer species, maybe on a dusty shelf at the back of DrBob's store room(s) ?

[Edited on 21-1-2019 by Sulaiman]

Quote: Originally posted by Dr.Bob

Not sure if I have ever seen any of those exact columns (based on a quick search to try to see what they are), but I have seen a variety of other odd or complex ones. I'll try to get some photos of what I have left of them, and see if any are useful for you. I have had poor luck with some more complex distillation systems as some were broken when I got them, due to their length or complexity. I think a long enough Vigreux will do the same thing, or even better a packed column, but I have sold all but a few of them better ones, and the remainder have mostly odd joints. But I will try to get some photos of them when I have some time and post them.

I'm confused,
do you want columns for a collection of different types for display or education?
or do you want a good working column for your experiments ?

If for actual use then there I consider there to be two basic modes of operation;

1) a column with minimal or no thermal insulation using ambient air to cause refluxing within the column,
with all vapours that exit the top of the column passed to the product condenser.
Typical of this type is a Vigreux column.

2) a column with perfect (requires column heater(s)) or good thermal insulation, with a reflux condenser at the top of the column,
some type of partial take-off of either vapour or liquid at the top of the column is required.
Typical of this type is a Hempel column.

Some stills use a combination of #1 and #2

Type 1 stills are quick and simple to set up but I'd expect performance equivalent to a few theoretical plates only,
type 2 stills require more equipment and much more time but can be equivalent to tens of 'plates',

If you are new to (or newly returning to) chemistry, then I suggest using type #1 columns because;
. you can directly compare your results with the majority of others
. to realise the fractionating potential of type 2 columns requires lots more equipment and attention to details, and it really needs to be a semi-permanent installation.
... three years and my type 2 still is still a dream / unfinished.

Due to my own stubbornness in wanting a fine fractionatin still I have not bought a Vigreaux column for 'quicker' distillations,
which has meant that I've done far fewer distillations than I otherwise could have during the last three years

Finally, type #1 stills fit into common sized fume cupboards whereas type #2 stills tend to be rather tall.

[Edited on 22-1-2019 by Sulaiman]

Quote: Originally posted by Dr.Bob

Not sure if I have ever seen any of those exact columns (based on a quick search to try to see what they are), but I have seen a variety of other odd or complex ones. I'll try to get some photos of what I have left of them, and see if any are useful for you. I have had poor luck with some more complex distillation systems as some were broken when I got them, due to their length or complexity. I think a long enough Vigreux will do the same thing, or even better a packed column, but I have sold all but a few of them better ones, and the remainder have mostly odd joints. But I will try to get some photos of them when I have some time and post them.

Quote: Originally posted by SWIM

There's an Australian supplier on Ebay who often has 250 mm Dufton columns. They've got some right now. Just search for Dufton column. A 250mm costs about $50 USD because of the $22 shipping though. I picked up what seems to be an Ace 1, (or maybe 1.1) meter vacuum jacketed Dufton column (With integral splitter.) on Ebay. Hard to be sure since you can't take it apart or see inside except the bottom end, but it looks like the end of a Dufton. Ace doesn't list such a thing anymore, however, and I've got no idea how many theoretical plates it has. Anybody seen any plate height estimates for Duftons?