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Boka / Bokabob 1.5" vs. 2" columns width and speed data?

Posted: Sat Dec 18, 2010 9:59 am
by montanadave
I've done hours of (really fun) research reading here and on yahoo about the Bokabob / Bokakob / Boka dual slant plate design. I've read through pages of design modifications and discussion about every adjustable aspect.

But, in all my research, I haven't found much about the actual difference in column diameter. It is clear that a wider column will produce "faster", but there is limited (if any) empirical data that shows just how much faster. I'd guess that a 1.5" column (with a cross section of 7.07 sq.in.) would have roughly half the production speed as a 2" column (with a cross section of 12.56 sq.in.)

Does anyone have any experience with the columns they could share to help those deciding between the 1.5" and 2"? The 2" is double the cost and harder to find, and for a smaller personal Boka, that might be acceptable. But, some say the 1.5" is painfully slow. Can anyone share their numbers? (Also, please let me know your BTU too to best compare apples to apples.)

Thanks!

Re: Boka / Bokabob 1.5" vs. 2" columns width and speed data?

Posted: Sat Dec 18, 2010 2:59 pm
by DrMalt
1.5" Bok
1 meter packed column
1000W electric Hot Plate
450 ml/hr during transitions
700 ml/hr on hearts
600 ml/hr average
94% ABV. I can get 94.5 if I run a little slower but I don't think it's worth while. Trying to run faster causes mixing and temp fluctuations.
I don't find it painful, it's a hobby and I don't need quantity just quality.

Re: Boka / Bokabob 1.5" vs. 2" columns width and speed data?

Posted: Sat Dec 18, 2010 3:31 pm
by Manback
53% the speed while maintaining identical quality etc in a 1.5" column.

Re: Boka / Bokabob 1.5" vs. 2" columns width and speed data?

Posted: Sat Dec 18, 2010 5:04 pm
by Ayay
Onya montanadave for doing the research and trying to get to the bottom of column diameter. Trust the theory that you have read about, build the biggest(within reason) and best you can and let the learning begin by doing.

There's too many variables for comparing numbers. What's the wash and %alc in the wash, the cutting, after treatment and personal tastes? That's before you get to the still where the design, construction, management, type of heat, effiency, etc all add up to different things even if the stills look very similar.

After building your still there's enough variables to keep you busy for years with only minor tweaks to the build.

Re: Boka / Bokabob 1.5" vs. 2" columns width and speed data?

Posted: Sat Dec 18, 2010 5:16 pm
by Manback
But regardless of that if you want the same vapor speed in a 1.5" column you need to run it at 53% of the power (after losses) that you would in a 2" column under the same conditions