Reflux - Head/Hearts Cut Detection

[undercover]

Hi All,

I'm happy with the reflux operation and can detect when the tails arrive and manage them with LM.

However, as the vapour temperature and abv during reflux remains constant throughout the heads and hearts cuts, apart from taste/smell, is there any other way of detecting the heads/hearts cut?

I appreciate it's very different from a pot still, where you have a relationship between the rising vapour temp, lowering abv and the different cut points but at least you can use temperature and abv as a guide.

UC

[OtisT]

If you are going slow enough for good separation and have a sensitive enough thermometer, you can detect a slight temp difference between heads and hearts, so I’m told. The difference is about .2 degrees.

Otis

[undercover]

Yes, the probes are sensitive enough for this.

I've noticed during each run, after initial full reflux/stacking and then opening the LM valve, the vapour temp increases linearly then levels off flat at azeo until tails start coming through. It is very subtle.

I concluded it could be:

1. Heads, given the ethanol/water vapour has a concentration of heads at differing lower boiling points entrained within it thus lowering the vapour temp until they are taken off.

or

2. The power was too low resulting in hybrid/pot still mode temp profile (basically a very slow increase).

The fact it levels off, you've given me some confidence it's heads and I'll try to repeat it and taste the cuts more around that point.

Thanks for you help. If you've cracked it I'll be a happy man.

UC

[NZChris]

I use temperature to help run my Bokakob, but I use my nose and tastebuds to choose my heart cut from a lineup of jars. Eventually, I'll have enough records to predict cuts, but I suspect I'll still use my senses anyway, the same as I've always done with my pot stills. There is nothing more humbling than boasting you have it all worked out, then including a jar too many from one end and letting a friend taste it.

[bluefish_dist]

Taste is the best indicator. I found after enough runs, 100+ I could do cuts by where I was in the run, but that was lots of runs worth of experience. I also had to finish the run before I could make them. Could not do it on the fly. I also found I could not do them by smell. Not sure why newbies are so adverse to tasting what they made. It’s not hard and most people can make cuts pretty easily within a jar one way or the other.

Temperature tells you proof and nothing else. Changes in temperature can be indicators that something has changed like the jump in temp at the end of a run. But if you reduce power and increase reflux you can delay tails a little bit more.

[Saltbush Bill]

Some good advice right there
Its no good trying to use anything but taste and smell untill you have LOTS OF EXPERIENCE, even then other things like temp and ABV are only rough indicators.
As has been said before a 0.01 change of temp on a good reflux still will denote the begining of tails.
That's about the only use for temp in my books.
By good reflux still I dont mean a pot still with a few half arsed cooling pipes running through the riser .

[still_stirrin]

...Its no good trying to use anything but taste and smell untill you have LOTS OF EXPERIENCE, even then other things like temp and ABV are only rough indicators...

+1

Commercial distillers can use metrics to run and cut because of repetition and experience. Hobbyists must be more engaged with both the still’s “quirks” and the cut portions in light of ferment variances.

Running the still once a month is worlds away from running the same product 5 days a week. Hats off the the DSP guys here.
ss

[Bushman]

Taste is the best indicator. I found after enough runs, 100+ I could do cuts by where I was in the run, but that was lots of runs worth of experience. I also had to finish the run before I could make them. Could not do it on the fly. I also found I could not do them by smell. Not sure why newbies are so adverse to tasting what they made. It’s not hard and most people can make cuts pretty easily within a jar one way or the other.

Temperature tells you proof and nothing else. Changes in temperature can be indicators that something has changed like the jump in temp at the end of a run. But if you reduce power and increase reflux you can delay tails a little bit more.

Couldn’t of said it better myself. As a side note once you’ve gained experience and are close to where you think you are going from heads to hearts and from hearts to tails start collecting in smaller containers to improve cuts. I have cut my collection jars to 1/3rd of what I used when I first started.