My rendition of a Nixon-Stone Offset Head Valve Reflux...

[zed255]

This is not complete yet, but rather just a snapshot of where I'm at right now. Some parts are permanently assembled, others not or are just in mock-up stage. Some items have received some machine work on my lathe, so may not appear as off-the-shelf components.

It is composed of:

50L stainless steel stockpot / turkey fryer - Not yet modified to its future purpose as the boiler, nor pictured. May bail out to a used keg, not sure yet.
2" x 3' column with threaded fittings for a modular approach
2" Wyes for the offset head, with threaded fitting, again for a modular design
2" cap for temperature monitoring, appropriate gland / fitting not yet installed
3" x 12" condenser shell, with a modified 3" to 2" reducer and modified 2-1/8" to 1-1/2" bushing to provide a drip edge
Coil is partially built, but will be a 2 layer design with a 1/2" cold finger
A modified 2" to 1/2" bushing for collection cup, reflux pipework not yet decided upon
1/2" x 12" or so secondary cooler for collected distillate, no outer sleeve yet. Ball valve to ensure total reflux with minimal volume trapped prior to collection
Modified 1/4" 'needle' valve to improve flow control of output

Any thoughts on my current state of being? I'm totally new and already settled on the basic design before becoming aware of the Bokakob design's popularity, so please work with me on the offset head. Constructive comments welcome.

And, yes, any of the 'brassy' looking fittings are lead-free...

IMG_1293.JPG

IMG_1294.JPG

IMG_1295.JPG

[still_stirrin]

...And, yes, any of the 'brassy' looking fittings are lead-free...

I'm not so sure about that... This is the MSDS for NIBCO brass DWV fittings:

red brass MSDS

And the nickel content is just as hazardous as the lead. Are you planning to "pickle" the brass?
ss

[der wo]

Yes, unfortunately the brass is not safe probably.

But in general the design is excellent. I like it.
You could copper plate (electroplate) the brass. With brass it is very easy. I had a few copper plated brass parts at two of my stills.

I wouldn't use a glass thermometer for a reflux still. It reacts too slow.

[Windy City]

If you could return those wye's they do sell them in plain wrot copper. Then you would not have to worry about pickling them.

[Yummyrum]

Y bashing has been covered . Tinning things suspect with lead free solder works and lasts longe than I would trust this pickling thing .... to me its a feel good solution .... my opinion .... I can see a layer of solder several years later ... I could never see a few atoms of sucked out lead ... or nickel ... just say'n

The way I see it is that there is no need for the reflux return line . If you have a needle valve on the outlet then any reflux will fall back down the slope into the packing .
You could install a reflux centering ramp at the bottom of the slope if you don't think that dribbling the reflux down the side will work .... as shown by those with glass stills to be not necessary

Like your work

[zed255]

At this point the wyes are not returnable as they are soldered together with the modified reducing bushing.

I will have to go back to the supplier and ask again about the product as I was quite specific that I needed lead free and was told that plumbing products sold in Canada by law could not contain lead. I will try to find some way of absolute verification, short of a laboratory assay. That was only one MSDS from one supplier, perhaps there are differences between suppliers and regional laws, or maybe not. I will try to find out. If it can't be verified lead free, or is verified to contain lead then that brings me to periodically pickling the head, or maybe consider an option like plating. If I were to ever make another like it then pure copper will be purchased regardless of cost, but for now I will continue to work with these parts.

I'm actually planning on using an analog electronic sensor seated in the tip of a piece of 1/4" down in the vapor path, the glass thermometer was illustrative. I will spin the tip of the 1/4" tube down to a bulb over a form an the lathe and seal it with solder. The sensor will be potted at the end in thermal compound. I'm not sure about the comment on reaction time though, this glass thermometer will actually respond quite noticeably with small changes in temperature. I suspect my planned sensor will not respond any faster, just differently given the digital output vs. analog. If I went with glass I would slide a o-ring over it as a marker to make small changes more noticeable given a fixed reference. As I understand it is more about temperature changes than absolute reading (playing into the idea of manufacturing tolerances), within reasonable limits.

Moving on from the already stated concerns, duly noted, any other comments? This is my first build, so if someone sees me about to do something that will impede function I'd love to hear it.

[zed255]

Y bashing has been covered . Tinning things suspect with lead free solder works and lasts longe than I would trust this pickling thing .... to me its a feel good solution .... my opinion .... I can see a layer of solder several years later ... I could never see a few atoms of sucked out lead ... or nickle
The way I see it is that there is no need for the reflux return line . If you have a needle valve on the outlet then any reflux will fall back down the slope into the packing .
You could install a reflux centering ramp at the bottom of the slope if you don't think that dribbling the reflux down the side will work .... as shown by those with glass stills to be not necessary

Like your work

I was thinking about tinning myself, when I read the comment about plating. I'm new and just covering my bases, but I will investigate the potential issue related to the wyes and make my decision from there.

The idea of using a reflux line is to minimize the pooling of distillate. If I just let it spill over that is quite a bit of pooled distillate, and it returns down one side of the column rather than the middle without adding something to the path.

Thanks for the comments so far.

[der wo]

Yes, the pool is smaller with the return.

I'm not sure about the comment on reaction time though, this glass thermometer will actually respond quite noticeably with small changes in temperature. I suspect my planned sensor will not respond any faster, just differently given the digital output vs. analog. If I went with glass I would slide a o-ring over it as a marker to make small changes more noticeable given a fixed reference. As I understand it is more about temperature changes than absolute reading (playing into the idea of manufacturing tolerances), within reasonable limits.

Yes, it's about temp changes. So a exact calibration is not needed. But you should be able to see a change of 0.1°C, and that's not possible with a glass thermometer. The faster the thermometer reacts the faster you will react and change the valve setting. I would place the sensor into the vapor, not in a jacket, which is in the vapor.

[rad14701]

I will have to go back to the supplier and ask again about the product as I was quite specific that I needed lead free and was told that plumbing products sold in Canada by law could not contain lead. I will try to find some way of absolute verification, short of a laboratory assay. That was only one MSDS from one supplier, perhaps there are differences between suppliers and regional laws, or maybe not. I will try to find out. If it can't be verified lead free, or is verified to contain lead then that brings me to periodically pickling the head, or maybe consider an option like plating. If I were to ever make another like it then pure copper will be purchased regardless of cost, but for now I will continue to work with these parts.

While the lead issue may be true for plumbing fittings for potable water the same may not be true for Drain/Waste/Vent piping and fittings... So just because you said something doesn't mean it was interpreted as you intended by those supplying the fittings if your intended purpose was not in line with what the parts are actually intended for... As an example, if a person went to a big box hardware store and wasn't specific about intended use the help there wouldn't know if a customer intended to use chrome plated brass drain pipe and fittings for water supply repairs... They are going to assume that you know those components are not meant for waste water, not potable water...

[zed255]

OK, moving past the brass 'issue' at this point in time, can I expect some azeotropic or near azeotropic from this arrangement if I run it slow with a fairly high reflux ratio?

[der wo]

Yes. But what do you mean with "run it slow"? If you mean a slow output because of the high reflux ratio, it's ok. If you mean a slow output because of low power input, it's not ok.
Try to find out the power short before it's flooding the column. This is probably the sweet spot with the best efficiency. And insulate the column.

[zed255]

I mean adequate heat input, not flooding the column but driving plenty of vapor up the column. I was referring to a slow take off rate with lots of reflux occurring. Column will be insulated, I'm just not at that point yet.

[zed255]

So, progress is slow but I've got a few more things worked out.

First time soldering copper and stainless, I think it turned out well.

IMG_1297.JPG

Organization of the head assembly. Parts fitted, still some soldering to do.

IMG_1298.JPG

A Liebig-style product cooler, 1/2" ID outer sleeve over 3/8" OD inner tube. Wanted to minimize product volume. Was going to use 1/4" OD tube but couldn't find suitable reducers.

IMG_1299.JPG

And a few shots showing the reflux line returning to the column. Milled the port into the 2" tube and hard soldered the 1/2" in place.

IMG_1300.JPG

IMG_1301.JPG

IMG_1302.JPG

Still have to finish my coil but need to get a few parts for that. Planning on trying the water method for supporting the tube but wanted to use valves, which rather inconveniently were not in stock anywhere near me.

[dukethebeagle120]

this may sound dumb,but why is brass unsafe.when you buy pex fitting at the hardware store they are brass.
hot and cold water run through every elbow.why would they sell them for water use if they are unsafe.
they know they are for use with potable water hmmmmmmmmm

[zed255]

Can we move past the brass and spend more time on design and implementation. Some feel comfortable with it and others do not. I accept and respect that. I'm personally comfortable using new products acquired from main stream vendors in my region. Period.

[Snackson]

this may sound dumb,but why is brass unsafe.when you buy pex fitting at the hardware store they are brass.
hot and cold water run through every elbow.why would they sell them for water use if they are unsafe.
they know they are for use with potable water hmmmmmmmmm

DWV brass and potable water brass are completely different. One is suitable for potable water use and one isn't do to the higher lead content as DWV is meant for drainage and waste systems.

[rad14701]

Can we move past the brass and spend more time on design and implementation. Some feel comfortable with it and others do not. I accept and respect that. I'm personally comfortable using new products acquired from main stream vendors in my region. Period.

We want to make sure other novices don't see your build and consider DWV brass as an acceptable material... Here in these forums we consider safety to be first and foremost... Just because you shun safety advice doesn't make DWV brass any safer for the masses... Period...!!!

Why not do yourself a favor and head to any store that sells paint and ask for a lead test kit and see for yourself whether those components are as lead free as you are assuming...

[zed255]

I should have new wrought copper wyes this week to replace the cast ones previously pictured. I reported my own thread in the hopes of having it removed by a moderator or administrator so I could begin a new one, deleting the pics and such that members found offensive, but my request was deleted and the thread remains untouched. Oh well. Not wanting to rock the proverbial boat, allow me to move forward with the current accepted best practices, no more about the DWV 'brass' please as it will NOT be used. Any brass parts proposed will be minimal and be of the potable water variety, likely just a couple small valves for reflux / take-off control

Here are a couple pics of my first coil, two layer with central 'cold finger'. This was done this way solely to make use of the first coil of copper I purchased, which I thought would end up being sacrificial but worked out decently well, was just too short for two layers. The copper wire serves to make the assembly quite strong despite the copper being well annealed and hold consistent / accurate spacing of the parts. As I gather form reading here, can I confirm that it would be most correct to feed the cold water into the two 1/4" pipes and drain it from the 1/2" centre tube? Seems we want the temperature gradient such that the coldest part of the coil is at the top, correct?

Coil is two layers of 1/4" soft copper, utility grade on the outside and refrigeration grade on the inside. Bought the utility grade first but realized the refrigeration grade can be wound tighter more easily later on. Used water to support the tube during winding. This worked very well.

DPP_0001.JPG

DPP_0002.JPG

DPP_0003.JPG

Made a tool for reforming the 1/4" tube where small deformation / flattening occurred when forming the tighter freehand bends.

DPP_0004.JPG

DPP_0005.JPG