Modular flute plate design. A few issues...

[Talix]

Hey guys

Yet another step to this ever-continuing (it seems) flute build.

The modular plates have decided to become an issue... I found a beautiful piece of 4" pipe for cheap at the scraps. I cut them out to pieces a 125mm in length and though that my mechanic/muffler guy could expand them to fit my 4" SS 416 sanitary ferrules... Unfortunately, even with oxy acetylene heating, the pipe splits...

I was going to silver bearing (soft) solder them in, but now I will have to braze them together, edge to edge...I hope it's gonna hold.

All my planned specs, sight glass positioning, drainpipe/downcomer height, distance between plates, have been screwed up just this afternoon... It would have been 135mm in height per module, perfectly fitting the sight glass near the top of the piece, with plenty of space to the plate. I've uploaded an A3 pdf file with that initial plan, which I was happy with. Along with is is a drawing of how my perforated plates (three of them so far) are made. Also, I have come up with an altered design (very squished compared to before) of what I may be able to build. The height has obviously changed (90mm of 4" copper instead of 125mm) and the sight glass have had to move down since I have to braze it to the copper before brazing on the SS ferrules (with lower temperature 45% silver solder).

Also, I've put my downcomer cups on the sheet with dimensions of how they are at the moment. The drain height can be cut if needed, or completely remade. I've designed it so that, by simply reheating the solder fastening the downcomer cup, I can lower or raise the downcomber, allowing for a difference in liquid level on a per session basis, anywhere from 0.5mm to 3.5mm.

Now, what specs should I go for? I've never really understood, nor found the agreed optimal for the following:
- Drain/downcomer height over the plate (the minimum level of liquid on the plate)? Some say half an inch (12.7mm) others up to an inch... What difference does it make?
- Sight glass height over plate or downcomer? I remember reading in the flute thread to align the bottom of the sight glass with the top of the downcomer pipe, but that was in 2012... What is the general concensus now? My sight glasses will 50mm in visible diameter if that matters...

On the drawing the sight glass is as high up on the module as it will go...The plate can move, the downcomer can move... I just can't see that best way of doing it.

I've propably forgot three things that will come back to me tomorrow...

What do you guys think?

[freefall]

I am planning to sit my plates with downcomer attached between sections. I am just going to cut my teflon gasket to fir the o.d.
It does look like the top of the down comer is sitting a little high above your plate. I think most have done it about 3/4, (19 mm) of an inch. I am sure someone on here will help you out on that.
I bought premade plates as a way to save time. So cannot assist you much on there build. But you do want to be able to see them through the glass. Thr biggeer the window the easier to see them.
viewtopic.php?f=17&t=69749

[yakattack]

One thing that you mentioned that would be a bad idea is re flowing the solder to change the cup height for the plates. As soon as you start flowing the solder you're going to have to do another cleaning run before you can run product. Open this helps avoid issues later.

[Swedish Pride]

I'd make the downcommer 3/4, know a few that have 1/2 that thinks it floods easily.
does your metal guy have a lathe? if so he could cut your ferrules to be like rings that fit over the pipe, else most aussies seems to get custom copper ferrules or make their own.
If I went modular I'd try to get the plate wedged between the ferrules.
My downcomers are at about 12- 18 mm, I'm not to fussy, many here know the pros and cons of bath depth better than me.

Best of luck in the build

[pfshine]

How hot did you get the pipe? I have swedged alot of 4" pipe and never had a problem. The end needs to be red hot then quenched before you expand it. It doesn't have to be cherry red but at least a dull glow. Hell even if it did split you can still put the ferrule in and solder/braze/weld the the split shut.

[Swedish Pride]

Aussie Pipe is differrent dimension PF, for some reason it's smaller

[pfshine]

It should still work. Regardless of the little bit smaller size it should expand enough to fit the ferrule.

Edit to add that the pipe only needs to expand 3.5 mm or so which is more than doable. If needed anneal expand a little anneal again and finish the swedging, although I don't think that would be necessary.

[Talix]

It does look like the top of the down comer is sitting a little high above your plate. I think most have done it about 3/4, (19 mm) of an inch. I am sure someone on here will help you out on that.
Done, thanks for that advise. As mentioned, I'll probably experiment a bit with the height as I go along.
I bought premade plates as a way to save time. So cannot assist you much on there build. But you do want to be able to see them through the glass. Thr biggeer the window the easier to see them.
I've raised the plate a bit, instead of lowering the downcomer drain, I think I'll be able to see it now.
viewtopic.php?f=17&t=69749
Thanks for sharing that link, confirmed most of what I had thought. However, it seems Like LWTCS advocates using a longer downcomer before the cap... I hope it won't make that much of a difference that mine are just 50mm... I can live with the occational bubble of vapor coming through, but if it means that the pressure will simply blow out all of the liquid from the cup out the top onto the plate, I will end up with either a completely flooded column, or the liquid draining through the perf plate itself, emptying the column... We'll see, new downcomers are easy to braze.

One thing that you mentioned that would be a bad idea is re flowing the solder to change the cup height for the plates. As soon as you start flowing the solder you're going to have to do another cleaning run before you can run product. Open this helps avoid issues later.

I appreciate the concern and I know we should really keep safety first on a gray-area-hobby forum like this. However, the flux I'm using for my soft solder is Zinc Chloride paste (common plumbers flux) with a trace amount of Amonium Chloride (also called salmiak, used in relatively large quantities in strong licorice where I'm originally from, Denmark). I've come to the understanding that this isn't really that bad... Please correct me if I'm missing something. And sorry for going off-topic, but I had a good long think about it... This is how I understand it:

When the flute is completed, this particular join (one for each of my three plates) might have used an absolute maximum 100mg of paste - it actually consists of around 30% Zinc Chloride, the rest is water, but lets assume that it is pure. Zinc Chloride is extremely soluble in water (432g per 100ml) and ethanol (430g per 100ml). It is pretty safe to assume that the majority of the remaining flux after the build will be removed by my initial cleaning in my sink. The cleaning runs take care of the last bit (and also cleans up my significantly more hazardous brazing fluxes). Now, if I was to reflow those three joins, I could never expose more than what was initially used (100mg), more than likely it will be significantly less. If, however I didn't clean it and just went ahead with a run, the flux would be cleaned up during the first few ml of fore shots coming up due to it's extreme solubility with ethanol and water... Actually, since Zinc Chloride's boiling point is 732°C I can't see it ever making it further than the plate where it was used as solder, rather it should eventually find its way back to the boiler...

Of course, if it is used in the PC, it's another matter, but that is not the case here. But even then, Zinc Chloride is not that harmful in small quantities. If by some chance the 100mg made it's way into my (lets say) 10L of product, it would be negligible. Zinc Chloride is present in some OTC mouthwashes and intimate douches for it's antibacterial properties.

Even if I had forgot to do my cleaning run on my original pot still (only used silver bearing solder and plumbing flux for that) I hardly used more than a few grams of flux, lets say 5g for example's sake. If all of that had found it's way into my (lets say) 10L product (and if I only distilled it once) that would give me a concentration of just 500mg/L. Even if I drank a liter of the stuff, no problem. Sure, it's disgusting and I'd never do it, but it wouldn't harm anyone. LD50 for pure Zinc Chloride goes from 350mg/kg (rats) to 1250mg/kg (mice).

I know it's not about "survival" but about health. In this case the stuff could/should never reach the end product, and even if it did, with the minuscule levels of the stuff, the body would simply break it down to the mineral zinc adding to your daily multivitamin... Am I reckless, or am I reasonable to think I could reflow three joins between runs?

I'd make the downcommer 3/4, know a few that have 1/2 that thinks it floods easily.
The diameter is 18.05mm with is 3/4". Unfortunately, in Australia, the pipe diameters go by OD, not ID, which means all my pipe are a tiny bit smaller than yours... That's also why I'm having trouble with the flanges...
does your metal guy have a lathe? if so he could cut your ferrules to be like rings that fit over the pipe, else most aussies seems to get custom copper ferrules or make their own.
I have access to a lathe, that's a really good idea! I'll try that, thanks
If I went modular I'd try to get the plate wedged between the ferrules.
I thought about that, but couldn't that reintroduce the issue that some of the early builders had with the lowest plate not filling due to the plate not being flush with the pipe? I would like to solder my plates in place so I know exactly where the vapor is going and no liquid disappears past the edges. Is this faulty thinking?
My downcomers are at about 12- 18 mm, I'm not to fussy, many here know the pros and cons of bath depth better than me.

Best of luck in the build

How hot did you get the pipe? I have swedged alot of 4" pipe and never had a problem. The end needs to be red hot then quenched before you expand it. It doesn't have to be cherry red but at least a dull glow. Hell even if it did split you can still put the ferrule in and solder/braze/weld the the split shut.

It should still work. Regardless of the little bit smaller size it should expand enough to fit the ferrule.

Edit to add that the pipe only needs to expand 3.5 mm or so which is more than doable. If needed anneal expand a little anneal again and finish the swedging, although I don't think that would be necessary.

Yeah, I'd ask him to do that, if he was more than my mechanic... I'd even say it should be possible by just expanding the pipe a bit, checking to see what section of the pipe expands the most (the part that will snap if left unchecked) and heating the opposite side while expanding again. This would also leave a more uniform swage... Unfortunately, I don't think he's willing to put in that much work... He tried, he failed, that's it...

Thanks so much for all your advice, it means a lot to get expert opinions when plans fail

[Yummyrum]

Talix have you looked at Emptyglasses expanded copper ferrules .
Two points here . Emptyglass uses Aussie 4" copper and expands it to slip over Aussie 4" copper and presses a triclamp compatable flange to it . So expanding can definitely be done .

Although I made all my flanges on my flute build when I went to make a packed section for it I just bought some of Emptys flanges ..... so much easier to deal with . ...... and no , I don't get commission from him