A small start on a bubble ball

[Anthoney]

After a lot of umming and ahhing I have made a small start. I cut the bottom off a stainless fire extinguisher and the top off a copper vase/jug. used a stainless dish for a plate and began the makings of a bubbleball.

The pics should tell you better. Comments welcome. Nothing is soldered yet and the plate is not drilled for the caps either. So now is the time to tell me if I am doing something wrong. Only four caps are shown in the pic but I intend seven plus the downcomer. My local Screwfix ran out of 28mm caps. up and down comers will be 22mm.

The whole thing is seven inches in dia and about eight inches high. outlet is 2" inlet will be a bit smaller as I will use the screw in spear fitting from the keg.

I beat the copper out from concaveish to convex. Used the bottom collar and bottom bowl of the fire extinguisher. Pulled a dimple in the side of the collar for the site glass fitting. Used inch and a half as that is what I had that looked to fit well. Used an RJT hygiene fitting for the outlet. Again just what I had lying around.

Any questions on how anything was done I will be happy to answer but don't want to bore you with a blow by blow. A picture paints a thousand words and the sequence should be fairly self explanatory.

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[Anthoney]

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[Anthoney]

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[Frosteecat]

Looking cool man...but does it need to be higher up?

[Prairiepiss]

I likey.

How bigoted this bubblecaps? Look awfully smallish in that big ball.

[Anthoney]

Thank You RC

I don't know FC does it? I know of a chap up in Scotland who has his bubble ball atop his keg followed by his spp packed column and it seems to work fine. I haven't finished it yet so it would be easy enough to add a little 2" below it if you think there is a reason to do that?

As mentioned PP the caps are 28mm and there will be seven of them on 22mm pipe. By no coincidence this gives the same 2" pathway as your design.

[Prairiepiss]

Sory missed that. But I think you will like it.

[Frosteecat]

Nope...I don't know anything for sure lol! Curious to see her run!
Looks like a nice Ethan Allen pitcher gave its life there...I have several on Death Row myself!

[Anthoney]

Ethan Allen? 70's perhaps? Hope it wasn't a priceless work of art lol.

[Frosteecat]

Naw pretty common. Should have a maker's mark on the bottom.

[Anthoney]

Nope must be a knock off in the style of... Relieved I haven't carved up the pension fund.

[LWTCS]

Hope it does what ya need it to....
As a matter of interest, what are you running now?
I am hopeful that you will have a reference with which to gauge the performance of your completed new add on.

[Anthoney]

I'm not running anything. This is my first build.

As you may have read elsewhere the idea of the ball is to act as an inline thumper and feed the column with higher concentrated vapour so the SPP can be driven with more power before flooding. I also plan to make the top of the 2" column 4" both to accommodate my nice double wound stainless coil I got from a beer cooler and also to reduce flooding of the SPP again by providing a 4" area of SPP for vapour to slow down and be less inclined to hold up the liquid returning from the reflux coil. This is experimental and I am not sure if it will work as I visualise it. I want the coil to be movable to manage the vapour by controlling the cooling of the column but not the cooling of the coil. As pioneered by Manu and Dad300. VM/CM hybrid with no valve and so no pooling.

I am thinking only two or three feet of 2" and only a few inches of 4" SPP packing at the top to try and create a reduced flood zone. Stainless SPP with maybe copper SPP at the top.

Trying for a shorter column with good purity and speed and depending on the ball and the SPP to make that work. May have to revisit Riku before I cut the 2" to length.

[pfshine]

Very nice and inventive. So are you planning to solder the copper top to the ss? I would just tig it if you had the welder to do it if it were me.

[Anthoney]

I am planning to use silver solder. I have three different grades to work with going up to 55%Ag. I do have a tig but it is three phase and at the moment I only have the single phase supply running. Surface preparation and fluxing are the main issues with joining the stainless and copper together this way. I have used easyflo flux in the past and it has worked well so I will try it again and see how it goes.

[Anthoney]

Big party over the weekend so only a little bit of progress...

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[Anthoney]

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[Anthoney]

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well that's all for this week folks.

[Anthoney]

Started to braze with silver solder to put it all together now. Bit rusty at first and made some stupid mistakes but the skill is coming back to me a bit faster than the first time I learned to do it.

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This is the funnel off the jug I have been recycling into the top of the bubble ball. Cut it in half across and used the bottom bit to make a bottom for the top bit so I would have a reflux redistribution tray to drop the reflux from the column to one side of the bubble plate. The downcomer goes on the other side so the reflux flows across the plate before exiting back to the boiler.

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Here is the finished tray ready to be brazed to the underside of the top of the bubble ball.

[Anthoney]

Here are the stages of adding the outlet pipe for the column to attach to.
First of all butt brazing the RJT fitting to the end of the pipe. A clamp to hold it while I get the first tack brazed on. Then braze around, grind it down, Check for leaks, rebraze, rinse and repeat. Took three runs around before it was leakproof. My first braze in some years. Solid as the parent metal though.

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Then slide the nut over and braze it into place on the top of the ball.

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[Anthoney]

Brazing the sight glass fitting into the stainless collar that forms the middle of the ball.

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Bubble tray drilled out. Top hole spaced differently to the others is for the downcomer

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here is the tray with the downcomer in place.

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[Anthoney]

And from the side showing the cut down cap used for the vapour lock.

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Totally rubbish first attempt to attach the top of the ball to the collar. Tabs are too large and it was drinking gas and silver to produce an ugly, ineffective, joint. Don't do this at home.

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OK, trimmed the tabs down and made much less of a pigs ear of the next attempt.
After getting some tabs brazed on around the rim I debrazed and trimmed those ugly first tabs. Very hard to cut through any solder on the copper. Had to do them hot. Strong stuff. Not done the lot yet but happy it will go ok and be leak proof with minimal use of silver and gas.

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[Anthoney]

The underside showing the reflux tray brazed in. It is only attached at the left hand side. There is space above it for the vapour to pass easily.

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I have seen people ask about using gauze instead of slots on bubble caps. They were always blanked with no reply at all that I have found. I take this to mean the answer was unknown to the people being asked. So I tried a little experiment using some 30 mesh stainless gauze scraps I had.

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I used a bit of welding wire and some tape to seal a gauze skirt around a 28mm cap. Stuck it in a jar with some white spirit (all I had besides water) Blew air underneath it.

Could see the air displacing the white spirit down the inside of the gauze. Bubbles came out from the gauze but only really at the top just underneath the edge of the bubble cap. Also mostly from the edge that was slanted highest. Seems to work though. 30 mesh might not be the best size to use. Something a little more open perhaps. Is what I have though. Main reason for using it is just to raise the caps a little higher to run with a deeper pool to bubble through.If it only comes from the top with ethanol as well then maybe there is no point as not getting more liquid vapour interaction from the bottom to the top of the pool. Will ponder some more before committing to an upcomer design.

Also brazed the inlet pipe from the keg into the bottom of the ball. No problem at this stage. Just more of the same.

Got to finish brazing the top to the collar. Finish and install the tray into the bottom then attach the top to the bottom. Wish I could think of a way to make that last stainless to stainless joint demountable for access. Bit big for a swing clamp though. Also odd size.

[Anthoney]

Update on the mesh skirt. After leaving the prototype in the jar with water I went back to it days later to show my nephew what I had been doing. When I puffed with the rubber ball on the end of the tube a cloud of tiny bubbles erupted from all around the skirt. Blowing hard produced a combination of big bubbles and tiny ones. It seems having time to become properly wetted has changed something. Some kind of surface tension effect I assume. The exact performance is obviously pressure dependant so I need to measure the pressure that is producing the cloud of bubbles and calculate the pressure in each of the seven upcomers to compare the two and have some prediction of how the 30 mesh skirt will behave in practice. I was just about to buy a small amount of 20 mesh to try but, if the pressures match, the 30 mesh is fantastic once wetted.

My friend has built and programmed a more modern version of the Russian electronic pressure sensor and added control capabilities so that it can turn off the heater if the pressure gets too high in the column. An anti flood/puke measure.

He lives in another town but he has finished it now so I need to get it from him as a use for it has become evident and imminent. Scared to have it posted as royal mail has just lost the last parcel I was expecting. Bit dear to drive up there to get it but I might have to do that or take a deep breath and risk the post again.

[Frosteecat]

Thank you for the step by step and observations! I appreciate yours in particular because you are going at it hammer and tong like most of us who attempt to use tools do... And I get to see you cut down those pitchers before I try to!

[Anthoney]

The whole point of admitting my mistakes instead of hiding them in the edit is to help others realise what does and does not work and why. I was ok at brazing a few years ago but this is the first project in awhile and I had forgotten the edge of what I knew. Relearning and remembering as I go. I do aim for a capillary joint as well as the visible silver. Strength comes from a capillary joint. The visible stuff is just doubling up against leaks. Or inevitable side effect of troweling on the flux. When brazing stainless the bench grinder and the Dremel are your friend. Don't think clean the surface, think resurface. Expose new metal and use borax based flux with the silver solder. Note the use of strategically placed fire bricks to reflect heat back to the joint being made.

[Anthoney]

Been slow progress and not much to report even now. Reason being I have decided I want the ball to open up easily and can't afford a 7" tri clamp with two 7" ferrules. Or even just the clamp. Only cheap solution I can think of is to cut flanges out of sheet, braze them on the halves and clamp them together with cleco clamps. The side pinch clamps like bulldog clips on steroids. 70lb or 31.75kg of clamping force per clamp.

Started one flange but having tried the feel of it after cutting it and putting the since acquired micrometer on it, I think it should be a dummy run as it seems too thin (.7mm) to me. Perhaps I could reinforce it but I would rather get something thicker, if I can, and start again.

The methodology seems to have been good though so I will share what I have done and perhaps someone will have some feedback to inform my next move.

First I drew some circles in thick blue marker for the inner and outer dia. Then, using a shallow punched centre I used my gasket cutter to scribe an exact circle, for each marking, in the blue marker and the steel below.

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Then I cut out the centre with a small angle grinder. Then freed the flange from the sheet (old butchers tray) also with the angle grinder.
I left plenty of margin inside and outside the scribed lines. The angle grinder is not a precise tool.

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Then I used the bench grinder to grind the outside of the flange down to the scribed line. I was not too worried about ultra precision as this is not a critical cut.

Then I put the flange in the vice and used the dremel with a cylindrical grindstone to grind to the inner scribed line. This is a fairly critical cut as it has to slide snugly over the ball half and braze solidly on.

Well that's all until I can find better stock to work with. 1mm or better seems like it might be enough. I could double this stuff up but too much of a fudge I think. Time to hit the charity shops for a couple of 8" or bigger stainless pans perhaps. Use the thick bases. Harder work than what has turned out to be a practice run but should be doable.

[Anthoney]

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[googe]

Thats awesome mate, you certainly have your brain switched on. Looking forward to seeing your stuff in the future

[Anthoney]

After stalling on the flange for some time I have now made some progress. I gave up waiting for some thicker stainless to turn up and made flanges from 10mm copper pipe. Then I went on to make a triclamp from plywood with a nice thick oak face. Offcuts from some uber expensive laminate flooring. Not finished yet but enough progress to be worth reporting.

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