Hi. I want to make a tight stainless tube coil to put into the neck of a carboy (see attached). How difficult is it to manipulate stainless tubing in this fashion?
Clayton,
Who did the one in the picture? How was that one made? It looks as if there is already a supplier. Some springs are turned on the lathe; I haven’t done but I believe that I have seen it done on Youtube. Tubing loves to kink upon small radii and therein lies some of the challenge. Tubing vendors often have minimum radius figures for various tubing products/sizes. Can’t go smaller and even with larger bends , the bending has to be applied very evenly to avoid kinks.
Regards,
Bob
That was made by an engineering student using aluminum. I need stainless for my Fermentation application.
What is the dimension of the opening on your carboy?
Also, can you give some insight into the process?
@yashsedai the mouth of the carboy is 1.25”. I’d want to use .25” OD stainless tubing.
Basically, I’d be pumping chilled water through the tubing to remove heat.
Just out of the curiosity of a brewer, are you gonna transfer hot wert into the carboy first?
Negative. I’ll cool the wort first. I’ll put a stopper on it and use to circulate cooled water to regulate fermentation temps when I need to pull down the temps.
Gotcha, interesting idea.
The bend radius is 2x D therefore the OD of the coil will be 5D.
1/4 tube coil will be marginal through a1.25 hole, but with care possible.
Bend it on a 3/4 mandrel. Carefully.
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You can also fill the tubing with sand to prevent the tubing from buckling but at that small size you may have issues getting it back out. I have also used low temp alloys (woods metal) to fill the tube and then melt it back out. I have some 168 degree alloy if you want to try it.
The advantage to doing either of these is the tubing then behaves like a bar and is much easier to bend.
Woods alloy or something else?
With woods alloy, my concern with that is if it is being used for something meant for food since it’s lead and cadmium based. Alternative Gallium alloys may cause corrosion problems for aluminium, but on stainless may be feasible but I don’t know I would want it for food stuffs even though it’s not toxic on its own.
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Based on the description, the coil is just a heat exchanger- the inside wouldn’t be in contact with food.
Ah,
In that case filling with woods would make this pretty easy.
Great point! Yes, I should have noted it would only be appropriate if not in contact with food products. In my experience with copper pipe it did not whet the surface but wonder if it could be processed to be safe.
Does it really need to be a coil? Why not a tube going straight down, a tight 180 back up, then down and up again.
You’d need an even number of runs, but you might be able to fit six straight pipes in the space allowed.
The shape would be reminiscent of this compact fluorescent tube (but with more straight runs.
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@HankCowdog it doesn’t have to be a coil…but if it could have easily been accomplished, it would have been cooler (pun intended)
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The way I used to do this was to chill it before putting it in the carboy. Same spiral heat exchanger, but you can use a larger diameter bend, and thus wind up with more linear feet of exchanger in contact with the liquid. Go get some copper tubing from the big box store and flare it. Wrap it around some pvc or sonotube to match your kettle diameter. Easy peasy.
This doesn’t replace chilling right after a boil, this is for maintaining proper temperature during fermentation. A lot of ales will want to sit mid 60s and lagers even colder. The more consistent you can maintain a set temperature the cleaner your final product.
For the record, I would just sit the carboy in a water bath and chill it from the outside, much like a commercial brewery uses jacketed fermenters, but this looks like a way more elegant solution if you can figure out how to make it.
There would be some fancy welding needed, but maybe you could go with a central 1/2 or 3/4" stainless tube and several 1/4 ( or smaller ) tubes back up the outside. You’d need a manifold at the bottom to connect all the outside tubes. The outside tubes could then be spiraled around the central tube. Should give you a much easier to attain bend radius.
I have a spiral chiller for cooling the wort before putting it into the carboy and pitching yeast.
It sounds like doing this with stainless is not within the skill set of a beginner maker. With the cold front coming in tonight, I’ll settle for leaving it in the cold garage with a heater wrap, and go back to using a fridge or small freezer in the summer.