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SkeeterPee
01-20-2020, 21:02
Read about this a while back. I had trouble finding a copper strip. I ended up finding a 2 ft section of 3/8 in soft copper tubing. I was able to make 3 pieces from it. I split it down the length with a Dremel, and then I flattened it out. it looks good, but I am wondering if soft copper has anything in it that would interfere with its use in warming the tank.

It did get red hot in the flame and it did warm the tank some based on one of the laser infrared thermometers. But that was giving weird results so I am not sure how hot it got. I could only touch the strip for a second so that had to be fairly warm.

Any one else use soft copper? I read it is 99% copper.

Does it normally blacken some at flame end, is that just the first time?

Starchild
01-21-2020, 09:37
It sounds like it's working, perhaps too well. If the walls are thick enough you will be transporting a bit more heat then desired. The result would be a colder flame and perhaps soot on the copper (so a bit more fuel for cooking and having the dirty copper), not a biggie. On the other hand, the other side of the heat exchanger, the canister has a possibility of getting too hot, especially when near empty or extended cooking. That last one is what to watch out for.

4eyedbuzzard
01-21-2020, 18:14
The black is either soot (unburned hydrocarbons) from cold metal in a rich flame, or it could be copper 2 oxide, which will appear black. It usually takes some time as bright copper first forms copper 1 oxide which is reddish brown. But heat speeds up oxidation. It will turn green as well as it reacts with other chemicals in the atmosphere, hence the patina on old statues.

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SkeeterPee
01-21-2020, 18:18
Thanks for the info!

cmoulder
01-22-2020, 08:18
Although I think that the soft copper will work, this (https://basiccopper.com/20milcost1x1.html) is what I've been using for a long time. Spec is 1" width, 20mil (.020") thick.

Used in the normal temperatures where canisters start needing a little help, say ambient 45°F and lower, there is no chance of overheating. I have tested at ambient 75°F by running stoves at full blast for 1/2 hour continuously in canister cozies and they did not explode. They did get quite warm, but then these are conditions where external heating would of course never be required.

The best, quickest test is the Touch Test — if you can hold your finger on the top of the canister while it's running you are fine. I've found that with a proper setup the the temperature on the top of the canister never even remotely approaches getting uncomfortable to the touch.

And yes, the strip will most definitely discolor and will oxidize, and it will turn bright red in use. Oxidation will eventually require replacement, but I've found that a single strip will last about a season for me, then it's time for a new one.