Please note that not all the facts are in and that this is a CAUTION only at this juncture. The potential consequences of a failure are serious enough that I think a caution is warranted even though all the facts are not in.
HJ
_________________________ Backpacking stove reviews and information: Adventures In Stoving
However, I'm not sure that the elements for an explosion are present. The gas won't burn without oxygen. Small drops of molten metal -- even though they are of high temperature -- don't have enough heat content to raise the temperature of the canister to anything like bursting pressure. Could they melt through the canister? Probably not -- not that I'd really like to find out. If I had a melting flux ring, I'm sure I'd turn off the burner.
Although explosion doesn't seem very likely, what could be really bad is if a sudden move or bump caused the metal to spatter. While it probably wouldn't be a problem to the canister, it *would* be a problem on skin -- or clothing first and then skin. This would produce a very bad burn.
Thanks for the heads up. It would be nice to see if JetBoil has a response.
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Registered: 12/16/11
Posts: 230
Loc: Orange County, CA, USA
Hi, Keith,
Yes, an explosion is the worst case scenario. However, as you point out, there are a number of things that could happen short of an explosion, none of which would be particularly fun to have happen when your three days from the nearest trailhead.
HJ
_________________________ Backpacking stove reviews and information: Adventures In Stoving
I have been looking at the titanium Jet boil ever since I saw it on the market. I didn't know that the flux ring was aluminum. I was wondering how they made it out of titanium and was still able to sell it for $150. But, here is what is nagging at me. Aren't all the other jetboil flux rings made out of aluminum? What makes this one different?
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Finallyme, I see two differences with the Ti Jetboil:
1) The Ti is less conductive so more heat will build-up at the base of the pot.
2) The Al heat exchanger has a different thermal expansion than the Ti pot so every time the pot is heated up and cooled down it puts stress where the two are joined together.
I am guessing in these failures the heat exchanger breaks free from the pot. As a result the aluminum is not being cooled by the water in the pot and begins to get much hotter.
Also, having put blowtorches on aluminum before, I am guessing the heat exchanger is not melting but is burning away. I would be surprised if you get globs of molten aluminum.
The explosion warning comes from the excess heat building up and warming the gas in the tank. This will increase tank pressure which could cause the tank to rupture. If that happens you have high pressure/temperature fuel, air, and flame... that equals explosion. I am not sure what the actual explosion risk is. Since you would probably get a similar result by running the Jetboil dry, I would guess they designed the system to withstand such an event without exploding.
Bought one earlier this winter when Amazon was having a sale and have yet to fire it up. Maybe I'll wait to see what Jetboil has to say (if anything) first.
Registered: 12/16/11
Posts: 230
Loc: Orange County, CA, USA
Originally Posted By BZH
I am guessing in these failures the heat exchanger breaks free from the pot. As a result the aluminum is not being cooled by the water in the pot and begins to get much hotter.
That's my surmise as well.
That's an interesting thought that the aluminum might actually burn rather than melt. Maybe there's a little of both going on? I updated my blog post to quote the original post I saw on-line. In that quote, he mentions drops of super-hot metal.
I also added links to various posts with reports of similar happenings.
HJ
_________________________ Backpacking stove reviews and information: Adventures In Stoving
There are so vastly many aluminum alloys with different melting points it's practically impossible to know what's occurring. Certain versions of aluminum do burn--yee haw! I guess it's a good thing the canisters are all steel these days (even if I miss the Primus and Coleman aluminum ones).
Finallyme, I see two differences with the Ti Jetboil:
1) The Ti is less conductive so more heat will build-up at the base of the pot.
2) The Al heat exchanger has a different thermal expansion than the Ti pot so every time the pot is heated up and cooled down it puts stress where the two are joined together.
I am guessing in these failures the heat exchanger breaks free from the pot. As a result the aluminum is not being cooled by the water in the pot and begins to get much hotter.
Also, having put blowtorches on aluminum before, I am guessing the heat exchanger is not melting but is burning away. I would be surprised if you get globs of molten aluminum.
The explosion warning comes from the excess heat building up and warming the gas in the tank. This will increase tank pressure which could cause the tank to rupture. If that happens you have high pressure/temperature fuel, air, and flame... that equals explosion. I am not sure what the actual explosion risk is. Since you would probably get a similar result by running the Jetboil dry, I would guess they designed the system to withstand such an event without exploding.
That makes sense. Now I am disappointed. Originally I was under the impression that the flux ring was titanium.
_________________________
I've taken a vow of poverty. To annoy me, send money.
That's an interesting thought that the aluminum might actually burn rather than melt. Maybe there's a little of both going on? I updated my blog post to quote the original post I saw on-line. In that quote, he mentions drops of super-hot metal.
I also added links to various posts with reports of similar happenings.
HJ
Yeah, after I posted I found the original report on BPL. What I believe happens, is the aluminum melts and the small droplets of aluminum quickly burn (oxidize). I am surprised he got molten aluminum. I am guessing most of the molten aluminum was created when he doused his stove with water. That rapidly reduced the temp of the molten aluminum and prevented it from burning.
Registered: 12/16/11
Posts: 230
Loc: Orange County, CA, USA
Interesting.
Do you think that burning aluminum could account for the 3 foot flames? Seems like aluminum wouldn't do that, but I don't really know. Seems more likely that the gas in the canister got really hot and overpowered the pressure regulator.
HJ
_________________________ Backpacking stove reviews and information: Adventures In Stoving
Do you think that burning aluminum could account for the 3 foot flames? Seems like aluminum wouldn't do that, but I don't really know. Seems more likely that the gas in the canister got really hot and overpowered the pressure regulator.
HJ
No, Aluminum burning would not account for the flames. It certainly suggests that the tank is getting hot. Does the stove have an actual regulator or is flow controlled by an orifice?
The Sol is said to have a regulator. I've never seen a teardown to indicate of what type. It would seem the failure mode is to fail open and prevent a canister bursting (IIUC this is how propane tanks work). Fun.
I don't want to be around for the experience, but I've seen Svea and Optimus blow-off valves go, so there's always the possibility.
Had mine out this weekend for 3 days and it worked beautifully. I had one of the originals and in my very unscientific opinion the Sol boils water faster.
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