I have been hearing that using a traditional windscreen on a canister stove set-up (msr superfly for example). I was wondering if this is substantiated in anyway or if it is just a potential hazard that won't actually happen. Not wanting to try it myself I was wondering if anyone has had any unfortunate experience with this problem?
Canister Stoves Exploding
I have never heard in 34 years of a canister tank exploding. I have been using them since 1978. And in winter or windy conditions I usually set up a wind break or wrap a shirt around the canister.
It is not just a rumor or hype. Your stove can and will explode! I have witnessed this first hand, and have heard many more tales of people having it happen to them.
It all depends on the exact conditions at the time, but this is a very real risk. The stove that I "witnessed" explode was at a trailhead camping area , the other group that was there darn near gave me a heart attack. It sounded like a claymore going off. They were about 20 yards away or so from me so I didn't see the whole thing unfold play by play, but they were using a windscreen with a pocket rocket to pan fry trout. And after doing several fish is when it happened. From all of the accounts I have heard of, it usually happens around 8+ minutes of use i.e. cooking a large meal or for a long period of time.
I had just been back in the states for about 2 weeks since returning from deployment, and I swear it sounded like a claymore. I hit the dirt and glad I did because some of the sharpnel from the canister went into the tent behind me.
The instructions that came with your canister stove specifically say not to use a windscreen. And the same statement is there on all brands of canister stoves that I am aware of.
My Advice: Don't do it. Read the instructions with all stoves, and follow them.
It isn't so much using a wind break or wrapping with a shirt. It is more so an actual 360 degree windscreen surrounding the canister/stove.
Here is a link to a thread from backpacker.com, about an incident a few months ago.
I'm going to assume you are referring to 'sit on top' style stoves where the burner screws directly onto the canister.
I have never had one explode, but it is my understanding that it is possible, and has happened, when the canister is overheated. This occurs when a windscreen is placed fairly tight around the entire stove trapping too much heat around the canister. This is one reason I prefer remote fueled stoves whether canister or white gas.
A few ways to get around this problem and still have a windscreen that I have seen used are:
1. Leave a size-able gap in the windscreen on the downwind side of the stove to allow some heat to escape.
2. Use natural windbreaks like logs, snow banks, or rocks.
3. You can make something called a kite screen, which is a long piece of fabric about 12 - 14 inches high set up with sticks placed in the ground, several inches away from the stove. These can be set up to shelter multiple stoves at one time. This is something I do when cooking in windy areas. Here's a photo and a link from Jim Wood's website where I got the idea.
As several of the above posters note, it can and has happened. And not only with canister (compressed gas) stoves, but also liquid fuel stoves. I have witnessed explosions of both types of stoves.
There are several circumstances that have to come together for the explosion. Basically, it happens when the fuel container (canister for compressed gas stoves, fuel tank for liquid fuel stoves) gets sufficiently overheated. In general, the two main things that have to come together are 1. using a reflective windscreen that blocks all airflow around the fuel tank or canister and 2. using a pan or pot of large diameter (as in the case mentioned by TheRambler above. And it happens with stoves of the "burner on top" configuration. That is, canister stoves where the burner screws or clamps on top (the aforementioned Superfly as an example of the screw-on-top type or the Svea 123 or Coleman Peak 1 as examples of liquid fuel stoves where the burner is on top of the fuel tank).
If you combine 1 and 2 with a burner on top of the fuel tank by putting a large frying pan on the burner and a tightly, completely surrounding windshield (especially the reflective foil type, though completely and closely surrounding with light-colored rocks was involved in one case I witnessed), the result is a LOT of heat concentrated on the fuel tank. When it gets hot enough, the pressure in the tank will pop the tank, releasing the vapors (and liquid fuel for liquid fuel stoves), which will ignite in a spectacular manor. The old Svea 123, Primus 71, Optimus 8 and 11, and similar stoves have a relief valve. When overheated, the valve releases, which can result in a blowtorch-like flame (saw this about 2AM in the old Biolay climbers campground in Chamonix in 1964).
The prevention is as simple as following the directions that come with the stove. For example, the Superfly has a metal reflective disk that fits around the stem of the burner and blocks the heat from the flame from heating the fuel canister, even with a large-diameter frying pan. The reflective windscreen for the Superfly, properly placed, shields the burner from the wind while NOT directing heat downward onto the canister.
The remote fuel tank stoves (MSR's Whisperlite, XGK, Simmerlite, and others, Primus MFS and Omni, JetBoil Helios, and many others) avoid this problem by placing the fuel supply outside the windscreen. Although... I have seen one XGK melt and blow out its pump when someone put a windscreen all the way around the pot, burner, and fuel tank.
Again, if you follow the manufacturers' directions, the probability of an accident is miniscule.
I haven't seen one go off, but have read several accounts by people who did. In one instance the valve blew out and someone picked up the canister and threw it as far as they could before it blew up.
The closest I came was setting my old XGK pump on fire in my kitchen while testing it out. It hadn't sealed right and it started leaking and melting the pump. Fortunately, I had planned for such an event and quickly put it out. Minor cosmetic damage only, but I learned my lesson with that one.
Yeah, back in the late 70's I recall reading about accounts of the SVEA 123R exploding ... I don't recall the details, but I think it involved over heating due to lack of ventilation. I think another issue was the use of large pots that deflected too much heat back to the stove. I ended up buying one anyway, my first backpacking stove :), but the thought of the explosions was always in the back of my mind.
I use a wind screen with my Simmerlite, but always keep the fuel canister on the external side of the screen, and even at that I leave an opening on the downwind side of the burner.
Thanks for all the back up. After Posting I read the package on the MSR windscreen and even it says in big letters not to use sit on top canister stoves. good ideas though about other options. I haven't had an issue because I use the snow peak giga power which has a windscreen that only covers the space between the burner and the bottom of the pot.
I use a wind screen, but it is a half screen, and does not surround the canister. It is just there to block the wind. Even better is to elevate the screen a bit so there is some circulation under it.
Cooking longer periods with larger pots exacerbates the heat buildup. A reflective shield over the canister helps, but will not prevent problems.
The trick: periodically put your hand on the canister. If you can keep contact with the top of the canister without saying "ouch" (about 120-130 F) you are fine. Canisters are often tested to 130 F, and are designed to burst at much higher temperatures than this. Each canister manufacturer has its own DOT exemption (for transporting a non-refillable fuel container), in which the DOT specifies the tests the canisters must pass.
If you want to check yours, look at the canister and get the DOT number (my MSR canister says, for example, UN-E-11914). Got to www.dot.gov and enter that number in the search box, starting with E-XXXX. You will find, among the search results, a document that describes the tests the manufacturer (Dae Ryuk Can Company in Korea, the same as Brunton, for the MSR) has to perform. In this case, 1 in each lot of no more than 1000 cans must be tested to destruction, and must not burst below 240 psig. In addition, the inside pressure when filled with fuel must not exceed 150 psig at 130 F. Each DOT exemption is a little different.
My Camping Gaz canister (E-9758) also specifies a minimum burst pressure of 240 psig, and a maximum allowable pressure of 125 psig at 130 F.
Beware that the vapor pressure of the fuel begins rising rapidly, so even though the pressure is less than 150 psig at 130 F, it does not mean you can go to 200+ degrees and be safe. The 130 F cutoff is a safe maximum, and is easy to tell because it is uncomfortably hot to the touch.
Thanks Chumango! Great resource.
I think that this topic sounds like a great idea for the Mythbusters. They had done something similar when they threw ammunition and other items (a half full beer keg) into a fire. I think something along these lines would make a pretty neat episode!
D&G, I gather you have some doubts about stoves exploding -
D&G - Roger Caffin at backpackinglight did some tests to prove this. He put canisters on hot plates and recorded variables, until failure. It is a fact. If you subscribe to that web site you can get the report.
He noted that there really was no reversal of the bottom of the canister before catastrophic failure, or rather that the reversal and failure were essentially simultaneous.
The really dangerous aspect of the failure is that when the canister fails, the reduction in pressure along with the elevated temperature of the fuel results in a significant fraction of the liquid fuel vaporizing. This gives the classic Hollywood fireball if there is a flame source (probably, the stove was burning). In technical jargon it is a BLEVE, boiling liquid expanding vapor explosion. The same concept applies to any fuel container, like propane. I have seen a film of a propane truck that was involved in an accident that caused the truck's relief valve to open up. An ignition source must have been there, because the fuel coming out of the relief valve ignited. The flame from the relief valve impinged the tank, heating it up. It eventually reached the point that the internal pressure, along with the elevated tank temperature weakening the steel, caused catastrophic failure. The resulting BLEVE and fireball were truly spectacular. A word of advice: if you ever witness something like this, resist the temptation to stay around to watch. You want to be far away. The fireball makes Hollywood explosions seem pitiful by comparison.
Bill, can you provide any details of how the failure with the XGK occurred?
I don't have doubts at all. Just thought it would be an interesting thing to see in a controlled environment (and not me doing it).
The XGK failure apparently resulted from a couple of professional guides doing something which is fairly common practice, but strongly recommended against - grouping 3 or 4 stoves under a large pot to speed the melting of snow for water and cooking for their climbing group. Apparently, from what one of their party told me, they were a bit careless in placing the windscreen/heat shield, and left one of the pump ends of the fuel bottle inside the windscreen. The heat melted the plastic pump, which allowed the pumped-up pressure in the bottle to blow out the pump with pressurized vapor and liquid fuel.
From my point of view, there was this yelling and the bottle and stove came flying out of the tent, trailing flames and landed in the snow. The spilled fuel burned fairly quickly in the minute or so until I could grab my camera and get the picture.
Tom D mentioned above melting an XGK pump and getting a fire. Same kind of thing.
Actually in my case, what happened was that the pump wasn't sealed properly to the fuel tube, so after I primed the stove and opened the valve again, it started spraying fuel which of course ignited, which then started to melt the pump-which is one of the old yellow ones. Regardless of the sequence, a few more seconds and I would have had a major fire in my kitchen to deal with. That's why I keep an extinguisher on hand. That time I just used a towel to put it out, but no more indoor tests for me.
The point being, any combination of fuel and fire can be dangerous if mishandled.
fyi, as I recall, one of the biggest dangers in pit fires at Indy used to be from refueling alcohol powered cars. They would catch fire and no one could see the flames. A number of drivers were killed or badly burned because of that. The fuel they use now has additives in it so you can see them burning.
The soda can alcohol stoves have the same problem. In bright light, it may be hard to tell they are burning.
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