The srv pip was replaced and carefully re assembled. I did crudely check it by depressing it after with a shank end of a drill bit, and it moved ok. I was going to take it to work and test it with air. We have calibrated drucks at work, but clearly didn't get the chance. The cause of the overheating was possibly that, I had just started using the stove with a msr gas canister stand, this stopped heat dissipating to ground. The overheating also expanded the tank base, this would make the bowing out more likely, I think due to tensile stress on the base. We could discuss srv replacement, but this is already well documented and I have had candle flames out of srv caps due to pip degradation. No harm done, but I was a little surprised. Thanks for your reply.
It certainly smells nicer! But seriously, this is a very unusual incident, especially as the stove wasn't being pushed beyond normal working limits.
As in the example I just gave of a paraffin-fuelled device gone rogue, it’s the operation and state of maintenance of any liquid-fuelled pressure appliance that ultimately determines its safety.
Yes, I have read your report before, very thorough. Yes, fired or similar products have inherent hazards. These hazards are largely controlled by suitable training, supervision while in use, maintenance and inherent good design.
Alcohol has the inherent danger of being invisible in lighted environment. I have a 4 inch burn on my leg from an accident involving alcohol stove mishap.
If you could kindly share some pictures of the damaged 123 so we can better understand how to avoid such an incident
Sorry, the tank is already disposed of, otherwise I would be tempted to repair it. The top looked OK, but the bottom was completely bowed out. So much it wouldn't stand up straight, I think the use of the msr stand caused the overheating. Only used the stand once and it creates an air gap rather than the ground soaking up some of the heat. The stove certainly seemed to heat up far quicker than my 8r, so I am used to self pressurising petrol stoves
Air gaps are usually advantageous as an aid to air circulation. Pity you’ve intrigued us with your post and deprived us of the reveal.
This is very interesting. I have used msr canister stands a lot, but not yet with my newly acquired Svea 123r. These stoves are small, and unstable, but also not designed for such a stand. It is a safety decision to use a stand, but also a compromise. Not running them long is an obvious tactic. It would be an interesting experiment to test how how hot they get in contact with the ground, versus on a stand with an air gap underneath. My assumption at first thought is that an air gap aids cooling. This assumption needs testing. in winter especially I use stove boards, as a stove snowshoe, and to insulate stoves from cold snow to improve their performance. A thin 1/8 plywood board, with home made fittings to hold the stove base and a loop of bungee to hold the tank in the case of msr stoves. The stove can be left assembled on the board, and the whole assembly loaded in and out of the toboggan bag for convenience. I have never tested this rig in terms of stove over heating, but that is not an issue with a remote tank stove, provided it is kept outside of the windscreen. Especially on snow in the cold. I am sure msr designers have tested how long the fuel hose should be for safety. Coleman single burners get quite hot in operation, enough I have shut them down out of caution a few times. I have also seen them run on a full tank until empty, getting very hot. But no explosions reported in my experience. Maybe this is survivor bias in action?
They get hot. That's normal. You can hear the fuel boil in many stoves. That's normal. Thinking about it, I've never even lit a Svea 123 except in conjunction with the Sigg set. I doubt whether an 'air gap' or 'ground contact' has anything to do with it, but of course I don't know. I've used the 123 and 123R innumerable times in the backcountry with zero problems.
I suppose it is actually a good thing, if not optimal for a hot lunch on the trail in this situation. The safety valve did not release for whatever reason, yet the stove failed gracefully as far as that goes. Still, it at least somewhat reinforces my instinctive reluctance to mess with the SRV unless there is an accurate measurement way of the specific psi which it lets go. For that matter, what is it? Has anyone documented what the specification is? One solution around this problem - does Optimus/Svea sell replacement fuel caps? This would be much simpler than performing open fuel cap surgery with maybe sketchy results. Insulating the stove from the ground will prevent conduction loss in cold weather. It won't improve performance per se.
The fuel hoses did get lengthened about once a decade, so I suspect that the "tested in the field" answer proved to be longer than the calculated answer. The Svea (and Optimus) designers aren't really the factor in the 123R case we are discussing. There are 2 questions: why didn't the over-pressure release work, and how did the stove overheat? There is a third possibility: How did the bottom panel Buckle under normal pressure? I'd have liked an autopsy on the stove, but we will all remain uncertain.
While replacement gas caps [w/SRV] may be available, they've also been on the shelf for decades and may have brittle rubber gaskets and pips. I have no experience with the fit and function of the Katydin[?] Asian Climber 123R gas caps. Maybe replacement with a fresh cap from Base Camp or Fogas was a good solution 15 or 20 years ago, but today, they're NOS -- New OLD Stock.
It is clear now that I should of photographed the stove, it gained temperature very quickly compared to my 8r. I am slightly wary of using a 123r again to be honest. I can source a tank from evil bay or Sweden, the stove was early 90s vintage and would I suspect been an early China version. The stand clearly did not help, the flame even with a new nozzle was not as good as my 8r
The Optimus/Svea is still in production. Obviously these include new fuel caps. Sorry for any confusion. They should fit, whether they are any good is another matter. I'm not persuaded a brittle SRV is dangerous, necessarily. It may well release prematurely. Does it necessarily follow it will not release when it should? We do know what happens when someone replaces the SRV pip without verifying the proper PSI where it should release, however.
Is there a link to a description of how to verify the correct pressure for a Svea valve? I am new to these stoves. Rebuild parts are easily available, but include only new pips and cap seals, not new springs, and only include mechanical assembly instructions, no testing procedures. There are lots of assumptions, and not much data that is easily available.
Just a safety note- anyone wanting to experiment please understand the factory test of the stove tank mentioned in the above threads would have been done hydraulically, this is standard practice when testing pressure vessels as failure will result in a jet of water rather than explosion. To test safety release valve opening pressure and to adjust, the safest bet would be an off-the-stove jig involving no pressure vessel.
