@ Roger – FMS-116T stove question

I am guessing that they do not mean the full flame, as you have experienced, Roger. Rather I believe this is a form of pre-ignition/final cumbustion. As you have noticed, there are several colors related to a premixed gas (a typical canister stove.) A lot depends on which elements and radicals are being broken down and recombined in the heat of the flame. Of interest to this discussion, is three basic regions, usually corresponding roughly to the heat of the flame. A lighter blue/whitish “flame front” around a “center core” that is colorless, since it is too cool to support combustion. The flame front in turn cools off and continues to combust with other less reactive molecules producing a dimmer/darker blue fading to non-visable flame.

The central core is not actively combusting. It is heating up to ignition temperature and is far cooler than the around 2000C degrees of the actual flame front. Pressure/Volume drive this through the little holes, essentially keeping the flame spreader or grate far cooler than the flame front. By turning it down to a very low level, you can actually have the flame front in very close proximity to the spreader, heating it to much higher temps than simply turning up the stove and allowing the gas pressure to cool it as it passes by. I don’t think of this as an “inside” flame, rather a stalled or slow motion ignition sequence of the gas. But if you consider the heating of the gas to kindling temperature, I suppose that would be correct. I kind’a doubt the rep had the english to explain what was happening in any detail. I had some old WG stoves that acted similar, I got rid of them…a grey PEAK 1 from way back and an old Coleman Exponent 1. Hmmm, I think I still have the Exponent now that I am thinking about it. Turning it down very low actually heated the stove itself more than turning it up.

Hi James

I understand flame chemistry. I also understand the concepts behind the basic Davy Safety Lamp, and how that blocks anything close to ‘pre-combustion’ from crossing the metal barrier. I have yet to see a stove show signs of any of this problem in all my years of stove play. And I have played with far more burner faces than shown in any of my articles – I made them myself. There never was a single problem.

Now, it may be that I have missed some recent developments in pyromania (aka combustion research). If so, I would LOVE to receive some references to the latest scientific literature on the subject. That will have to be respectable research papers, not blogs or scare articles in psuedo-outdoors magazines.

Guessing wildly. Maybe someone at Fire Maple came up with a stove design which had this problem, and management got wind of it and threw a fit. I very strongly doubt the engineer I used to email with was involved: he knew what he was doing. But he was just a techie, not a sainted manager.

Cheers

I may be slightly wrong about the source of the rumour.
I did find one person on bushcraftusa.com who claimed that his canister got very hot after running his BRS-3000T stove for a long time (maybe 20+ minutes) on a very low simmer to keep his coffee warm. Well, that is a VERY small stove after all, and it is probably not designed for that use.
Apart from that, I cannot find anything else on the web. ymmv

Cheers

Well, there is a LOT of real science on the web about this. Of course mostly it relates to engine power.
Here are a bunch of images and graphs I just looked up: https://www.google.com/search?biw=1680&bih=942&tbm=isch&sa=1&q=Combustion+premixed&oq=Combustion+premixed&gs_l=psy-ab.3…7931.12127.0.14924.9.9.0.0.0.0.156.1177.1j8.9.0….0…1.1.64.psy-ab..0.6.811…0j0i67k1j0i8i30k1.0.voad_PpBSLQ#imgrc=0qK6aFyYD846nM:

Though this describes the richness of the fuel/air mixes you can easily see that severe limits on the overall pressure would place the reaction front closer to the source.
Again, on the same search:
https://www.google.com/search?biw=1680&bih=942&tbm=isch&sa=1&q=Combustion+premixed&oq=Combustion+premixed&gs_l=psy-ab.3…7931.12127.0.14924.9.9.0.0.0.0.156.1177.1j8.9.0….0…1.1.64.psy-ab..0.6.811…0j0i67k1j0i8i30k1.0.voad_PpBSLQ#imgrc=_N2RDygNwc6FEM:
Here it is clear that the phases of combustion are present in most premixed flames. Since these are always present in a pressurized system, it can be assumed that the premixed gases will alter the temperature of the input nozzel based on the proximity of the flame front, something he assumes is a constant (and is after a few minutes of operation for our purposes, though it may not be in the oscillating environment of a diesel engine.)

I agree, you have to get by all the BS on the web… there has been a LOT of research in this field…though, not much by way of camping stoves.

BTW: These slides also show that the flame spreader/tube body may not be necessary on your V2 design. A simple jet designed to induce turbulence will work according to these models. Perhaps a baffled angle as it leaves the jet nozzle to induce turbulence?

Hi James

I am familiar with a lot of the combustion chemistry research. A lot of it is aimed at industrial burners of the 50 kW size. I have yet to see anything at the camping stove size though. Maybe indicates where the funding is.

These slides also show that the flame spreader/tube body may not be necessary on your V2 design. A simple jet designed to induce turbulence will work according to these models.
Well, maybe. Very much more susceptible to any wind though. The chambered vortex burner is fairly wind-proof – which is good for us.

Cheers

So here is the reply I finally received from Monoprice about why one shouldn’t run the stove at a very low flame setting for an extended period of time. I am guessing that they had to contact Fire Maple first, and are just passing their reply on to me.

“Dear Gary Dunckel,

We’re sorry for the late reply, we experienced a large influx of emails and are catching up.

The reason that is not recommended by the manual is because there is a possibility for the flames to go out but the oil (sic) would still leak out slowly. This could lead to a few dangerous things happening it is recommended not to have the flames low for an extended period.”

The second paragraph seems like a Chinese reply in English. But whatever we do, we don’t want the oil to leak out slowly, and have a few dangerous things happening, do we…? But to heck with them, I’m going to do an extended low simmer anyway, just to show them that I can control my oils.

A most revealing reply. First of all, I suspect the writer had close to zero knowledge of canister stoves, as they refer to ‘oil’ as the fuel. That suggests the original idea comes from the use of an antique kerosene stove, as the kero fuel used to be called ‘paraffin oil’ in the very old days.

Now, there is indeed some reason to suggest that a kero stove on very low could suffer a flame-out – if the pre-heat tube was no longer being heated enough. Kero stoves were generally not designed for a gentle simmer. My experience with even modern kero stoves would go along with this.

The relevance of all this to a modern canister stove is … left as an exercise for the reader.

Cheers

At any rate, this reply didn’t seem to indicate that the weak flames would stay inside the stove and destroy it, like the earlier explanation suggested.

I still like this stove’s excellent simmering capability. The only other ones, besides the heavy MSR Windpro II, I have that truly do a good simmer are the Coleman F-1 Powerboost with its 2″ wider burner head, and the recently introduced Jetboil MiniMo stove (which has just a 1″ diameter burner head, but it has a delicate simmering capability). However, these 2 stoves are darned heavy (5.2 oz for the Coleman and 4.6 oz for the MiniMo, compared to 1.7 oz for the FMS-3000T).

Regarding the “oil” reference on the response. The whole thing reads like a Google Translate sort of thing. I’m wondering whether it’s one of those errors for “gas”.

Now you’ve got me worried about my small, folding Brunton canister-top burner I use for 3 season backpacking. It’s burner head is larger than “usual” and that’s partly why I bought it.

Hi Eric

WHY? Ignore and just use it.

Cheers