What is the difference in the physics of the fuel source for a wick type vaporizer as opposed to a non-wick stove. I have used and understand how a Svea 123 draws the fuel into the burner through capiliary action and the difference in prwssure inside and ourside the fount. Also operating an Opie 00 and and the Radius 43, which rely solely on a fuel tube and pressure to draw the fuel onto the burner. What would it take to create a wickless 123r or 8r? Or for that matter a wickless 9061? Guess I shouldn't spend so much time sitting in traffic thinking up this stuff 8-[
Hi, I think wicks in Pressure stoves act a bit like a diode in an electronic circuit. They have a resistance to back-pressure so that high pressures can be built up in the vaporiser. So the sequence of events is: 1 The tank is sealed and fuel transfers to the burner head by capillary action and some pressurisation caused by gentle warming of the tank. 2. The priming fuel is then lit and the burner/tank are heated. Fuel vapour is created in the burner/vaporiser and once the valve is opened this vapour flows out of the jet and can be ignited. 3. Pressure rises in the tank due to thermal feed-back, and this combined with some capillary action keeps the vaporiser supplied with additional liquid fuel....and so the process continues until the flame is extinguished using the valve, or all fuel is consumed. I guess that the wick might also act as a flame arrestor to stop flash-back into the tank if the fuel level was to drop dangerously low. The addition of a fuel pump, or other means of tank pressurisation, should enable a wick-less 123 to operate... Or am I being wit-less? Best Regards, Kerophile. PS I believe that trees generate high pressures in their branches and leaves by the action of capillarity and transpiration, illustrating the power of capillary action.
Biggest problem I see with a wickless 123 would be the shape of the bottom of the fount. You'd have to have a pretty strange pickup tube to get usable burn time out of it I would think
kerophile said: With all due respect... I believe "flashback" to be a myth. "Flashback" as a theory flies in the face of science (physics). "Flashback" also does not agree with the physical properties of gasoline/naphtha when vaporized and combined with oxygen. If "flashback" existed, Bordes would not exist. Nor would Optimus 111B's or 22B's or 199's, Radius 43's, Primus 41's, etc. None of which have wicks. All of which burn, or can burn, gasoline/naphtha. Itchy and Dwarf have it right. Wicks exist to enable the pick-up of fuel from oddly shaped tanks without the use of complicated pick-up tubes. Wicks are/were used by manufacturers because pickup tubes are/were more expensive to fabricate and install. Or, such is my opinion.
Hello Gary, I've missed seeing you here! 8) So QED with the pick up tubes. That explains the frankie you built for me having a pick up tube. (Still a superb stove I might add) Thanks to all of you who have writen in. Chef BC
My understanding was in a self pressurising stove the wick bought fuel to the jet when cold which is then vaporised and burnt. As the stove heats up the extra pressure forces more fuel up to the jet which is why these stoves start slowly and build up over the first minute or so. Pump up stove like the m1950 have no need for for a wick as they have pump pressure to get the fuel to the jet. Thats why they start with a hiss roar and search for the eyebrows. As an aside what is the biggest self pressurising stove?
Hi Gary, with all due respect. Flashback is not a myth and certainly does not fly in the face of Science: http://en.wikipedia.org/wiki/Flashback_arrestor http://www.iigas.com/fba.htm http://www.elmactechnologies.com/flamearresters/productoverview.html It is possible that the design of the petrol fuelled stoves you mention ensures that flash-back is avoided by the detail of design but the phenomenon certainly exists and is a serious concern in many industries. Best Regards, George.
In the most literal meaning of the above underburn is a type of flashback or at least caused by flashback
Kerophile: To be quite clear - flashback in stoves is a myth. There is little if any connection between the industrial references you make and the realities of petrol stoves. The physical properties of gasoline/naphtha preclude the possibility of flashback in the stoves which we see here at CCS and which people use and collect. Please research those physical properties and burning chacteristics and you will be educated on the subject. The design of all these stoves is such that a flashback into the tank is simply not possible. Promoting the fallacy of petrol stoves having flashback serves no purpose other than to frighten people. If flashback in petrol stoves were a reality, we'd be hearing about these stoves exploding. Such is clearly not the case. If you disagree, then please cite references to actual verifiable occurrences of these exploding stoves. Additionally, if flashback as you have promoted it as a hazard were possible in petrol burning stoves, Primus Omnifuels and Optimus Novas would not be depressurized at the end of use by flipping the tank. Once again, flashback in stoves is a myth. Stoves don't go boom from flashback into the tank. Let's please put this erroneous notion to rest and move on. Thanks. Just my informed and researched opinion, of course, and if folks rather live in fear of their petrol stoves, that is of course, their choice. I'll say no more on the subject in these forums.
Gary's right, the only time you can have flashback is when you have a fuel/air mixture within ignition and proper ratio, and little or no gas velocity. In any given pressure stove, the fuel feed is so fuel rich, flashback is all but impossible, let alone the fuel vapor velocity at the jet far exceeds the flame front burn velocity rate. Add to this the relative mass of the brass jet versus the minute size of the jet port, and the mass acting as a heat sink to prevent flame propagation past it...well, put it this way, I won't lose ant sleep over flashback issues, myself. Murph
One reason why I feel so much at ease using kerosene over coleman fuel or gasoline on my stoves. Alas, some nicer stoves run on coleman fuel or gasoline - not that I live in fear using them since I try to operate them safely by not opening the tank cap around any open flames or heat sources that would cause any liquid or vapor to ignite instantaneously. Ron
Morning all. I'm having difficulty understanding how my 1st 123 stoves base suddenly changed from being concave to milliseconds later being convex .. so convex that it wouldnt stand . Was cooking eggs (large fry pan ) & the violent internal volume expansion was of sufficient force to throw the pan . If not 'flashback ... Then ... ?? Unfortunately I dont have the stove ( returned via retailer to manufacturer ... full cah refund). Have also witnessed extreme upwards deformation of the (formed in tank ) 123 primer annulus . I'm thinking rapid , extreme internal pressure rise in the tank , created by ??? I'll err towards flashback ... Reckoning , I dont 'phaze' easily .. this kept me away from petrol stoves for about 10 years . I know what I'VE experienced . Sidenote ; Had an interesting post l.s.d 'flashback' @ 300m A.G.L on a Paraglider . If not Flashback ... what ? Keep it Blue . Nick
Flashback arrestors in gas pipelines are just mesh screens. They quench the flame by cooling it as it passes through it. Same principle as miners lamps that will give off a popping sound if cpmbustable has enters it. The flame never exits the mesh screen. That same quenching effect makes a flame passing through the nipple impossible. For the fuel inside the tank to combust, the mixture has to be right, and a spark present. Failing that the pressure need to be extreme, more than the tank can handle. I think expanding tanks are more to do with temperature reaching that of the fuels boiling point or even critical point. The fuel needs to become vapor and, there you go. Instant ball-shaped tank.
My obversation is that there's a lot of overthinking going on here. 123's work. who cares how? The important thing is to develop a long term protocol so one's 123 doesn't get run dry and scorch the wick as that will convert a fun lil' almost bulletproof camp stove into a cute lil' brass conversation piece. I've bought several 123's. 71's and 8r's that wouldn't run for chump change then mended them to nearly as new by denuding an old cotton mop for wick material. Easy peasy. All that could have been avoided by the simple practice of topping up the tank before EVERY light-up. My personal 123 non-r is forty five years old, has all it's original parts, and has yet to fail me or even hiccup. It has also been used. A lot. What a wondrous little machine, would that all manufactured things were as good. From the time my first child was born, that stove sat on a shelf for fifteen years half full of Coleman fuel. When I returned it to service, it fired up like it was brand new and has never done otherwise since. Is as rugged and reliable as an anvil. Gerry
