Hi everyone, This is well known old Primus 96. I found it on a Swedish auction, as a matter of fact only pump washer had to be exchanged. Details presented above are importatnt for dating and closer evaluation of P 96.It is discussed in a brilliant way HERE I was really surprized, when I started it for the first time - shortly before spirit burned out, I could observe auto - start ( or self ignition ) without pumping. So I decided to make a footage and place it on You Tube ( never did it before ) This film you can see HERE ( www.youtube.com/watch?v=qz9We0Hdk14 ) Of course with 3 - 4 strokes the flame is four times higher Thanks for watching CU
Burmos 21's are quite prone to doing this too, my most often used example does it nearly every time. I have only ever had it happen a few times with 1/2 pint stoves though, and always indoors or in summer when everything is that bit warmer. I wonder if it is down to the machining of individual tank lid and release valve threads- a tighter fit on a less well used stove may be enough to allow pressure to build in the tank even when the valve is unscrewed.
Hi there @Blackdog , Seems to me, it is nothing unusual. I observed this phenomenon on my various stoves - most of them had English provenience ( Monitor, Veritas - see my discuss with @Nicola Francesco Elia ) . I was to lazy to do a footage at that time ). Moreover - even the rare version - silent - of Rekord stove made in USSR has also this function.
All due to slight individual variation in manufacture I reckon. But it's often a surprise when it happens on a stove which doesn't normally do it- whichever of us is doing the cooking will remark "Ooh, the stove has lit itself!" Always handy when preparing food, one does not have to interrupt cutting up carrots to close the pressure release valve and pump...
@Blackdog For me it is the matter of thermal conduction between rising tube ( or, better said, spirit bowel ) and a tank. The shorter is rising tube , the better and the thicker, the better.
@Delphicstove Hi, As far as I know, the best conductivity of heat ( what concerns metals ) have silver, copper, gold and alloys of copper, e.g. brass ). So the thin layer of nickel shouldn't have significant influence on it. Regards Stanisław
Hi. Somewhere ( I no longer remember where) I read that a tightened vent screw during the preheating process, can promote such a phenomenon as you have shown here in the video. Also, in large stoves, a screwed down vent screw (located on the side of the filler hole) during tank priming and further during preheating can also trigger the burner in this way. I once forgot to unscrew the pressure screw and there was a kerosene leak through the nipple during warm-up ( lots of smoke and flames) so I don't know how reliable this information is. I write about it because I noticed in the video that you do not touch the pressure screw. Greetings
A tightened vent screw during preheating will often result in a flare-up as liquid paraffin is released and ignites. I'm sure any of us have done this at some point! My theory is that because machining tolerances vary, some stoves vent more air than others when the pressure release screw is open. A few oddities may be restrictive enough to allow enough of the increasing pressure to escape to prevent liquid paraffin rising under thermal expansion and flaring up, but allow enough pressure to build up that vapour is released and the stove begins to burn.
@Knee Hi, Of course, the vent screw must be tightened, otherwise the pressure in the tank is equal with atmospheric. Leak through the nipple occurs when pumping too early with vent screw tightened ( my observations ) Greetings Stanisław
....unless the machined threads are a very tight fit, or the machined groove in the design of some release screws is incorrectly made. Then there can be enough pressure build up for the stove to auto-light and run for a short while with the release valve open. I have a Burmos 21 which will reliably light itself every time without releasing liquid paraffin and flaring up, with the release valve left open. The stove will run by itself for half a minute to a minute, after which the release valve needs to be closed for it to keep running at a simmer output. Another Burmos 21 of mine will never do this, I believe the threads have been machined slightly slacker, so release air effectively enough to allow no pressure to build up.
