Why doesn't fire flow back INTO the cylinder? Let us take into a consideration a (pressurized) kerosene stove.
The pressure drives fuel out of the nozzle, like

or in a much simpler arrangement as in

Question-
Why doesn't fire flow back into the fuel cylinder from the stove's burner tip, via the fuel inlet at the very bottom; what interface thingy keeps fire ignited only above the burner.
P.S. I have never seen an LPG powered stove, but I am sure that besides the difference of self-pressurized fuel cylinder & valves- the burners work in a pretty similar manner.
I can't find appropriate tags for this question, so I am open to suggestions about them also :)
 A: A flammable liquid in its liquid state will not burn, you can throw matches into a bucket of liquid petrol all day long without a problem. its only when you get gas/vapour coming off it that you gotta run
ABSOLUTELY DO NOT TRY TO TEST THE ABOVE EXPERIMENT
I know you know but just to be sure (not being smart with you) its LPG in the cylinder, Liquefied petroleum gas , so you don't need any device where you think there should be one.   
A: It takes more than kerosene to burn.  You need kerosene and oxygen.  The flame does not go back further into the cylinder because there is no oxygen there to allow it to burn.
A: The cylinder is pressurised. It's pushing kerosene out quickly, so oxygen can't get in.
A: Combustion is a chemical reaction and for this to happen you need the molecules to be sufficiently near to each other for the electrical forces to take over and cause the reaction. Thus you need to atomize the fuel and mix it well with air/oxygen in the presence of heat (= highly energetic molecules to bring collisions). This is why you have a long column of fuel in the jet just before reaching the hot spot(plate) without experiencing much of a combustion. As the liquid fuel hits the hot metal spot (note you need to give heat at the start by other means) it splashes, gets heated then mixed with air then react.
The same happens around the wick of a candle in a slow version of this. The hot wick (heated at the start by a match stick) heats the fuel and atomizes it which then gets mixed with the entrained air/oxygen then reaction starts.
In oxy-gas fule systems for welding, you can have a case of the flame travelling back into the fuel cylinder causing explosion- since in this case you already have atomized mixtures and the little heat needed to start the reaction is carried out by the flame front. For this reason you need what is called 'flame suppressors' (one way valves in essence) to stop such accidents. 
A: Why because any fuel can't fire without the helping of oxygen and when the fuel and oxygen mixed together and it will be converted into heat state i mean it is utilized and there fuel will not be there, So again and again it will be utilized (i.e loss of fuel) so that only there's no way to return fire into the cylinder and also the inside pressure is more than the out side pressure so never the fire will not entry into the cylinder definitely it goes upward position, that is it. 
