That sure sounds like a stupid question but, hear me out.

This was brought up in another forum and I thought I would bring it here for further debate.

There seems to be some confusion as to the definitions of atomization and vaporization of gasoline. I have been a mechanic for 20+ years and I have always used, as part of my underlying knowledge, certain physical properties of the components involved in making an engine run. One of those components is gasoline and how it behaves under different circumstances.

My question is this: Does the liquid portion of gasoline burn or is it only the vapors that burn? Or both?

If the liquid part of gas will burn then, I will have to go back and re-evaluate my assumtions of what it means to have a 'flooded' engine.

Thanks,
Ben

 

A flooded engine is one that the PLUGS are flooded on. They are too wet to fire. Yes the liquid gas burns, but it needs the flash from vapor igniting to light.

 

I've always heard that liquid gasoline doesn't burn. The thing is, it's next to impossible to have liquid gasoline without vapors right next to it, so you'll never know if it was the liquid of the vapor that burnt.


The more I think about this, the more I think that it must burn as a liquid, but possibly at a much higher temperature than the vapor.

 

Liquid gas will burn, but not very well. If you stick a lit match in liquid gas, it will go out. (DO NOT TRY THIS AT HOME. The vapors around the gas will blow up.)
Liquid gas burns with an orangish flame and puts out lots of black smoke- think of TV news footage of a burning gas tanker.

I believe that the liquid gas shorts out the plug so that no spark is created, hence no ignition. I've never had the guts to try soaking a plug with gas, and seeing if it would fire, though, so I'm not sure.

 

its the vapor that burns. no liquid will burn without O2 and if there is O2 present than it is vapor. if you submurged a spark plug in gas and sparked it, the gas would not ignite

 

This is not entirely true.

A flooded engine won't fire because there is too much fuel and not enough oxygen. You need to have a proper air/fuel mix in order for the explosion to happen. A fouled plug can be a result of this - but a fouled plug is one that the spark is not correct - it can be caused by other things than excessive fuel/wet plugs. People check for a soaked plug to find out if the engine is flooded - that doesn't mean your not getting spark - it means theres too much fuel to cause an explosion. You see a lot of fouled plugs in 2 cycle engines because of carbon buildup on the plug screwing up the spark.

There are three parts to a fire/flame/explosion...

Oxygen
Fuel
Heat

Without the proper arrangement of each - no fire. An explosion is just a rapid burn - where there is the right amount of oxygen present to quickly spread a flame. It can happen so rapidly that the forces involved are incredible and are what cause the internal combustion engine to work.

I've always been told it's the vapors that are flammable - which is the reason why you can have gasoline explode without the liquid being touched. Thats as far as I am able to get into that.

 

I offer this web site not as conclusive proof but rather as evidence supporting my assumtions:http://www.turborick.com/gsxr1127/gasoline.html

Here is the paragraph that most relates to this disscussion:

5.2 Why are there seasonal changes?
Only gaseous hydrocarbons burn, consequently if the air is cold, then the fuel has to be very volatile. But when summer comes, a volatile fuel can boil and cause vapour lock, as well as producing high levels of evaporative emissions. The solution was to adjust the volatility of the fuel according to altitude and ambient temperature. This volatility change has been automatically performed for decades by the oil companies without informing the public of the changes. It is one reason why storage of gasoline through seasons is not a good idea. Gasoline volatility is being reduced as modern engines, with their fuel injection and management systems, can automatically compensate for some of the changes in ambient conditions - such as altitude and air temperature, resulting in acceptable driveability using less volatile fuel.

Thanks for your input so far guys!
Ben

 

Liquid gas does not burn as stated above only the vapors. The orangish flame and black smoke is the impuritys burning in those crashes. The fire gets so hot the aluminim tanks melt and burn as do the tires hence the black smoke.

 

It has often been said that:
If one was able to get a lighted match past the gasoline vapors the gasoline liquid would extinguish the match.

So the answer is yes

 

this kinda reminds me -

when your spinning tires how come the smoke is white and when your burning tires(not that i ever have) on a brush pile it burns black?

and i was always told that cold gas burns better than warm gas.
then i want to know whats wrong with all my cars ant trucks in the winter .

lmmfao

 

I lean more towards the absense of oxygen to keep the match alive with a flame. It enters an environment of complete fuel saturation and therefore no oxygen...

You can light off sparks all you want in a gas tank - without oxygen it won't explode. It's precisely the reason we are able to use electric motors in the intank fuel pumps for EFI.

 

Actually, I think the orange flames and black smoke have little to do with "impurities". Rather, black smoke is a byproduct of burning gas/oil with not enough air. Just like a diesel engine belching black smoke, it is a result of too much fuel to air.

 

Yes, just like boiling water, if you heat it up hot enough and dump it on your skin you will get scalded.

 

Hey Neb, think how a candle burns. You light a match, touch it to the wick of the candle and pull it away too quickly and you see the wick smoking. Put the match in the "smoke" and the candle lights. Solid wax doesn't burn, that smoke that lit up like that was wax vapor. But wax isn't as volitile as gasoline so it needed the heat of the match to turn it into a vapor which can burn. Gasoline will vaporize at room temperature. So a flame can ignite the vapors on the surface of liquid gasoline.

Atomization is what a fuel injector does. Or a carburator or a ladies' perfume sprayer. It is what you get when you shoot, or siphon, a stream of fuel into rapidly flowing air which breaks it up into tiny particles. This gives the fuel a lot more surface area. As soon as it is exposed to air it starts to evaporate. When those particles are contained in a hot intake manifold the "vaporization" or evaporation takes place at an accelerated rate. And at that point, it is highly volitile. If all is going well, as it is sucked into that swirling madhouse of a combustion chamber it is entirely evaporated and is highly explosive.

But if the engine is cold, it may only be half evaporated because the colder it is the slower the evaporation. So then you need a choke to put in a richer mixture. How does that help? you ask....... It makes millions more of those atomized gasoline particles so that there is much more surface area for vapors to emanate from. But until you achive a certain temperature not all that fuel will burn because it is not all going to evaporate. The available air becomes saturated with gasoline vapor so it will run your engine but you are going to get black smoke in your exhaust, which is unburned hydrocarbons. Sort of gasoline ashes.

Referring to the article you posted the exerpt from: They used the term "vapor lock" which was incorrectly used in that thread that closed down. A vapor lock is what happens when a fuel line is heated to the point that the gasoline vaporizes inside the lin and upstream from the fuel pump. The pump being designed to pump liquid fails to move vaporized gasoline so the engine starves and cannot be restarted until the fuel line is cooled and the fuel is re-condensed to a liquid form. Which is a good illustration of why the oil companies vary the volitility....... (the temperature at which gasoline vaporizes)........ seasonally. Winter fuel is more volitile. It evaporates at lower air temperature. In summer everyone would be suffering from vapor lock using winter fuel.

 

Thanks Bdox. It seems that more than a few folks don't understand the difference and that's why I thought it would be useful to bring it up. I just regret putting that article in there so soon after starting the thread. I should have let the thread take it's course so more people would participate and thus a little more correct information would be made available.

And yes, the vapor lock statement stood out like a sore thumb to me as well but, given the climate of that thread, I decided to let it go.

Vapor lock might be a good subject for a new thread?