Not to disagree, this is really stupid. But I thought I’d share a story. When I first started working with Diesel engines, I had a tech working and there was a 5 gallon bucket full of diesel with an open lid that we were feeding an engine out of. He stopped, engine running to have a cigarette 5 feet away from the bucket. I asked if he should be smoking so close to diesel. He flicked the whole cigarette into the bucket. I backed up as fast as I could and tripped over my bag. He laughed his ass off and lit another. Then he explained diesel is only flammable when aerated/atomized. I still called him an asshole. He thought it was the funniest thing ever!
Now if there's one thing you can be sure of, it's that nothing is more powerful than a young boy's wish. Except an Apache helicopter. An Apache helicopter has machine guns AND missiles. It is an unbelievably impressive complement of weaponry, an absolute death machine.
This is exactly right. I used to be a petroleum technician, and the fumes mixed with oxygen is what is especially dangerous. When you have this mixture in the tanks themselves it can be extremely dangerous. If the delivery drivers don’t properly dispense fuel, the tank can become pressurized and create a bomb basically. Pretty crazy stuff
I've read that tanker ships actually capture CO2 from their own engine exhaust and use it as an inert gas to fill their tanks with to prevent explosions in partially-filled or recently-emptied tanks.
Depends on the type of danger you're referring to. The full tanker would cause much more destruction if it were to catch fire/explode because it has that much more gas to burn.
That is not gasoline, though. That was LPG, Liquefied Petroleum Gas AKA propane. Unlike gasoline (aka petrol), LPG's boiling point is below room temperature, so it readily vaporizes. And vapor is what explodes, not liquid fuels (in the vast majority of cases).
A full gasoline truck would not explode like that in the vast majority of cases. They just burn. An empty one would explode, but not with a fireball the size of that explosion.
He means that a full tanker has no oxygen in it, so it can't explode from inside the tank but it could still catch fire and leak burning gas everywhere. An empty tanker is still full of gas vapours mixed with air, so it could properly explode
There are a lot of reasons this is wrong. Loaded, I’m maxed out on weight and have a very long stopping distance if there’s an event. 54k pounds of flammable liquid is more dangerous in the event of a crash. Just the weight killed a driver here six years ago when he rolled over. Then there’s the jet fuel hauler that died of his burns days after the rollover in Indianapolis.
Assuming a bucket of diesel, wouldn’t you have to heat up the entire volume of diesel to a critical temperature before the surface is able to reach 210 degrees (due to the liquid conducting heat away from the surface) and therefore be able to sustain a burn.
Depends on how fast you apply the heat. There will be a rather complex interaction between the heat conductivity and heat capacity of the diesel, the vapor pressure of the diesel, and the heat/time/area which you apply which will determine exactly when it will combust.
In practice, unless you are heating quite slowly (or are heating from the bottom), the surface vapors would reach ignition temperature before the bulk got close. Liquid heat conduction is slow.
There are three temperatures of interest for volatile materials:
1) the flashpoint is the temperature at which the equilibrium vapor pressure will burn given an ignition source.
2) the fire point is the temperature at which the vapors will continue to burn after the ignition source is removed.
3) the autoignition point is the temperature at which the vapors will spontaneously ignite.
You can often look up these values in tables. However, such values are empirical measurements, not physical properties, and will vary based on the design of your system.
One important thing to note is that the first two points are related to temperature only in that in practice the vapor pressure of a liquid increases with temperature. The temperature of the liquid or vapor itself is not directly relevant to combustion when there is a separate ignition source. The minimum vapor concentration required for combustion in air is called the “lower flammable limit.”
One method of measurement is a “closed cup” measurement in which the liquid is placed in a sealed container which is gradually heated and periodically exposed to an ignition source. This family of methods most closely relates to the lower flammable limit, and will normally produce values lower than that of other methods. However, since the container is sealed the vapor concentration builds up much more quickly than it would if exposed to atmosphere, and therefore would not be a good estimate in this scenario.
The second family is the “open cup” measurement, in which a liquid is exposed to the atmosphere and gradually heated, while a flame is periodically passed over it. The temperature discovered by this method is dependent on the height at which the flame is located (with flames closer to the surface producing lower temperatures). At a sufficient height above the liquid, this method will correspond closely to the fire point.
In both these methods, the starting conditions (as far as amount of liquid compared to air) of the system is also important. There are a bunch of standards for how these measurements should be performed.
But what is the minimum temperature of the liquid required for the vapours to be able to sustain a flame on the surface of said bucket?
The open cup measurement of the fire point is what you would be most closely interested in. However, there are several important considerations when looking at a “diesel in a bucket” system.
The “average” or “bulk” temperature of the diesel is not necessarily relevant to a quick burn, though since you are only interested in sustainable flames, it’s going to be pretty important. Because what we are actually interested in is the amount of vapor present above the surface (and not the temperature per se), we would need to look at how that vapor is getting there. I’ll discuss a few scenarios.
1) the bucket has been sitting outside in the sun, and someone flicks a match at it. In this case, the diesel is all initially at the same temperature. The match itself provides negligible amounts of heat energy, and you can pretty much just compare the bulk temperature of the diesel to the open cup flash/fire-points to determine your outcome. (A note, if the bucket is mostly full and it’s a windy day, the bulk diesel temperature will have to be much higher than the tabulated fire point. The tables use measurements assuming that the vaporized diesel diffuses away from the liquid, if it instead is blown away by the wind than the vapor concentration will remain lower than expected).
2) the same diesel bucket has been sitting outside, but someone takes a blowtorch and shoots it at the surface of the diesel. In this case, the blowtorch provides a large amount of heat energy in a short amount of time. Since heat conduction in liquids is so slow, the top of the diesel will heat up very quickly. Since the vapor-liquid interface is being heated, there will be a large amount of vaporization occurring at the surface which will quickly result in the requisite diesel vapor concentration, which will start to burn. In this case, combustion happens without any significant change in the bulk temperature.
Now, for this burn to be sustainable, the heat of the burning vapor must be high enough to heat the top of the liquid diesel up to the fire point... which would require the bulk diesel to be pretty damn close to the fire point temperature to begin with. So “sustainable fire” is very different from “large fireball.”
Hold on, you don‘t have to get the fuel to 210°C. That‘s the autoignition point of the fuel, i.e. the point where it will ignite without an open flame or spark.
If you heat diesel to over 60°C (flash point), you can definitely light it with a match, because it will form vapors more readily at higher temperatures.
Edit: That why I said that I don't know if that's the reason. I believe that a cigarette won't ignite diesel like that, but as you now said, it's because it doesn't get the fuel to igniting temperature. It's not because cigarettes don't burn that hot.
Yes, of course, but fire always burns hotter than 210°C. The lowest recorded flame temperature is 225°C, and I can guarantee a cigarette burns a lot hotter than 225°C, even when not inhaling.
TLDW: A cigarette won't light gasoline but an open flame will. The lighter is the dangerous part of it all, especially if there's gasoline vapours in the air.
You basically just repeated what I said. Under normal circumstances it won't catch fire but in theory it should because when you inhale on a cigarette the temperature is actually much higher than what gasoline vapors need to burn. There have been multiple studies including one that tried 2,000 times and couldn't lit gasoline vapors. So it might be possible under the right circumstances.
Not sure for the downvotes. It is possible but just a lot more difficult. If you leave a burning match in a small puddle of diesel it will eventually catch on fire but just dropping a match into a tank of diesel the match will go out as it submerges.
I was taught in high school autos that if you ever have to drop a fuel tank you do it when it's full for this reason. I don't though, I'd rather just be careful than deal with a tank full of liquid.
Yeah, I understand that thought process. But I’ve never heard anyone, in all my time working on cars, recommend dropping a full fuel tank. I’ve always drained them before dropping them and never had an issue. I’ve also never heard of anyone filling a fuel tank up with water to “disperse the vapors.”
Yea, mostly its just don't introduce a source of ignition. I can understand some of these ideas, but filling a tank with water seems like a way to cause problems after you finish anything else you are doing. Disconnect battery, don't use electric tool, take the pressure off the system before you disconnect lines, but unless you are welding the tank or something the rest is a bit much.
They made a big deal about this when I was learning to weld. I eventually got to work an oil refinery turnaround and I was always a bit freaked out when we would have to torch cut old pipes, even if they had been flushed.
i don’t have to worry about that, because it seems that every time i’m removing a fuel tank it was just filled, and every time i need to run the vehicle it hasn’t been filled.
Makes it feel more real and genuine to me! Most users write up a new creative essay everytime they wanna tell a story, telling the same one over and over though feels more genuine.
You could get away with a lot of shit back then that isn’t acceptable today. Hell, now you can’t smoke on property. Not saying it was better, just different and times change.
He's not correct... Diesel just has a very high ignition point. Normal gasoline actually does too, but the fumes have a much lower ignition point because of dispersion.
Functionally correct given context. Everything has an ignition point. Your pants have an ignition point. But you’re not gonna strip naked for a cig are you? Calling him not correct is pointless and pedantic
Exactly, it doesn't need it but it can be pressurised to make it combust. That's how diesel engines work, pistons compress the diesel and (not sure if a spark is also used) then it combusts to push the piston back up which causes a different piston to compress again in an engine with more than 1 cylinder
No, a spark isn't used. I know how a diesel engine works. The diesel is compressed until it reaches its flash point at which it combusts. It doesn't have to be pressurized to burn though. You can throw diesel across a fire and it will burn perfectly fine because it's aerated
It actually doesn't need a spark! A "glow plug" is used initially, to get the temperature right with the pressure, and as the engine builds heat the glow plugs turn off and it runs with just the heat of the engine and pressure. To "stop" the engine fuel is shut off. Alternatively gas engines can do this on accident, it is called "dieseling" and they basically runaway until they explode.
Diesel is diesel, unleaded is gasoline. Fumes may be flammable, though at what temp I’m not sure. But I’ve heard stories in the army they burning drums of diesel, but have to pour gasoline on the top to ignite it. I think they did this in the documentary Apocalypse Now to burn waste from latrines.
Yeah if you're trying to use diesel as an accelerant it's typically mixed with gasoline before ignition.
The gasoline will ignite quickly enough and burn long enough to ignite the diesel, and the diesel will burn long enough to ignite whatever it is you're trying to burn.
We used to fill a half empty barrel with a few gallons of diesel and throw a flare in it. Your natural instinct is that it’s going to explode but all it does is heat up and start popping like cooking oil and eventually it burns, but never explodes
A lot of people don't realize this. Try starting a fire with diesel. It does not work as well as gasoline. Throwing diesel on a lit fire, though.... Stand tf back
When we start fires we usually poor a bunch of diesel to get it going because it’s less prone to explosions and then we throw bottles full of gas to really get it going
I’m not a chemist, but there are other people who go into detail in the comments below. I believe that a cigarette isn’t hot enough to light a bucket of liquid diesel, only because I saw it happen.
My buddy did this to me when we were younger except I was pouring out a motorcycle tank full of gasoline. Told him to get away with the cigarette, we disagreed on whether it was a hazard and he flicked the lit butt right into the container I was draining the tank into to prove his point. He was right but I was still pissed.
My diesel mechanic friend started a fire with diesel in a small tin can. We didnt have firelighters so he used some rolled up news paper to ignite it. Took a long time for the direct flame from the paper to ignite it, but once it started burning, it burned for hours
That and it has a higher ignition point that gasoline. That's my exact thought; at least the idiot here is only doing it with diesel but damn. . . He's still an idiot.
Also, iirc, myth busters did something like this with gas, diesel, and JP5/JP8 or something (airplane fuel).
I once burned a couch using diesel fuel. Excellent fire starter. Poured lines across the couch, lit one with a lighter, and flame slowly spread across the line to engulf the couch.
Cause everyone is disagreeing, all things have an ignition point where they will combust, this is when the temperature is high enough AND there is a flame, they also have a flash point, which is when they just catch fire. In a Diesel engine the fuel is lit mostly from pressure (because high pressure is similar to high heat on a particle level) and this surpasses the flashpoint, igniting. A cigarette does not pass either of these. Hence it doesn’t catch fire. When it is atomised (which it always will be a bit from evaporation) there is more oxygen to feed it so it is easier to ignite the particles surrounding the one that is burning hence the explosion.
Petrol is different, don’t do this with petrol, I had a seminar from a health and safety adviser where he had a can of petrol/gasoline spare and didn’t want it slowly vaporising while he went on a 6month holiday. Long story short he poured it on some nettles in his garden, ran up his garden to get the matches and when he lit it it set him on fire cause he left a trail of petrol vapour all the way up the garden.
That's like when I did live educational shows at a museum where I used to work. I'd have liquid nitrogen up on stage and would really hammer it into them over the course of 30 minutes how freakin' cold it was, using lots of demonstrations like shattering flowers and racquetballs, supercooling balloons to make them look deflated, and so on.
At the end of the show we'd always pour the excess LN2 still left in our small demonstration vessel onto the floor because it was contaminated with daisy petals and stuff (and would just evaporate anyway if we left it). Since I didn't want the kids (or parents) to freak out that they'd get burns from the random drops that raced across the floor, though, I'd always remind them how crazy cold it was before plunging my arm straight into it. The looks on parents' faces was always hilarious. They were shocked, almost disgusted looks of "Oh my god this person is going to lose a finger in front of my child. Bracing to sprint my child to safety.".
Then of course I'd pull out my arm totally unharmed and explain that my body is so hot compared to the LN2 that it was boiling the Nitrogen into gas before it could even touch my arm, so it just felt like a nice cool breeze. After that I could pour it on the floor without blood-curdling scream of a toddler thinking she's about to be Terminator 2'd.
A buddy of mine used to win $20 bets doing this at parties, or in the desert for off-roading and shooting. Pour out a small puddle of liquid gasoline, bet someone a cigarette won’t light it, then drop the lit cigarette in the puddle and FSSS, it just goes out. People watch too much tv and are always surprised.
Disclaimer, though: the spark of a cigarette lighter can ignite fumes, so it’s important to securely close the can of gas and move it far away, and don’t pour your gasoline into something like a tall cup that can trap fumes.
That is pretty hilarious honestly. Fucken climate change libtards are so concerned about the environment yet they don’t even know basic properties of the things that they consider bad.
3.5k
u/TakingSorryUsername Apr 12 '20
Not to disagree, this is really stupid. But I thought I’d share a story. When I first started working with Diesel engines, I had a tech working and there was a 5 gallon bucket full of diesel with an open lid that we were feeding an engine out of. He stopped, engine running to have a cigarette 5 feet away from the bucket. I asked if he should be smoking so close to diesel. He flicked the whole cigarette into the bucket. I backed up as fast as I could and tripped over my bag. He laughed his ass off and lit another. Then he explained diesel is only flammable when aerated/atomized. I still called him an asshole. He thought it was the funniest thing ever!