Here I am

Diesel fuel explosive?

Attention: TDR Forum Junkies
To the point: Click this link and check out the Front Page News story(ies) where we are tracking the introduction of the 2025 Ram HD trucks.

Thanks, TDR Staff

Issue #38

Mechanics' opinion needed:

I didn't know diesel fuel was explosive. CNN is reporting the FedEx truck exploded from a rupter in the fuel tank.

http://www.cnn.com/2002/US/Midwest/10/29/fedex.explosion/index.html
The truck was cut off by another vehicle and went off the road, rupturing the fuel tank and sparking the explosion, said Sgt. Ed Ensminger of the Missouri Highway Patrol. Another official said the fuel tank ruptured when the truck's trailer struck the post of an overhead sign.

I find this hard to believe. I know that diesel will burn, but I thought it didn't evaporate fast enough to become explosive. I'm sure that there is someone here who knows more about diesel fuel than me though.



Or maybe it was Hollywood diesel? Or someone shipping fertalizer? ;)
 
Last edited by a moderator:
If pressurized (as in the tank was being crushed as it ruptured) diesel is very explosive. It is the principle that our engines run on. Also if heated it will explode violently, don't ask how I know that :D.
 
Originally posted by LSMITH
If pressurized (as in the tank was being crushed as it ruptured) diesel is very explosive. It is the principle that our engines run on. Also if heated it will explode violently, don't ask how I know that :D.

Testing your microwave, were you? :) I would have thought you would know better than to put a sealed vessel of #2 in there. :D :D

Fest3er
 
Man I ran thru the door to make a post about this tonite. mdlowry, ya just plain beat me to it. Now I remember as a kid my bud's older brother pored some out on the ground and we dared him to douse his cig in it ..... so the dumbas$ did and ... ... nothin , nada ,zip ... . man we were bummed. Then a couple years ago we were on the topic of Jp5 ... Jet fuel and that is even more non flamable than diesel. So how in gods given was there a "75 foot fireball" that wasn't sooty when it extinguished? "It was a briliant yellow fireball that was HUGE" ... . hmmmm sounds fishy to me anyways.
 
TMTT, I've seen someone try to light a small amount poured on the ground. The match wasn't able to light it.



I thought most fuel tanks were right by the cab. The report was of the trailer exploding. This means the fuel tank by the cab was crushed, ruptured and sprayed diesel fuel halfway back to the end of the trailer where it hit a small localized high pressure area and exploded. :rolleyes:
 
A couple more points on diesel fuel.

It has a relatively high flashpoint and low vapor pressure. These characteristics are mainly attributed to the average length of the carbon chains that make up the molecules of the fuel. Diesel has an average of something like 14 carbons and gasoline has 8. So, a larger carbon chain relates to a heavier molecule which does not move around as much and does not vaporize or burn as easily as a smaller hydrocarbon (such as propane). On the other hand, the longer the hydrocarbon, the higher will be its density. This means that for a fixed volume of fuel, the larger (diesel), will have more potential energy. This is one of the reasons our diesels burn less fuel than a gasser of the same HP. As far as diesel fuel exploding at room temperature... . surface area!! So you try to light a can of diesel on fire. Nothing happens. Now, spray the fuel through a nozzle like the one on an oil burner or a fuel injector and..... poof, it lights right up. This is because the surface area of the fuel exposed to the ignition source is greatly increased. With the can of fuel, the fuel itself is absorbing the energy of the ignition source so much that it will not even come close to igniting. With very small droplets of fuel, the ignition source is able to heat them to the point where they will burn and ignite neighboring droplets of fuel... BOOM.



The truck explosion still sounds a bit fishy though... ...
 
Hehehe... . now lets see here... . Are we REALLY sure that somebody from UPS wasnt playing a joke on the Fed-Ex guys? :--) :D :D



General concensus seems to be that the *explosion* sounds fishy. Most likely is.



Fuel tank probably got ruptured, run over, or whatever... . and the fuel sprayed out and got misted. News says the truck was cut off, so they would have been into the brakes pretty hard... there's your probable ignition point (hot shoes). and there's the fireball. :) this reminds me of goofing off while pop-testing injectors. :rolleyes: Uh no sir... that wasnt me!!!! ;)

And we all know that diesel, Jp-5, jp-8, kerosene, etc. burns hotter than h*** once its going and the end result is a crispy trailer. Its nothing but aluminum, some wood and plastic anyways (other than the steel undercarriage)



Just my 2 cents on a probable scenario... . feel free to modify as u wish. :)



PS... remember Wuyawega WI (sp???) where the LPG tankers derailed and caught fire??? everybody said there was an explosion at the beginning..... riiiiight. One of the tankers got gutted by a rail when it piled up, and up she went, nice fireball... but no explosion, otherwise the town would have been gone right at the start. Same thing here with the Fed-Ex truck,if that tank blew..... do u think there would be a tractor left???
 
Temps?

The flash point of #2 diesel is running around 130* to 160* so if the fuel in the cell is that temp, or exposed to a flame while in finer form, it will ignite. Our jet fuel/aviation grade kerosene, is running around 110* to 128*flash. However, explosion with Diesel is rare, much rarer than gasoline which has an atmosperic flash.
 
I have some cases of a tank exploding when someone sticks the the fuel nozzle in a hot tank. After a long trip the tank is full of hot fumes and a static spark will set it off.
 
No explosion but 2000 gallons of gasoline contaiminated diesel fuel spilled in the Clark Fork River after this Cenex tank slid 280 ft on top of the guard rail yesterday.



#ad
 
Most diesel fires on diesel trucks are caused by the previously mentioned reasons and one more the most important one electrical current. You all are basically right that under normal atmospheric conditions diesel won't ignite by a simple flame but if you were to put 12 volts into it by which fuel guages are powered you will have ignition. Add to this that the truck is running and circulating warm back to its fuel tanks in an enclosed area and now you have heated, contained, atomized fuel with an electrical source of ignition that probably was shorted on impact. Every day we see fools fueling diesel vehicles while smoking with the same train of thought it wont blow up. Every year there are many people hurt because we assume (ass u me) they are right, Know that they are wrong all fuel trucks have a ground cable for this reason. PK
 
I would think that the fuel was pretty warm already. The fuel injection pumps on these trucks recirculate the fuel, and it does get pretty hot, if the rig was running for awhile
 
Exploding Locomotives

I know when freight locomotives have collided head-on their was an instant fireball from the diesel fuel. When locomotives have a serious derailment I don't think they generally blow up in a fireball but spill diesel all over which catches on fire.



Of course you know when jetliners crash there is always a spectacular fireball (unless they are out of fuel).



These fuels are hard to light, but once they get started are probably worse than gasoline. In the instances of planes and trains crashing, we are talking about an enormous amount of kinetic energy and heat, impossible to not set something on fire.



Vaughn
 
I knew of an excavating contractor that got burned up when the tank exploded on a Cat he was repairing. This was back 30 years or so. I kinda remember there was some welding or a torch involved.
 
Back
Top