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I'm a Chemistry student preparing an in-class lab demonstration that involves the combustion properties of jet fuel used in typical US based airliners.

Is all jet fuel the same, or do I need to consider specific blends when designing my experiment? Is there a standard chemical formula for jet fuel?

And for bonus points, are there any critical handling considerations?

Farhan
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wposeyjr
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    about that last point; contact the fire department in advance, they will probably have a foam truck standing right next to it in case things go wrong. – ratchet freak May 07 '15 at 12:59
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    Your reference to the Twin Towers is conspiratorial at best. The collapse mechanism is well understood and replicatable. It does not need steel to melt, only to soften and lose strength which is easy to do with a big enough fire. – Simon May 07 '15 at 13:07
  • @Simon Oh I know man it's just to get credit for this class. I don't actually care about the conspiracy this is just clever ya feel? – wposeyjr May 07 '15 at 13:11
  • Is this question not on topic? It has two down votes and I thought it was right on point? – wposeyjr May 07 '15 at 14:13
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    it is badly off-topic: the question has nothing to do with aviation, except that the fuel is used in aviation. – Federico May 07 '15 at 14:27
  • @Federico Oh see I thought this stack was basically for all aspects of aviation. That would be totally my mistake sorry about that guys. Should I remove this question? I feel like it could be useful to future people with this question but I got my answer and I'll remove if you guys think I should... – wposeyjr May 07 '15 at 14:32
  • So is this flagged because of the section in the help center about: "Resource location Where to buy a specific part, "Which headset is the best?", etc." yeah? So should I remove my question or not? It is what I was intending to ask and it very well could be of use to future questioners but I'll remove it if that's necessary... – wposeyjr May 07 '15 at 14:48
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    please read the on-topic page. your question is not within a single one of the on-topic points. – Federico May 07 '15 at 14:51
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    There are different types of Jet fuel. See Jet-A, Jet-A1, Jet B, and the JP fuels used for military operations. Regarding the burning properties, there is no specific 'burn temperature' for jet fuel (or any fuel, for that matter.) It will burn at any temperature above the one at which sufficient activation energy is supplied. If you burn enough of a fuel, you can reach almost any temperature you want. The "jet fuel doesn't burn hot enough to melt steel" stuff was nonsense made up by conspiracy theorists who don't understand either physics or chemistry. – reirab May 07 '15 at 18:01
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    @reirab: There are different types of Jet fuel, but civilian aircraft always use Jet-A in USA and Jet-A1 in most other places and the difference is very small anyway. +1 for the rest; it can burn at almost any temperature given the right conditions. – Jan Hudec May 07 '15 at 18:24
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    @reirab -- well, fuels are limited by their adiabatic flame temperature; however, the "jet fuel doesn't burn hot enough to cook/spaghettify structural steel" balderdash is just that -- propane has a lower adiabatic flame temperature than kerosene/jet fuel, and a big enough propane torch will make light work of unprotected structural steel! – UnrecognizedFallingObject May 08 '15 at 03:12
  • @UnrecognizedFallingObject True, though keep in mind that smashing a giant fuel tank into a concrete/steel structure isn't a constant pressure scenario like what you have with a torch. – reirab May 08 '15 at 13:18
  • @reirab -- indeed; I'm just saying that I seriously doubt that you couldn't get a fire hot enough to do cook steel with jet fuel. – UnrecognizedFallingObject May 08 '15 at 22:08

3 Answers3

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The fuel used by civilian airlines, fueled in the USA, is Jet A. To acquire some, go to a nearby airport which can handle operations by Turboprop or Turbofan aircraft. Some of the smaller airports, only supporting piston aircraft operations, may not be able to help you, but anything which can handle a Lear Jet should be able to supply you with examples of it.

There's no specific chemical formula for this. It is a mixture of a variety of compounds. And no, you can't isolate just one particular compound and use it as a representative sample. There are reasons for the various additives, and all of them will have SOME effect on the burn characteristics.

Try not to breathe the fumes, before or after combustion. Do not operate any kind of radio transmitter (including a cellphone) within 50 feet of the vapors of it (when the fuel is exposed to air, before or during combustion). Make sure that whatever vessel you're going to burn it in is metal (plastic doesn't respond well to burning petrochemicals :-) and make sure there is good electrical conductivity between the vessel and the ground. Have a large, CO2- or Halon-based (NOT water or dry chemical) fire extinguisher nearby.

When I was refueling F-16s in the Air Force:

  • no radio transmitters (walkie talkies, at the time) were allowed with 50 feet of refueling operation
  • the aircraft and the refueling vehicle BOTH had to be grounded and connected to each other BEFORE connecting the refueling line
  • no refueling ops were permitted if there was lightning within 5 miles
  • no refuelings ops were permitted without a 50-pound halon-based fire extinguisher and a dedicated person (fire guard) to man it

This should give you some idea of proper safety around this stuff.

Farhan
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Meower68
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  • Thank you so much for your response. This is quickly becoming too much for my setting. This stack has saved me so much time by showing me this would be more difficult than I was expecting. Thanks so much man. – wposeyjr May 07 '15 at 13:34
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    @wposeyjr - you thought burning jet fuel would be a "beaker, bunsen burner, job done" kind of experiment? oooohkay! – Jamiec May 07 '15 at 14:10
  • @Jamiec yeah. I thought it'd be a bit more difficult because it has such a high burning temperature but I wasn't aware that it would take quite this much haha. My bad honestly. Just unaware! – wposeyjr May 07 '15 at 14:12
  • Also note that if you opt for the halon-based fire extinguishers to bring along a PBE (portable breathing equipment) so you don't inhale the halon. – casey May 07 '15 at 15:05
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    Well, when manipulating a quart of it in laboratory, you don't have to be so careful about static electricity (no radios, grounding) like you have to be when loading couple of tons in an aircraft outside. You still should have a fire extinguisher with good rating for extinguishing burning liquids (type B), but you need one when handling gasoline (which is more dangerous than Jet-A) anyway. – Jan Hudec May 07 '15 at 15:09
  • Thanks, Meower68. Could you elaborate on why ground refueling procedures seem more stringent than in-air refueling procedures? Thanks. – dotancohen May 07 '15 at 21:34
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    The main problem you're dealing with is fuel vapors. When you're pumping fuel into the plane, there's a vent under the wing where vapors are pushed out from the fuel tanks as liquid fuel is pushed in. And since the vapors are heavier than normal air, they can "pool" in the vicinity of the jet during fueling. Any static discharge, in the presence of such vapors, can result in a fire and/or explosion. At 10k+ feet and 100+ knots, there's not much probability of pooling vapors. Also, the IFR receptacle is on TOP of the jet while the ground receptacle is underneath. – Meower68 May 08 '15 at 17:34
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If you have any intention of doing this, and I DON'T ADVISE YOU LIGHT A POOL OF JET FUEL ON FIRE... EVER...

But if you insist take a look at this Material Safety Data Sheet which outlines all the safety and emergency aspects of Jet-A as well as other important info on it (provided by Hess).

One extremely important thing you must note is that the flash point (point where the fuel becomes vaporous and can ignite) is only 100°F this is not very high and a temperature that can be achieved in common settings. So make sure to transport it safely.

The Airport Facility Directory will tell you what fuel every airport has and will list it as either Jet-A1 or Jet-A. You may also see 100LL or 110LL; this is not what you want, this is for piston engines.

TALK TO A FIREMAN BEFORE DOING THIS!! I am still advising that you avoid this in the first place but if you insist please consult with a fireman (potentially from an airport) on the proper things you will need to put out a fire and how and where the best place to do this is. You should assume you will need to be outdoors.

fooot
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Dave
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    Flash point is 100°F. Compared to minus 45°F for gasoline… – Jan Hudec May 07 '15 at 15:13
  • @Jan, you are correct I was simply mentioning that it could become vaporous on a hot day or in a hot car. All fuels should be transported in approved containers with care and should avoid direct sunlight. – Dave May 07 '15 at 15:51
  • @Dave It can also become vaporous when exposed to burning Jet-A... That tends to get things above 100 F pretty quickly. – reirab May 07 '15 at 17:49
  • @reirab But with a fire already burning wouldn't it tend to combust immediately rather than forming a mixture with a large volume of air? Plus, there's a difference between transportation (in his vehicle) vs the setting in which it is being deliberately ignited (hopefully not around anything else flammable for a good distance around). – Random832 May 07 '15 at 20:11
  • @Random832 Immediately upon vaporizing in the presence of a flame, yes, provided that sufficient oxidizer is available. So, it won't fill the room, then explode all at once, if that's what you're asking. – reirab May 07 '15 at 20:18
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As the other answers have said, you really really don't want to try this experiment yourself, and especially not indoors, but in fact jet fuel is surprisingly difficult to ignite, unless you atomize it or vaporize it first. The safety hazard comes from the fact that it is even more difficult to extinguish a jet fuel fire than to light it.

The standard safety demonstration by our works fire department includes dropping a lighted cigarette into a bucketful of fuel, which has no effect whatever. The start of this video is a more dangerous version of that test - and to repeat, don't try this yourself!

Farhan
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alephzero
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