Diesel, JP 8, or Jet A...whats the difference

[kurtperry]

Ok, Here goes..... In my last thread, I told you all about my trials with the "Green unleaded pump"



It spawned a few side discussions into "Premium Diesel and Cetane rating"



I recently retired from 23 years in the Air Force. While deployed to various locations, we routinely pumped Jet A or JP 8 out of the airplane and into fuel bladders so that we could then pump it into our Hummers, 5 tons, armored vehicles, tent heaters, ect. ect.



I have told this to various people over the years and they either accept it without question or call me a liar.



If one of you learned people out there knows what the difference is and would care to share with the rest of us, have at it!!

 

[DHayden]

I am no expert, but I was also in the military, my realm was helicopters. Diesel though different from gas still has something the equivalent of octane, I don't recall the actual term off the top of my head. Being in for 23 years, and if you were working on planes and not vehichles, I'm sure you noticed that the switch from JP-4 to JP-8 was very noticeable. It burned alot dirtier, loss of performance and increased egt's in the turbine engines. Jet A was even better than JP-4 but JP8 was the best middle of the road fuel the military could use that the aircraft could still run on and the vehichles could handle for the purpose going to one fuel for everything to cut down supply issues. JP-4 burns VERY hot in vehichles and the engine probably wouldnt last long running JP4 for any amount of time.

One time we were low on fuel in a training area and landed in front of a tanker going down the road, it was dark and we needed to get home, he was carrying diesel so we bummed enough to get home (all military ofcourse) the aircraft was noticeably weak performing but we got it and us home.



Don't know if I answered anything or not, but your no liar.

 

[drewRoberts]

from what Ive seen on the difference between JP-8 and DF-2 (standard Diesel) is the lack of lubrication on JP-8. some of the guys in the desert are adding as much as a quart of 30 weight oil to the fuel tanks to keep the injector pump from frying

 

[TRLRTRSH]

Jet A or JP8

My son works for a Helicopter air ambulance outfit, whenever they do major work requiring defueling of the aircraft they pump the jet A into drums, CAN NOT reuse the fuel.

My previous CTD was a 95, my son(Ferd guy) would bring the Jet A home and pump it into our trucks, I have burned as much as 75/25% jet A, noticed no difference in performance of the CTD, smelled like a turbo prop under the hood have not burned any in the "03", dammmmed sissy engine would most likely have a heart attack

 

[RedRam401]

As a driver for a major oil company in CA, I hauled a lot of jet A.

The specific gravity of jet A and our #2 diesel were both about . 61 (Weight of a particle, substance or chemical solution in relation to an equal volume of water at 15C. Abbreviated as Sp. Gr. ).

I am not sure about the lubricity (load carrying ability), however it would be cleaner.

It would appear that JetA does not contain the lubricity needed for our engines.

This is interesting reading:

http://www.bakerhughes.com/bakerpetrolite/additives/Lubricity_Additives.htm

 

[mgonske]

Dave Fritz's Site has some info on which fuels are compatible with which injection pumps...

 

[eoseabee]

The difference is lubrication i hear from our mechs is that you can run jp8 but if you don't change the pump it will fry we run it in all of our stuff we have loaders though we have had to go back to diesel i wouldn't run it in my truck

 

[WDaniels]

Kurtperry,

First of all you are right about pumping fuel out of the tanks into blatters for vehicles. Have seen it quite a few times.

JP8 does not have any of the benezines and higher distillates in it and is a combustable fuel. It does have a coking problem. If engines that were not designed to burn JP8 have problems especially in cold weather. JP 4 had all of the "zine" brothers and stuff like that and was a flammable fuel. The military except some of the army all went to JP8 because of the lower combustability of the fuel for equipment and life loss. They also figured that if they got rid of all the "zine" and associated stuff it wouldn't be as harmful. But they are finding that the JP8 is just as harmful if not more so because it doesn't evaporate off of your skin as fast and more of it is absorbed into your body.

REDRAM01,

The specific gravity that we use on our MEC(main engine control) for the JP8 on the CFM56-2A is anywhere from . 78 to . 81.

 

[SGibson]

higher number higher flash point

 

[Alan Reagan]

If I remember right, I was told when I worked for Standard Transpipe that the numbers represent the ratio of kerosine to Naptha. JP 4 is a 4:1 mix. JP 8 is an 8:1 mix. The higher the number the less "dangerous" it is because of the higher flash point. Naptha and anti icing compounds keep the engine operating at high altitudes. Since it is kerosine, the Naptha is necessary to make it light off when starting up.



They do pump it into bladders. All of the 2-1/2 ton trucks the Navy runs are made to run on JP 8. They are a multi fuel engine and will run on #2 diesel, too. Jet fuel has poor lubricity for our engines.

 

[GSherrill]

I have been an army helicopter pilot for the last 15 years, JP-8 and Jet A are the same thing, one is a military designation the other a civilian one, they are basically one and the same fuel and interchangeable as far as use. JP-8 just has a anti-fungal and anti-ice additive, to make Jet A the exact same it is called Jet A+. And around 1995 the army went to one fuel, JP-8, not partially as some say here. There are some civilian procured sedans and vans that burn gas, but every tactical army vehicle burns JP-8 and has since 1994-1995 or even sooner.

 

[WDaniels]

To all that are really interested, go to the "vermont siri" MSDS site and look up the difference between JP8 and JP4. That will eliminate speculations, half heard ideas and I've been told so's.

WD

 

[ToolManTimTaylor]

My previous CTD was a 95, I have burned as much as 75/25% jet A, have not burned any in the "03", dammmmed sissy engine would most likely have a heart attack

OMG That is funny :-laf :-laf

 

[WDaniels]

GSherrill,

Don't know about where you are at but the army choppers in Faribanks Alaska still use the JP4 fuel.

WD

 

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[jhenderson]

Where did that drivel come from?