Diesel less volatile than petrol

tdiclubfan

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Does it mean a diesel car will less likely result in a fire in the event of a catastrophic crash?
 

Ol'Rattler

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2006 BRM Jetta
Yes it is true. Diesel is a lot safer in a crash although once ignited it does have more heat energy than the same volume of gasoline.

The "flash point" of a chemical is the lowest temperature where enough fluid can evaporate to form a combustible concentration of gas. (evaporated or gaseous liquid)
The flash point is an indication of how easy a chemical may burn. Materials with higher flash points are less flammable or hazardous than chemicals with lower flash points.

Gasoline Flash point = minus 45F.
D2Diesel Flash Point = Plus 125F.
 
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VeeDubTDI

Wanderluster, Traveler, TDIClub Enthusiast
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Look at that! By our very own compu_85. :cool:
 

compu_85

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Ha, I saw the title of this thread and was going to post that!

IMO it does make things much safer. Diesel can still burn, but it takes more heat to get it going initially.

-J
 

PDJetta

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I do feel much safer in my TDI, from a fuel fire standpoint.

I know gasoline is more dangerous, but when I was a teenager I dropped a lit cigarette into a cup filled with gasoline and to my suprise, it extinguished the cigarette and never caught fire.

If you ever watch a severe impact of a diesel-fueled vehicle, sometimes the fuel will burn. Severe locomotive crashes fit this category. What I think happens is that the impact atomizes the fuel as the fuel tank is compressed and the fuel sprays out in a fine mist and this creates a greater surface area and it lights off.

Flour and wood dust can ignite explosively as well. You ever see a grain elevator explosion? Brutal.

--Nate
 

Nutsnbolts

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2000 Jetta, Silver Arrow
Not to mention that in a locomotive, the fuel pump is capable of supplying over 1 gallon every 20 seconds for consumption, and still have fuel left over for return cooling. The turbos are a lot larger, as are the manifolds, and they sit on the top of the engine. I would think that a ruptured external high-pressure fuel line (like in a GE) would certainly atomize the fuel enough to cause ignition. But, by comparison to car crashes, I think it's apples and oranges. If you get into a bad enough impact that a locomotive rolls over, that's where the danger is. I've never seen a locomotive burn from impact alone.

-Rich
 

jettawreck

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75/25 diesel gas mix is excellent for getting the brush pile going!
Yep, works great! Way safer than just gas, which can go wooof!! when its warm out and the diesel burns slow enough to get the brush started good. When its below 0F, you need to increase the mix to about 50/50 to get it to light.;)
 

duwem

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Gasoline engines dont have problems with runaways like diesels do...so although diesel is not as volitle, the engines will run on "other than diesel" and will continue to run until that fuel is eliminated.
 

tdiclubfan

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Gasoline engines dont have problems with runaways like diesels do...so although diesel is not as volitle, the engines will run on "other than diesel" and will continue to run until that fuel is eliminated.
What safety mechanism is there to prevent this from happening?
 

pedroYUL

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What safety mechanism is there to prevent this from happening?
From catastrophic turbo failure, none. Otherwise keep your pipes and intercooler reasonably clean and this should not happen
 

megaladon6

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Danbury CT
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2003 Jetta GLS
it helps that gas engines have a throttle valve that cuts off most of the air flow, diesels may have an ASV, but it doesn't activate when you come off the pedal...
I know gasoline is more dangerous, but when I was a teenager I dropped a lit cigarette into a cup filled with gasoline and to my suprise, it extinguished the cigarette and never caught fire.
hollywood lies!
mythbusters tested diesel in one of it's episodes. basically the propane torch ignited the diesel it was next to, but couldn't ignite the trail of fuel.
 

whitedog

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Bend, Oregon
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2004 Jetta that I fill by myself
Yep, works great! Way safer than just gas, which can go wooof!! when its warm out and the diesel burns slow enough to get the brush started good. When its below 0F, you need to increase the mix to about 50/50 to get it to light.;)
How do you turn a cat into a dog?

Soak it in gasoline and light it on fire.

It'll go "WOOF!"
 

compu_85

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La Conner, WA
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it helps that gas engines have a throttle valve that cuts off most of the air flow, diesels may have an ASV, but it doesn't activate when you come off the pedal...
Try again ;) 2004+ cars have a throttle that's opening and closing all the time (too much air makes NOx). My Passat has two throttles... one in the normal place, and one part way down the exhaust :eek:

-J
 

tdiclubfan

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From catastrophic turbo failure, none. Otherwise keep your pipes and intercooler reasonably clean and this should not happen
Does a failing turbo give plenty of warning before it gives up the ghost?

Is it safe to keep a jerry can full of diesel in the trunk if you want to experiment with hypermiling?
 

compu_85

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La Conner, WA
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Turbos sometimes give warning.

I'd be more worried about a diesel can in the trunk spilling and making the interior stink that starting a fire.

-J
 
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