Ignition/Flash Points of Diesel – vs – Gasoline Liquids and Vapors

"By the way, it takes a lot of heat to ignite diesel, but that's another subject..".

Not if its in a fine spray , and some has vaporized.

FF said:

"By the way, it takes a lot of heat to ignite diesel, but that's another subject..".

Not if its in a fine spray , and some has vaporized.

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For reasoning sake; what are the potentials (opportunities that exist) for the following:

1. Fine spray and/or vaporization of diesel fuel to occur in a pleasure boat, i.e. a Trawler's engine, gen set, or fuel tank locations, and;


2. The temperature being reached in any of those locations that could ignite the fine spray and/or vaporization

What temp is required to ignite fine spray/vaporized diesel fuel?

Art said:

For reasoning sake; what are the potentials (opportunities that exist) for the following:

1. Fine spray and/or vaporization of diesel fuel to occur in a pleasure boat, i.e. a Trawler's engine, gen set, or fuel tank locations, and;


2. The temperature being reached in any of those locations that could ignite the fine spray and/or vaporization

What temp is required to ignite fine spray/vaporized diesel fuel?

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Had it earlier on my trip going into Beufort, NC. Only a 3 year old, external high pressure developed a pinhole in it and was producing a mist so fine it took some to even find where it was coming from. SCARY! but the tornado watch all around on a very narrow part of the ICW was what was panicing my crew so I had split emotions...

Fortunately I knew there wasn't any really high temp sources or sparking in my engine room so I wasn't too worried...zip tied a oil diaper section arund the leak to keep it from vaporizing (now only a drip) till I got to Beaufort.

I have seen several burned sportfish boats from this very issue that had the old style dry turbos that were hot enough to ignite the vapors...but not sure what would on most of our boats...not too many red hot objects or open flames these days...but if you have one such as a diesel heater/boiler....I guess that could be an issue if the misting was close enough.

Originally Posted by Art
For reasoning sake; what are the potentials (opportunities that exist) for the following:

1. Fine spray and/or vaporization of diesel fuel to occur in a pleasure boat, i.e. a Trawler's engine, gen set, or fuel tank locations, and;


2. The temperature being reached in any of those locations that could ignite the fine spray and/or vaporization

What temp is required to ignite fine spray/vaporized diesel fuel?

psneeld said:

Had it earlier on my trip going into Beufort, NC. Only a 3 year old, external high pressure developed a pinhole in it and was producing a mist so fine it took some to even find where it was coming from. SCARY! but the tornado watch all around on a very narrow part of the ICW was what was panicing my crew so I had split emotions...

Fortunately I knew there wasn't any really high temp sources or sparking in my engine room so I wasn't too worried...zip tied a oil diaper section arund the leak to keep it from vaporizing (now only a drip) till I got to Beaufort.

I have seen several burned sportfish boats from this very issue that had the old style dry turbos that were hot enough to ignite the vapors...but not sure what would on most of our boats...not too many red hot objects or open flames these days...but if you have one such as a diesel heater/boiler....I guess that could be an issue if the misting was close enough.

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Thanks for quick reply... does that mean vaporized diesel fuel could also be igniteed via electric spark off an electrical circut or electric apparatus or starter/alternator in contact range? What is the temp required to ignite diesel vapor, as compared to igniting gasoline vapor?

Art said:

Originally Posted by Art
For reasoning sake; what are the potentials (opportunities that exist) for the following:

1. Fine spray and/or vaporization of diesel fuel to occur in a pleasure boat, i.e. a Trawler's engine, gen set, or fuel tank locations, and;


2. The temperature being reached in any of those locations that could ignite the fine spray and/or vaporization

What temp is required to ignite fine spray/vaporized diesel fuel?



Thanks for quick reply... does that mean vaporized diesel fuel could also be igniteed via electric spark off an electrical circut or electric apparatus or starter/alternator in contact range? What is the temp required to ignite diesel vapor, as compared to igniting gasoline vapor?

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Here's where it get's into theory and I'll let the "internet experts" both real and imagined discuss it till we puke.

I think diesel needs o be around 144 degrees to reach flash point....so here's where I can't be too sure....a bucket of diesel, a bilge full of diesel or a diesel covered engine (mine stays belor 144 for the most part) may have a very tiny layer of vapor over it at 144 deg so the chances of it igniting without trying pretty hard would be difficult....but it is possible.

Now atomize that diesel in air that's 144 deg and you can start some sort of ignition...once it starts, it will warm the adjacent vapor and not a flame from is established.

So there's the layman's paractical experience with the stuff (actually have show many eople how hard it is to ignite a bucket of gasoline under the same principles)...but I'm sure someone can refine or dispute a lot of it from their experience or hypothetical bs.

Art said:

Originally Posted by Art
For reasoning sake; what are the potentials (opportunities that exist) for the following:

1. Fine spray and/or vaporization of diesel fuel to occur in a pleasure boat, i.e. a Trawler's engine, gen set, or fuel tank locations, and;


2. The temperature being reached in any of those locations that could ignite the fine spray and/or vaporization

What temp is required to ignite fine spray/vaporized diesel fuel?



Thanks for quick reply... does that mean vaporized diesel fuel could also be igniteed via electric spark off an electrical circut or electric apparatus or starter/alternator in contact range? What is the temp required to ignite diesel vapor, as compared to igniting gasoline vapor?

Click to expand...

Art,

Diesel has a Flash Point of >62 °C(144 °F) and an Autoignition of 210 °C (410 °F)
Gas on the other hand is −43 °C (−45 °F) and Autoignition of 280 °C (536 °F).


So as one can see gas has a wider range of ignition temps than Diesel. Both by Spark or Auto. As far as spark goes I was always under the impression that if in liquid form (as in a container or on the floor) a spark could ignite gas but it took an actual open flame to ignite Diesel. This is due to the amount of fumes or the evaporation rate difference of the two liquids. But if atomized into enough of a fine vapor Diesel can be ignited by a spark as well. But the spark has to be right at the point of the atomization where as gas will have vapors that spread over way larger areas. So thus the safety of Diesel.

psneeld said:

Here's where it get's into theory and I'll let the "internet experts" both real and imagined discuss it till we puke.

I think diesel needs o be around 144 degrees to reach flash point....so here's where I can't be too sure....a bucket of diesel, a bilge full of diesel or a diesel covered engine (mine stays belor 144 for the most part) may have a very tiny layer of vapor over it at 144 deg so the chances of it igniting without trying pretty hard would be difficult....but it is possible.

Now atomize that diesel in air that's 144 deg and you can start some sort of ignition...once it starts, it will warm the adjacent vapor and not a flame from is established.

So there's the layman's paractical experience with the stuff (actually have show many eople how hard it is to ignite a bucket of gasoline under the same principles)...but I'm sure someone can refine or dispute a lot of it from their experience or hypothetical bs.

Click to expand...

OMG - A BIG Can O' Worms Is NOW OPEN! I can hardly waite to read the guru debates... Let's Get It On, re ingition/flash-point of diesel vapors as compared to gasoline vapors...

Art said:

OMG - A BIG Can O' Worms Is NOW OPEN! I can hardly waite to read the guru debates... Let's Get It On, re ingition/flash-point of diesel vapors as compared to gasoline vapors...

Click to expand...

might want to move this to a different thread..easier to put on a ignore list....

Ignition/Flash Points of Diesel – vs – Gasoline Liquids and Vapors

This is a new thread moved from the thread, “Carnival Triumph”, i.e, Posts #36 thru #44... and, maybe a few beyond.

Link: http://www.trawlerforum.com/forums/s3/carnival-triumph-8913-3.html


In line with this new thread, the following is an interesting factual statement quoted from JD's #42 post on "Carnival Triumph", i.e. thread mentioned above:

JD said:

Diesel has a Flash Point of >62 °C(144 °F) and an Autoignition of 210 °C (410 °F)
Gas on the other hand is −43 °C (−45 °F) and Autoignition of 280 °C (536 °F).

So as one can see gas has a wider range of ignition temps than Diesel. Both by Spark or Auto. As far as spark goes I was always under the impression that if in liquid form (as in a container or on the floor) a spark could ignite gas but it took an actual open flame to ignite Diesel. This is due to the amount of fumes or the evaporation rate difference of the two liquids. But if atomized into enough of a fine vapor Diesel can be ignited by a spark as well. But the spark has to be right at the point of the atomization where as gas will have vapors that spread over way larger areas. So thus the safety of Diesel.

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Please Go To New Thread - regarding the following...

Ignition/Flash Points of Diesel – vs – Gasoline Liquids and Vapors

http://www.trawlerforum.com/forums/s3/ignition-flash-points-diesel-%96-vs-%96-gasoline-liquids-vapors-8991.html

The above title is a new thread moved from this thread, “Carnival Triumph”, i.e, Posts #36 thru #44... and, maybe a few beyond on this thread for intro references.

My fault for making the side comment about igniting diesel....

But I think the question of "what broke, and why didn't their redundancy schemes work" remains quite pertinent.

Art said:

Please Go To New Thread - regarding the following...

Ignition/Flash Points of Diesel – vs – Gasoline Liquids and Vapors

http://www.trawlerforum.com/forums/...-%96-vs-%96-gasoline-liquids-vapors-8991.html

The above title is a new thread moved from this thread, “Carnival Triumph”, i.e, Posts #36 thru #44... and, maybe a few beyond on this thread for intro references.

Click to expand...

I guess the mods did their mod stuff... on this thread that I began earlier! :lol:

Good topic though!

Because the ignitability of GAS is well known GAS boats are required to install "spark proof" parts.

Alternator , starter ignition and bilge blowers are an example.

Since diesel is harder to ignite the equipment rules are less stringent.

With the amount of juice it tales to power a cruise ship , thousands of amps at higher voltage ,

is a single spark igniting a vapor not realistic?

To get a captains license in Canada you have to take a "Marine Emegency Duties" course which includes fire fighting training. At Port Colborne in Ontario they ahve a mockup steel ship on land which they routinely set on fire then teach you how to put it out. They have pans of diesel fuel on the "ship" which they light with a blow torch. They demonstarated that the diesel could not be ignited with the torch so they had to add some gasoline to the mix to start the fire.

The reason they used diesel is due to the incredibly dense black smoke its combustion causes and they want that smoke because they want you to fight the fire essentially blind.