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Old 10-12-2015, 06:26   #46
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Re: Gas in Diesel Tank

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Originally Posted by reed1v View Post
So in theory gas by itself will self ignite. Thus cars should be blowing up all over the place. Carpenters use to fill nail kegs with gasoline, no cover, just wooden barrels(pony size). Should have flashed over before the buildings were finished. Of course a diesel works by compression of gas, not by a spark plug. You can compress gas to kingdom come and not much is going to happen. However make it into an ultra fine mist and then compress the droplets, they will go bang. Compress it while removing the excess heat from compression and nothing will happen(why cold engines knock).
BTW, unless gasoline has reached a certain vapor point, it will not do much. Refine diesel and you get gasoline. Both can be ignited with open flames, explosions, or extreme heat(which works by converting the liquid to a gas).
Meanwhile all those folks who have added gas to their diesel for over a century probably should have been blown to bits by now according to the recent posts.
Gasoline fumes in a non-ignition protected environment and an ungrounded fuel fill system would be my concern, just google "boat fire image" ... lots of photos of gasoline powered boats on fire.
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Old 10-12-2015, 06:40   #47
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Re: Gas in Diesel Tank

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Originally Posted by reed1v View Post
So in theory gas by itself will self ignite. Thus cars should be blowing up all over the place. Carpenters use to fill nail kegs with gasoline, no cover, just wooden barrels(pony size). Should have flashed over before the buildings were finished. Of course a diesel works by compression of gas, not by a spark plug. You can compress gas to kingdom come and not much is going to happen. However make it into an ultra fine mist and then compress the droplets, they will go bang. Compress it while removing the excess heat from compression and nothing will happen(why cold engines knock).
BTW, unless gasoline has reached a certain vapor point, it will not do much. Refine diesel and you get gasoline. Both can be ignited with open flames, explosions, or extreme heat(which works by converting the liquid to a gas).
Meanwhile all those folks who have added gas to their diesel for over a century probably should have been blown to bits by now according to the recent posts.
I'm just guessing you've never seen a fuel dock fire. I watched one from about 150 feet. Boat went POW.

It's not that I think gasoline is inherently unsafe--I've worked around refineries and gas engines my whole life. But lack of respect is immature.
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Old 10-12-2015, 08:33   #48
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Re: Gas in Diesel Tank

If concerned about lack of lubrication with modern low sulphur diesel (a valid concern, especially as in 'some places' low sulphur central heating oil can be sold as 'diesel'), I have found marine synthetic two stroke oil works very well for essential injector pump lubrication.

If in doubt, I add it at a 100:1 mix ratio, and it may even work well enough at 150:1 (I erred on the side of caution after a friend had his injector pump blow due to lack of lube, until a more dependable supply was available).

You can usually pick up heavily discounted two stroke in end of season sales, and non marine (e.g. chainsaw synthetic two stroke) should work well enough as well, though I do like the idea (perhaps unreasonably) of lower temperature use formulations perhaps being better suited.

Wrecking injector pumps is not a hobby I seek to get interested in.

PS that flashpoint graph looks deeply suspect to me.
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Old 10-12-2015, 10:53   #49
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Re: Gas in Diesel Tank

We just add that little blue bottle of fuel additive to offset the lack of wax in diesel nowadays. But your suggestion is a good one. Looks like the 85% fuels are coming which will kill most gas engines.
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Old 10-12-2015, 11:28   #50
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Re: Gas in Diesel Tank

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Originally Posted by ozdigennaro View Post
(In a previous life I was a chemist.)

Gasoline and diesel are simply mixtures of hydrocarbons, different mixtures. They will mix completely.
2% gas in diesel will not be noticed.

(I admit that I don't understand the "lubricity" argument. I'm sure it's real but the effect will be quite minimal.)

Have fun. Don' worry!
The effect is NOT minimal. A small amount of gasoline has a big effect on lubricity. Just the addition of 1% gasoline can increase the wear scar test result by 100u - enough to change ULSD from acceptable at say, 500, to completely unacceptable at 600u.

If the fuel pump fails on a VW TDi, they test the fuel, and any gasoline contamination at all will invalidate the warranty.
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Old 10-12-2015, 12:15   #51
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Re: Gas in Diesel Tank

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PS that flashpoint graph looks deeply suspect to me.
Basis for comment?

I spent many years testing petroleum and running labs. The graph is well with in the range of normal. It is correct. The start point is 135F flash, which is standard, and gasoline generally causes flammability (flash less than 100F for road use) in blends over 1%. Gasoline itself has a flash far below zero.

It's correct.
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Old 10-12-2015, 13:49   #52
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Re: Gas in Diesel Tank

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Basis for comment?

It's correct.
Doing a lot of distillation. You have to get temperatures quite high for extremely volatile aromatics (even more volatile than petrol) to even start releasing.

Easy way to check. With a small quantity of diesel, plunge a lit cigarette into it. It will put the cigarette out.

Try it at normal room temperature with 5% petrol by volume added and thoroughly mixed in.

Obviously use safe procedures in the process.
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Old 10-12-2015, 14:02   #53
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Re: Gas in Diesel Tank

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We just add that little blue bottle of fuel additive to offset the lack of wax in diesel nowadays. But your suggestion is a good one. Looks like the 85% fuels are coming which will kill most gas engines.
15% ethanol in petrol destroys fuel economy too.

By slightly over 30%.

I fail to see the sense in burning more petrol unnecessarily, with no savings.

When you add in the energy used growing the crops, the energy used in fermentation and distilling, it adds up to a chronic and not inexpensive waste of energy.

I first used 15% ethanol mix on a trip to Spain on my motorbike. Usual touring mileage before needing a fill up, was around 185 miles before the low fuel light came on (this with a very efficient fuel injected engine).

The ethanol mix had the low fuel light coming on at 120 to 125 miles from fill up. Ethanol wrecks the energy content of the fuel.

It should be banned.
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