Octane question

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Just about none of that is technically accurate...
And running AvGas in a saw is stupid and terrible for your health.. Not to mention the fact that it will in many cases make your saw run worse.
Then I'm dumb all over, and a little ugly on the side.

My saws will sit overwinter, and start right up spring with no carb problems, 026, 028, 036, 038M.....
 
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Av gas vs pump gas is a bad comparison. The octane doesn't have anything to to with performance or shelf life. Avgas is a different formulation of fuel. It's an alkyd based fuel, which does have benefits over pump gas save the lead content and cost. The cost I could stomach, the lead content I won't. I haven enough going for me for getting cancer don't need to breath in the lead fumes from running avgas. Besides that it's over $6.00 gal.
How much i$ canned fuel$?
 
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Interesting, I've never heard of it or seen it at any of the local airports. I'm all for getting a alkyd fuel, but will not run leaded fuel of any type.
It's also known as UL91. Not widely available and I have never seen it.
The problem is aviation piston engines are very old technology wise and it's a royal pain to get anything new certified. It's even more of a pain to get old engines certified to run on unleaded fuels. As a result very few aviation motors are certified to run on unleaded fuels even though most don't need the lead or the octane level.
 
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Using aromatics does boost octane, but they are not without any downsides. Fornatarters there not good to breath at all, which is why the EPA severly limits them in the gas pool. They also are very hard on rubber and plastic parts, like crank seals, etc.
You'd be surprised how much aromatics are in gasoline.

Benzene is quite toxic, the ones with alkyl-side chains much less so. EPA primarily is concerned with benzene. I've seen no evidence aromatics are hard on fuel system parts compared to saturated hydrocarbon components.

I used to outfit organic chemistry labs with proper tubing for transfer of all sorts of organics, some halogenated, and have observed the effect of solvents on various tubings.

We used to purify benzene to remove thiophene. Extract with concentrated sulfuric acid then distill from calcium hydride.
 
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Don't use 100ll. It does have more lead in it than pump gas. Find yourself an airport that sells MOGAS. 91 octane and no lead and none of the additives of pump (even e-free) gas. My lawn takes 1-1/4 to 1-1/2 tanks to mow on pump gas with ethanol. Using MOGAS I can do it using less than 1.
Where are you located?

Airports here have not replaced 100LL with unleaded yet.
 
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We have a railroad siding right behind the building I work out of. In the winter the leave those damn trains idling all night and the smell is terrible.
That stuff take my wind away like instantly every time I get a good breath of it. I try like hell to stay away. It will make you real sick if your truck leaks fumes in the cabin all the time.
 
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You'd be surprised how much aromatics are in gasoline.

Benzene is quite toxic, the ones with alkyl-side chains much less so. EPA primarily is concerned with benzene. I've seen no evidence aromatics are hard on fuel system parts compared to saturated hydrocarbon components.

I used to outfit organic chemistry labs with proper tubing for transfer of all sorts of organics, some halogenated, and have observed the effect of solvents on various tubings.

We used to purify benzene to remove thiophene. Extract with concentrated sulfuric acid then distill from calcium hydride.
No, I wouldn't. I see the analysis every day at work. There is very little.
And yes, the EPA was primarily concerned with Benzene due to it being a known carcinogen. However the refinery units that remove benzene also remove the other aromatics.
Aromatics being tough on rubbers and plastics is well documented.
 
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While they aren't good for you, gas fumes no longer contain lead or aromatics which were the real nasties in gasoline back in the day.
AV gas contains both...
BULL ****!!!

Gasoline of all sorts contain aromatics. I've done GC/MS analyses that identified and quantified each one, even separated the isomers of xylenes (dimethyl-benzenes) and mesitylenes (trimethl-benzenes). Have you?

It is not practical to remove aromatics by distillations from crude. And not economically feasible by chemical means.
 
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No, I wouldn't. I see the analysis every day at work. There is very little.
And yes, the EPA was primarily concerned with Benzene due to it being a known carcinogen. However the refinery units that remove benzene also remove the other aromatics.
Aromatics being tough on rubbers and plastics is well documented.

So explain how refineries remove aromatics from the stream of saturated hydrocarbons with near/the same boiling points? As a chemist I'd like to know, IF you know. For instance iso-octane bp = 100 oC and toluene bp = 111 oC. This is not a trivial separation in the laboratory to get close to near 100% separation

I have done all sorts of distillations with all sorts of sophisticated laboratory equipment, including vacuum/reduced pressure and steam distillations. This includes purifying novel new compounds created in the laboratory.
I wonder how much better it really is?

Google is evil personified. This track you and sell the information to the highest bidders.
 
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So explain how refineries remove aromatics from the stream of saturated hydrocarbons with near/the same boiling points?


Google is evil personified.
There are a variety of ways. Most involve catalysts and the introduction of hydrogen. It all depends on how complex the refinery is. Some just strip off the C6-C8's right off their main column and sell the results to chemical companies.
 
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BULL ****!!!

Gasoline of all sorts contain aromatics. I've done GC/MS analyses that identified and quantified each one, even separated the isomers of xylenes (dimethyl-benzenes) and mesitylenes (trimethl-benzenes). Have you?

It is not practical to remove aromatics by distillations from crude. And not economically feasible by chemical means.
I work at a refinery and see the analysis every day. I'm not guessing.
Distillation is where refining starts and is a small part of the overall refinery... again, I am not guessing.
One of the reasons ethanol use took off was it allowed refiners to lower aromatic content. Aromatics are high octane streams and in the absence of lead use was a way to crank out decent octane fuel. Ethanol replaced thse aromatics as a high octane stream. Now the refiners can sell the aromatics to Chem plants which bring good money. Most of the really big refineries have Chem plants attached to them so they just pipe them over to the Chem side.
At one time BTX was between 20 and 50% of the gasoline pool. It's well under 10% in most cases and often below 5% with Benzene levels below .6%.
These figures are for RFG. Areas not mandated to use RFG may be different.
 

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