Okay, this was way back. Like when we were driving an almost brand new 84 Escort GT. There was a gas station on I35 in Farmer's Branch (just north of Dallas) that sold various "high premium" fuels. One of them as 112 octane "uncracked". Just what does that mean? I'm "old enough" to have put Sunoco 120 in my 427 Galaxie 500. Um, when I was doing the quarter, it kind of needed it. -- - dillon I am not invalid "Jimmy, I'm sorry your girlfriend turned out to be a cylon." -Special Agent Tim McGee, "NCIS"
Taken literally ('cracking' is the process of using catalysts to separate the components of crude oil), it would have been crude oil. ;-) I'm assuming that it was a marketing term that refers to something else.
You have been misinformed. Distillation is used to separate the components of crude oil. One of the liquids the still produces is octane. Perhaps there were gas stations selling pure octane in the old days. Sounds implausible but.... The catalytic cracking unit (cat cracker) uses something called "gas oil" as its feedstock. It's like kerosene. The gas oil is cracked and reformed or alkylated to produce more gasoline than crude oil would contain naturally. All fairly low-tech now. As always, the goal in refining is to work safely and have no fatalities. Nobody want to end their shift deceased.....
All I can say that "cracking" is part of the refining process where individual hydrocarbon types are separated by specific temperature ranges. What it means in your reference is a mystery to me though.. Weren't all Sunoco blends in the 200 range? Seems to me that My old Studebaker Avanti would barely tolerate "260" which IIRC was the highest available blend. JT
At least not in the Houston area. More explosions etc that have killed several people. BP is not highly regarded in these heeyah pawts... JT
Amusing. I hope that wasn't a serious post. I'll have to remember to pick up some "liquid octane" on the way home from work... For those who want to know: http://en.wikipedia.org/wiki/Cracking_(chemistry)
You are easily amused....Ignorance is bliss... Hope springs eternal.... Your link doesn't work. Octane IS a liquid: Octane Definition: Any isomeric saturated hydrocarbon found in petroleum and used as a fuel and solvent.
It was Sunoco "Blue" 260. Top of the commercial line. The only thing better was the 115/145 purple avgas down at the air base.
It worked for me. But more to the point of this thread is this page: <http://en.wikipedia.org/wiki/Fluid_catalytic_cracking> For those interested... <http://en.wikipedia.org/wiki/Octane> <http://en.wikipedia.org/wiki/Octane_rating> Note that "octane" and "octane rating" are NOT the same thing.
Another purple pump. http://news.google.com/newspapers?nid=953&dat=19580428&id=La4LAAAAIBAJ&sjid=YlUDAAAAIBAJ&pg=2455,4372763 drag image around as in google earth http://www.goantiques.com/scripts/images,id,1943645.html
separation by temperature is called "distillation". "cracking" is either extreme heat [inefficient] or catalysis.
A long time ago when a junior in high school, I "cracked" gasoline into components by temperature. That said, "octane" was one of these compounds. But rather than me try to explain it from memory, I found this. "One cannot talk about the chemistry of gasoline without understanding octane numbers. When gasoline is burned in an internal combustion engine to CO2 and H2O, there is a tendency for many gasoline mixtures to burn unevenly. Such nonconstant and unsmooth combustion creates a "knocking" noise in the engine. Knocking signifies that the engine is not running as efficiently as it could. It has been found that certain hydrocarbons burn more smoothly than others in a gasoline mixture. In 1927 a scale that attempted to define the "antiknock" properties of gasolines was created. At that time, 2,2,4-trimethylpentane (commonly called "isooctane") was the hydrocarbon that, when burned pure in an engine, gave the best antiknock properties (caused the least knocking). This compound was assigned the number 100, meaning it was the best hydrocarbon to use. The worst hydrocarbon researchers could find in gasoline (which when burned pure gave the most knocking) was n-heptane, assigned the number 0. When isooctane and heptane were mixed, they gave different amounts of knocking depending on their ratio: The higher the percentage of isooctane in the mixture, the lower was the amount of knocking. Gasoline mixtures obtained from petroleum were burned for comparison. If a certain gasoline has the same amount of knocking as a 90 percent isooctane, 10 percent heptane (by volume) mixture, we now say that its "octane number" is 90. Hence, the octane number of a gasoline is the percent isooctane in an isooctane-heptane." From: http://www.chemistryexplained.com/Ny-Pi/Petroleum.html I remember my mother being semi terrified of my gas boiling experiments in the basement... JT
I wonder why. ;-) There is a difference between "iso-octane" ( a compound) and "octane rating" (a measurement). I was amused at being 'corrected' by someone who didn't know the difference, and who thought gasoline was still made by 'turn of the century before last' methods. They don't generally add iso-octane to gasoline, they add other compounds and use the rating system based on it, as you explained. It also amuses me that people associate "high octane" with "highly explosive" because it's more the opposite: kerosene would have a much higher "octane" than gasoline, IIRC.
You have drawn conclusions from my reply that do not reflect my assertions. The term Iso-octane is not particularly descriptive since there are 18 isomers of octane. I was referring to Normal Octane (n-octane) which is just basic octane liquid. Iso-octane can be one or all of 17 isomers: 2-Methylheptane 3-Methylheptane 4-Methylheptane 3-Ethylhexane 2,2-Dimethylhexane 2,3-Dimethylhexane 2,4-Dimethylhexane 2,5-Dimethylhexane 3,3-Dimethylhexane 3,4-Dimethylhexane (meso compound) 3-Ethyl-2-methylpentane 3-Ethyl-3-methylpentane 2,2,3-Trimethylpentane 2,2,4-Trimethylpentane (isooctane) 2,3,3-Trimethylpentane 2,3,4-Trimethylpentane 2,2,3,3-Tetramethylbutane All of these, and many others, can be components of the gasoline we use to fuel our vehicles. Why you think otherwise is problematic. Do you have any background in refining? Benzene is no longer used as a motor fuel because it is so carcinogenic. Obviously, octane and octane number are two different animals. Forgive my assumption that you were sophisticated enough to draw this conclusion from my post. My bad. Also, kerosene does not have a high octane number. If you had spent some time with a knock engine you would know this. My research tells me kerosene has an octane number of "between 15 and 25". Finally, your amused ignorance is becoming so very tiresome. You might want to think about picking-on someone who shares your limited intellectual prowess. "It is better to remain silent and be thought a fool than to open one's mouth and remove all doubt. (Voltaire)"
Brand name, not octane. -- - dillon I am not invalid "Jimmy, I'm sorry your girlfriend turned out to be a cylon." -Special Agent Tim McGee, "NCIS"
Unless you're a trial lawyer (most of whom, ironically, don't go to trial). -- - dillon I am not invalid "Jimmy, I'm sorry your girlfriend turned out to be a cylon." -Special Agent Tim McGee, "NCIS"
