Is more octane added at refinery,depot or station?

[LoneRanger]

87 octane reg unleaded, 89 octane "plus" and 92/93 octane "premium." When is the 89 and the 92 or 93 grade product mixed, is it refined as all 87 octane then bumped up to 89 or 92/93 at the depot, or when loaded onto the tanker truck, or does it happen at the pump at the feuling station? i.e. does the tanker truck have three compartments one for each grade of gasoline, or does it only carry base 87 octane reg unleaded and the gas pump at the station adds additive in ato make 89 or 92/93?

 

[Vilan]

I believe there are only two compartments, one for 87 and one for 92/93. When someone requests mid-grade 89/90, the pump dispenses a mix of regular and premium. But the 87 and 93 are made that way at the refinery, the station doesn't bump anything up.

 

[LoneRanger]

That seems like a dicey way to blend 89. I would assume then that the blending apparatus on the truck is required to be calibrated and tagged/inspected regularly to ensure accurate delivery of the 89 grade?

 

[Bobert]

It's blended at the station AFAIK. The truck unloads 87 octane in one tank 93 in the other. When you request 89 at the pump, it draws predetermined mixture from both the 87/93 tanks to give you 89 octane.

 

[CaspianM]

I hate to fill up super when I see the pump previously pumped 87. I probably get one gal of 87 before 93.

 

[gomes512]

I believe the refinery distills out carbon chains from C7 to like C11 or 12. They then crack them and when you see the label 87 octane it basically means 87% of the gas is octane (C8) and the other 13% is heptane (C7). Now of course they add additives such as detergents and ethanol to.

 

[doctorr]

All the replies are right, except that last one about % of "octane".....

There may actually be NO "octane" in your gas.

Octane is a specific paraffin molecule that may be in gasoline, and has little to do with it's "Octane Number".

The refinery blends the two grades, and the pump mixes midgrade at a straight 50/50 ratio, no magic.
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doc

 

[Camu Mahubah]

When lived in Florida one could usually get 87, 89, or 93. Here in the Nebraska Panhandle one can get 85, 87, or 91. And the 87 is E10, ten percent ethanol. By the way I only run 91octane premium which cost me $3.19 last fill up.

I know it seems this way but in NE there is no real midgrade only regular, E10, and premium. I have seen E85 but have not used it.

 

[Shannow]

Quote:

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I believe the refinery distills out carbon chains from C7 to like C11 or 12. They then crack them and when you see the label 87 octane it basically means 87% of the gas is octane (C8) and the other 13% is heptane (C7). Now of course they add additives such as detergents and ethanol to.

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octane is 2,2,4 trimethylpentane, a short compact molecule that is relatively hard to get to auto-ignite. Normal Heptane is a long straight molecule that is relatively easy to get to auto-ignite.

The "octane rating" of a fuel is the equivalent resistance to knocking of the tested fuel, and a blend of iso-octane and heptane which have the same knocking characteristics, under the test standard that it's being tested for (R.O.N. or M.O.N.)

Before "Octane" rating became standard, they had other ratings with other standard reference fuels, such as "Toluene Rating" in the early 1900s

 

[mfisher1967]

I work as an operations supervisor for the 3rd largest American refinery. We make 87 and 93 octane grades, which are usually closer to 87.5 and 93.5 to ensure that they meet product specs. Being a little above the target octane is OK, but being a fraction too low can cause an entire shipment to be rejected. Most refineries make unbranded gasoline. This simply means that gasoline from one refinery goes into a pipeline which is shared between many other refineries. As long as the gasoline meets the required octane rating (called being on-test) it really doesn't matter who makes it. Each company's (Shell, etc) additive package is added at the terminal where the tanker trucks are loaded. Most gas stations have three underground tanks for gasoline, one for each grade. The tanker truck will fill the 87 and 93 tanks and then use a 50/50 mix of the two for the 89 tank.

 

[Panzerman]

There are a chain of Kangaroo gas stations where Iam at and have seen the same truck and driver deliver to all the stations, they are about 2 miles apart, They all have different brands, BP, 76, Chevron and Kangaroo brand. Ive never saw the driver add aditives, so whats the story here, I wonder.

 

[Drew2000]

Originally Posted By: Panzerman
There are a chain of Kangaroo gas stations where Iam at and have seen the same truck and driver deliver to all the stations, they are about 2 miles apart, They all have different brands, BP, 76, Chevron and Kangaroo brand. Ive never saw the driver add aditives, so whats the story here, I wonder.


The tank trailers have multiple, isolated compartments which can carry different brands/products. When I ran a large Exxon station, the gasoline delivered was definitely Exxon branded as per the invoice.

The contract delivery driver told me that after the generic pipline unleaded gasoline is delivered to the tank farm the major brands maintainted seperate leased inventory storage at the tank farms for quality control of their additive-branded product.

The generic brands got the tank farm "house brand" unleaded with addivives that "meet" minimum EPA requirements.

Drew