Fuel octane ratings: RON versus AKI

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Fuel octane ratings: RON versus AKI

Minh Nguyen-2
This week's weeklyOSM [1] included a suggestion to minimize the number
of fuel:* subkeys, which reminded me that the fuel tagging situation in
the United States is actually quite complicated. The same generic grade
of gasoline ("regular", "mid-grade", "premium") may have a different
octane rating at one gas station than the station across the street, and
each state has a different standard for the minimum octane that may be
labeled with a particular grade. [2] What would be sold as premium
gasoline in Alaska would be regular in South Carolina.

Compounding the matter, for several years, the fuel:* wiki page has
specified that octane ratings must be expressed in RON, which is used in
more countries. [3] In a few countries including U.S., octane ratings
are only posted in RON, not AKI. Converting between AKI and RON would
require knowing the MON, which AFAICT isn't published anywhere.
Wikipedia does offer estimates for regular and premium grade, but they
aren't reliable or specific enough to use as subkeys. [4]

I've updated the wiki page with statistics demonstrating that octane
ratings are consistently mapped based on AKI in the U.S. [5] (If I'm
wrong about this, then OSM is a better resource for finding unlawful
stations than lawful stations.) It stands to reason that mappers would
tag what they can plainly see rather than learn the intricacies of
metrology.

 From a data consumer's perspective, it's unfortunate that there's no
single worldwide standard. But I think more data consumers would need to
differentiate between different grades in the same region than across
national boundaries. If we do want to remove the current ambiguity, we
could define separate fuel:ron_* and fuel:aki_* subkeys, but that seems
like a lot of work for little gain.

[1] http://weeklyosm.eu/archives/12232
[2] https://en.wikipedia.org/wiki/U.S._State_Fuel_Octane_Standards
[3] https://wiki.openstreetmap.org/wiki/Special:Diff/1033280
[4] https://en.wikipedia.org/wiki/Octane_rating#Measurement_methods
[5] https://wiki.openstreetmap.org/wiki/Key:fuel#United_States

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Re: Fuel octane ratings: RON versus AKI

Minh Nguyen-2
On 2019-07-19 17:24, Minh Nguyen wrote:
> Compounding the matter, for several years, the fuel:* wiki page has
> specified that octane ratings must be expressed in RON, which is used in
> more countries. [3] In a few countries including U.S., octane ratings
> are only posted in RON, not AKI.

This was a typo: I meant to say that, in a few countries including the
U.S., octane ratings are only posted in *AKI*, not in RON.

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Re: Fuel octane ratings: RON versus AKI

Andrew Davidson-3
In reply to this post by Minh Nguyen-2

On Sat., 20 Jul. 2019, 10:26 Minh Nguyen, <[hidden email]> wrote:

Compounding the matter, for several years, the fuel:* wiki page has
specified that octane ratings must be expressed in RON
  
That edit would appear to be an undiscussed edit by one mapper, I wouldn't take it to be gospel. As you pointed out the octane rating is being mapped in whatever the local system is. 

Perhaps the best thing to do is to change the wiki to say this. 

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Re: Fuel octane ratings: RON versus AKI

Paul Johnson-3
In reply to this post by Minh Nguyen-2

On Fri, Jul 19, 2019 at 7:25 PM Minh Nguyen <[hidden email]> wrote:
Compounding the matter, for several years, the fuel:* wiki page has
specified that octane ratings must be expressed in RON, which is used in
more countries. [3] In a few countries including U.S., octane ratings
are only posted in RON, not AKI. Converting between AKI and RON would
require knowing the MON, which AFAICT isn't published anywhere.
Wikipedia does offer estimates for regular and premium grade, but they
aren't reliable or specific enough to use as subkeys. [4]

This is one of those situations where I generally reject the advice in the wiki.  For octane ratings, I don't think most people even look to tell if they're rating it in RON or AKI.  I take AKI for granted because it's the number available at the stations.



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Re: Fuel octane ratings: RON versus AKI

Nita S.
Without attempting to complicate this subject further, there is the issue that some fuels ( same octane rating) do not contain ethanol. Around here those are referred to as 'marine fuel', because the absence of ethanol helps prevent moisture collecting in the fuel tanks. Those few stations that carry marine fuel also carry the common variety with ethanol. 

On Sat, Jul 20, 2019 at 1:59 PM Paul Johnson <[hidden email]> wrote:

On Fri, Jul 19, 2019 at 7:25 PM Minh Nguyen <[hidden email]> wrote:
Compounding the matter, for several years, the fuel:* wiki page has
specified that octane ratings must be expressed in RON, which is used in
more countries. [3] In a few countries including U.S., octane ratings
are only posted in RON, not AKI. Converting between AKI and RON would
require knowing the MON, which AFAICT isn't published anywhere.
Wikipedia does offer estimates for regular and premium grade, but they
aren't reliable or specific enough to use as subkeys. [4]

This is one of those situations where I generally reject the advice in the wiki.  For octane ratings, I don't think most people even look to tell if they're rating it in RON or AKI.  I take AKI for granted because it's the number available at the stations.


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