[Vwdiesel] Diesel Rap

[Dana Morphew]

Here is an interesting bit posted by Brian Kmetz 4 years ago.  I don't know whether he is

still on the list:

>
> Hello All,
>
> Now we have a thread that I can talk about!  Part of my job is to
> extract the BTUs through oxidation (burn) from mass quantities of
> methane and fuel oils so I have a clue how some of this stuff works.
>
> In the USA, all diesel fuel must meet the specifications set forth
> by the American Society for Testing and Materials (ASTM).  In
> Canada it is the Canadian General Standards Board.  They have web
> pages at www.astm.org and www.pwgsc.gc.ca.  One can order
> documents for a fee.  Diesel fuels are covered in documents ASTM
> D-975 and CGSB 3.6-M90 and 3.517-93.  Their documents cannot be
> previewed.  The CGSB lists the ASTM as a reference, they are that
> close.  All the specifications for cetane, pour points, viscosity, flash
> point, BTU content, etc.,etc., are in these documents.
>
> The most common question, Cetane?  What is cetane?  Cetane is
> to diesel fuel what octane is to gasoline.  It is a measure of the fuel's
> ignition quality and performance.  Cetane is actually a hydrocarbon
> chain, its real name is 1-hexadecane.  It is written as C16H34, or a
> chain of 16 carbon atoms with 34 hydrogen atoms attached.  All HC
> chains are also referred to as paraffins.  Cetane is a hydrocarbon
> molecule that ignites very easily under compression, so it was
> assigned a rating of 100.  All the hydrocarbons in diesel fuel are
> indexed to cetane as to how well they ignite under compression.
> There is very little actual cetane in diesel fuel.
>
> Most of the hydrocarbons in diesel fuel have similar ignition
> characteristics as cetane.  Cetane is abbreviated as CN.  A very
> loose way to think about cetane is if the fuel has a CN of 45, then
> the fuel will ignite 45% as well as 100% cetane.  Diesel engines
> run just fine with a CN between 45 to 50.  There is no performance
> or emission advantage to keep raising the CN past 50.  After
> that point the fuel's performance hits a plateau.
>
> Diesel at the pump can be found in two CN ranges: 40-46 for
> regular diesel, and 45-50 for premium.  The minimum CN at the
> pump is 'suppose' to be 45.  The legal minimum cetane rating for
> #1 and #2 diesel is 40.  Most diesel fuel leaves the refinery with a
> CN of around 42.  The CN rating depends on the crude oil the fuel
> was refined from.  It varies so much from tanker to tanker that a
> consistent CN rating is almost impossible.  Distilling diesel is a
> crude process compared with making gasoline.  Gasoline is more
> of a manufactured product with tighter standards so the octane
> rating is very consistent.  So the CN rating at the pump can be
> anywhere from 42-46.  That's why there is almost never a sticker
> on a diesel fuel pump for CN.
>
> Premium diesel has additives to improve CN & lubricity, detergents
> to clean the fuel injectors and minimize carbon deposits, water
> dispersant, and other additives depending on geographical and
> seasonal needs.  More biocides added in the south in summer,
> more anti-jell added in the north in winter.  Most retailers who sell
> premium diesel will have little brochures called POPs (Point of
> Purchase) at the counter explaining what's in their fuel.  Please
> don't ask the poor clerk behind the counter any technical questions
> after reading this post, all they know how to do is sell you beer,
> milk, cigarettes, lottery tickets, and take your money.
>
> Texaco and Amoco are two big names who sell premium diesel
> in limited markets.  Amoco mostly sells its Premier to specialized
> industrial and agricultural markets.  I cannot get either in my area.
> Most fuel retailers buy additives or buy treated fuel.  In the northern
> plain states, Koch is a well known marketer of premium diesel.  I
> buy it when I travel into northern Wisconsin.
>
> Because there are no legal standards for premium diesel yet, it is
> very hard to know if you are buying the good stuff.  I have good
> news.  An ASTM task force has drafted standards for premium
> diesel.  When the new specifications are accepted, information
> will have to be posted on the fuel pump.  Retailers will no longer
> be allowed to label cheap blended diesel as 'premium'.  They will
> have separate pumps with clear labels on both informing the
> customer what in being sold.  The marketing and labeling will the
> same as with regular and premium gasoline.  Retailers selling the
> real thing use this system now.  Enforcement of all fuel standards
> is done on the state level in the USA.
>
> Diesel fuel is an international commodity for industry with no brand
> name recognition.  Because of this it's made as cheap as possible
> and is transported through most of North America by pipeline.  At
> the area terminal you will see tankers with every oil company logo
> ever imagined all filling up with the same fuel.  So don't get too
> picky about where you fill up.  Shop for price from a large volume
> retailer so you have the freshest fuel.  That's about the best advice
> I can give.
>
> The reformulation of diesel fuel in North America is due an
> international effort for lower emissions.  Cleaner diesel emission
> laws are on the way.  Diesel fuel is going to be reformulated into
> a cleaner fuel in general.  Without getting too technical (this is
> very simplified and over generalized), diesel fuel for the most
> part is made up of two different hydrocarbon families: paraffin's
> and aromatics.  The paraffin's have a naturally high cetane index,
> burn clean, but cause that annoying jell problem in winter.  The
> aromatics have a naturally high lubricity, low cetane index, and
> cause a lot of diesel emissions and soot.  Reformulated diesel
> will have a higher paraffin content, higher cetane number, and a
> much lower aromatic and sulfur content.  It will also be more
> prone to jelling and have a lower lubricity.  Big oil is working on
> improved additives as I type this.
>
> The reason nothing has happened yet is because of infighting in
> the EPA on its new Tier II Emissions standards for gasoline and
> diesel.  Ultra-clean technology for gasoline and diesel engines is
> almost ready to go but the refiners have to lower the sulfur level
> drastically in both fuels.  Something should be formally set by
> the EPA by year 2000, with oil and auto industries whining and
> slowly complying shortly after.
>
> When I learn more, I'll post more.
>
> Brian Kmetz
> brian.p.kmetz at ucm.com
> MBCA Central Illinois
> Chicago VW Org.
> 85 MB 300D-T (Rudy Sr.)
> 97 VW Passat TDI (Rudy Jr.)
>
>


Dana