On the stale unleaded petrol (gasoline) myth

[RFguy]

right. good one.

so its not that the ULP goes stale, more that it becomes contaminated and changes, and develops unwanted characterists and afterproducts.

The single Kwinana pipeline. golly. LOL.

Seems the overiding advice is for bowser ULP- test if possible and otherwise immediately. and with AVGAS, we are paying for some care with the fuel. I've still heard plenty of suspect AVGAS stories.

 

So what's the purity like then of "bulkfuel" (ULP) ? I guess you give yourself a fighting chance, depending on the supply chain, how it was bottled etc.

 

 

 

 

 

[onetrack]

Bulk fuel quality delivered for automotive use, is generally satisfactory for "average requirements". Oil companies and fuel distributors take reasonable levels of care in fuel handling to ensure standards are met - but the fuel is handled multiple times, and humans are regularly involved, and humans make mistakes.

AFAIC, the biggest single source of contamination potential is at the final stages - service stations, and then purchaser handling. Service stations are manned by people who are low-paid, time-poor, under a great deal of stress to ensure everything keeps running smoothly. They're not trained to deal with possible contamination events.

 

Service repair people are called to deal with "events" such as fuel contamination, and bowser operation problems - and the best the servo operator can do, is simply make the pumps unavailable after an "event" is discovered. Meantimes, hundreds of fuel purchasers may have been affected by the "event".

 

I am predicting there will be a massive upsurge in fuel contamination problems with the recent flood events in NSW and Northern Victoria. Keep well away from servos that went under water in the floods.

 

Chevron have put out a "Technical Review" specifically on Aviation Fuels and refining, and it is almost a thesis, such is its comprehensive coverage. Despite being specifically oriented to U.S. fuel refining, 99.9% of the information covers refining and fuelling procedures globally.

Appendix A ("Aviation Fuel Distribution and Handling", from page 74 on) may be of interest to you, and it shows the massive complexity involved in fuel handling and storage and cleanliness efforts. 

 

Naturally, fuel distribution and handling procedures for automotive fuels contain much lower levels of requirements than the strict levels set for aviation fuels - so this is where you, as end-user, must be alert to satisfactory fuel storage and handling procedures, and the potential areas for fuel contamination.

I think the vast majority of light aircraft owners are aware of this, but it only takes a small amount of carelessness to introduce contamination.

 

https://www.chevron.com/-/media/chevron/operations/documents/aviation-tech-review.pdf

 

What I found interesting in the Chevron review, was how refineries still have no precise control over the final fuel product from the refinery - it is totally dependent on the type and origin of the crude oil, and the refineries can only practice meeting fuel standards specifications. If the fuel does not meet specifications, it must be re-refined.

[Methusala]

Related to this story of fuel contamination being most likely during manual handling at delivery, I read that jet A is to be supplied to the 2nd Sydney airport by tanker trucks. Does this mean we should suspect the quality of fuel supplied to airlines at this terminal?

 

[Blueadventures]

2 minutes ago, Methusala said:

Related to this story of fuel contamination being most likely during manual handling at delivery, I read that jet A is to be supplied to the 2nd Sydney airport by tanker trucks. Does this mean we should suspect the quality of fuel supplied to airlines at this terminal?

 

Only if their Russian.

 

 

 

 

Haste makes waste and errors occur:)

[facthunter]

It is always accepted that more stringent controls apply to Aviation fuels . I know samples are  kept of every tanker on a major airport. Nev

[onetrack]

I purchased an ex-RAAF refuelling truck and tanker once. You would be staggered at the level of fuel treatment in those outfits, that ensures 100% perfectly-clean fuel.

[kgwilson]

That's why I always use my Mr Funnel when refuelling. Filters water, rust, sand, dirt & other debris down to 74 microns. I have not had any dirty fuel yet that I know of. I get my fuel from the same busy servo 3 minutes from my hangar & only looked in detail for a while so could possibly have filtered out some crap. There is always 50 ml or so in the filter sump at the bottom which I use as weed killer at the hangar door.

[Blueadventures]

1 minute ago, kgwilson said:

That's why I always use my Mr Funnel when refuelling. Filters water, rust, sand, dirt & other debris down to 74 microns. I have not had any dirty fuel yet that I know of. I get my fuel from the same busy servo 3 minutes from my hangar & only looked in detail for a while so could possibly have filtered out some crap. There is always 50 ml or so in the filter sump at the bottom which I use as weed killer at the hangar door.

I like the Mr Funnels so much I have two, one in aircraft in a pumkin head cover (for trips away) and one in a box on the wall of hangar with two fuel testers so myself and anyone else can use when refuelling.

[skippydiesel]

I agree - filter all fuel in, will vastly decrease the chance of fuel contamination.

 

I am using a Mr Funnel now but last aircraft had both fill points on side of fuselage. Mt Funnel  requires nice horizontal/vertical fill points to work successfully (yes I know there is angle adapter - still would not do the job) - Modified two Alemlube  funnels with special fuel filter cloth. Had a home one & a go away,  screw lid both ends. Used for 11 years. Amazing the crap they caught.

 

https://alemlube.com.au/web/product/product_detail/e5c7795b-e5fc-4762-9bdb-3cfcd2b8db5b

[old man emu]

2 hours ago, kgwilson said:

There is always 50 ml or so in the filter sump at the bottom which I use as weed killer at the hangar door.

Whoo! Whoo!  Step away from the container and assume the position!

[facthunter]

Probably one of the more safe weedkillers. Stinky fuel. Works a treat.   Nev

[Carbon Canary]

In relation to pumping different fuels down the same pipeline, I vaguely recall the same practice was used from the Whangarei refinery in NZ down to Auckland.  I also recall from a previous life that the Mobil Stanvac refinery that once existed south of Adelaide (next to where the desal plant is now) produced lube oils and bitumen amongst other things......but the larger market for bitumen was in Melbourne. Hence the bitumen was blended with kerosene so it could be easily shipped to the Mobil Altona refinery where it was treated in the 'Cutback Bitumen Unit' to separate the bitumen from the kero by simple distillation, with the kero then becoming Jet A1.

I also vaguely recall the avgas contamination crisis way back in the late '80's (?) which I believe had some origins in the alkylation unit at the Altona refinery.  At that time the sulphuric acid-based akylation unit experienced frequent upsets which led to acid carryover to downstream distillation processes.  To reduce the corrosion impact, loads of amine-based corrosion inhibitors were dosed into the distillation columns.  The presence of the amines in the ultimate Avgas product were not kind to rubber seals, etc. 

 

I was involved in oil refining back then, but no doubt some of our more 'senior' forum members may be able to refresh my memory.

[Carbon Canary]

Oh, and back then the various refineries had a seasonal bias as to what crudes they would source.  For example, the Viva (ex-Shell) refinery at Geelong had a base diet of Gippsland crude from Bass Strait.  This crude was great for making 'light's such as petrol, LPG etc but not that great for diesel and heavier fractions such has heating oil which was used a lot in Vic, way back when.  Hence, leading up to harvest time, the crude buyers would source Indonesian and middle east crude that would produce a greater diesel fraction and in winter heavier crudes for a greater heating oil fraction.  As the product demand changes, so too must the crude oil diet to the refinery.  Of course that's all largely academic now as Australia imports most of its fuel as finished product.  If anyone is interested, I could bore them for hours on the hydrocarbon chemistry in an oil refinery !  

[kiwiaviator]

20 minutes ago, Carbon Canary said:

Oh, and back then the various refineries had a seasonal bias as to what crudes they would source.  For example, the Viva (ex-Shell) refinery at Geelong had a base diet of Gippsland crude from Bass Strait.  This crude was great for making 'light's such as petrol, LPG etc but not that great for diesel and heavier fractions such has heating oil which was used a lot in Vic, way back when.  Hence, leading up to harvest time, the crude buyers would source Indonesian and middle east crude that would produce a greater diesel fraction and in winter heavier crudes for a greater heating oil fraction.  As the product demand changes, so too must the crude oil diet to the refinery.  Of course that's all largely academic now as Australia imports most of its fuel as finished product.  If anyone is interested, I could bore them for hours on the hydrocarbon chemistry in an oil refinery !  

Certainly not boring CC. I remember the Avgas quality issue in 1999 as it also affected NZ supplies. I was doing some work in Nelson  and had to made a decision on returning home in a hired C172 across Cook Strait.

Even though I am no expert in the industry, I have heard that water slugs in shared pipelines are used often. Always do a fuel drain, always...

[facthunter]

That's a requirement. Even if you filled it the night before. Allowing time for it to settle never hurts either. The best engines still need clean fuel. Nev

[Carbon Canary]

Cycling back to an earlier part of this thread regarding ethanol......

 

Be aware that ethanol forms an azeotrope with water.  That is roughly 95:5 water.  This means that despite the difference in boiling points, you can distil an ethanol/water mixture all day long, but you won't separate them beyond 95:5.

 

Keep this in mind if the day ever comes when you want to use ethanol in an aircraft engine.......and you won't see the presence of water (in the ethanol) in a fuel drain check.

 

[facthunter]

Till the % of water is high enough to stay out of solution. Ethanol would be OK to remove water from your system. A well designed drain system will take fuel from the spots where water would naturally collect. Low points.   Nev

[onetrack]

CC, isn't that the same as the old bush trick of utilising methylated spirits to absorb any water in petrol, so it will be burnt?

Metho is only ethanol with smelly additives to deter people from drinking it.

 

The problem with the old metho trick of course, is that it does reduce the octane rating of the fuel. However, I don't recall anyone having any problems with using the metho trick in vehicles, as long as they didn't go overboard with the quantity. By the same token, vehicle engines were more tolerant of the range of fuel qualities in the "old days".

 

Edited November 28, 2022 by onetrack

[facthunter]

Ethanol and methanol don't mix with Paraffinic (Petrol) and cyclic (benzine) without a common mixant.  Alcohol has quite a high octane rating. Methanol fuelled speedway bikes run compression ratios above 12;1  Nev

Edited November 28, 2022 by facthunter

[Carbon Canary]

Onetrack - well, sort of....

 

Ethanol and water are completely miscible and ethanol is hydroscopic, so will tend to scavenge water from petrol so the old bush trick holds some merit..  However you will still be left with petrol + water/ethanol mixture which you may or may not be able to separate out.  Fortunately, as you say, engines will tolerate a bit of entrained water in fuel to an extent anyhow.  You could probably run an engine on whiskey.....if you could afford it !

 

Methylated spirits is approx 90%ethanol /10% methanol and added benzoate agent to make it taste bad.   I was once jokingly told that if you strain Metho through burnt toast first, it then tastes alright.  I chose not to test the theory.  There could actually be a scientific basis for it though with activated carbon stripping out the benzoate....but let's not go there.

 

Just saw Facthunter's good reply as well.  Key point is that "petrol" is not a single molecular product but is a mixture of a bunch of different hydrocarbons and that's before value-added additives are thrown in for marketing reasons.

[RFguy]

Thanks CC for the nicely written input.

I did have to look up "Azeotrope". My year 12 chemistry is a long time ago...

An azeotrope is a mixture of compounds with the same composition in the vapour as in the liquid. In other words, an azeotrope is a liquid mixture that has a constant boiling point and whose vapour has the same composition as the liquid.

[facthunter]

Just means it can't be separated by distillation.. That's a process used a lot in refining Crude oil. Gases to waxes and everything in between which is there.. Catalytic cracking is another process to make more of certain products from the base. If  a liguid is cloudy, you have an emulsion or colloids in suspension. (particles so small the bouncing of the molecules stops it settling and precipitating out)., A mixture mat have a  colour but should be clear .  It's good practice to agitate oils before poring to get even Distibution of some additives. Nev