Refueling trailer fuel quality question
 

I have a 300 gallon refueling trailer used to remote fuel my helicopter with 100LL Avgas. I've been operating from airport for the past 5 months so have not refueled from the trailer during that period. I keep the trailer slightly tilted toward lower draincock. I just drained about a pint into a glass jar to check quality and found it to be pristine clear blue, no visible water and a few black pieces of sediment.

I set the pint (with no cap) on a potting bench near the driveway, in full sunlight, intending to transfer it to my mower. I left it there for a couple or more hours and and came back to find it to be a cloudy greenish colour with a thick clumpy yellowish suspension at the bottom.

I'm not pumping into my copter until I know what the heck that was all about. Is it just the sunlight breaking it down in the clear glass jar or indicitive of something more sinister going on in that tank (presence of water, mold, chemical breakdown)?

It drained and appeared fine until I left that clear jar in the bright hot sun. Anyone know what happened? Is five months too long to keep the fuel?

Carryout a pump through and recirculate the fuel in the fuel bowser and then take another jar for testing. If the same happens clean your bowser, but if in doubt don't use the fuel. Better safe than sorry in my opinion.

Yes, I agree. If you don't want the fuel, let me know and I'll be happy to dispose of it free of charge through my competition car's engine, which is fine as it is an old engine with out a cat convertor, just to ensure it's done in a safe manner.. ;)

Info Link (Chevron)

Hope this helps!

I have noticed that small amounts of avgas in pots goes green - and it happens with new avgas too. I use the stuff from my sampling pot in my mower. Incidently, I don't leave the delivery pipe full of fuel as it seems to go green in the pipe if left for a few weeks. On the basis of this I dont think you have a problem with the fuel in your bowser.

I take the view that if its blue and crystal clear out of the pump, Ill burn it in the aircraft. The stuff I have now is about 9 months old, and it still looks good.

I don't know if its light, evaporation or oxidation that makes it green but I suspect it is the loss of some volatile componant.
Try the same experiment with a sealed vessel if you are that bothered.

Danger, Danger,

what you have is plain old.. H2o,

the tank you have is it insulated?, if not then you will always have a moisture content that is really only seeable once the juice is oldish, the tank should have one of those big fuel filters after your pump, that will take out most of the moisture and slowly expand so as to stop you pumping anything with a high moisture content in it , then you are forced to change the thing, and clean out your tank.

I have refurbed a lot of trailer Bowsers and find they all suffer from moisture if they are not insulated, in fact I picked up a 320gall tank one day to be told its half full and we cant pump anything out!, reason Filter totally blocked by swelling due to moisture, so contents pumped out and into a new couple of barrels to see what its was,... oh it was half full alrightl , but made up of roughly 120 galls of water with about 50 gals of Avgas,, possibly the mans Jet R could have had some new sort of H2o burning turb..

Any uninsulated tank will make a suprising amount of moisture, even though the lid may never be opend for long, its pure physics, fuel gets warm in daytime, tank gets cold at night, your fuel then starts to float on the unseen peril of the sky.

Insulate or Die, or scrap your Bowser and get a new one, insulated and fully bunded so as to be within the new rules!

PeterR-B
Vfr:(

Following a rotors running pick up of Jet A1 at another operators base some years ago my trusty 206L1 settled gently to the ground from the low hover, whilst I was pre-occupied with idly wondering why the TOT was down around 320 C. The engine continued running on the ground.

I, and the ashen-faced refueller, took samples from both aircraft and bowser. Sure enough they were both quote "pristine clear blue, no visible water and a few black pieces of sediment". This is because they were both pure water!

Quite surprising how much a jar of water that's been living in a bowser smells of fuel. Beware.

Peter,
Agreed, you can't be too careful with fuel.

Both my bowser and storage tank are stainless and insulated and I have a Flightline Supplies big black filter in the delivery line. The filter drain is always blue avgas and I check the filter element a couple of times a year. It still looks OK.

Thats probably why my fuel stays blue.

Phil

EDIT

I have just had a delivery TODAY of fresh avgas into an empty bowser. Ill do the experiment of leaving two samples, one old and one new, open in a jar to see if it goes green. Ill post the results here in a day or two. Watch this space. (I might not be able to do the sun bit cos it constantly pisses down here:* )

Much to consider. This has been illuminating discussion.

I drained the original sample from the "dump valve" on the bottom of the tank (unfiltered). I'll try to recreate same with a sample through the filter and the nozzle. I'll also test for suspended H2O.

Gaseous - Keeping an eye out for the results of your experiment. Thanks!

That link that Flingwing pointed to has this sub-page, which is my guess as to what was happening:

"Microbial activity tends to concentrate at the gasoline-water interface. Moderate activity may cause the gasoline to lose brightness and clarity. Severe activity may stabilize gasoline-water emulsions and contaminate the fuel with visible particles of microbial sludge (biomass). Anaerobic microbial activity may generate hydrogen sulfide, giving the gasoline a "rotten egg" odor."

Moisture is present in every temperature change, where the tank vents breath in moist air, and cool conditions can condense it. The quote says "emulsion" as in a colloidal suspension of water and gas. The sunlight could have made some tiny airborne algae particles happy guys for a while. Modern anti-polution fuels get biological growth more easily, and biocides are recommended.

If it is suspended water with biological contamination (could there be a simple test for it?) the fuel is gone. Good for bonfires and the like.

Gin clear skies up here in Lancashire today, so after all this talk of moisture in fuel and little guys living off it , try this with your wasted (moisture laden) Avgas, mix 50/50 with any diesel fuel for any oil burning vehicle, they really run well from it and cope with the water in suspension, however dont run on pure contam avgas, the old Derv engine then runs too hot on pure and tends to crack heads...! no prizes for how I found out!!


Way Way back I read a very interesting true " " story about the Microbal affects of contaminated Avgas on Navy Aircraft, it was only dicovered that Microbes would live in fuel after several unexplained ditchings, then one hero pilot realised something wasnt quite right and managed to get his A/c( Fairy Gannett) back to the carrier, the rest as they say is History

Also the sluge that is left after the tank is empty is sticky and slimmey, it can only be removed from most tanks by the liberal application of plenty of high pressure steam or nearly steaming water, then ati microbal spray and a good drying, but after steam has been used the latent heat normally dries it all perfectly, cant you tell who operates the dishwasher in my wifes house!!


Peter RB

I'll pick up the bowser tomorrow (Wednesday) and do the test.

Meanwhile I found out that oxidation causes precipitation and loss of clarity but I have not found over what time scale
reference
http://www.royalpacificpetro.com/htm...as_content.htm

I also saw a reference to sunlight affecting the dye but it wasnt too specific.I have lost the URL to that and cant find it again.

Edit: Found it
http://www.eaa.org/education/fuel/re...practices.html

Digging in Flingwings chevron link, I found this.

Full text at:
http://www.chevron.com/prodserv/fuel...8_ag_perf.shtm

also
full text at
http://www.chevron.com/prodserv/fuel...#contamination

Both pages worth reading if you store avgas

Storage of 100LL was once explained to me to be for a maximum of three months, after that it was said to start to lose its ability to "Bang" to specification , I seem to think this was from the Fuel servers at EGNH, when we purchased quantities for motor racing and bike racing, but I wasnt really listening that hard so what Ive just written could be a complete load of junk! :ooh:

Vfr

Ok, I've got the fuel.

Both samples come direct from the wholesaler so haven't been hanging around at an airport. The new sample was delivered on Monday, the old in August 2004. The old sample has been stored in a sealed insulated tank until yesterday when it was pumped into the aircraft so is representitive of what I am burning. The sample was drawn from the gascolator.

It is immediately obvious that the new fuel is a much more intense blue. The old fuel is still blue but with a greenish tint (if you know what I mean??). Both samples are crystal clear (no turbidity). When (if) we get a sunny day I'll see what happens. Till then they stay dark and sealed.

(If its nice on Friday, Peter, you could maybe come over to be an independant scrutineer and then we could fly to Whitewell for lunch)

The picture gives an idea of the difference. Old sample on left.

http://myweb.tiscali.co.uk/avenuedentistry/AVGAS.JPG

Gaseous - mine was in a similar sized jar and left un-capped in direct sun at about 24C for 3-4 hrs. The clumpy precipiate at bottom will remix with the rest to a lightly cloudy green. I'd show you, but don't have a IMG host sight to use.

So the heat and UV breakdown something, but what and will it do same with fresh?

Phil,

Looking at the grey mess above my pile of bricks I doubt if we'll ever see sun again this month, But yes, most defo, if the Current Bun doth come out I'll give you a ring, or verse vicer on my mob.

PeterR-B



Um'm the antisipation of crispy battered fish and giant chips, or even Fish pie, is starting to make even the Grey stuff seem insignificant.

:ok: :ok:

AVGAS TEST
 

Cross eyed.

Test Complete.

The two jars were opened at 8.30 this morning. both were still clear. There is a reasonable amount of sunshine. By 1400, both samples turbid with white precipitation at the bottom of the jar. The old fuel is more cloudy than the new, but the new is not much better. There is an approximately equal amount of gunge in the bottom of each sample.

The old fuel is OK for burning as Vfrpilotpb and I have just flown to the pub and back on it.

My verdict. Sunlight , and being in an open pot causes degradation of avgas which leads to precipitation of an unknown solid. The age of the avgas is irrelevant as it happens with new avgas. I will try to post a photo later to show what has happened.

I stick by my original statement that if it runs blue and crystal clear from the bowser I will burn it.

What you do with yours is your decision.

Hope this helps

EDIT:

At 1700 they are both more cloudy. The level has dropped by about a third due to evaporation. both samples have a greenish tint.

Phil.

Gaseous

That's very helpful. Since my first sample was unfiltered, bottom of bowser stationary for 5 months, then placed open in high heat/sunlight, I got similiar but a bit more dramatic results. I ran a sample through from the nozzle (which is filtered) and got similar results to you in slightly cooler conditions and less sun. I think the heat/sunlight/evaporation is the reason, not likely microbial (more typical of Jet A and quite fragrant).

I've ran my weed trimmer, mower, and gas blower on the samples and did not have to autorotate any of them. However, I'm ordering a field test kit for water and microbials before I fly the fuel. I'm feeling much more optimistic that it will check out.

Thanks for all the input. Here are a couple more relevant websites I found along the way:

http://www.globalsecurity.org/milita...-1/CHAP13.HTML

http://www.faa.gov/fsdo/orl/files/advcir/AC20-43C.TXT

Gaseous and Cross-eyed,

This is one great thread! You fellows posed a problem, discussed it, and then conducted some nicely done experiments to settle the issue. I think this thread and you guys deserve a round of applause!

Stopping by pprune is never dull, always fun and always enlightening. Thanks!

Thanks Nick,
praise indeed.

Final update on the experiment.
I got the camera out to photograph what is left only to find that both samples have gone! evaporated totally, leaving just pale blue powder in the bottom of the jars - in a little over 24 hours!!

It has been fairly sunny and warm for Lancashire- but by no means hot.

Volatility and control of evaporation is obviously a major issue for correct storage. We all know about the water issue but this was a new one to me. As a result of this I am going to paint my storage tank reflective silver rather than the dark brown it is to help keep the temperature down on sunny days. It could do with a repaint anyway.

I have learned quite a bit about avgas from this thread, mainly not to take it for granted that it will be OK, and it MUST be treated properly.

PPrune at its best is a great educational safety resource.
At its worst it drives me nuts!
I agree, its never dull and usually fun.

Phil.