Used my auxiliary avgas transfer tank for the first time this weekend. Worked awesome and I'm super happy with it. Weird thing which I wasn't expecting; when I returned home after a two day trip, color turned from pretty blue to distinct green - yellow in the filter bowl. What causes this and should it rise concerns?

Thanks!
-Ryan

BTW, the tank was baking in the sun @ ~80 deg F during the day.

I just did a quick Google search and found a couple of snowmobile forums mentioning this. Apparently 100LL changes color from blue to yellow if it is stored in the sunlight in glass jugs. I don't recommend storing gas in large glass containers myself, but apparently snowmobile racers have other ideas about safety.

Somebody took a whiz in it when you weren't looking.

Brenco Aerial Patrol C-172s had STCd flat aux tanks in the baggage and back seat area. They leaked pretty badly. The blue die would make a thin film, when it dried, that you could peel off. I hated them and only filled when near one of Uncle Rick's thousand gallon tanks that I would have been fired if I passed up. Transfer was just to the left tank, awkward, and not entirely accurate. If you started the transfer too soon it just ported out the left tank vent. It was a real pain in the neck.

Anyway, blue die is weird stuff.

Spent a good part of the day looking for something specific.

Found an article about "phase separation" in fuels at low temps. = yellow results.

http://www.lcbamarketing.com/phase_sepa ... l_blen.htm

Started with - snowmobiles fuel turning yellow - to get the above article.


You did not state how old your tank is or what other use it might have been used for. SO.

I giggled "yellow fuel in glass jars"

Found two DIESEL trouble shooting links that end up with a yellow wax in suspension.

PDF Common diesel problems part one

Reeds diesel engine troubleshooting handbook


Hope it helps
Chris C

Chris, thanks for the healthy research. I researched for a while as well and hadn't found anything conclusive yet either.

Background on the tank; Tank is brand spanking new off the pallet from Northern Tool and is approved for Avgas [url]http://www.northerntool.com/shop/tools/product_200637851_200637851
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Fuel pump and filter are also brand new. It has been sitting empty in my garage located in the OR's high desert. I think that water contamination is unlikely. All I can say is the fuel in the bowl probably got exposed to a lot of UV while sitting in the parking lot.

I have an answer, and it sounds legit.

I talked with two engineers from the tank manufacturer (RDS) and the pump/filter manufacturer (Fill-Rite). The gas hose that is used in most fuel lines is BUNA-N tubing. When these hoses are manufactured, they are impregnated with an oil that keeps them moisturized, soft, and flexible. Through use, this oil is replaced by the oils in the gasoline which then keeps the hose soft. But during the first uses, these oils bleed into the fuel lines and typically turn auto gasoline orange. Since 100LL fuel is blue, orange + blue = green / yellow.

The only questions is; is it safe? The fill-rite engineer doesn't know. So next time I fill up, I will flush the system from the green-yellow fuel into my Jeep where reliability is already compromised (haha) and fill the airplane with the fresh blue fuel. Over time, the oils should dissipate and this will no longer be a factor.

Chris, Thanks for all your input!

-Ryan

Hi Ryan,

Thanks for posting this information. I recently came across the same issue with a new tank/hose/pump set up and disassembled several fitting joints to take samples and find the source of yellowish fuel. It’s definitely from the hoses. I’m curious how long it took before you stopped throwing the AV fuel into your Jeep and no detectable yellow fuel was flowing? It started out very yellow and now it seems to be slowly resolving itself.

-Mada

Hence whymaybe on the fill rite pumps is a decal that reads "Not for Aviation use" Not that it stopped me from using one on my avgas tank

I have yellow fuel in a glass jar in my hangar..................oh wait