How did they get around the issues of deterioration with fuels?

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#1

So this company is well known for their composite tanks. One thing that they claim is that their ranks are resistant to deterioration from fuels. This may be the case with race fuels (which is different then pump gas and commonly regarded as “harsher” but in reality from what my research has revealed is that there is nothing truly as harsh as oxygenated run of the mill pump gas (ie ethanol blends that have become ubiquitous).

FAA advises against any fuels with ethanol blends due to damage to engine components (aluminum and plastic/rubber components). Automotive components are no different and are subject to the same damage, injection system etc. Also the FAA advises against because of the increase in relative volatility and the decrease in energy per unit fuel.

anyways… any ideas how they would achieve a resistant tank without any liners or coatings?

quotes from their FAQ
Q. Will I have to drain my race fuel from my tank?

A. The epoxy matrix we use has never exhibited any problems with race fuels over extended periods of time.

Q. Do your tanks require a bladder and or do I have to apply a fuel proof coating on the inside such “Kreem”?

A. Neither. FuelCels are inherently fuel proof and leak free by creating an impervious shell matrix. In fact, a coating would have nothing to stick to and could peel off and get into your fuel system.

http://www.eti-fuelcel.com/order.html

Thanks.

#2

I notice that their Q & A ask whether there is a need to drain the race fuel…Note the term ‘race fuel’, ie it contains no ethanol.

I don’t think that they are stating that there tanks are ethanol blended fuel resistant, they omit that information.

My understanding was that phenolic resins were resistant, however it is yellowish in tint and therefore unable to produce a ‘crystal clear’ finish. I am no expert, just an enthusiastic amateur, so I look forward to more detailed answers from more experienced and knowledgeable people, so that I can learn some more.

#3

Thanks for the reply. Yes that was my assumption aswell. They are omitting the etoh blends and strictly stating race fuel.

I too am if the understanding that phenolics are suppose to be etoh resistant. BUT from what I have gathered from marine guys that have done sample testing in fuel baths the phenolics have a failure aswell and there is no truly resistant resin. Also from what I recall from memory, more experienced folk aroun here have said in the past that phenolics are very noxious and toxic to work with( again just going off recall )

Any ways I did send them an email regarding my concerns about etoh but we’ll see how much detail they will divulge.

#4

Here is a study comPleted my some univ students regarding sealers and e85 fuel

http://www.umaine.edu/mecheng/peterson/classes/design/2007_8/project_webs/csc_e85/pdf/report.pdf

#5

There are many adhesives and sealants that are very hardy when it comes to fuels. Ppg epoxy polyamide is a IFC primer. You can pour in and drain out. http://www.ppg.com/coatings/aerospace/coatings/coatingsproducts/Documents/Epoxy_Polyamide_Corrosion_Preventative_Primer_Coating_515X346.pdf

Ppg also makes great sealants “pr1440 a2” is a great product for fuel cells. Works great with kerosene. Unsure about ethanol exposure longevity. Here’s a great article about sealants. http://www.vansairforce.net/articles/tank_sealant.pdf

I added the above info in case someone searches the forum and the above info helps them out in regards to fuel cell sealants and primers. To answer your question there are many toughened resin systems out there that are very very chemical resistant. Miller Stephenson makes some fine products in this regard. Chances are the company making the cells has found a product as such that makes a long lasting cell with the right adhesive of course. Your run of the mill ve or epoxy would probably not suffice. A good example would be people using a traditionally non uv stable resin for cosmetic parts then adding a compatible resin modifier for uv stability. Same goes for toughening the resin for chemical resistance.

#6

I can’t tell you how long I have been researching this topic and have come up with only a few pieces of useful info.
Thanks! greatly appreciated.

#7

I’ve been doing the same thing. Found a 3M Aerospace sealant that looks promising finally. Still need to do a bit more research on it though.

http://solutions.3m.com/wps/portal/3M/en_US/Aerospace/Aircraft/Solutions/Aerospace_Sealants/Products/Integral-Fuel-Tank-and-Fuselage-Sealants/

#8

I have emailed 3M, PPG, and one of the aircraft supply sites to see what they recommend. I emailed PPG on Wed and still no resp… I’ll keep posted.

#9

Sealants classes are tricky

A is for brush coat applications

B is structural assembly (faying surface and fillet)

C is extended use and injection typically.

For instance in a wing of an airplane everything is usually assembled with B class sealants. Then brush coated with A or B. then primed in some cases. But all metal surface are painted with a fuel primer.

If i was building say a motorcycle tank. I’d order a toughened epoxy system. Then use a b class sealant to to seal pit xxxxs and fuel cap component flanges and so on if that makes sense.

#10

Dallasb84
Please can you give some Infos about this tank issue thank you on advance
1-Then which strong epoxy system would you use for the gas tank?
2-You speak about a very strong gas tank sealer do you have an idea about which one?
3-And for the end if it’s a 2 parts tank ( it has to be…) then which epoxy glue would you use?
(carbon fiber tank)
I was thinking about vinyl ester but I think that for carbon fiber epoxy will be better
If you have some advise I like to make some motorcycle tank but I want to feel save with the issue of the gas

#11

You’ll have to find a product that best suits you as far as a resin goes. I already mentioned a manufacturer that makes chemical resistant epoxies.

I would suggest using the highest quality and grade adhesive you are willing to buy.

After inspecting and working on aircraft that has 30+ years with the use of sealant exposed to fuels I’m confident in my recommendation of an integral fuel cell sealant.

You could essentially brush or roll sealant onto a prepared mold and layup over top incorporating the sealant in the stack up. Just and idea… Then do a faying surface seal at the flanges during assembly and bonding.

On the flip side… You can brush roll the sealant directly after pulling peel ply for a good bond. Either way the possibility are endless.

#12

Thank you for your fast reply
I appreciate everything you say and yes you are right to get the best I agree with you
You said you already mention an epoxy manufacturer
In this thread? I will read again

But here is the point in the best conditions and money is not an issue (im not the NASA :slight_smile: my question is with your experience
can you tell which companies would you use for this project “gas tank”
1- the epoxy system ?
2- the epoxy glue (for 2 parts tank)
3- the sealer for the fuel in the tank
I will use Carbon fiber twill min 6 oz then some Kevlar Infusion I think
Oven cure and post curing
By the way would you apply clear coat on parts before or after post cure?
I have an oven available and vacuum pumps also
I Am new in this field but I know about mold and plastics as well as metal molds and casting metal
there is so many Epoxy systems ,glue and sealers available that it will be easier if you know which company to use
It will be only to get a direction then I will do my homework about it
I have been reading the forum for about 2 weeks and I can say its a fantastic place for Infos with very nice and professional people around…experts also

#13

Yes you right Dallasb84 you already post some products name before sorry about that
I will look into it

#14

I would look into Fasco products. They have Fas-stick 110 which is supposed to be over 5000 psi breaking strength from chatter I have read. Their website lacks a lot so I would give them a call. They list coatings for fuel tanks as well as a wide range of epoxy adhesives.

http://www.fascoepoxies.com/

#15

I had received a call from a rep abot my questions. They said that the sealer will be resistant to etoh. But he didnd know if the sealer could adhere to itself once cured (ie. several layers or slosh coating once 2 halves are assembled to seal the bonded seams). It’s been a week or more and I hav not heard back about the thing he couldn’t answer so I will try and give another call to follow up.

#16

we had used this stuff for my bosses boat once, but to be honest I dont know how good the stuff really works, and if it will meet your requirements

http://www.velocityxl.com/wiki/index.php?title=Jeffco_Fuel_Tank_Sealer

#17

I was thinking about Vinylester
It’s apparently fuel resistant
What about making the tank in epoxy and carbon fiber
Let it cure ,post cure and then to coat the inside with the Vinylester?
Will it bond to the epoxy?
Then the issue will be which glue to use to bond the 2 parts of the tank
What would you think about the reaction between the Epoxy and the Vinylester
Thanks

#18

from what I have gathered historically many boats had compositie tanks before ethanol was popular and they were made with poly or vinyl or epoxy and none of them had problem, until ethanol was added to the fuels and then all had problems.

#19

Most sealants adhere to themselves after cured. They can be sanded also for better adhesion.

#20

If I may ask which Rep’s Company are referring ?
Thank you