V

Vlad

Well Known Member
I replaced stock tank drains o-rings with vyton ones. Yesterday I noticed that after fuel sampling both drains were wet and I couldn't "work" them shut. I've read somewhere in the forums that vyton isn't tolerant to lower temperatures but couldn't find the topic. Should I switch back to regular O-rings? I burn a fair amount of ethanol laden fuel.
 
Vlad said:
I replaced stock tank drains o-rings with vyton ones. Yesterday I noticed that after fuel sampling both drains were wet and I couldn't "work" them shut. I've read somewhere in the forums that vyton isn't tolerant to lower temperatures but couldn't find the topic. Should I switch back to regular O-rings? I burn a fair amount of ethanol laden fuel.
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Are you at a temp of -15F or below?

http://www.marcorubber.com/materialguide.htm
 
simpkinsona said:
Just heat the leaking sump valves with a lighter ��
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Nowhere near enough heat in a lighter. Plumber's torch is much more effective.

Notice: The owners of this forum take no responsibility for the strange sense of humor of some posters
 
more direct method.....MUCH safer eh!

Surely someone will recommend just putting your lips around the leaking drain, and blow?
( caution, fuel may contain lead, a chemical known to the state of common sense to contain compounds causing stoopid ideas like this!)
 
Buna-N o-rings will have more flexibility at low temperature than viton. Viton only remains flexible down to about 5 degF. Buna-N should be good to -22degF.

To add a bit more, viton is a trade name for FKM elastomer, which happens to be the same class of material used in the space shuttle booster o-rings up to and including STS-51L (Challenger's last flight), the famous failure of which was written up to low temperature related stiffness (proximate, not root cause).

Buna-N is a type of nitrile rubber which also has good chemical resistance and lower temperature tolerance .


Both Buna-N and Viton are compatible with ethanol containing fuels.
 
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I have gone away from the Viton on my brake calipers because of exposure to cold, so yes, I think I'd try Buna-N if you want to keep something there year-around.
 
I've got a similar kit. If you buy it via Prime, it's about the same <price + shipping> as a couple of o rings from a 'regular' supplier would be, and you'll never run out again. :)

Charlie
 
We're only two days away from the 30th anniversary of there being a similar problem on the Space Shuttle...:(
 
Downside of Buna ?

Assuming the fuel system is otherwise ethanol tolerant, what is the failure mode of Buna tank valve orings. If it drips, replace it. If it dumps the tank in flight or the hanger that's different. Which is it ?
 
Larry DeCamp said:
Assuming the fuel system is otherwise ethanol tolerant, what is the failure mode of Buna tank valve orings. If it drips, replace it. If it dumps the tank in flight or the hanger that's different. Which is it ?
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Buna-n (nitrile rubber) is supposed to be good for blended ethanol fuels, however for use in pure ethanol it is only rated C in the Cole-Parmer database. It would be prudent to inspect at least annually and replace as necesssary.

http://www.coleparmer.com/Chemical-Resistance

Ref for E85 compatibility:
http://iqlearningsystems.com/ethanol/downloads/Ethanol & E85 Material Compatibility.pdf
 
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