Gary Casey wrote:

Viton (flourocarbon)  is a commonly used O-ring material in fuel systems.
Compared to BunaN (Nitrile) it has better high temperature properties, but below
maybe -20C it is not good (not enough elasticity).  On certain applications we use
one Viton seal and one Flourosilicone.  The flourosilicon is excellent at low
temperatures, good with fuel, but is not very abrasion or tear resistant.  On
cars, fuel injectors can get very hot after the engine is shut off and that is why
Viton is used.  Viton is usually colored tan or brown.  I can't imagine an
aircraft getting that hot so I would think that a BunaN (usually black) or
Flourosilicone (usually colored green or blue) would be a better choice.  Silicone
seals (always red in color I believe) is definitely not the thing to use with
gasoline.

 
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