Also Sprach K. Smith :

I think you'll have a hard time even buying a fuel tank vent that isn't
fitted with a flame proof gauze.

Actually, I did buy one here in the US. It was crap, I returned it.

For those of you wondering how this works, the mesh screen acts as a
quenching device preventing a flame in the fuel vapor outside the vent
from passing inside the vent. The type of flamable vapor determines the
size of mesh (or orifice) reqired. It's been a while, but seem to recall
that the quenching distance for gasoline vapor in air is somewhere around
2mm. I've seen several vents with large gauge mesh which I suspect would
not prevent flame spread.

BTW Chuck, I do think that Karen is correct on this one. We use what you
describe all the time in aircraft engine installations, it's called
firesleeve.

http://www.sacskyranch.com/h_fire.htm


--
Skill without imagination is craftsmanship and gives us many useful
objects such as wickerwork picnic baskets. Imagination without
skill gives us modern art.
-- Tom Stoppard