"Jon Woellhaf" wrote:

(a) You can go through the math all day long and still not explain
why I have drained the (hangared) 182 after a particularly humid day
or two and get a tablespoon or two of water in the quick drains.

Dan Luke calculated there could be 14 grams of water in 20 gallons of
air.

1 tablespoon = 15 milliliters = 15 grams

Yes. I also noted that that would be in extreme conditions. And even
if *all* that water condensed inside the tank (impossible: condensation
could not remove all the water from the air), not all of it would
necessarily enter the fuel; some would be in drops on the surfaces of
the tank that were not submerged in fuel.

(b) You cannot explain why "drain the sumps" is a daily check list
event for both fuel trucks AND airplanes.

(c) You cannot explain why CessBeePipMoo all have drains at the low
point of the fueling system. It would be a hell of a lot cheaper not
to have to put them in there. Somebody somewhere thought it was a
good idea.

Water can enter tanks in ways other than condensation.

Just so.

The condensation bugaboo is an old wives' tale. Perhaps, if an airplane
is parked for months with half-full tanks, a measurable amount of water
might accumulate due to heating/cooling respiration of the tanks, but it
might as easily be due to tiny leaks in the gas cap seals. I've never
found any in my airplane, which is parked two miles from Mobile Bay.

--
Dan
C172RG at BFM