Gasoline "Snow"?

We've had a (not uncommon) problem with one of our tip-tank quick drains
leaking. If you don't get it to snap shut, properly, it will set up a
regular drip-drip-drip that, over time, will cost a fair amount of gas.
(And yes, I know how to clean and replace the O-ring that's probably got a
tiny chunk of crud stuck in it, but, man, it's COLD outside!)

Note: This is on a 1974 Piper Cherokee Pathfinder (235) with four fuel
tanks.

It's unusual for us to go more than a few days without flying, but due to
the holidays and some nasty weather, we went twelve days without "getting
high." (I was starting to twitch uncontrollably... :-) When we opened the
hangar I immediately noticed a white chunk of ice, about 3 inches tall, on
the astroturf floor of our hangar, right under the leaking tip tank.

Up on the quick drain, some 40 inches above the "snow ball," was a smaller
matching "stalactite" of ice. I picked the "snow ball" up off the floor,
and it appeared (by the smell, and what it melted into) to be pure gasoline.

Is it possible for this to be pure gasoline? It had been extremely cold
the night before (5 above zero), but I wonder what the freezing temperature
of gasoline is? Does it have to somehow pick up water vapor/moisture in
order to freeze like this?

What's going on here? (We found no water in any of the tanks before
flight.)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Jay Honeck wrote:
When we opened the
hangar I immediately noticed a white chunk of ice, about 3 inches tall, on
the astroturf floor of our hangar, right under the leaking tip tank.

Up on the quick drain, some 40 inches above the "snow ball," was a smaller
matching "stalactite" of ice. I picked the "snow ball" up off the floor,
and it appeared (by the smell, and what it melted into) to be pure gasoline.

Is it possible for this to be pure gasoline? It had been extremely cold
the night before (5 above zero), but I wonder what the freezing temperature
of gasoline is?

The melting point of pure octane is -57C (-71F) and gasoline is a
mixture of similar compounds so should be somewhat lower.

My guess is that the snowball was almost pure water with
just enough impurity to give it a scent. If the
gasoline was slowly dripping out and evaporating it
would pick up some condensing water vapor from the air.
The gasoline then evaporates and leaves behind the
water that freezes.

Jay Honeck wrote:

Is it possible for this to be pure gasoline? It had been extremely cold
the night before (5 above zero), but I wonder what the freezing temperature
of gasoline is?

It varies between -180 and -240 degrees Fahrenheit. At that, it looks sort of
like wax.

George Patterson
The desire for safety stands against every great and noble enterprise.

On Thu, 16 Dec 2004 15:47:49 GMT, "Jay Honeck"
wrote:

We've had a (not uncommon) problem with one of our tip-tank quick drains
leaking. If you don't get it to snap shut, properly, it will set up a
regular drip-drip-drip that, over time, will cost a fair amount of gas.
(And yes, I know how to clean and replace the O-ring that's probably got a
tiny chunk of crud stuck in it, but, man, it's COLD outside!)

Note: This is on a 1974 Piper Cherokee Pathfinder (235) with four fuel
tanks.

It's unusual for us to go more than a few days without flying, but due to
the holidays and some nasty weather, we went twelve days without "getting
high." (I was starting to twitch uncontrollably... :-) When we opened the
hangar I immediately noticed a white chunk of ice, about 3 inches tall, on
the astroturf floor of our hangar, right under the leaking tip tank.

Up on the quick drain, some 40 inches above the "snow ball," was a smaller
matching "stalactite" of ice. I picked the "snow ball" up off the floor,
and it appeared (by the smell, and what it melted into) to be pure gasoline.

Is it possible for this to be pure gasoline? It had been extremely cold
the night before (5 above zero), but I wonder what the freezing temperature
of gasoline is? Does it have to somehow pick up water vapor/moisture in
order to freeze like this?

What's going on here? (We found no water in any of the tanks before
flight.)

I doubt the gas can freeze at the temperatures we experience in the
Midwest.

My guess: The evaporative cooling of the gasoline is condensing
moisture out of the air.

-Nathan

I have seen gasoline become rather viscous like syrup at -54, but I have not
been in temperatures colder than that and the gasoline still flowed well
enough for the engine to run.

Given that the chunk of ice was white instead of 100LL blue (or you use red
gasoline, don't you?) I suspect that it is water that merely smells like
gasoline.

What? No picture?

Jay Honeck wrote:
It's unusual for us to go more than a few days without flying, but due to
the holidays and some nasty weather, we went twelve days without "getting
high." (I was starting to twitch uncontrollably... :-) When we opened the
hangar I immediately noticed a white chunk of ice, about 3 inches tall, on
the astroturf floor of our hangar, right under the leaking tip tank.
Up on the quick drain, some 40 inches above the "snow ball," was a smaller
matching "stalactite" of ice. I picked the "snow ball" up off the floor,
and it appeared (by the smell, and what it melted into) to be pure gasoline.

Up on the quick drain, some 40 inches above the "snow ball," was a
smaller matching "stalactite" of ice. I picked the "snow ball" up off
the floor, and it appeared (by the smell, and what it melted into) to be
pure gasoline.

What? No picture?

Dang. I had the camera with me, too. Never thought of it.

I'm leaning toward the water-condensing-out-of-the-air-as-the-droplet-fell
theory, at this point.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

"Jay Honeck" writes:

It had been extremely cold
the night before (5 above zero),

In contrast, see for instance

http://www.wallacecompany.com/E45/ca...0-0800_Ec2.jpg

Pine Mountain Lake Airport Webcam

I agree it possibly had something to do with local chilling taking
water out of the local air. But air at that temp already has very
little water vapor in it. That seems hard to believe, and I've never
seen what you described. Huh!

Gasoline will dissolve a small amount of water into solution. The
amount that will dissolve goes down with temperature, creating a fine
ice crystal "snow" in your fuel tanks under severe cold conditions.
When flying, this snow will accumulate on any filter screens (such as
in the gascolator) and can eventually block your fuel flow requiring
only a very tiny amount of water.

I know - it happened to me (see Sport Aviation Dec 1986)

Remember that your fuel that morning was probably colder than it had
ever been since it was made at a refinery in some warmer climate. For
that reason I add a small amount of isopropyl alcohol to my fuel
whenever the local temps go below freezing.

Beware of fuel that has been severely chilled before it was last
filtered.

Remember that your fuel that morning was probably colder than it had
ever been since it was made at a refinery in some warmer climate. For
that reason I add a small amount of isopropyl alcohol to my fuel
whenever the local temps go below freezing.

Really?

I guess this throws out my concerns about finding alcohol in my mogas!
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"