On Sun, 16 Nov 2008 16:30:04 -0500, "Roger Long"
wrote:

I'm glad there is someone out there more compulsive about fuel treatment
than I am

Nothing wrong with discussing it and taking the precautions you have.
Cheap insurance.
Not nearly as bad as the Honda freaks changing their brake fluid every
year or two because brake fluid is "Hygroscopic."
We'll let you know when you step over the anal line.

--Vic

"RichH" wrote

Why store the oil in a tank with an atmospheric vent only to have it uptake
water (vapor), etc.?

Exactly.

Please confirm that I'm correct in the advice to others (some outside the
newsgroup) that there is no point in filling the tank unless it's filled up
into the vent so that the surface area of fuel available for water vapor
transfer is the cross section of the vent pipe and not the whole top of the
tank.

Since this is impractical in many vessels and impractical in most normal
operation, the whole topping up the tank thing is a crock.

I'm going to put a desiccant vapor trap on my sounding tube for the winter
which is easy to do and tape over the vent.

--
Roger Long

"Capt. JG" wrote

Water absorption in diesel? Seems to me that would be a very, very small
issue, given that they don't mix.

But they do. See Rich H post below.

If the bio is stuck to the sides, why would you want to knock it free?

So that it can get into the filters to be removed and not come off at an
inconvienient time. Biocide is just a way of assisting its removal but the
stuff is nasty and tends to dump a lot of stuff into your filter system all
at once if the tank is badly fouled. The mechanical action of slack tanks
gets some of it into the system more gradually; especially with some
assistance from something like StarTron.

Keeping the tank "topped up" to the extent practical in normal operation
usually means that there will be full air and water vapor access to the
entire surface of the fuel. The difference between that and a slack tank is
insignificant (for a nearly straight sided tank) and, as Rich points out,
more fuel volume for the same air/fuel contact area means more water
absorbtion.

--
Roger Long

The issue of one 'sludging' ones filters from a cruddy tank is more
than just a 'fine point'. Just earlier this year, supposedly a Brit
lost his boat onto the jetty into Charleston SC Harbor when his engine
failed and he got caught in the rage of the inlet.

..... and for that very reason its a good idea to have a well
maintained fuel system, even a few gallon 'day tank' that holds back a
few gallons all 'ready to go' in case of such an event. The more and
more I think of it a small reserve tank of a few gallons makes all the
sense in the world - enabling one to motor on an hour or two; instead
of power-puking into the bilge while trying to change a damn filter
set. :-)

That constantly replenishing emergency tank idea of yours is one of the best
I've seen in this group. I'm still trying to figure out how I might
implement it but space, even for just the gallon I would need, is pretty
tight in a 32 foot boat.

I think it's very long odds that that the big Shelco filter would suddenly
load up. I would have advance warning from the Racor flow stopping and it
ought to take a lot longer for the Shelco to become critical. If I had to
change out a Racor filter, I would focus on getting into a safer position.
I also have two tanks so switching to the other one as well as switching the
fuel supply to the polishing output would be part of the drill if the Racor
loaded up. I'm a sailboat as well so I usually have an alternative
propulsion source.

--
Roger Long

Please confirm that I'm correct in the advice to others (some outside the
newsgroup) that there is no point in filling the tank unless it's filled up
into the vent so that the surface area of fuel available for water vapor
transfer is the cross section of the vent pipe and not the whole top of the
tank.

Since this is impractical in many vessels and impractical in most normal
operation, the whole topping up the tank thing is a crock.

I'm going to put a desiccant vapor trap on my sounding tube for the winter
which is easy to do and tape over the vent.

--
Roger Long

Here's a website that gives a brief tech description of what is
happening .... sorry that its JetFuel but the same happens with
diesel, etc.:
http://www.flowmeterdirectory.com/fl..._07082401.html

My professional (filtration engineering) work in this area has
included the ultra-pure ultra-dehydrated oils used in high voltage
transformers, contactors and tap changers ... although sealed,
eventually become contaminated with water (free, dissolved and
emuslified) which radically changes the dielectric strength of the
oil. The water uptake is all by 'chemical equilibrium'; you put in
ultra-dehydrated oil - come back in 2-3 years and remove the water
( or replace the equipment if if shorts out due to the water and
generated particles). Simple physical-chemical equilibrium at work.

Bruce reported using oil that was barreled in WWII. Entirely possible
if the barrel was filled at temperature that sterilized the contents,
is totally sealed, no water entered, and no fungal spores got in.
After all, that oil is zillions of years old and it stayed in the
ground because no microorganism used it as a nutrient source, etc.

"Roger Long" wrote in message
...
"Capt. JG" wrote

Water absorption in diesel? Seems to me that would be a very, very small
issue, given that they don't mix.

But they do. See Rich H post below.

If the bio is stuck to the sides, why would you want to knock it free?

So that it can get into the filters to be removed and not come off at an
inconvienient time. Biocide is just a way of assisting its removal but
the stuff is nasty and tends to dump a lot of stuff into your filter
system all at once if the tank is badly fouled. The mechanical action of
slack tanks gets some of it into the system more gradually; especially
with some assistance from something like StarTron.

Star Tron disperses the bacteria, but it doesn't do anything for a badly
fouled tank. If you're talking about a tank that's pretty good, maintained
with good fuel and you're careful about water egress, then the amount of
bacteria stuck to the sides would be minimal. In fact, they would die when
covered with fuel, and then they would pass naturally out of the tank. If
action is needed to get the bacteria out, I would much rather take that
action in a known timeframe vs. have it slowly clog a filter. If you're
going that route, then get a pressure gauge and put it on the filter. Then,
you'll know when the bacteria are starting to clog it. I can't imagine
wanting the sloshing action to break loose a bunch of decent size pieces and
have it immediately kill the engine.

If one has a badly fouled tank, that needs to be dealt with next to the
dock, not at sea.

Keeping the tank "topped up" to the extent practical in normal operation
usually means that there will be full air and water vapor access to the
entire surface of the fuel. The difference between that and a slack tank
is insignificant (for a nearly straight sided tank) and, as Rich points
out, more fuel volume for the same air/fuel contact area means more water
absorbtion.

I don't understand. If the tank if full, it's full. If you're using the
engine, you're using the engine, and when you get back and top it off with a
couple of gallons, it's full again, and whatever bacteria is alive for that
brief period when it's not full will quickly die and drop to the bottom. I
also don't understand the "absorption" issue with diesel. The diesel and
water don't mix, so whatever there is would be minimal to say the least and
it certainly won't hold bacteria.


--
"j" ganz @@
www.sailnow.com

"The diesel and water don't mix"
NOT so.

Water to a small amount dissolves in diesel
Diesel to a small amount dissolves in water
Emulsions are formed between the two phases of oil and water ... and
disperse throughout the oil

Only FREE water doesnt mix with water as it has gravimetrically
settled out of the oil due to gravity.


THREE phases of water in oil: Free water, dissolved water, emulsified
water.

This whole subject could be easily put to bed by calling your local
fuel polisher and asking the age of boats that need polishing.
I think you'll find all the 70's and 80's need cleaning and the 90's
will need cleaning in the next few years. Anything newer and there is no
problem. Meaning that if your system is clean, it's probably good for 20
years. At least, that's the way it is in the Puget Sound area. I suppose
warmer, more humid areas could be worse.
That said, I run dual Racors mainly because they were freebies and my
neighbor polished my fuel when I installed the Racors.

Gordon

"RichH" wrote in message
...
"The diesel and water don't mix"
NOT so.

Water to a small amount dissolves in diesel
Diesel to a small amount dissolves in water
Emulsions are formed between the two phases of oil and water ... and
disperse throughout the oil

Only FREE water doesnt mix with water as it has gravimetrically
settled out of the oil due to gravity.


THREE phases of water in oil: Free water, dissolved water, emulsified
water.


Some amount of my skin molecules become part of my computer keyboard and vis
versa. This is meaningless in the scheme of things for both me, my keyboard,
and for diesel/water in a tank. If it wasn't meaningless, the engine would
quit or wouldn't run to begin with. This doesn't happen unless the fuel is
contaminated (and the amount of water you describe clearly isn't enough in
most situations), the engine can't get enough air, or the fuel filter/line
is clogged. If you want to further limit the emulsification, then limit the
sloshing, which is exactly what a full or near full tank will do.

I stand by my original statement for real-world, sailboat applications.

--
"j" ganz @@
www.sailnow.com