Posted by seychellois_lib (mcunningham@…>)
Fargo,
You must be the one who’s experience I used when I modified the top of
the settee seat plywood so I could easily remove a center section to
observe tank fill status. My tank configuration is exactly as you have
described yours. There is no way I should be having the type of tank
expansion I am experiencing: enough to damage the surrounding structure.
Posted by seychellois_lib (mcunningham@…>)
Skip,
No offense taken at all, I’m open to any ideas. However I am able to
blow air back into the tank with some effort and I am able to suck
water back through the hose, again with some effort. I am not able to
establish a siphon flow just able to get some water to dribble out so
it appears a physical connection to the tank exists. I am going to
remove the electrical panel and see if there is any kinking in the top
of the loop. Perhaps the pressure is building in the tank more quickly
than the kinked tube can release it.
Posted by katorpus (jrb@…>)
I don’t want to get into a pissing match on the Freedom board…but
you guys are completely WRONG about the tank pressure from the water
standing in the vented loop and/or the inlet line.
You have confused hydrostatic pressure of a fluid at rest (what this
is) with hydrokinetic pressure (which occurs in a closed system when
force is applied, pressure is increased, and fluid movement results)
There is NO pressurization beyond the weight of the water in an open
system. In order for a pound of water to generate more than a pound
of pressure over the entire area on which its weight is being borne
(or contained), you’d have to either expend or create energy to
provide pressure. The water would have to be “driven” by some force
(other than gravity) which would expend energy…the gravitational
force is what creates the “weight”.
If you could figure out how to create more energy from the simple
weight of water than the energy it takes to elevate that water to a
point at which it would produce energy by gravitational fall, then
you’d be the master of the universe.
Fargo’s “formula” ascribes no difference to the pressure produced by
a column of water 3/4" across and one that’s 340 miles across…if
the heights are the same. This is simply wrong…and the difference
is the weight of the entire water column.
The water in the “top half” (or any other arbitrary portion) of a
(full) open topped tank of consistent dimension constitutes
the “water column” that is increasing the pressure at the bottom of
the tank. The taller the tank, the higher the pressure at the
bottom…due SOLELY to the weight of the water “in column”.
The pressure at the bottom is the same no matter what the altitude of
the tank bottom is…save for the difference in the weight of the
atmosphere at varying altitudes. The relationship between pressure
and tank height is entirely linear, and it’s all due to the weight of
the water. It doesn’t work the same if weight of the water column is
less than the tank diameter, again due to weight.
It IS about “pressure”, but one pound of water produces a TOTAL of
one pound of pressure, and you have to KNOW how may square inches are
being “pressured” in order to determine how many pounds PER square
inch of pressure are being produced by that pound of water…that
holds for liquids OR solids.
The analogy of “one foot under the ocean” is incorrect. If the ocean
were a “closed system” it would be correct, but it isn’t. In
an “open” system, the pressure increases as the depth increases. In a
pressurized closed system, which is NOT static…the system pressure
is relatively constant throughout…until something gives way,
whether it be the ram moving (as designed) or the failure of some
component in the closed system.
You’re probably on the right track with your “restricted overflow”
concept…if the “open part” of your system (inlet hose to inlet
fill) is somehow “sealed”, in which case you will be pressurizing the
tank to the extent of the water pressure that’s driving the water
through the hose minus the outflow pressure (however small) through
the vent line (ignoring friction).
If you slow down the inlet flow rate to be no more than whatever the
vent line can handle, you’ll eventually fill the boat (save for the
bilge pump), but you’ll never “fill up” the inlet line, since the
vented loop is lower. The reason for that is that the weight of the
water column in the inlet line (above the level of the vent loop) is
greater than that in the vent loop, and it displaces that water in
seeking equilibrium. When you’re done filling and overflowing, the
water in the inlet pipe will be at the same level as the vent loop.
You could “test” your outlet flow line by filling the tank to the
point at which you get overflow and then continuing to fill while
measuring the outflow into a container over a defined period of time,
then duplicating the same test with a known-good piece of hose
(either attached to the vent line port on the tank or another
container). You would have to measure the quantity of water going IN
during both tests, or make certain that the flow rate and time at
which it’s flowing in is constant over both tests (which would be the
same thing, but harder to accomplish).
You aren’t getting a siphon flow back through your vent line because
that’s the way it’s designed. The “pickup point” of the water flowing
into the vent line is at or very near the high point of the tank…to
PREVENT siphoning…once the air reaches that point (after you’ve
evacuated the vent hose), the siphon is broken. A full tank might
lose some water to the bilge upon heeling the boat, but anything that
permitted a siphon to begin would empty the tank down to the point of
the pickup tube once that started…and you sure don’t want that.
— In FreedomOwnersGroup@yahoogroups.com, “seychellois_lib”
<mcunningham@…> wrote:
Skip,
No offense taken at all, I’m open to any ideas. However I am able to
blow air back into the tank with some effort and I am able to suck
water back through the hose, again with some effort. I am not able
to
establish a siphon flow just able to get some water to dribble out
so
it appears a physical connection to the tank exists. I am going to
remove the electrical panel and see if there is any kinking in the
top
of the loop. Perhaps the pressure is building in the tank more
quickly
than the kinked tube can release it.