Jim I have a 1/4 inch line about 18 inches in length. It then goes into
a
half inch ball valve. I have not pulled
any measured, amount just enough to
move my barometer and check for leaks.
My pontoon is on hold yet. I had to
have my shoulder rebuilt, still have a
few months of healing to do.
yes some of texas gets cold, you
should come up to Minnesota, it has
been abnormally warm here. Have
only hit -28 this year and even above
zero most days hehhehe
Dean
In a message dated 1/11/2011 9:21:17 A.M. Central Standard Time,
JimToddPsub@aol.com writes:
Good morning, Dean,
Aha! Last week I thought about the holding capacity
of the line, then dismissed it as being too small. However at that
pressure it's holding about 8.5 times its volume at 1 ATM. What's the
approximate length and diameter of your line? I haven't yet run any
calculations to see how much air I would have to pump out to achieve 1" or
2" of pressure drop and consequently how long I'd have to run the
pump. I'm sure I'll be asking more questions as the design gets into
more detail.
Anything new on your pontoon support
vessel?
I'm about to head for Texas for a few days and won't be
online much. It's cold even there right now.
Best regards,
Jim T
In a message dated 1/11/2011 8:11:19 A.M. Central Standard Time,
Recon1st@aol.com writes:
Jim sorry been gone for a while.
You are correct not very clear.
The volume of air that is removed is
only in the line between the pump and
the ball valve to the exterior. This small
volume seems to work well for a controlled amount of vacuum. I
turn the pump on and pump to 125 psi or so
shut the pump off and then open the
ball valve.
Dean
In a message dated 1/6/2011 9:22:53 A.M. Central Standard Time,
JimToddPsub@aol.com writes:
Hi Dean,
Copied below is the part I didn't understand. If
you pump [it] up to 150 psi, that seemed to imply a tank. What is
holding the 150 psi if not a tank? It could be a very small one
integrated in the pump housing.
The pump could only over-pressure the cabin at depth
if it were drawing air from some source other than the air within the
cabin. Drawing air in one end of the pump and out the other would
not create any additional pressure within the cabin.
In order to overpressure at depth (to lessen the
pressure differential at a given depth) you have to introduce more air
(more molecules) into the cabin or heat the same amount of
air.
Best regards,
Jim
In a message dated 1/5/2011 10:56:04 A.M. Central Standard Time,
Recon1st@aol.com writes:
I pump it up to a
150 psi or so turn it off and then open
a ball valve to the exterior. The pump
will go up to 250 psi so I could actually
do a little overpressure condition at depth if needed.