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Brian,
To test all you need to do is make up a through port simulation and screw
it to the end of a garden hose to see what it will do at about a hundred feet,
depending on your domestic water pressure.
Holding the plug in the hole at 10,000 feet would be difficult but not the
most difficult part. That would be getting it in without tearing your skin
off with the water stream.
Dan H.
----- Original Message -----
Sent: Tuesday, January 06, 2009 11:11
AM
Subject: RE: [PSUBS-MAILIST] Soft ballast
venting valve
Dan,
It would be interesting to do a test ( on dry land ) with a O ring missing and
see what kind of spray one would get through that .050 gap at various
pressures. It would be easy enough to simulate. Didn't the Germans
have small wedges of wood to plug holes in case of emergency
?
" At a depth of 10,000 ft the bore of
a 1/4"tube bulkhead fitting would need a plug load of less than 125 lbs to
keep seawater out" ( from Man Beneath the Sea, Penzias and
Goodman) ............food for thought.
Brian
Brian,
I agree with Jim on the clearance, and you'd be surprised how much
water can squirt through only .050 inch clearance. Don't forget, in a
P-sub you don't have many pounds of wiggle room for being to heavy to get
back to the surface and even less wiggle room to get unseated, turned around
and contorted into position to deal with a water leak.
Once I was submerging in the passenger position with someone else in
the pilots seat of my sub. I was instructing the guy through a
dive. He secured the hatch dogs when I told him, but barely
tightened them. When the hatch seal submerged a thin spray of water
wafted down on both of us. It happened so fast, even with the
hatch in less then a foot of water, that neither of us could react until we
were pretty wet. I grabbed for the MBT blow valves and brought us back
up really quick. We only took on about a quart of water plus what
was dripping from our pants. Some of those drips had a
yellowish tint, I might add.
Immediately after the incident I realized if we submerged any deeper
the pressure on the hatch cover would have sealed the leak, but there was no
time to think that through with water spraying in.
Dan H.
----- Original Message -----
Sent: Tuesday, January 06, 2009 7:32
AM
Subject: Re: [PSUBS-MAILIST] Soft
ballast venting valve
Hi Brian,
I agree with your concept about shaft/ fitting and thats my reason
for being very comfortable with it while Frank is not.
I have to take exception to your clearance. Mayby it's a typo, but 50
thousanths is WAY to loose for ANY O ring seal in mu opinion and extrusion
is expected.
I will hace about 5 -10 thousandths. I do this by boring the sleeve
slightly undersized then welding the sleeve in place. After welding ream
to size with a propersized reamer.
I wish I could get tighter, but doing the reaming freehand that's the
best result I can get.
I am also using a Block V seal which I feel is better than an
oring.
The idea ame from Gary Sluis.
Best Regards,
Jim K
----- Original Message -----
Sent: Tuesday, January 06, 2009
12:53 AM
Subject: RE: [PSUBS-MAILIST] Soft
ballast venting valve
Hi Frank,
When you figure the diameter of the
shaft and the diameter of the shaft fitting, that the shaft goes into,
there is only a difference of like 50 thousandths of an inch. Even
if you forgot to put the O ring in that fitting, it's not like going to
be Niagra falls coming into your boat. You could probably put some
bubble gum on it and the leak would stop. You would be
able to address a problem like that as soon as it
occured. The hydrolics would add too much of an extra thing for me
to deal with. I wonder if there is a way to smooth out those
cast fittings so they could be polished? I will probably put
a T into my ballast vent valve inbetween the valve and the ferro body
for HP air. It would be nice to have a LP air generator for
"topping off" the ballast air so as to float yourself higher
on the surface. I seem to remember the Tang would do that to try
and get maximum speed on the surface, they would run the
compressors into the ballast and the exess air coming out the bottom of
the ballast would cut down on the friction against the water.
giving them an extra knot per hour speed.
Brian
Hi Brian. That makes good sense. Save a few bucks and go with
what works. As for matching up the two materials, There's always going
to be the corrosion factor to deal with. Zinc sacrificial anodes will
help but not eliminate the problem. On the plus side, bronze and
stainless won't "gall" when screwed together. I'm using a lot of brass
bolts mated to stainless lock nuts. Although replacement of the brass
will be needed sooner than stainless bolts would, at least I know I'll
be able to get them apart without a big hassle. Some places I'll be
using stainless bolts and brass nuts, because I need the extra shear
strength of the stainless, but again, it comes apart easily after a
long time in salt water.
I too am going with the bronze valves. They
are pressure rated to 600 psi, are cheap to replace, and when polished
they look really good. Very "Capt. Nemo" like. Also, the highly
polished surface corrodes much slower than the regular cast surface.
I've got quite a few of the interior valves, unions, elbows, nipples,
and related bushings and adaptors and when polished, they look really
good. The HP air will be like yours, Swagelock and stainless
tube.
I haven't cut in any through-hulls yet, but
those will all be stainless nipples. Then a bronze ball valve on each
one where it enters the sub. Complete shut-off at every penetration if
a problem develops. Even the electrical through-hulls will be valved
off. I want to get all the components mounted before I start cutting
in the nipples. The largest is 2 inch, while the smallest is 3/8 inch.
The main ballast will all be 1 inch. Maybe a little slow to submerge
but I don't expect that to be a problem.
You said you're using rod linkage to
operate your valves? Wouldn't a small hydraulic cylinder work just as
well?
When the weather gets a little better,
I'll cruise down on my bike for a visit and a cold beer. Frank
D.
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