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.