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[PSUBS-MAILIST] PSUB Fatalities...View Ports...Shatterproof
Richard, I got your e-mail (below) and I thank you for responding, but for a
design pressure of 60 ft, 1/2 inch to 3/4 inch polycarbonate is way over
design. I also realize that "round symmetry" works best with pressure, but
actually spherical symmetry works even better than that. The canopy that I'm
designing is round, but in some places, it's actually more spherical than it
is round. Canopies are typically round anyway, aren't they? what type of
canopy did you imagine I was going to build? As far as reading books on
plastics, I think I've read a few. I've also designed lots of products and
injection molds, blow molds, transfer molds etc., for PE,PVC,PP,PS,PMMA,
PA,PEEK,ABS, to name a few. I haven't read the code that you are refering
to, but I certainly will. Thanks. WOW, you actually tested your view ports
to 3280 ft? Lab hydro no doubt. And yes, maybe if I were taking my sub down
beyond 1000ft, I may consider PMMA, but around reefs and other protrusions,
UV stabalized, scratch resistant polycarbonate can't be beat, especially
1/2" to 3/4"!
Again, good discussion on this. I would welcome any valid information to the
contrary that in low depth, low pressure situations, polycarbonate is not
the plastic of choice. Finally, I intend on testing my canopy to several
hundred feet. I'm more concerned with the sealing surface though, than I am
with the strength and properties of the PC.
Suds
You wrote:
Paul,
Paul, you need to read some books on the subject and this will turn the
lights on as far as viewport design and fabrication go.
Also you might want to read the archives back about a year and read what
Gary Boucher had to say about viewports.
Also look up the ASME PVHO-1 code there is also quite a bit about viewports
in there.
The canopy concept is not a structurally sound one for a one-atmosphere
manned submersible, round symmetry works best with pressure.
The material you should work with is acrylic, nothing else is safe according
to code.
The only way to test viewports is under hydrostatic pressure, nothing else
will do. I tested a few of my viewports a while back and had good results
down to 3280'.
Richard Hess
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