[PSUBS-MAILIST] Commercial Grade O2 vs. Medical

[Sean T. Stevenson via Personal_Submersibles]

Spherical pressure hulls approximate pure compression, so using the compressive yield strength is reasonable in that case. When only a single yield value is quoted for concrete, you can assume that it is the compressive value. With cylindrical hulls, the load case is more complicated - you have compressive loading in the circumferential and axial directions, but also interframe bending which could precipitate a crack on the interior mid-bay surface. At that point, it's up to the reinforcement design. A reasonable assumption is to design assuming that the steel must carry all tensional loads, but this is getting beyond me. My experience with composites is limited to fiber-reinforced matrix materials. I have no idea how to analyze a steel-reinforced concrete structure in this application. I would consult an engineer with specific experience in this area.

Sean

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-------- Original Message --------
On Jan 3, 2018, 12:10, hank pronk via Personal_Submersibles wrote:

> Hi Sean,
> I am just curious how you calculated the depth of a concrete sphere.  What did you use for yield strength?  It seems to me the compressive strength should be close to the yield strength?
> Just for interest sake Lafarge is producing High Performance concrete at 12,000 psi  after  12 hr cure, amazing.
> Hank
>
> On Wednesday, January 3, 2018, 12:04:32 PM MST, hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
> Steve,
> Here in Canada we can not keep our original tank, it is swapped out.  I fill  from a 122 cu ft tank into my small aluminum medical tanks.  I think Sean's suggestion of a charcoal filter on the scrubber is a good idea to maybe pick up a nasty.
> Hank
>
> On Wednesday, January 3, 2018, 11:10:41 AM MST, Steve McQueen via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
> I tried to search the archives but it wasn't very friendly.  Sorry to again ask about something I know has probably been discussed.
>
> I wanted to double ck. my O2 strategy.  After some investigation it seems I will buy a new steel high pressure oxygen tank for external mounting. My plan is to have it refilled with "commercial grade" O2 vs. medical grade 02.  As long as I keep my "personal" tank and not allow the filler to swap tanks I should create a "chain of custody" that will help me feel good about not having contamination.
>
> I am wondering how others are managing.
>
> Thanks,
> Steve
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