[PSUBS-MAILIST] O2

[Alec Smyth via Personal_Submersibles]

Hank,

In addition to the 1 atm rule Sean mentioned, there is a second
requirement. The uncontrolled release of the contents of one tank of O2
should not raise the cabin O2 content above 23 percent. This second
condition I suspect you will find more onerous than the first.

Best,
Alec



On Thu, Jan 30, 2020 at 8:31 AM Sean T. Stevenson via Personal_Submersibles
<personal_submersibles at psubs.org> wrote:

> Plumbing all of your oxygen cylinders into a manifold using check valves
> should suffice. The idea being that any single failure should not empty the
> entire bank, and the individual cylinders need to be small enough to keep
> the total pressure increase below 1 atm if you do happen to lose one.
>
> Examine your entire plumbing system, identifying every connection and the
> consequences of it failing. Either the consequences need to be acceptable,
> or you have to have a response plan for that failure.
>
> As far as corrosion protection for through hull fittings, if you
> overlooked something in design, plating or cladding with corrosion
> resistant materials can be an option. At work, I have some vessels that I
> designed in A105 steel (similar to A516 gr 70, but forgings), that I am
> sending out to have the fluid exposed surfaces clad with Inconel 625 for
> corrosion resistance. Of course, I'm dealing with much worse stuff than
> seawater: hydrogen sulphide-saturated acidified high salt brines at
> elevated temperature. Still, it's always worth a look at costs of such
> processes versus the lifetime cost of maintenance. I was expecting the cost
> of cladding to be far higher than the quote I received. On the other side
> of the coin, I have some parts in the same system with deep holes that
> can't possibly be clad or painted, so I had to have them machined out of
> Hastelloy C276. One 8" end cap is worth more than my truck.
>
> Sean
>
> -------- Original Message --------
> On Jan. 30, 2020, 06:04, hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>
> Sean, okay that is where I missed the boat.  I know about the do not
> exceed 1 atm rule but did not realize it meant a single tank.  If I lost
> all my O2 it would be a problem.  I am using multiple tanks so all is good.
>   I do not have room to drill out the steel plus changing an O2 tank would
> really suck with this new body. Forget about a change if the sub is in the
> water.
> Hank
>
> On Thursday, January 30, 2020, 5:12:49 AM MST, Sean T. Stevenson via
> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>
> Nothing wrong with internal tanks as long as you can prove by calculation
> that the unintended release of the contents of any single cylinder
> (provided they are individually valved - hard plumbed manifolded cylinders
> where a single failure would empty them all would need to be considered
> together as one) will not raise the pressure of the occupied space by more
> than 1 atm.
>
> Through hull shouldn't be a big deal either. Drill larger if necessary,
> and use a stainless insert.
>
> Sean
> -------- Original Message --------
> On Jan. 30, 2020, 04:58, hank pronk via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>
> Hi All, here is an interior picture of Limiting Factor that shows what
> appears to be O2 tanks.  I thought it was not an approved practice to have
> that much compressed gas onboard.  My original design in E3000 was to have
> external O2 supply but I prefer internal.  I messed up in two ways.  First
> off I provided a steel penetrator opening for O2.  The other screw up is
> when I built the new body I completely neglected access to change out the
> tank.  So I am going with internal tanks unless someone can talk me out of
> it.
> Hank
> [image: Image result for deep sea limiting factor images]
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