[PSUBS-MAILIST] O2

Thu Jan 30 13:27:09 EST 2020

Brian. The through hull is steel. But that can be changed with a bit of effort.  My bigger problem is the tank location and it’s difficulty in swapping it out. I could leave a big tank in place permanently as a emergency supply and use a small tank inside for day use. If I do that why not just have all the O2 inside. Also remember that at 3000 feet I have to leave 1300 psi in just to protect the tank. 
I am perfectly comfortable with the supply being inside. Like Jon says the K boats are all like that originally. 
Hank
Sent from my iPhone

> On Jan 30, 2020, at 10:19 AM, Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> 
> Hank ,  What exactly is the issue of not going with external O2 tank?   Is it that the thru hull is not bronze ?  
> 
> Brian
> 
> 
> 
> --- personal_submersibles at psubs.org wrote:
> 
> From: hank pronk via Personal_Submersibles <personal_submersibles at psubs.org>
> To: "Sean T. Stevenson via Personal_Submersibles" <personal_submersibles at psubs.org>
> Subject: Re: [PSUBS-MAILIST] O2
> Date: Thu, 30 Jan 2020 13:44:03 +0000 (UTC)
> 
> Sean thanks.  As always I keep it simple and cost effective, so I will have small O2 tanks with no manifold.  I will just swap them out as needed.  The beauty of small tanks is you only end up filling one or two per trip.  
> Hank
> 
> On Thursday, January 30, 2020, 6:31:16 AM MST, 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
> 
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