[PSUBS-MAILIST] First Stage Regulator for O2 service Questions

[Alec Smyth via Personal_Submersibles]

Hi Alan,

Just to clarify, I was referring to HP Oxygen. For air I do bring HP into
the hull and there is a 1st stage inside for the BIBS.

Thanks,
Alec

On Mon, Dec 25, 2017 at 3:28 PM, Alan via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Steve,
> another factor that may influence your decision is how you want to
> set up a BIBS. If you have a divers regulator for emergency breathing they
> normally operate off 130 psi. Hmmm got me thinking now; if the emergency
> regulator is operating off a line directly from the  1st stage regulator
> external
> to the hull then it will see 130 psi above ambient. So at your max depth
> it will
> see 255 psi.
> Conversely if you had a high pressure line to your sub & a regulator
>  dropping
> the pressure to 130psi, then if you needed to flood your sub to get out
> the
> regulator would only see 5 psi above ambient by the time the sub filled,
> if you
> were escaping from 250ft.
> Alan
>
> Sent from my iPad
>
> On 26/12/2017, at 8:56 AM, Alec Smyth via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Hi Steve,
>
> I use a 1st stage outside the hull. As you say the flow regulator can
> handle the tank pressure, so it is not strictly necessary, but I do so as
> an extra safety precaution to avoid bringing high pressure O2 inside. If
> doing it again I would the reg directly on the tank, so that way all of the
> tubing would see only low pressure.
>
> I'm using a 1st stage that is incredibly inexpensive ($60), but I'm
> delighted with the quality and what is a big plus for me, it's a
> particularly simple design. I've collected three of them by now, and not
> any problem at all.
>
> https://www.piranhadivemfg.com/item/Balance-Piston-Din-
> First-Stage--For-Pony--Stage-Bottles--Nitrox-Ready-11738
>
> I do my own oxygen cleaning on tubing and penetrators, but prefer to buy
> O2-clean regs and valves. You may notice this reg is advertised for Nitrox,
> not pure oxygen. I spoke to the owner of the business selling it, and he
> told me the cleaning and materials are identical for partial or full O2,
> but that they advertise it only for partial O2 use as a legal CYA.
>
>
> Best,
> Alec
>
> On Mon, Dec 25, 2017 at 12:50 PM, Steve McQueen via Personal_Submersibles
> <personal_submersibles at psubs.org> wrote:
>
>> All, I am purchasing the system components for my K-250’s O2 system.  I
>> am not a SCUBA diver so I lack some experience with regulators. I am
>> considering sealed/balanced options for the first stage regulator (it will
>> create an intermediate pressure downstream of the O2 tank (located external
>> of the hull). These get pricey and I don’t really want to overspend for
>> options I do not need (sealed vs. not, balanced vs. unbalanced, O2 ready
>> vs. needing cleaned).
>>
>>
>>
>> A couple of questions:
>>
>>    1. They sell regulators that are already suitable for 100% O2 use.
>>    How difficult to clean one that is not O2 ready?
>>    2. The pediatric flow regulator (located in the hull) can directly
>>    handle the O2 tank pressure so I am wondering why we use the first stage
>>    regulators at all.
>>       1. I assume to remove as many HP leak sources from within the hull
>>       especially since it is 100% O2 (safety).
>>
>>
>>
>> Thoughts/recommendations?
>>
>>
>>
>> Steve
>>
>>
>>
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>>
>>
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