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

[roberto alvarez via Personal_Submersibles]

Why are using puere oxigen, i  practice scuba diving and we use compresed
air, can use mix with 40% , but why puer oxigen on the sub?

2017-12-25 22:08 GMT+01:00 Alec Smyth via Personal_Submersibles <
personal_submersibles at psubs.org>:

> 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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