[PSUBS-MAILIST] Scuba Tank DIN connector to JIC

Thu Oct 13 18:55:59 EDT 2016

Hi Mark,
Most SCUBA regulator first stages (the bit that goes onto a tank) will drop
the pressure to about 150PSI, and you could happily adjust most of them to
100PSI instead.

Bear in mind a regulator adds lots of different failure modes and if your
shutoff is after the regulator you may well lose all the gas in the
cylinder if there is a failure.  Probably doesn't matter in your
case!  This is also a reason regulators have an overpressure valve (OPV) -
in case they fail open and deliver full cylinder pressure into the low
pressure downstream line.  Quite important if you don't have a SCUBA second
stage (that bit that goes in your mouth) installed.

Also after the regulator there is no way of knowing what's left in the
cylinder.  A contents gauge is only useful on the high pressure side.

A useful resource for dealing with SCUBA regulators:
http://www.airspeedpress.com/newregbook.html

The cheapest SCUBA regulators are for argon and/or drysuit inflation.  Ie:
https://www.divegearexpress.com/inflation-regulator-w-opv
They are not adjustable (but generally set to lower pressure, more like
100-125PSI) and often have slightly less flow.  I don't think the
difference would be particularly significant for you.  They also tend to be
200bar DIN - so if you have a 300bar DIN valves they won't fit.

SCUBA regulators for breathing are more expensive, but have higher flows
and are meant to be more reliable, and adjustable.  You'd be looking for a
DIN "first stage" (they are pretty much all dual 200/300bar compatible) and
then you'll have to get a separate OPV. Ie:
https://www.divegearexpress.com/regulators-spgs

You'll also need one of these adaptors to turn the regulator outlet into
NPT: https://www.divegearexpress.com/adapter-1-4-inch-npt-female-3-8-inch-m

Cheers,
Steve

On Fri, Oct 14, 2016 at 12:55 AM, Mark via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Steve,
>
> Thanks for the clarification on the DIN connector.  In terms of the
> pressure regulator, what device do most people use to regulate the air
> pressure?  Is this something I could purchase from a SCUBA parts supply
> company?
>
> Regards,
>
> Mark Widman
> 910-638-5229
>
> Sent from iPhone.
>
> On Oct 13, 2016, at 9:17 AM, Sean T. Stevenson via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> 300 is short for 300 bar, or the recommended maximum pressure of the
> fitting, indicating that it is a deeper thread than 200/232 bar fittings.
> The latter can be used with yoke style regulators (CGA-850) by using an
> insert in the female DIN on the tank valve. The 300 bar connection, being
> deeper, precludes this but is stronger. Similarly, if you have a 300 bar
> DIN fitting on your regulator, and screw it into a 200 bar DIN tank valve,
> it is compatible, but will show a couple of exposed threads which can be
> entrapment points.
>
> DIN 477 is the actual thread specification.  Rarely seen in SCUBA
> equipment catalogs, but necessary if you're going to have a DIN thread
> machined.
>
> Sean
>
>
> On October 13, 2016 6:26:49 AM MDT, Mark via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>>
>> Thanks Steve,
>>
>> This is exactly what I'm looking for.
>> (1/4" m NPT x DIN 300 m)
>>
>> Sean recommended a DIN 477 connector, is there a difference (DIN 300 vs.
>> DIN 477)?
>>
>> Lastly, I would like to regulate the air pressure to something more
>> reasonable like 100 or so PSI.  Can you recommend an air pressure regulator?
>>
>> Regards,
>>
>> Mark Widman
>> 910-638-5229
>>
>> Sent from iPhone.
>>
>> On Oct 12, 2016, at 10:27 PM, Stephen Fordyce via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>> Hi Mark,
>> I have that sort of thing in my catalogue (TFM Engineering Australia),
>> but being down under, not a lot of point sending them to you in the USA
>> when you get can from the likes of:
>> http://www.northshorecompressor.com/products/17B477D22-M-NPT-x-
>> DIN-300-M.htmlhttp://www.northeastscubasupply.com/
>> search.php?search_query=DIN+NPT&Search=
>>
>> You might be able to do a bit better if you look around - but avoid the
>> ones with bleeders for your application in ca! se it gets knocked.
>>
>> Cheers
>> Steve
>>
>>
>> On Thu, Oct 13, 2016 at 6:44 AM, Mark via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>>> Hi Sean,
>>>
>>> I have four SCUBA tanks mounted on the outside of the sub.  The SCUBA
>>> tanks are used to provide/control air for the external ballast tanks.  The
>>> air line runs from the SCUBA tank to a thru hull fitting in the sub (to a
>>> control valve) and then back out to the ballast tanks.  I need to acquire a
>>> connector from the SCUBA DIN to either NPT or JIC.
>>>
>>> If I can order a DIN 477 to NPT that would suffice.
>>>
>>> Regards,
>>>
>>> Mark Widman
>>> 910-638-5229
>>>
>>> Sent from iPhone.
>>>
>>> On Oct 12, 2016, at 3:15 PM, Sean T. Stevenson via Personal_Submersibles
>>> <personal_submersibles at psubs.org> wrote:
>>>
>>> That's an oddball to find as a single piece, but you can certainly find
>>> male DIN 477 to e.g. NPT, and adapt that to a NPT/JIC.
>>>
>>> What are you building?
>>>
>>> Sean
>>>
>>>
>>> On October 12, 2016 12:49:50 PM MDT, Mark via Personal_Submersibles <
>>> personal_submersibles at psubs.org> wrote:
>>>>
>>>> Good afternoon, Psubs team:
>>>>
>>>> Do you know if and where I could purchase a SCUBA tank DIN to JIC connector?
>>>>
>>>> Regards,
>>>>
>>>> Mark...
>>>> 910-638-5229
>>>>
>>>> Sent from iPhone.
>>>>
>>>> ------------------------------
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