[PSUBS-MAILIST] Scuba Tank DIN connector to JIC

Thu Oct 13 19:53:37 EDT 2016

Mark,
sorry if I am insulting your intelligence here, but if you have a 
standard regulator inside the hull reducing the pressure to 100
psi then you won't be able to blow your ballast tanks below 50ft.
As Steve suggests, a scuba first stage regulator will give you
130 psi above the ambient water pressure, enabling you to put
air in your ballast tanks at any depth.
Just mentioning this because this mistake has been made before.
Cheers Alan

Sent from my iPad

> On 14/10/2016, at 11:55 am, Stephen Fordyce via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> 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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