[PSUBS-MAILIST] valve ID

[Sean T. Stevenson via Personal_Submersibles]

The CGA-870 pin-indexed yoke connection (medical oxygen) is a yoke style connection, where the reg has a yoke screw on the back side of the post which tightens it against the O-ring / gasket. This is similar to the CGA-850 SCUBA connection that many of you will be familiar with.  While these yoke type connections are quick to connect and disconnect, IMO they are less than ideal for any sort of permanent installation. I long ago migrated away from CGA-850 in SCUBA because of the decreased entrapment potential and the greater security and pressure capability of the 300 bar DIN 477 connection. For submarines, consider the application. If you are buying industrial oxygen or breathing air supplied in cylinders, (or wish to retain the capability to use such cylinders) it makes sense to employ the CGA 540 (industrial oxygen) or  CGA 346 connections (industrial breathing air) to mate to them as supplied. Certainly, you need to use standard valve connections on any cylinder which you intend
to have refilled elsewhere. Conversely, for cylinders which are part of a permanent installation on a submarine, such as outboard oxygen, breathing mixtures or ballast air cylinders, I would question whether cylinder valves are necessary at all, provided you have a means of charging them. I might be inclined to replace a cylinder valve with an adapter to convert the NPS thread in the cylinder neck to e.g. 1/4 NPTF and plumb that into the hull or a general purpose regulator directly, provided of course that you employ the appropriate shutoff valves where necessary. If you only employ as many oddball fittings and connectors as it takes to convert to something standard and common, you reduce your inventory of spare parts and increase interchangeability.

Note also that you can buy all manners of CGA gas connections to mate with standard cylinder valves which have NPT(M/F) on the other side. This allows you to manifold a bunch of cylinders together and plumb them to any general purpose regulator.

Sean



On January 10, 2017 6:39:26 PM MST, Private via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>Hi Hank,
>
>The kind Sean is referring to is recognizable by two little metal pegs
>in the regulator yoke, and it seals with a rubberized flat washer.
>Well, although that's the standard one I have to say I've found it to
>be the least reliable seal ever devised. May I suggest a reg with a
>CGA-540 instead? You can get pediatric regulators with those on eBay
>(new) for about $20, and adapters from CGA-540 to NPT are readily
>available.
>
>Best,
>
>Alec
>
>> On Jan 10, 2017, at 7:58 PM, Sean T. Stevenson via
>Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> 
>> Standard medical oxygen is CGA-870.
>> 
>> Sean
>> 
>> 
>>> On January 10, 2017 3:42:28 PM MST, hank pronk via
>Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>> Hi all,
>>> I lost a valve that goes in Elementary 3000 and I need to replace
>it.  The valve is an oxygen shut off valve that a paediatric regulator
>fits on.  I can steal one off a medical oxygen tank but I built the sub
>to take a valve with 1\4 pipe male fitting.  I can't find one because I
>don't know what it is called?
>>> Hank
>>> 
>>> Personal_Submersibles mailing list
>>> Personal_Submersibles at psubs.org
>>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
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