Nitrox Compatibility

[darylm74]

I pieced together a brand new Apeks DS4 1st stage with a US Divers SEA4 second stage primary (bought used but in prime condition, hardly a scratch) and a US Divers Cousteau safe second (new, still in box but was made in 1989). I am planning on using this set up for my Nitrox class. I know the DS4 is safe up to 40%, however I'm wondering about my 2nd stages. I didn't know how much the 2nd stages were involved with respect to Nitrox safety vs. the 1st stage. Would this set-up be ok or do I need to look for other pieces?

 

[DA Aquamaster]

There are the o-rings on each end of the hose, the o-ring on the inlet fitting, the o-ring on the orifice and the seat that are all potentially exposed to O2 at intermediate pressure. But even at that, the second stages should not be a problem if you stay at or below 40% nitrox as the big O2 issues are in the first stage. To be safe though I would have them properly cleaned and serviced with current o-rings and lubricants (christolube).

 

[Otter]

I'd have it looked at even if you were just diving air. The safe second's o-rings have been exposed to air for 15 years, who knows what condition they are in. While the externals of the other 2nd stage seem ok, I'd still want to look at the innards. A good servicing, adjusting the intermediate pressure, with oxygen compatible lube and o-rings should alleviate ALL of your concerns.

 

[darylm74]

Thanks, I was planning on having the 2nd stages cleaned and serviced anyway, just was wondering about the Nitrox compatibility. They are going in to my LDS this week so all should be good. Thanks again guys.

 

[rescuediver009]

As long as you are using the right lubricant you don't have to worry about anything below 40%. And even then it is mostly in the HP areas that you have to be 'clean'. The DS4 as mentioned is clean to 40

 

[MikeC]

Am I nuts, DON'T answer that!!! I seem to remember a warning from AquaLung/ US Divers back around '94-'95 advising NOT to use their gear with NITROX??? I do not remember if it was the shop I was dealing with or the ANDI instructor who had the info. (the shop is long closed and I forget the instructor.)

Any old farts with good memories around???

Something about not making o2 do more than 90 degrees in curves or bends thru the valve and first stage.

 

[DA Aquamaster]

The potential exists for fast moving O2 to encounter hot spots (whihc are potential ignition sources) in tight bends. But this is mostly just an issue when the reg is first pressurized. Turning the valve on slowly with the purge button depressed on the second stage is good practice with nitrox or O2 regardless of what reg you are using.

Nitrox was dissavowed by both training agencies and equipment manufacturers until they realized they could make a lot of money off it. And then to really cash in on Nitrox, equipment manufacturers claimed the need for dedicated nitrox regs for as long as they possibly could before admitting most regs worked just fine with proper cleaning with mixes up to 40%.

So I don't doubt that a US Divers dealer was saying in the mid-90s' that a US Divers reg should not be used with Nitrox.

 

[rescuediver009]

Am I nuts, DON'T answer that!!! I seem to remember a warning from AquaLung/ US Divers back around '94-'95 advising NOT to use their gear with NITROX??? I do not remember if it was the shop I was dealing with or the ANDI instructor who had the info. (the shop is long closed and I forget the instructor.)

Any old farts with good memories around???

Something about not making o2 do more than 90 degrees in curves or bends thru the valve and first stage.

No man, old wives tail. Keep it going slow and cool thats all.
you can blend mixes with 3 easy steps..
1. slow
2. slow
3. slower