O2 reg suggestions

[normblitch]

I'm starting to make up a EAN100 pony for deco...

Looking for suggestions for a first stage that is:

Easily made 100% O2 safe,

Compatible with the low-performance DR 2nd stage, and

Often seen available used and reasonable...

(20' max depth use)

Thanks!
Norm

[Tegg]

Apeks DS4

[ARY]

Easily made 100% O2 safe,
Compatible with the low-performance DR 2nd stage, and

Norm, i use Oceanic CDX very simple yet small size first stage with DR second stage and pressure gauge type HPP plug. 02 cleaning for CDX was not a problem. Make sure you have LP hose long enough to route comfortably around your neck. I think i paid $80 for new CDX and $35 for gauge-plug.

I hope you are diving this weekend!


ARY having flu.

[Mike B.]

Look for a sherwood someone has laying around. Easy to work on,bulletproof performance, and cheap.

[John L.]

Any piston first stage would be easy to put into O2 service. Scubapro MK4, tusa, sherwood. Usually the entry level ones.

[crazyduck]

As a side note- US Divers is putting a “heat shield” in the 1st stage to stop with the heating processes of the first stage while using oxygen. I was recently advised that Air-liquide (SP) requires all US Divers/Aqualung products to pass the same testing process as their gas systems. I have not actually seen anything in print but if it is true then we have another barrier between the diver and the heating process and possible burning of oxygen.
When you look into the 1st stage on the legend you should see the metal plate with a series of holes that is the "heat shield."

Outside of that I agree that any simple piston 1st stage will probably work. Please keep the unit specifically for the O2 tank, and you need to clean the unit regularly and store in a clean enviroment. Hydrocarbon and debrie build up can lead to an ignition source. Also you would benefit from a DIN fitting over a yoke fitting.

Andrew

[normblitch]

Any piston first stage would be easy to put into O2 service. Scubapro MK4, tusa, sherwood. Usually the entry level ones.

(And Thanks to all for the ideas!)

The opinions amd PM's have generally split 50/50 between specific high-end products and general-use pisto 1st stagess...The "general-use pistons" crowd usually adds the caveat that O-rings "age" RAPIDLY with 100% mix...does this mean 6-months rebuilds with Moderate use?

Norm

[Genesis]

Depends.

If you use EPR (EPDM) O-rings, and you should, there should be no issues with regular service intervals. There can be issues with things like diaphrams though, as I've yet to see anyone be real clear about exactly what kind of material they're made of and how their lifetime is impacted by pure O2.

One thing that IS important is to dedicate the reg to pure O2. If you NEVER boost into your 100% tank, filling ONLY by transfilling from an O2 supply cylinder, there is never any contamination source that goes into the tank, valve - or your reg. This radically reduces the risk of an "event".

If you DO boost, then you have raised the bar considerably, because now there's a booster there that can cause contamination or "shed" particles that can become trouble. If you don't own the booster, then you've just added an unknown as you have no way to know when it was last torn down and overhauled or what kind of internal condition it is in. If you exchange the reg onto other tanks, ditto - as soon as you jack it on a tank that contains anything other than pure, gas-supplier-provided O2, you are introducing contamination. Even with a hyperfilter on the gas supply (which should be used IMHO on ALL breathing gas systems - and I'm well aware it often is not!) very small amounts of contamination do get through, and their impact is cumulative.

My personal protocol is that my O2 reg ONLY goes on my O2 bottle, and when not on that bottle is capped with a sealing delrin DIN cover. The O2 bottles themselves are dedicated to this service and never see anything other than a transfill off an O2 supply cylinder. I trust my gas supplier not to sell me a contaminated O2 tank, because odds are that if they did it would blow up in their facility - before I got my hands on it. This is easy for me to do, because I mix my own gas - this level of control is a LOT tougher if you BUY gas from a shop, because you have no control over the transfill whip used or how its handled (did the guy who used it last get finger oils on the DIN filler O-ring?) and, if they boost anywhere along the line (even from their supply to a storage tank) then the cleanliness issue is off the table.

If you can't maintain this level of control then I'd be tearing that reg, tank and valve down every six months and giving the valve and reg a good O2 cleaning in the Ultrasonic, plus giving the tank a good wash-out with Blue Gold.

I also like first stage regs for this purpose with nice, short, straight gas-paths internally with no convoluted places for gas to impinge on and cause adiabatic heating. IMHO simpler is better, and there's no point in a balanced design, since you can't breathe the O2 below 20' anyway. All the balanced design does is add twists and turns, along with nooks and crannies, to the gas path.

And, of course, always crack valves and fill O2 tanks S.L.O.W.L.Y.

There is no guarantee when it comes to O2 incidents. Be aware that despite the claims of "O2 compatability" nearly all seats used in regs today will indeed "poof" if enough heat is present at a high enough FO2, and so will Viton and EPR O-rings - despite their "O2 compatable" claims. For that matter, Christolube will decompose if it gets hot enough according to its MSDS, and what it decomposes into is really unhealthy to breathe. Adiabatic heating on a localized basis can be quite extreme if you slam 3,000 psi gas into a closed HP orifice or sharp corner.

An awful lot of avoiding incidents come down to not doing that. No heat, no fire.

[DeWayne]

I have yet to have any problems with viton lasting a year or better between service. The key is as Karl mentioned above, dedicate your system and keep it well maintained and clean. I would venture to guess that most of the problems reported have more to do with high pressure O2 and resultant cross contamination. I have yet to see a need to bring deco O2 above 2400 psi and my DR 1200 is still supplying it with no problems.

[curtschu]

Question, What is the biological advantage to using 100% o2 Vs. a lower Ppercentage? I am assuming this is a deco gas. I remember discusing these aspects at lenth several years ago and the concensus then was that anything more than 50% O2 was enough for final deco. I have been out of the loop for some time and I'm just entering back into the Tech diving realm. Has something changed?