Breathing Nitrox through non-compatible reg?

[2Tours N Iraq`]

Thanks for all the posts, it alleviates my concerns for breathing <40% nitrox on my reg. Thank you for adding to my knowledge about this great sport.

 

[san diego diver]

i switch from 21% on my wednesday night shore dives to 32% on my weekend dives off my boat and have never had anything O2 cleaned. make sure that your LDS either blends the gas in a stick or ues a membrane. If they fill pure O2 and then add 21% then you need to clean your tank,and if they do they will insist that the tank be cleaned anywaay.

 

[Lead_carrier]

What you are more likely to run into is the shop that requires you to have your regulators "O2" cleaned and serviced. For no purpose other than to make themselves money.

 

[oxyhacker]

I think (but can't swear) that this is a myth, as regards the Conshelfs. In the early days of nitrox, Air Liquide (AL's parent company) did a lot of very thorough, and very aggressive testing, in which they tried to get regs and valves to combust, using nitrox with fast opening valves, etc, and surprisingly often succeeded. They concluded from this that most of their current regs and valves were not suitable for use with nitrox, and came out with several new dedicated nitrox regulators, and a every odd nitrox valve.

However, everyone else went on using the old stuff and didn't blow themselves up, and AL retreated - at least I can't recall seeing that nitrox valve lately!

There were old regs (Conshelf?) that weren't nitrox compatible but I don't think anyone makes regs anymore that aren't compatible up to 40%.

 

[divecon15]

There are 3 ways to make Nitrox
1) Partial pressure blending, Take and empty O2 CLEAN tank and put in X psi of oxygen then fill to end psi with hyper-clean air (air that has gone through a filter the removes hydrocarbons, which is what reacts with the pure O2)
2) Stick blending, O2 is blended in a special mixing stick which mixes the O2 with air BEFORE it goes into the compressor. Because the air and O2 are thoroughly mixed before th compressor there is no pure O2 under pressure to cause problems.
3) Membrane, NO O2 is added but rather Nitrogen in removed from regular air. Nitrogen molecules are larger than O2 and therefore can be removed thus increasing the pecentage of O2.

The only method that requires O2 clean tank is partial pressure.

As far as Regs most all of them are good to 40% right out of the box...

Brent

 

[colsonn]

My lds tells me that they clean their air differently (or better than most lds's, something with their filters, I don't remember), so I can switch from 21% to nitrox and back all I want, as long as I only use their air with my reg. that is O2 clean.

So either I found a great lds that is saving me money, or trying to kill me... I got a 50/50 chance, I'll take it...

 

[Damselfish]

My lds tells me that they clean their air differently (or better than most lds's, something with their filters, I don't remember), so I can switch from 21% to nitrox and back all I want, as long as I only use their air with my reg. that is O2 clean.

So either I found a great lds that is saving me money, or trying to kill me... I got a 50/50 chance, I'll take it...

They're probably producing O2 compatible air which is good as it wouldn't crud up a Nitrox cleaned reg or tank such that it can't be used with > 40% or for partial pressure blending. (Good chance they are doing O2 compatible air because they do PPB.) But if you're always using <40% it doesn't matter, you can use other air and don't have to only use his. He's not saving you money or trying to kill you - if anything probably just trying to keep you coming back there.

 

[Atticus]

My lds tells me that they clean their air differently (or better than most lds's, something with their filters, I don't remember), so I can switch from 21% to nitrox and back all I want, as long as I only use their air with my reg. that is O2 clean.

So either I found a great lds that is saving me money, or trying to kill me... I got a 50/50 chance, I'll take it...

Without knowing the full story I can only guess, but it certainly sounds like a little bit of pride combined with a little bit of hogwash.

As has been said previously in this thread, the vast majority of the industry treats 21%-40% the same as air with respect to modern regulators. The only times you need to be concerned are:

1. When using greater than 40% nitrox (non-recreational).
2. When filling a tank using partial pressure blending (where straight oxygen is first put into the tank prior to topping with air).

Issue #2 only relates to the tank and valve, not to the regulator, so as a diver renting tanks this is totally transparent to you.

The shop I work with does partial pressure blending so our nitrox tanks and valves need to be oxygen clean and should only ever be used with oxygen compatible air.

The shop I used to work with uses a membrane system so nothing had to be oxygen cleaned.

 

[rockjock3]

There were old regs (Conshelf?) that weren't nitrox compatible but I don't think anyone makes regs anymore that aren't compatible up to 40%.

Don't think that yet. A buddy of mine bought either an atomic or a sherood reg (High end to) and it wasn't. He uses Nitrox a lot and his reg started having flow issues after about 6 dives. He took it in to get it repaired and the store contacted the manufacturer who advised them that that reg has to to have a kit installed to anything over 21% O2. His orings were falling apart. He later contacted the man. to confirm this and they told him the same thing.

You are right though that MOST all regs manufactured today will handle 40% and less out of the box.

 

[Atticus]

Someone want to fill me in on how 21%-40% nitrox can cause the O rings to "fall apart"?