Breathing Nitrox through non-compatible reg?

[2Tours N Iraq`]

Has anyone ever breathed Nitrox through a regulator that is not nitrox compatible? Other than contaminants and lubrication issues, what would cause a regulator to not be nitrox compatible? I am only basic Nitrox certified, therefore, I'm not breathing anything above 40% O2. Is this a problem if the reg I use is not nitrox compatible? Do I need to get a new reg even though I'm staying under the 40% O2 mark?

 

[DiverBuoy]

First question. Yes. I have seen divers switch back and forth on the same boat between dives, thought it's frowned upon. Once you get a regulator O2 cleaned, it should not be used for standard air diving. If this occurs, the regulator should be cleaned again before going back to enriched air.

Second question. You should be concerned with any materials or components in the regulator which may present an increased risk of flammability, or the potential to start a fire, when exposed to enriched 02 breathing gas. At 100% O2 just about everything burns, but you would not want to expose yourself to the increased risk, of having the wrong type of lubricants and o-rings in your regulator. Of course if it was O2 cleaned already, the rings will be fine, but "bad" air can pollute the system with oils and greases or other potentially flammable materials, you wouldn't want to take the risk.

 

[scubatoys]

There are 2 schools of thought on this -

1. If using anything higher than 21%, treat it like pure O2 - make sure everything is O2 clean.

2. If you are staying below 40%, use any reg, go back and forth from air to nitrox all day long and it won't hurt squat.

I'm with #2 here... and DAN studies have shown that they have not documented one problem.... ever... from using up to 40% in gear that wasn't O2 clean. So I'll use that to defend my position. I would use any gear, anytime with standard 32 and 36 mixes, and have done that for years with no problems.

 

[DivesWithTurtles]

First question. Yes. I have seen divers switch back and forth on the same boat between dives, thought it's frowned upon. Once you get a regulator O2 cleaned, it should not be used for standard air diving. If this occurs, the regulator should be cleaned again before going back to enriched air.

Second question. You should be concerned with any materials or components in the regulator which may present an increased risk of flammability, or the potential to start a fire, when exposed to enriched 02 breathing gas. At 100% O2 just about everything burns, but you would not want to expose yourself to the increased risk, of having the wrong type of lubricants and o-rings in your regulator. Of course if it was O2 cleaned already, the rings will be fine, but "bad" air can pollute the system with oils and greases or other potentially flammable materials, you wouldn't want to take the risk.

DiverBuoy, why would you O2 clean a reg for <40% nitrox?

 

[Dr. Doug Ebersole]

The fire risk for less than EAN 40 is negligible so that you do not need to have the reg O2 clean. As most recreational divers never breathe any mix richer than EAN 36 there is not a problem with equipment compatibility other than cylinders. As many places fill cylinders by partial pressure blending which first puts 100% oxygen into the cylinder, that could be a fire risk. Regulators are not a problem.

Regulators for 100% O2 and deco bottles -- obviously another story.

 

[The Kraken]

There is another scenario, also.
Many shops fill nitrox mixes by first filling a certain percentage of O2 and then top off with "O2 compatible air", that is, air that is compressed along certain specific regulations and procedures.

One can fill an O2 cleaned tank with "O2 compaitble air" with no concern of compromise.

the K

 

[Jamdiver]

There are 2 schools of thought on this -

1. If using anything higher than 21%, treat it like pure O2 - make sure everything is O2 clean.

2. If you are staying below 40%, use any reg, go back and forth from air to nitrox all day long and it won't hurt squat.

I'm with #2 here... and DAN studies have shown that they have not documented one problem.... ever... from using up to 40% in gear that wasn't O2 clean. So I'll use that to defend my position. I would use any gear, anytime with standard 32 and 36 mixes, and have done that for years with no problems.

Thanks for that scubatoys,
I've been worrying that if and when I become nitrox certified i'll have to get a new reg!
Thankfully that doesn't appear to be necessary .

 

[DiverBuoy]

DiverBuoy, why would you O2 clean a reg for <40% nitrox?

There are schools of thought which differ on this subject. Some local dive shops have hard and fast rules for rental equipment for example. And as I mentioned before there are dive boats locally which don't care, and folks switch back and forth between Nitrox cylinders and Air cylinders all day.

 

[StSomewhere]

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%.

 

[BigJetDriver]

There are schools of thought which differ on this subject. Some local dive shops have hard and fast rules for rental equipment for example. And as I mentioned before there are dive boats locally which don't care, and folks switch back and forth between Nitrox cylinders and Air cylinders all day.

There are always some renegades somewhere, or folks who shape the local version of the rules to their own ends, but the consensus in the industry is this:

Up to and including 40%, any and all equipment will work.

Above 40%, and all cylinders used for Partial Pressure Blending, clean and prepare for oxygen service (i.e. cleaning, rings, seats, o-rings, and lubes, etc.)