"nitrox-ready" regs

[haneym]

hi all. got a question for ya about nitrox. i am not nitrox certified yet but plan to take the class when i have some free time that i want to spend in the class rather than water. when i am browsing around looking at regs, some say "nitrox ready" and some dont. what does this mean?? i have an older set of US Divers regs (conshelf se2 primary) that i am currently using because they were free. i would like to upgrade some time next year but was wondering if i can breathe nitrox off these or if i have to upgrade first. granted, i dont know much about nitrox as i havent taken the class yet so i apologize for that. i dont really know what having gear "o2 cleaned" means or why its needed, but im sure ill learn that in the class. i did a search and found a couple threads where some guys say that nitrox ready is just a marketing gimmick, is this true? thanks in advance

 

[garyfotodiver]

Two things. First, my Nitrox instructor and my SSI book mentioned the "40% rule". This simply means that, with gas mixtures up to 40% O, no special equipment preparation is needed. Remember, the two common Nitrox mixes are 32% and 36% O.

Second, the dive shop that services my 10 year-old Conshelf SE3 said that it is ready for Nitrox up to 40%.

 

[Wayward Son]

You can use most any reg for nitrox up to 40%. Over that it has to be O2 cleaned. You'll cover this in your class, but the short version is that at higher O2 percentages, things ignite a lot easier. If they do, they burn until either the fuel is gone or the O2 is gone.

But for rec diving on under 40%, most any reg will be fine.

 

[MikeC]

Hello Michael, back in the mid 90's all the way to the middle of year 2000
USD/Aqualung did not support the use of breathing air with a oxygen content
higher than 23.5% and it was even stated in the owners manuals. This was
primarily because of a lack of adiabatic testing to insure that the regs were
indeed safe to use. Fast forward to July 2000 and Aqualung had finished up
adiabatic testing (Very expensive) on all our current in-line regs and made the
necessary changes to insure their safe use out of the box to EAN 40% when
dedicated. None of the older regs will be tested in this manner and will more
than likely never be approved for anything other than use with air to 23.5%.

Sincerely,

Todd A.
Aqualung Repair Dept..

From Aqualung's service department. Dated May of this year. I'm not sure if that statement was based on the gear or what a lawyer told them to do.

 

[ScubaSixString]

hi all. got a question for ya about nitrox. i am not nitrox certified yet but plan to take the class when i have some free time that i want to spend in the class rather than water. when i am browsing around looking at regs, some say "nitrox ready" and some dont. what does this mean?? i have an older set of US Divers regs (conshelf se2 primary) that i am currently using because they were free. i would like to upgrade some time next year but was wondering if i can breathe nitrox off these or if i have to upgrade first. granted, i dont know much about nitrox as i havent taken the class yet so i apologize for that. i dont really know what having gear "o2 cleaned" means or why its needed, but im sure ill learn that in the class. i did a search and found a couple threads where some guys say that nitrox ready is just a marketing gimmick, is this true? thanks in advance

just completed nitrox certification. All modern regs are "nitrox ready" to 40% (the recreational limit) which means they can handle it. O2 servicing and cleaning is needed to use a mix higher than that. Any reg that you use with an air fill (that is not o2 compatible) will have to be at least cleaned again if not reserviced. O2 compatible air is not commonly used in an air fill. So unless you plan to dedicate that rig to nitrox, don't worry about its "nitrox ready" label. Nitrox ready might not even mean 02 serviced at all.

Tanks are a different matter. If 02 is put in at all (ie its not mixed outside the tank) you need to have an 02 cleaned and serviced tank. Same thing applies about using non o2 compatible air though

 

[jmps]

I read about people using air on some dives and nitrox on others on the same day. Are they just ignoring the cleaning rule between air and nitrox?

 

[mossym]

nope, you can put air in nitrox claen tanks as long as it is clean enough, grade e i believe

 

[DA Aquamaster]

From Aqualung's service department. Dated May of this year. I'm not sure if that statement was based on the gear or what a lawyer told them to do.

It smells like a very conservative legal answer.

From a tech perspective, given that the Conshelf 14 is still produced and would be a current in-line reg and that SE whatevers are Conshelf derivatives with different port sizes and use Conshelf service kits, it would appear to be pretty safe to assume that a properly cleaned older Conshelf, Pro diver, SE whatever, etc first stage will work fine with nitrox as long as a new and current annual sercice kit is installed and all the old o-rings are replaced. After all, they are all using the same general design, chrome plated brass construction, o-ring and seat materials. But use your own judgement.

From the company attorney perspective, I suppose unless they can show definitive testing for a specific model that they could then use in court to show nitrox use was demonstrated to be safe in that particular model, (and therby inferring that the castastophy was due to the diver screwing up or doing something wrong to cause the accident) they are not going to ever say it is ok, as that would leave them open to liability.

 

[rescuediver009]

It is difficult to say whether your conshelf is Nitrox ready in its present state. Different service centres use different methods of lubrication etc when servicing regs. So I would be carefule and ask them on that.
As for a new reg, they are allok for up to 40% out ofthe box as they use the proper lubricants and assembly parts (nothing too fancy) to support this.
Also I think that taking the nitrox course will eliminate alot of confusion for you.

 

[ScubaSixString]

I read about people using air on some dives and nitrox on others on the same day. Are they just ignoring the cleaning rule between air and nitrox?

Its not a problem if they are using regs/tanks that aren't 02clean/serviced.

ALL recreational nitrox diving is done between 21 and 40% o2 (the most common blends being 32% and 36%). As long as the precentage of oxygen flowing through your reg doesnt exceed 40%, there is no need for o2 servicing and cleaning (although my instructor mentioned something about local laws in places may not allow it). Tanks can be a problem if the put in O2 first and then add air to make the blend (partial pressure blending) but your regs should be safe. In the case where a diver does a nitrox dive followed by an air dive (assuming the air isn't o2 compatible) 1 of 2 things occurs. Either the diver's equipment was not o2 clean and serviced.... or it loses its o2 rating and will have to reserviced.