Do I need multiple dive computers or HP hoses?

[Scuba J7]

I'm confused. Some of you seem to be saying that it's okay to use a 1st stage that is not O2 Clean with a tank full of EAN40.

Is that correct? It's okay to expose non-O2 Clean reg internals to 3500 PSI of 40%?

Yes, you can verify the information on any manufacturer’s website. I used Scubapro’s webpage to double check.

 

[Damselfish]

Greetings all, I have been Nitrox certified for a number of years....

How many years is "a number of years"? Early on as Nitrox started to come into usage in rec diving, there was a certain level of paranoia about cleaning things, making sure Nitrox compatible o-rings and lubes were used which wasn't the default then, warnings in reg manuals, etc. Everyone was generally figuring things out. That went away over time as everyone understood better what mattered and what didn't, and things adjusted. Assuming you're talking recreational Nitrox <40%, there's no need to have a separate set of regs, and therefore no need to swap a computer anyplace. (Yes, swapping between two computers so that neither has your whole profile, that would be bad. Having 2 computers is useful for some people, but only if you dive with both so if one craps out the other is a real backup.)

I believe with a reg being shipped for use with up to 40% Nitrox, the main thing you are assured of is Nitrox compatible o-rings and lubes. If the reg was shipped "clean" then used with air, it's possibly not clean anymore anyway, and it doesn't matter - at these levels the concern is not that something will catch on fire. But compatible o-rings will be less prone to degrade with higher concentrations of O2.

We usually dive Nitrox but have certainly bounced between <40% Nitrox and air without concern about our regs. I've never seen anyone worry about it. Tanks are a different matter if they're being partial pressure filled and seeing high concentrations of O2.

 

[Blasto]

I'm confused. Some of you seem to be saying that it's okay to use a 1st stage that is not O2 Clean with a tank full of EAN40.
Is that correct? It's okay to expose non-O2 Clean reg internals to 3500 PSI of 40%?

By the book, of course it isn't.

In practice... it's being done all the time in rec diving, no one ever checks. A compressor that would contaminate a reg, shouldn't be used for breathing air in the first place, and fortunately today most compressors run sufficiently clean. So if your reg is reasonably modern, you bought it new, got all your fills from reputable dive ops, never got signs of dirty air - the general assumption is that your reg should be good for slightly enriched air.

Since there doesn't appear to be a stream of fire accidents from the use of rec nitrox, that assumption seems to be holding up very well.

 

[Compressor]

I'm confused. Some of you seem to be saying that it's okay to use a 1st stage that is not O2 Clean with a tank full of EAN40.

Is that correct? It's okay to expose non-O2 Clean reg internals to 3500 PSI of 40%?

Correct.

 

[Scuba J7]

By the book, of course it isn't.

In practice... it's being done all the time in rec diving, no one ever checks. A compressor that would contaminate a reg, shouldn't be used for breathing air in the first place, and fortunately today most compressors run sufficiently clean. So if your reg is reasonably modern, you bought it new, got all your fills from reputable dive ops, never got signs of dirty air - the general assumption is that your reg should be good for slightly enriched air.

Since there doesn't appear to be a stream of fire accidents from the use of rec nitrox, that assumption seems to be holding up very well.

Actually it is “by the book”, at least our modern books. We are not assuming that it’s ok to run up to 40% O2, the manufacturers and training agencies are telling us it’s ok.

 

[markmud]

I'm confused. Some of you seem to be saying that it's okay to use a 1st stage that is not O2 Clean with a tank full of EAN40.

Is that correct? It's okay to expose non-O2 Clean reg internals to 3500 PSI of 40%?

Hi stuartv,

I am sorry for piling-on; however, I think I can answer your question by example.

Here are the dive ops that fill my tanks and type of systems they use:

1. My favorite dive shop for people, service, training and gear:
   1. They teach tech diving; therefore, they use a partial pressure blending system.
      1. Your tanks need to be O2 clean for all nitrox fills. Your regs need to be O2 clean for all gas above 40% EANX.
   2. My second favorite dive shop uses a Stik method for creating EANX into a bank.
      1. No O2 cleaning for any piece of gear is required (including the tanks).
   3. My third choice for EANX fills are from SoCal dive boats.
      1. They use a membrane system for creating Nitrox to 36% (the membrane separates Nitrogen from O2, CO, and CO2.
         1. No O2 cleaning of any piece of gear is required (including the tanks).

Sometimes, I am worried about the equipment on some of the dive boats, so I usually keep a dedicated dive boat tank that is not O2 clean or if it is O2 clean, it is not used for partial pressure blending. PP blenders don't seem to mind filling tanks that I declare to have been filled on a dive boat. I am worried that there could be some oil contamination and cause a CO problem or an uncontained chemical reaction.

To iterate in synopsis form:

No, you don't need O2 clean gear to use EANx (40% or lower).

markm

 

[markmud]

Greetings all, I have been Nitrox certified for a number of years, but have rarely used it. I am thinking about getting back into it. I know not all remote locations offer Nitrox fills, so there could be a situation where I do some Nitrox dives and some air dives.

Due to safety concerns, I am putting together a Nitrox-cleaned set of regs (1st stage, 2nd stages, LP hose, etc.). However, I don't want to use a second computer, as that would compromise my nitrogen loading (or is my thinking wrong here?). So, my question is this: am I safe to use the same (air-integrated, Nitrox-ready) computer with both sets of regs, and just purchase an additional HP quick disconnect hose?

Is there anyone out there who does this? I would love to know!

Hi bdeliashea,

Um...why complicate things? Why don't you use the same regulator and computer system for both air and EANx? I do. All the time. And yes, I am following the "book".

I do use two computers. It has paid off. I had an HP hose failure while diving from a live-aboard dive boat. I was able to borrow an SPG but could not use my AI computer for the rest of the trip.

No worries, I had my wrist mounted computer that contained all of my nitrogen loading for the last two days. I dove without interruption. Redundancy on the ocean is the only way to live.

markm

 

[stuartv]

So, if I buy regs that are O2 Clean and I use them on a tank that was filled with regular (non-O2 Compatible Air), it's still okay to use those regs on a tank that is filled with EAN40. That's what y'all are saying? So, a 1st stage that is not O2 Clean on a tank full of EAN40 is okay?

 

[Scuba J7]

So, if I buy regs that are O2 Clean and I use them on a tank that was filled with regular (non-O2 Compatible Air), it's still okay to use those regs on a tank that is filled with EAN40. That's what y'all are saying? So, a 1st stage that is not O2 Clean on a tank full of EAN40 is okay?

Yes, up to 40%, anything above that requires O2 clean equipment. Now, every shop and dive site I use, and probably every shop I know of, use O2 clean air. They all PP blend and none of them have the space or resources for separate air compressors.

 

[tbone1004]

So, if I buy regs that are O2 Clean and I use them on a tank that was filled with regular (non-O2 Compatible Air), it's still okay to use those regs on a tank that is filled with EAN40. That's what y'all are saying? So, a 1st stage that is not O2 Clean on a tank full of EAN40 is okay?

yes, however you rarely see EAN40 outside of scientific diving. If you are concerned, you can get a personal in-line filter and use that while filling your tanks that will make the air going in oxy compatible, but no need for O2 cleaning up to EAN40.

Due to chambers closing and a higher need for multiple O2 clean regulators, I have recently broken down and O2 cleaned all of my tanks/valves/first stages. I'll probably "o2 clean" the seconds meaning at least use O2 clean tools and lube the next time I rebuild them, but that won't be for several years.