How does Nitrox work?

[sabbath999]

Nah, that won't help. The two deaths to bad air in Roatan a few years ago were on nitrox from a poorly maintained compressor. This is why I carry a CO analyzer and test every tank.

Which one do you have?

 

[DandyDon]

Which one do you have?

Pocket CO - Miniature Carbon Monoxide Detector and Dosimeter

 

[alewar]

Pocket CO - Miniature Carbon Monoxide Detector and Dosimeter

not to hijack the thread, but did you ever find too much co2 in a tank?

 

[sabbath999]

DD, how about starting a new thread to discuss this subject?

 

[MXGratefulDiver]

This is an intresting discussion on the nitrox issue. My husband and I are new divers (certified last year and now have 40 - 50 dives). On our dives of 60 feet or so, my husband uses up air significantly faster than I do, or most of the other divers in our group (15 minutes of so per dive). Would nitrox help with that specific issue? I'm getting the impression the answer is no. Thanks.

Nitrox does not in any way affect your air consumption rate. New divers typically have high consumption rates, due mostly to poor technique. The best way to remedy this is to get out and dive as often as possible to get more comfortable with your basic skills. Perform weight checks to make sure you are not overweighted (a common problem with new divers), and slow down (most new divers tend to swim around like baby harbor seals ... which will burn through your air supply much more quickly). Bigger cylinders can be a short-term remedy, but keep in mind that it's an equipment solution to a skills issue, and once you remedy the skills issue those bigger cylinders will no longer be needed.

I remember that thread about accidents involving fillings with bad air. It seems to me wise to dive on Nitrox while on vacation in a bad-regulated country. Am I wrong?

Nah, that won't help. The two deaths to bad air in Roatan a few years ago were on nitrox from a poorly maintained compressor. This is why I carry a CO analyzer and test every tank.

Don, I followed that accident closely, due to the fact that I had been to that resort just prior to it happening, and had dived with the DM who died. I'm not sure the cause was due to a poorly maintained compressor (although I AM convinced that there was bad gas in the cylinders). The resort parked their boats on the dock just outside the compressor room ... and the prevailing wind had a tendency to blow diesel exhaust right into the fill stations. The nitrox station was situated closer to the boats than the air station, and I am fairly convinced that what was happening was that diesel exhaust fumes were getting sucked into the compressor and pumped into the tanks. We experienced, one time, a situation where everyone on our boat with nitrox tanks could smell diesel fumes coming out of their tanks (keep in mind that CO is odorless, yet we could clearly smell the gas coming out of our tank valves). We replaced all of the nitrox tanks with air tanks for that dive. Based on the number of dives we did while there, and the fact that this only happened once, I would believe a combination of timing (filling while the boats were idling just prior to the morning and afternoon dives) and wind direction (blowing the diesel fumes into the compressor room) were the culprit.

I haven't been back since, but I would have to believe that this situation has been identified as the most probable cause, and remedied by moving the intake to the compressors to the other side of the building ... away from the boats.

I am putting together a dive trip to Kona in August, and all the places seem to charge about 12 bucks a tank extra...

I will be doing 5 two-tank trips, two people each trip, so the extra cost would be 120 bucks to use Nitrox.

The dives we will be doing are mostly under 60 feet and the limiting factor won't be NDL but rather air consumption... I can go about an hour and no more on an AL80 if I stay at 50 feet or under... mostly, since we are going to be shooting pictures, we are going to be pretty darned shallow the whole time.

At only two dives per day, and most of them nowhere near the best effective range for Nitrox, it would be nuts to pay the extra 12 bucks per tank to get them, yet I have actually had one of the operations I am talking to trying to upsell me on it.

I want to congratulate them for being kind enough to eliminate themselves from the running of the operations I am considering going out with by trying to upsell me a product I don't need.

Would I dive it on those dives if the cost were equal? Absolutely, headroom is a good thing... but frankly I don't NEED it.

Given the description of your circumstances, I'd have to say no ... nitrox wouldn't give you enough benefit to justify the cost.

That's the thing ... you can't really make blanket statements about how worthwhile it is, because it almost always boils down to looking at your dive profile and circumstances (e.g. how many dives per day you plan to do). The benefits of nitrox almost always apply to situations where you will be doing fairly aggressive dives (pushing close to NDL limits) and/or multiple (three or more) dives in a day.

... Bob (Grateful Diver)

 

[DandyDon]

not to hijack the thread, but did you ever find too much co2 in a tank?

I'm testing for CO, a tremendously more dangerous gas. Nah, haven't used it but a few trips and hope I never do find any - but never had a house fire either, but keep smoke detectors on guard and fire extinguishers charged.

DD, how about starting a new thread to discuss this subject?

Have in the past. Maybe I should do a new one with updated info...?

Don, I followed that accident closely, due to the fact that I had been to that resort just prior to it happening, and had dived with the DM who died. I'm not sure the cause was due to a poorly maintained compressor (although I AM convinced that there was bad gas in the cylinders). The resort parked their boats on the dock just outside the compressor room ... and the prevailing wind had a tendency to blow diesel exhaust right into the fill stations. The nitrox station was situated closer to the boats than the air station, and I am fairly convinced that what was happening was that diesel exhaust fumes were getting sucked into the compressor and pumped into the tanks. We experienced, one time, a situation where everyone on our boat with nitrox tanks could smell diesel fumes coming out of their tanks (keep in mind that CO is odorless, yet we could clearly smell the gas coming out of our tank valves). We replaced all of the nitrox tanks with air tanks for that dive. Based on the number of dives we did while there, and the fact that this only happened once, I would believe a combination of timing (filling while the boats were idling just prior to the morning and afternoon dives) and wind direction (blowing the diesel fumes into the compressor room) were the culprit.

I haven't been back since, but I would have to believe that this situation has been identified as the most probable cause, and remedied by moving the intake to the compressors to the other side of the building ... away from the boats.

You could be right? CCV promised a full disclosure as soon as the facts could be collected, then did an about face - pulling the discussions from their own board and sending their fans here to challenge the discussions. It was before the Passings forum was established and the Accidents thread got hijacked with emotional outbursts - tremendous sorrow for the dead DM but scarcely any of the Texas tourist who died or his wife and others injured. The thread here vanished, but then the Passings forum was established and the rules for Accident forum changed. So very little can be found on the case; DAN's Accident report just shows two deaths there that year.

I spoke with a renown dive boat skipper who had been there before, had his reg fouled with oil, inspected the compressor, and described the sorry condition. My info is second hand from a renown source who understandably does not want to publish. CCV fans would organize revenge and put him out of business for that.

So CCV won. All you can find are rumors like mine. And you can be damned sure I'd never step foot on their property or one of their boats again, altho I learned about their boats when I tried to take one to Utila once.

 

[offthewall1]

Back to the original thread... I may have changed my mind about Nitrox... not because you've all convinced me... but listen to this story... this actually just happened.

A customer of mind just came into my store... in fact he's still sitting next to me as I type this...

He just got back from a dive trip to North Carolina. He is a recently graduated student who is NOT Nitrox certified.

He just informed me that the outfit he dove with in NC filled his tanks with 30% Nitrox. He had told them he wanted air... and when he went in to get his tanks... they told him they had filled it with 30% Nitrox. They told him "don't worry about it - it'll be OK."

No education... no mention of MOD... no requirement for a C-card... and apparently no-concern for the customer's safety.

I suppose I would find this outrageous... except that it seems to fit the mentality of those on this board that oppose my opinion. Nitrox is the end all be all gas... totally safe... no worries.

Now that I know dive operators are out there filling peoples tanks with 30% Nitrox without an educational requirement... I just may have to join you guys... and certify everyone in Nitrox... at least I'll be able to sleep at night knowing they're educated on its use.

Am I the only one that sees a problem with what this operation did?

 

[DandyDon]

I find that difficult to believe. The MOD for 30% is deeper than the hard bottom but still - I doubt that a charter would do that.

If he posts the details with the name of the charter, I might reconsider.

 

[Blackwood]

I am putting together a dive trip to Kona in August, and all the places seem to charge about 12 bucks a tank extra...

I will be doing 5 two-tank trips, two people each trip, so the extra cost would be 120 bucks to use Nitrox.

check your math...

He just informed me that the outfit he dove with in NC filled his tanks with 30% Nitrox. He had told them he wanted air... and when he went in to get his tanks... they told him they had filled it with 30% Nitrox. They told him "don't worry about it - it'll be OK."

...

Am I the only one that sees a problem with what this operation did?

I guess it depends. Was he renting tanks and using them independently? Or were they giving him gas to use on dive sites of their choosing (shallow enough bottom that it doesn't matter)?

If the former, that's egregious (although on a couple of single tank 30% dives I find it unlikely he'll run into tox issues... Perhaps the shop in question promotes 1.6 max bottom PO2). If the latter, no harm. Even if he mistakenly gets the idea that 30% and air can be used interchangeably no matter what, without a nitrox card he likely won't get the chance to hurt himself with it.

except that it seems to fit the mentality of those on this board that oppose my opinion. Nitrox is the end all be all gas...

When did we start talking about Trimix




(Personally, I RARELY use nitrox as a bottom gas.)

 

[offthewall1]

I find that difficult to believe. The MOD for 30% is deeper than the hard bottom but still - I doubt that a charter would do that.

If he posts the details with the name of the charter, I might reconsider.

Quite frankly I don't care what you find hard to believe... they did it... and I questioned it myself... until after I checked his tank (not labeled for Nitrox) and it had 29.8% in it.

I know he didn't put it in there... so I have to assume they did what he said.

I'd also like to know how you can assume the MOD was deeper than the hard bottom.. there are dives in NC deeper than 121 feet at 1.4... mind you this was given to someone who wouldn't know the difference between 1.4 and 1.6 (143 ft.) Now while you are correct in your assumption.... they dove a bottom at 110 feet... that doesn't excuse what they did.

In fact, they used what they did to espouse the benefits of Nitrox and tried to sell him a $50.00 class after they had put it in his tank... how unscrupulous is that?

I know the outfit he dove with and I know how unprofessional they are. I had warned him prior to going not to go out with them... but he couldn't get a spot with the outfits we had recommended (Olympus, Discovery and Atlantis IV,) so he took what he could get... you always have to wonder why some boats are full and some have plenty of room dont you.

I was out on the ocean a couple of years ago with a third party boat when the crew of this same unscrupulous outfit... who were fueding with another outfit down there... lined up along the rail and "mooned" the crew and customers of the other boat they were feuding with. Maybe crew to crew is OK... but paying customers shouldn't have to look at a bunch of bare ass...

Don, you just like to disagree with everything I say... I say it's time to get a job