Nitrox Is it customary to reanalyze it at the dive boat?

[Mark Vlahos]

Sorry to go off topic, but I see everyone saying there are kits that can be had at a fraction of the price if I'm willing to solder....well, I'm willing to solder. Does anyone have a link to one in particular. I don't really see any kits at OxyCheq, but I could be looking at the wrong thing....Thanks

Doh, scratch that I found the kit at OxyCheq's web site....if anyone can recommend others, that would be appreciated as well.

I built mine from the YDI Kit available at RC Dive Technology. I chose to get the longer life sensor for a little extra, all they did was charge me the difference in price between the standard sensor and the long life one. I found the directions easy to follow, the hardest part is cutting the rectangular holes.

Mark Vlahos

 

[matt_unique]

This is a trick question, right?
I calibrate mine before every use by removing the cap from the sensor and waiving it around in the ambient air.

Ideally, additional checks on 100% O2 and 100% Helium are a nice check on the condition of your sensor.

Likewise - I would not trust the contents of any tank for calibration purposes. I want the analyzer calibrated for air - not the contents of another tank. I know people that do this and it does not make any sense to me.

--Matt

 

[ScubaMarc]

I was down in Curacao and had my tank fill by Ocean Encounters. I told them I wanted EAN32, I checked the 2 tanks and found the % was 24% and 26%. ALWAYS CHECK!

 

[HarleyDiver]

It's obvious that I analyze my tank when picking it up at a shop or any place when it is filled a la carte. But, I think, the original poster's question is referring to a different situation.

Imagine a liveaboard; let’s say 10 days, 5 dives a day, 12 divers, 3 divemasters. You assemble all your gear once. Then after every dive while you are off-gassing, having food/snacks, filling logbooks, doing whatever, dive deck staff refill the tanks, they don’t even need to take them off BCs.

When you’re ready, you gear is ready. If that’s air you’re diving, there is no issue.

Now, imagine that liveaboard has a membrane nitrox station, and instead of air they are pumping 32% nitrox.

Do I disconnect my reg and analyze before every dive? Does every one of the twelve guests/divers and 3 DM on that liveaboard analyze every time? Becomes troublesome… All 15 tanks were just filled from the same source. Perhaps, it’s sufficient to analyze just one tank... That nitrox station has a built-in analyzer, and the tanks were just filled from it. Do I need to analyze at all? Paranoia? Why wouldn't I analyze air then if the same liveaboard, same crew were puming air?

I’ve never been on a liveaboard with nitrox station. But, returning to the original question, what’s the custom?

Just got back from a week on the Nekton Rorqual & YES you check every tank, every dive. They use a Membrane system.

After each dive you disconnect your first stage, that tells them to fill it. When they are done they cap it, that tells you its ready. Then you analize, and sign for the tank, put your first stage back on & dive.

 

[detroit diver]

If you don't analyze your mix, you would be quite foolish. What happens if they put pure oxygen in your tank and you get to 70 feet? Mistakes happen to the best of us, and I wouldn't do a "trust me" dive on nitrox.

In fact, during last year's DEMA conference, a group of us went diving on a charter. We ordered 32%EAN in advance. When we got to the boat, our tanks were set up and marked 32%. We asked for an analyzer to check it, and were told they didn't have one on board and that the person who mixed them had been doing this for 15 years and was a nitrox instructor. This was not good enough for us, so we asked if we could take the tanks back to the shop to get analyzed. They said we could not, because there was no time. We started to pack up our bags to leave, and, fortunately, one of the other divers told us he had an analyzer in his car. We got it, and the dive was saved. PS-all tanks analyzed close to 36 percent, not the 32 we requested and was marked on the tank.

Don't put your life on the line for something as simple as an analysis.

 

[caymaniac]

All the places we've dived with Nitrox ahve had an analyzer to use, and "yes" you should always check it or don't dive with it.

Dive Safe,
Caymaniac

 

[Lemonade]

Just got back from a week on the Nekton Rorqual & YES you check every tank, every dive. They use a Membrane system.

After each dive you disconnect your first stage, that tells them to fill it. When they are done they cap it, that tells you its ready. Then you analize, and sign for the tank, put your first stage back on & dive.

Cool. Makes perfect sense. How did you calibrate the analyzers? And how many divers/analyzers were there?

 

[oceancrest67]

It's obvious that I analyze my tank when picking it up at a shop or any place when it is filled a la carte. But, I think, the original poster's question is referring to a different situation.

Imagine a liveaboard; let’s say 10 days, 5 dives a day, 12 divers, 3 divemasters. You assemble all your gear once. Then after every dive while you are off-gassing, having food/snacks, filling logbooks, doing whatever, dive deck staff refill the tanks, they don’t even need to take them off BCs.

When you’re ready, you gear is ready. If that’s air you’re diving, there is no issue.

Now, imagine that liveaboard has a membrane nitrox station, and instead of air they are pumping 32% nitrox.

Do I disconnect my reg and analyze before every dive? Does every one of the twelve guests/divers and 3 DM on that liveaboard analyze every time? Becomes troublesome… All 15 tanks were just filled from the same source. Perhaps, it’s sufficient to analyze just one tank... That nitrox station has a built-in analyzer, and the tanks were just filled from it. Do I need to analyze at all? Paranoia? Why wouldn't I analyze air then if the same liveaboard, same crew were puming air?

I’ve never been on a liveaboard with nitrox station. But, returning to the original question, what’s the custom?

I have not dived a liveaboard operation...not yet...but, I have been diving for about ten years. With nitrox...be slightly paranoid and cautious...check your own...it is you and your well being / dive plan. Check your own. Double check your own.

The other thing, I dislike resorts / operations that have DMs set up equipment for divers...I insist on doing my own...always. I tried it once on one day out in the Caymans...DMs half hung over early in the morning...after checking my equipment...my bc was loose etc. I insist on doing my own or I go with another operation. My equipment, my dive plan, my enjoyment, my well being...I rig my own.

Now...if some liveaboard has a deck system and operation...where gear has to be stowed a certain way etc...I am willing to compromise. Still, I insist on setting up my own, then I know it is done right my way.

Just my 02

 

[frankdr]

Regarding the question about how it's done on liveaboards. On my last trip, there was the option to dive nitrox or air. The boat has two different fill whips, one for each gas type. The boat supplied the tanks for nitrox divers, and it was labeled with a nitrox sticker and the tank was an ugly lime green color. Some people brought their own tank for nitrox, but more than once I heard the people doing the fills trying to be sure they put the right mix in the personal nitox tanks.
Each person who was diving nitrox had a page in a dive book on the camera table. If you didn't test, log and sign for your tank, the divermaster didn't let you in the water. They would call you out during the dive briefing and make sure you did your analysis before you were allowed in the water.

 

[watermonkey]

I'm headed for a trip to Cozumel, and I wanted use Nitrox. This would be my first trip to use it, and when I asked about analyzing it at the boat, I was assured that it would be mixed by a certified center. My question is, after my recent Nitrox class, I felt we were supposed to reanalyze the tanks ourselves, isn't that customary? Do dive operators that provide Nitrox, also provide an analyzer, or... do you trust the mixer? We don't have one, obviously, and It's at least another 200 bucks to get one. I've already spent too much money just getting there, if you know what I mean Your thoughts please!

Sorry if this is blunt but here it is:

1. You never saw the calculations for the mix
2. You never saw the mixing being performed
3. You never saw the analyzer being calibrated properly
4. You never saw the technique used to analyze the gas or the results
5. Nothing has been done to crosscheck the results ( 2 tests with different analyzers )
6. If you OxTox you will most likely die from drowning
7. OxTox happens without warning

Nitrox is great but like most things that provide increased capabilities it requires greater discipline. Since around here Nitrox fills are usually almost 2x the cost a normal fill the cost of an analyzer in the long term is small compared to the total cost of diving Nitrox.
If you don't test it with gear you know and trust, how do you know?