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

[MAGELLAN]

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!

 

[beir]

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!

I just took the Nitrox class myself. I think it's more than customary. I wouldn't dive the tank unless I knew for sure what was in it. How can you trust your max depth if you don't know for sure....I think any reputable dive shop/boat will have an analyzer.

 

[mddolson]

I do not know what others do, but we require nitrox customers, to read the analyser and sign for thier mix in our log, when the pick up their tanks. We fill in the contents label in front of the customer.
The log contains tank serial number, date, customer name, blenders name, mix % ordered and actual analysed % oxygen.
This way there is no mistake.
The customer knows the mix and the MOD before he leaves the shop.

On some occations such as during a Nitrox course, we deliver the tanks to the customer at the dive sight. In this case we bring a portable analyser and check the mix on sight. The customer still signs for his mix.

You can build your own personal O2 analyser for $100 US from Oxycheq like I did.
http://www.oxycheq.com/index.html
It's called the El-cheapo II and it's every bit as accurate at the commerical units
costing $300

regards

Mike D

 

[MAGELLAN]

That's my impression too. It would seem to me that a dive operator would offer the use of an analyzer if they offer Nitrox. I'm wondering if that's normaly the case though.

 

[jkennedy]

Analyse your tank at the shop the day or night before and they should have a sticker that you signed and have the mix info. After you dive tear or peel the tag off. When you return to the dive shop tag your next tanks. I think I'm having a Brac attack......

 

[netmage]

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!

All dive shops where I have taken my tanks to get filled require ME to analyze the gas and fill out the logbook. They supply the analyzer.

I have heard that in some Florida locations it is assumed you provide the analyzer - as the volume in Nitrox sales is incredibly more significant. But if push comes to shove, I imagine they would let you use theirs.

Now - fast forward to a remote dive location, such as cozumel. In cozumel, it is my understanding that most dive operators do not have their own compressors. They load up tanks each day and go to a large fill station that may churn out a few hundred tanks of AIR and Nitrox each day. I doubt the fill station PP blends all the gas on an individual tank basis - but I could be mistaken. (As it could be increadibly time consuming) Each dive operator would likely not provide an analyzer.

In general - I only analyze nitrox fills. I don't analyze air fills. But I'm leaning towards carrying my analyzer around in my dive kit as a few people much smarter than I have suggested analyzing any gas I intend to breathe.

If your slightly handy with a soldering iron you can make your own for ~$100. The most expensive part is the sensor itself. Check out www.oxycheq.com or www.airspeedpress.com

-netmage

Edit:

P.S. I forgot to mention....
Analyze the gas when the tank has had an opportunity to cool. You want to ensure the reading your getting is after the gases have achieved a mixed consistency. So If your sitting on a hot fill, and then the next day hit the water, the readings could differ. Is that scenerio, I would analyze it on the boat.

 

[DandyDon]

I do not know what others do, but we require nitrox customers, to read the analyser and sign for thier mix in our log, when the pick up their tanks. We fill in the contents label in front of the customer.

Good to hear, but he's talking about Cozumel - where rules are only suggestions.

Yes, be sure to analyze your mix. The Nx there comes from one supplier already in the tank, and I've been impressed with how accurate the lables are, but still - test it yourself. If they handle Nx, the should be able to supply a test kit. If they can't, change operators.

 

[miketsp]

One tip, check the pressure as well as the O2 content.

I witnessed one situation where only one person out of a full boat was insisting on diving Nitrox and demanding a DM to accompany him, also with Nitrox. Now this was going to be a rough trip and the operator was trying to dissuade the guy from having a much longer bottom time than the rest of the group but he insisted. Anyway I saw him check the O2 level and sign the sticker, but he didn't check the pressure.
At dive time, when he set up his gear he saw that he was about 15% underfilled & his bottom time was now going to be the same as everybody else's.
There was a certain amount of stress and the operator refused to accept the complaint saying that it was the diver's reponsibility to check the O2 level AND the cylinder pressure before leaving the shop!

 

[Lemonade]

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!

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?

 

[MB]

Some thoughts:

1. I teach a fair amount of nitrox. My lesson is very direct: Analyze every bottle of nitrox before you breathe it.

2. I also dive using nitrox on about 75% of my dives. My personal practice as a diver: Analyze every bottle of nitrox before I breathe it.

3. I haven't experienced the issue in FL where the customer is expected to have his/her own analyzer. Every reputable fill station I know expects that the customer will want to read the mix directly before taking it away from the fill station. Some operators might be willing to short cut this protocol, but they know that its seriously bad business to refuse to allow the customer to read the mix. (Custom might vary in some locales, especially if they are dealing with "specialized" clientele.)

4. Then there's Cozumel... As noted in a post above, most operators do not mix, but they pick up bottles of pre-mix from a central supply. Then, the op delivers the bottle to a boat - as a measure of customer service (and to control loss). At the boat, there's been a 50% probability that the operator will not have an analyzer on the boat (or at the dock), so if you want the bottle of mix that you already paid for, you have to close your eyes and "have faith" that the mix inside matches the label. Then again, since many divers know this, there's a good chance that a fellow diver will have an analyzer handy. Given the situation, you are often allowed to borrow that analyzer... Of course some Coz ops are better than others and make it easy for the divers to read their mixes...

Hey, if you don't want to build your own this early in your nitrox career, OxyCheque has a nice analyzer. What the heck, its only money... Be nice and your significant other might bring you one for Christmas, Kwanza, Valentine's Day, Heartbreak of Psoraisis Week, or some other celebration. Best price I know is thru Chris at covci.com (also an ScubaBoard member).