First Time Nitrox Diving

[bdizzle]

As the title says, I am contemplating diving Nitrox on an upcoming trip to St. Croix this week.
I have my EAN cert, and have also picked up an analyzer (O2EII) from scubatoys.
After calibration with a regulator tank of air (20.9), and then finding the mix of the EAN tank, is there anything else I should know while in the water? Have also set computer to reflect the 1.4max PO2. Should I set it for 1.3 or lower??

Looking for all input/advise/suggestions at this point, as I am just nervous not having dove nitrox before. Any advise and help is greatly appreciated.

Thanks all for the help
-brandon

[fisheater]

If you have the certification, your questions about how to dive nitrox should have been answered in class. From your post, it's hard to understand what information you're looking for.

Have you talked again to your instructor?


Sent from my iPad using Tapatalk HD

[bdizzle]

Rereading the books now but basically was looking for advise/input from people having dove nitrox what their first time experience was like and if I missed anything as far as safety goes, just a little nervous thats all

[flyandive]

1.4 is fine, as far as the dive goes, you won't even notice a difference. This is why agencies don't require training dives with it anymore. They were pointless. Some people claim they feel less tired afterward but it may just be a placebo.

[WB2GLP]

I've never found a need for a personal analyzer short of doing you're own blending. Places that rent nitrox tanks will have an analyzer or two in the shop or on the boat depending on where they store your tanks..

In a nutshell: Test your tanks, sign off on the mix, set your computer's %O2 accordingly before diving each tank. Repeat daily or as needed.

Don't forget to change your computer's %O2 between dives.

[TMHeimer]

Of course, you will probably know the depth of your dive. I always like to know how deep the maximum possible depth could be. It's not that I will then monitor my depth less diligently, but it's nice to know that you can't possibly exceed 1.4 ata without digging a hole in the bottom. If available, I will choose my O2 % based on a bottom not deeper than 1.4 as I will be on the bottom as a shell collector. If the mix I want isn't availble, there is always Air.

[bbarnett51]

Check your max depth. If your dive is going to put you close you might want to dive air then switch to nitrox fit the shallower dives to follow.

Set computer to 1.4 and your percentage then go diving. You won't notice a difference.

[Caryam]

I remember being very nervous on my first Nitrox dive last year. My instructor (or perhaps it was the PADI book,) had me quite frightened of the consequences of diving too deep or not knowing my mix.

I was nervous during the dive, but just tried to keep aware of my maximum depth, etc. The dive was uneventful, and over a couple of days my nervousness faded.

I was happy to find that diving EAN really does seem to be easier on the body. After four dives in a day I still had plenty of energy in the evening -- something unheard of for me on air.

Good luck!

[bleeb]

Something to be aware of: Some computers will reset the O2 content to some 'conservative' default after a certain amount of time. IIRC some will do so if you don't start the dive within as little as 10 minutes. This can make both N2 and O2 calculations excessively conservative, in assuming you're both diving on air for NDL calculations while at the same time assuming you're diving on 50% or 100% O2 for the purposes of MOD calculations. This functionality has confused more than one diver the first few times they've dived with a computer in Nitrox mode.

[ScubaSteve1962]

Having your own analyzer isn't a bad thing, I actually ran into and instance where the ops wasn't working. Don't be nervous, you won't be able to tell the difference. It does make you less tired, I actually stay up 2 mins longer than I did when diving with o2 :sleeping2:

[muddiver]

What's fun is having to clear your ears in the morning when you get up if you have done more than one dive on a higher oxygen content gas. :D

[GillScales]

Iirc most places on st croix use air. Go with cane bay or order your tanks the day before So the shop you're using can get em filled there.

[ianr33]

1) Assuming your mix is no more than 32%, do not go deeper than 110 feet
2) Make totally certain your computer is set correctly before each dive. (Some computers have an annoying habit of resetting to 79%N2 for deco calculations and 50% O2 for oxygen toxicity calculations if you do not manually set the O2% before each dive)
3)Have Fun!

[weitodive]

As others have said, don't be nervous. Just be aware. You should always check your depth constantly anyway. Go out and have fun. Computer diving will make it fairly simple. 1.4 is fine. 1.3 will just make your MOD shallower. Always check your computer in between dives and you will be fine. Nothing worse than having to sit at 60 ft because you forgot to change your o2 setting.

[Quero]

Nothing to be nervous about, bdizzle. And let fisheater's critical comments slide right off. Diving nitrox feels no different--at least during the dive--from diving air. If you did your course planning dives by using the tables rather than by using the computer, I can understand how setting your computer up might raise questions you didn't get answers to during your time with your instructor. Essentially, dive computers have the option of resetting the ppO2 fraction manually just in case you want to. Unless you have a well thought-out reason for setting it at a fraction other than 1.4, as some technical divers do for decompression stops, just go with 1.4 since it's the recreational standard, industry wide.

Here are a couple of SB threads you might find interesting:
http://www.scubaboard.com/forums/advanced-scuba-discussions/286906-oxygen-partial-ppo2-setting-dive-comp.html
http://www.scubaboard.com/forums/basic-scuba-discussions/27294-what-o2-partial-pressure-do-you-use-nitrox-calculations.html

[bdizzle]

Any way to find out of the oceanic vt4 is one of these "resetting" computers?
During my class I used tables rather than the computer. Been reading up on the settings and functions for nitrox diving.
I appreciate all the great responses from you guys...thank you!

[weitodive]

Oceani a all have that feature on it.

[bdizzle]

Oceani a all have that feature on it.
Just noticed this in the manual. the FO2 50% default option...on or off. Currently set to Off. Thank you for your help Wei

[weitodive]

Look for something in the nitrox menu that says fo2 50 on/off. That is the feature. On will reset the nitrox mix to 50 after each nitrox dive. Off will leave it at the nitrox mix you set at the beginning of the day. Pretty easy to get around.

[weitodive]

Good deal. I used to teach with oceanic computers so if you have questions just ask.

[fisheater]

Nothing to be nervous about, bdizzle. And let fisheater's critical comments slide right off.

Sorry. I wasn't intending to be critical. I was puzzled by the open ended nature of the original question.


Sent from my iPad using Tapatalk HD

[bdizzle]

Sorry. I wasn't intending to be critical. I was puzzled by the open ended nature of the original question.


Sent from my iPad using Tapatalk HD

No worries, didn't take it as critical, I appreciate the input.

[TonyErnst13]

Since you have your own analyzer, test it when the tank will be at the temperature you will be using it at... especially if you are right at your MOD - the mix will change at different temps. In addition to the computer help above, i always keep my computer in Nitrox mode. I just set it to 21% when not using it because sometimes a computer will either default back to an odd percentage, OR lock you out if you switch back and forth too many times between air and nitrox.... have fun!!

[Agility]

Just noticed this in the manual. the FO2 50% default option...on or off. Currently set to Off. Thank you for your help Wei
leave it off and (re)set the fO2 before every dive. once it becomes a habit, you will do it automatically when reading the analyzer.

[electrix]

Tony how does the mix change, first time I think I have heard that?

[TonyErnst13]

I'm sorry, the way I wrote that came off incorrect. The mix inside the tank is the same, however analyzing the contents after a hot fill and then analyzing the results after the tank has severely cooled, or vice versa will result in a slightly different reading.

The monitor may provide a reading in "percent oxygen," but it is actually measuring the partial pressure of oxygen. Change the pressure, and the oxygen reading changes, too.


Changes in temperature will also affect the rate of the chemical reaction in the fuel cell and, consequently, the reading of the monitor. While nitrox analyzers typically have temperature-compensation circuitry, problems can arise when a cold monitor is suddenly taken into warm conditions or vice versa. Always allow your nitrox analyzer to reach ambient temperature and calibrate the monitor to a known standard, typically compressed air at 21 percent, before putting it into action.

[Searcaigh]

I have noticed changes when analyzing tanks in airconditioned areas compared to repeating outside when it is 40C.

Always use my own analyzer to check.

Last year in Jeddah, one dive operator was renting out Nitrox tanks without an analyzer to check the O2, dived on air that day.

[SnorkelLA]

I didn't read the whole post, only skimmed, but it seems like you're asking what you should set your pO2 to? I leave mine at 1.3, but depending on your mix and the depth that you plan to be diving you could set it to 1.4 and be fine

[ianr33]

I have noticed changes when analyzing tanks in airconditioned areas compared to repeating outside when it is 40C.

Always use my own analyzer to check.

Last year in Jeddah, one dive operator was renting out Nitrox tanks without an analyzer to check the O2, dived on air that day.

That's could be due to the humidity. (Probably more likely in Florida than Jeddah I'm guessing!!)

Ambient pressure will stay the same (1ATM) If half the gas molecules are water vapor then the O2 % will be lower.

Calibrating an O2 sensor from a known air tank (rather than waving it around on a humid day) is most accurate. (But I don't typically bother)

[JerseyMike]

You don't need an analyzer. All dive shops and boats have/should have them if they provide Nitrox.


As the title says, I am contemplating diving Nitrox on an upcoming trip to St. Croix this week.
I have my EAN cert, and have also picked up an analyzer (O2EII) from scubatoys.
After calibration with a regulator tank of air (20.9), and then finding the mix of the EAN tank, is there anything else I should know while in the water? Have also set computer to reflect the 1.4max PO2. Should I set it for 1.3 or lower??

Looking for all input/advise/suggestions at this point, as I am just nervous not having dove nitrox before. Any advise and help is greatly appreciated.

Thanks all for the help
-brandon

[alexunderpressure]

1.4 is fine, as far as the dive goes, you won't even notice a difference. This is why agencies don't require training dives with it anymore. They were pointless. Some people claim they feel less tired afterward but it may just be a placebo.

in my experience, itīs not a placebo. Iīve never heard I would be less tired while on EAN, so I wasnīt influenced by any sugestion. I just stared noticing I didnīt feel like a long nap after three tanks.

[Dive the World]

Hiya

"picked up an analyzer (O2EII) from scubatoys" WOW you are really dedicated to the nitrox. I don't have one, just use the clubs or dive shops usually have them and you can use theirs for your mix.


"After calibration with a regulator tank of air (20.9), and then finding the mix of the EAN tank, is there anything else I should know while in the water?"

You don't need to calibrate using a regular tank, you are surrounded by 20.9% all around you, why would you calibrate using a regular tank. Unless you are testing your tank within 5m of a gas compressor with all its fumes.

WHat you need to do - once in a while - is calibrate (test) against an 100% O2 tank to make sure the O2 cell is healthy.

"Have also set computer to reflect the 1.4max PO2. Should I set it for 1.3 or lower??"

No, not at all - only worry about that if you are diving with a deco gas or doing technical diving.

[Bigd2722]

You don't need an analyzer. All dive shops and boats have/should have them if they provide Nitrox.

Not necessarily correct when out of country. Some shops don't always have a knowledgable sales associate on hand when you pick up your tanks. I have a couple of friends with non diving spouses who occasionally pick up tanks for their diving spouses. These are just a few reasons to have your own analyzer

[pridkett]

You don't need to calibrate using a regular tank, you are surrounded by 20.9% all around you, why would you calibrate using a regular tank. Unless you are testing your tank within 5m of a gas compressor with all its fumes.

WHat you need to do - once in a while - is calibrate (test) against an 100% O2 tank to make sure the O2 cell is healthy.


Actually, depending on the model, you do need to calibrate it. The reason is that some sensors need a flow of gas over them to ensure that they're getting the correct reading. Furthermore, humidity can affect a reading, so using air from a normal tank to calibrate can be really helpful here. My LDS also trained me to do this as another check to make sure the nitrox analyzer was working.

It doesn't appear that this sort of analysis is necessary with the Analox O2EII, but it does recommend calibration because of changes of pressure. There certainly isn't any harm in doing the additional check.

[Dive the World]

You are right pridkett - there is not harm in doing the additional check.