First Time Nitrox

[sea_ledford]

4 pages and no one has mentioned how precise an O2 analyzer is? +/- 1.5 is what I remember off the top of my head, and that is assuming it was calibrated correctly in the first place.

In theory rounding to safety is the correct thing to do, in reality round up or round down, it is completely irrelevant. Don't try to measure a football field with your cars odometer.

-Chris

 

[Storker]

4 pages and no one has mentioned how precise an O2 analyzer is? +/- 1.5 is what I remember off the top of my head, and that is assuming it was calibrated correctly in the first place.

In theory rounding to safety is the correct thing to do, in reality round up or round down, it is completely irrelevant. Don't try to measure a football field with your cars odometer.

-Chris

Which gives some perspective to an earlier claim that rounding the wrong way could have fatal consequences for a tech dive...

 

[USMC CPL.]

I feel that my OW class was no where near thorough enough. I felt very unprepared for my first dive after my check out dives and I'm glad I did a refresher with an instructor. I have learned way more from reading online and from DMs.

So when the DM told me to just consider the 33.5 tank as 32, I thought this was negligence, but now looking back on it, it is possible she wanted me to consider it as 32 for safer NDLs since we would not be near our MOD.

Remember when you get a nitrox fill be at the fill station and visibly verify the % of mix you are getting. I took my course here in Az with SSI and my instructor made it a point that the diver needs to verify what mix he or she is getting due to O2 toxicity.

 

[tbone1004]

4 pages and no one has mentioned how precise an O2 analyzer is? +/- 1.5 is what I remember off the top of my head, and that is assuming it was calibrated correctly in the first place.

In theory rounding to safety is the correct thing to do, in reality round up or round down, it is completely irrelevant. Don't try to measure a football field with your cars odometer.

-Chris

they aren't quite that bad. It's quite late over here, but I know it isn't +1.5 on the PO2

@topher10 Many believe in EAN32 being the ideal gas mix. The standard gases are based on creating roughly the same PO2 and PN2 as EAN32 when breathed at 4ata/100ft. It's a good balance between cost/narcosis/deco efficiency/etc etc
Air has it's place though, it's super cheap and if you aren't getting any ndl benefit from diving nitrox, then I just dive air. Saves quite a bit of money in certain parts of the world

 

[BRT]

Remember when you get a nitrox fill be at the fill station and visibly verify the % of mix you are getting. I took my course here in Az with SSI and my instructor made it a point that the diver needs to verify what mix he or she is getting due to O2 toxicity.

You do need to verify your mix. You don't want to be diving air when you think it is 32%. You don't want to be diving 50% thinking it is 32%. 32% to 34% is in the error range of the analyzer and in the foggy area of the NDL's and O2 toxicity tables.

 

[barth]

Which gives some perspective to an earlier claim that rounding the wrong way could have fatal consequences for a tech dive...

For ean50 or ean100 it doesn't matter for me...

The lower the oxygen percentage the more important analyser, calibration etc becomes.

But for ean32 it also doesn't matter for me. I don't understand why people care so much about rounding for ean32.

 

[uncfnp]

I agree it likely makes little *in the real world* difference though I do wonder if it would hold true through my 3 to 4 dives a day/7 day dive trips. And I admit to diving a higher MOD then some and a tighter NDL.

But why purposely add even less precision (to the less *safe* side) to an already imprecise procedure.

 

[NAM001]

If i have 32.5 mix I use 33 for mod and 32 for ndl. 32 goes into the computer... If i had any reason to tink i was close to the O2 limit ii would round up for NDL. Seldom is O2 the driving factor to remaining dive time.

 

[barth]

I agree it likely makes little *in the real world* difference though I do wonder if it would hold true through my 3 to 4 dives a day/7 day dive trips. And I admit to diving a higher MOD then some and a tighter NDL.

But why purposely add even less precision (to the less *safe* side) to an already imprecise procedure.

For me my mod for ean32 is just 30m/100 feet. I got a lot of tanks. When doing a dive which requires stages the mod is already on the tank. It says 30m I don't care if the analyzing was 30,5 or 34,0. some people are writing down the mod on every tank for every dive.

We plan the dive and it is easy to remember the mod for me and my buddy's. Because we all use the same mod of 30m/100 feet for ean32.

When we adjust the diveplan underwater we all mean how much deco we have and how much decogas we will need. Because we all use the same parameters. And we always use that parameters.

For techdiving you are using a lot of gasses. It is almost impossible to have a table with the right percentage of all the gasses.

If my bottomtimer fails at the end of the dive I can just check my buddy's bottomtimer. It is no problem if my bottomtimer fails.

It is just a choice which is made by me and my buddy's. I accept it is less accurate. But it make diving and planning much easier for me.

 

[IBjones]

I woulda used Nitrox as well. Firstly, Scuba certainly isn't a sport you get into if you're concerned about pinching pennies.

Secondly at 50 feet I'll never be able to reach the OPP tox level at 50 feet anyway before I run out of gas on two dives. At 50 ft I'm at .80 OPP. At .80 OPP I'd have to be diving for 7.5 hours to reach a 100% OxTox level. For me, about all I get from a 80 is 60 minutes at 40 feet. So I'd have to be at depth for over 7 hours in that 24 hr period. Could be done I guess over a 24 hour period if you were a real busy diver like on a weekend live aboard or something.