1.4 vs 1.6

[jsmith89]

First off Happy New Year Everybody!!!

Ok, I am currently taking TDI's adv nitrox course and had a question for everyone here. I know padi teaches that 1.4 ppO2 as the max but TDI teaches it as 1.6 ppO2 (actual average toxic limit). My question which do you use for your dive planning, which do you think is better to use and why?

 

[dschonbrun]

1.4 is more conservative, 1.6 more liberal. It is a personal choice.

Part of the issue is that every individual responds to oxygen levels differently... so in order for you to know which to use, you need to push your own body to limits under controlled circumstances, with Medical supervision. Most people aren't willing to do that.

 

[DeepBound]

Just about everyone uses 1.4. The TDI manual is rather out of date. The TDI advanced nitrox and deco manual says to use 1.4 as your MOD, and 1.6 only for decompression stops.

 

[H2Andy]

as a safety measure, i plan the active parts of the dive on 1.4 and the restful part of the dive (deco stops) on 1.6

would it be safe to do both on 1.6? probably yes ... but hey, it doesn't hurt to add a little bit of extra safety in there

heck, you could probably get away with 1.8 on most dives ... but that would further cut back on your safety margin ... and ... you never know ...

the bottom line for me is that it isn't a clear-cut line. i do 1.4/1.6 but just as easily could do 1.6/1.8, but why push it? what am i going to gain, really?

i'd rather have some margin of error on the safe side

 

[dannobee]

Because of some recent ox tox cases, some people are going even lower; 1.2 max on the dive and 1.6 only for deco. GUE recommends 1.2 for the bottom gas, FWIW.

 

[H2Andy]

it's funny that you should mention that, because most of my actual PPO2's are right below 1.2

they just work out that way with the depths i dive and the gas mix i mostly use (32%). i wasn't aware GUE recommends 1.2

but i calculate my max depth (which i usually dont' get close to) using 1.4

 

[rawls]

I agree with Andy...I have my advanced nitrox through TDI. It was a great course. As Andy said...1.4 for the working part of the dive and 1.6 for the resting part....

 

[Colliam7]

... to use 1.4 as your MOD, and 1.6 only for decompression stops.

This appears to be a common practice. I use 1.4 for the 'working' MOD and 1.6 during deco stops, when not exerting to any signficant extent.

 

[Charlie99]

Exposure TIME is a factor also. The longer the exposure time (either with or without air breaks), the more conservative you should be.

 

[dab]

bottom mix = 1.4, deco stops = 1.6

pretty standard.