28% Nitrox
- Thread starter James228
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Blackwood
Contributor
Did you learn about EAD in your nitrox course?
Knock it down to 21
You likely won't find a table for specific Nitrox blends other than 32% and 36%. You have two options:
1: work out the EAD (equivalent air depth) and then use air tables. You should have been taught this approach in your Nitrox course.
2: use a deco program to cut you a custom table for 28%.
The second is slightly more involved as it involves finding a suitable program, learning how to use it and cutting a table correctly. The first you should be able to do easily as it only involves a simple calculation (which you should have been taught to do) and then using air tables like you always would.
Edit: I see that Blackwood beat me to it.
1: work out the EAD (equivalent air depth) and then use air tables. You should have been taught this approach in your Nitrox course.
2: use a deco program to cut you a custom table for 28%.
The second is slightly more involved as it involves finding a suitable program, learning how to use it and cutting a table correctly. The first you should be able to do easily as it only involves a simple calculation (which you should have been taught to do) and then using air tables like you always would.
Edit: I see that Blackwood beat me to it.
DevonDiver
N/A
PADI don't make such tables. As others have stated, you are expected to calculate the EAD and use Air tables for the dive.
Here's a reminder... from Wiki http://en.wikipedia.org/wiki/Equivalent_air_depth
Calculations in metres
The equivalent air depth can be calculated for depths in metres as follows:
EAD = (Depth + 10) × Fraction of N2 / 0.79 − 10 Working the earlier example, for a nitrox mix containing 64% nitrogen (EAN36) being used at 27 metres, the EAD is:
EAD = (27 + 10) × 0.64 / 0.79 − 10 EAD = 37 × 0.81 − 10 EAD = 30 − 10 EAD = 20 metres So at 27 metres on this mix, the diver would calculate their decompression requirements as if on air at 20 metres.
Calculations in feet
The equivalent air depth can be calculated for depths in feet as follows:
EAD = (Depth + 33) × Fraction of N2 / 0.79 − 33 Working the earlier example, for a nitrox mix containing 64% nitrogen (EAN36) being used at 90 feet, the EAD is:
EAD = (90 + 33) × 0.64 / 0.79 − 33 EAD = 123 × 0.81 − 33 EAD = 100 − 33 EAD = 67 feet So at 90 feet on this mix, the diver would calculate their decompression requirements as if on air at 67 feet.
Here's a reminder... from Wiki http://en.wikipedia.org/wiki/Equivalent_air_depth
Calculations in metres
The equivalent air depth can be calculated for depths in metres as follows:
EAD = (Depth + 10) × Fraction of N2 / 0.79 − 10 Working the earlier example, for a nitrox mix containing 64% nitrogen (EAN36) being used at 27 metres, the EAD is:
EAD = (27 + 10) × 0.64 / 0.79 − 10 EAD = 37 × 0.81 − 10 EAD = 30 − 10 EAD = 20 metres So at 27 metres on this mix, the diver would calculate their decompression requirements as if on air at 20 metres.
Calculations in feet
The equivalent air depth can be calculated for depths in feet as follows:
EAD = (Depth + 33) × Fraction of N2 / 0.79 − 33 Working the earlier example, for a nitrox mix containing 64% nitrogen (EAN36) being used at 90 feet, the EAD is:
EAD = (90 + 33) × 0.64 / 0.79 − 33 EAD = 123 × 0.81 − 33 EAD = 100 − 33 EAD = 67 feet So at 90 feet on this mix, the diver would calculate their decompression requirements as if on air at 67 feet.
Blackwood
Contributor
I believe IANTD has tables for a multitude of blends other than I and II. IMO, if you aren't teaching IANTD nitrox, they offer questionable value.
Concur with previous posts on choices available to you...EAD/air tables and deco/dive planning software. You can download, for example, Suunto dive manager from their website which includes a tool call dive planner which allows you to configure it for whatever mix of interest and plan the profiles you may have in mind.
Other tool you could perhaps use...the dive planning function of your dive computer, if so equipped (and Nitrox compatible). If you just enter 28% in your Nitrox function and then switch to your dive planner, it should provide you with NDL for the various depths you are contemplating (square profile only).
For multilevel and repetitive dives..I would revert to a dive planning software.
Other tool you could perhaps use...the dive planning function of your dive computer, if so equipped (and Nitrox compatible). If you just enter 28% in your Nitrox function and then switch to your dive planner, it should provide you with NDL for the various depths you are contemplating (square profile only).
For multilevel and repetitive dives..I would revert to a dive planning software.
Use either END or dive planning software like v-planner.
What is your max depth and bottom time planned?
What is your max depth and bottom time planned?
paddler3d
Guest
The MOD for EAN 28 at a ppO2 of 1.4 is 132fsw, which is at the accepted limits of recreational diving.
If you are asking the question, you may want to question if you are ready for such a dive?
If you are asking the question, you may want to question if you are ready for such a dive?
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