How many of you are doing Nitrox?
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scubakat
Senior Member
Darn... I guess I thought that Nitrox could bring world peace too.
-kate
-kate
Madder_Than_Hell
Guest
I always use NITROX on dives deeper than 60 fsw while spearfishing. It give a lot more botttom time for hunting those grouper and cobia. Plus the surface interval is much shorter.
For shallow water dives arount15 meters I dont think there is a lot of increased DCS risk between nirox vs. air even having a PFO.
So for those depths you might use air.
If going deeper, around 30 meters than i guess in would be better to use nitrox ( regarding DCS ).
So Madder_Than_Hell i agree with you.
Fa
So for those depths you might use air.
If going deeper, around 30 meters than i guess in would be better to use nitrox ( regarding DCS ).
So Madder_Than_Hell i agree with you.
Fa
blacknet
Contributor
Hello,
"NITROX breathing gas mixtures are normally used for shallow dives. The most benefit is gained when NITROX is used shallower than 50 fsw, but it can be advantageous when used to a depth of 140 fsw"
source USN dive manual vol 2, chap 10 section 1, paragraph 2.
Ed
"NITROX breathing gas mixtures are normally used for shallow dives. The most benefit is gained when NITROX is used shallower than 50 fsw, but it can be advantageous when used to a depth of 140 fsw"
source USN dive manual vol 2, chap 10 section 1, paragraph 2.
Ed
Ed,
I don't know how the US Navy defines benefit, but they've either made a mistake or there's a typo involved. At 50 ft or shallower, there's little benefit from nitrox. Using air on tables (using a computer magnifies this) few divers can get very close to their NDL's because they run low on air. Deeper than 50 ft, the NDL starts to become the limiting factor on bottom time. Nitrox benefits are most pronounced between 50 ft and around 130 ft. Shallower than 50 ft and your air/nitrox supply is usually the limiting factor. Deeper than 130 ft and your nitrox mix is so close to air, the additional bottom time becomes very small indeed. Nitrox is beneficial if used on shallow repetitive dives as a means to assist in off gassing.
WWW
I don't know how the US Navy defines benefit, but they've either made a mistake or there's a typo involved. At 50 ft or shallower, there's little benefit from nitrox. Using air on tables (using a computer magnifies this) few divers can get very close to their NDL's because they run low on air. Deeper than 50 ft, the NDL starts to become the limiting factor on bottom time. Nitrox benefits are most pronounced between 50 ft and around 130 ft. Shallower than 50 ft and your air/nitrox supply is usually the limiting factor. Deeper than 130 ft and your nitrox mix is so close to air, the additional bottom time becomes very small indeed. Nitrox is beneficial if used on shallow repetitive dives as a means to assist in off gassing.
WWW
blacknet
Contributor
Hello,
Not to talk bad here but the USN manual does NOT state 'practicality' they state facts. Those facts are true (just look at all the experiments done with 100% oxygen rebreathers at shallow depths and the new flying after diving and flying after oxygen breathing)
Benefits from nitrox at depths less than 50 fsw is primarly used for deco. This is highly advantageous. We are not just talking NDL here but total use of nitrox. (BTW for those who don't know 10-70 fsw is the standard deco depths for 0-130 fsw dives)
With out a doubt the most beneficial 'blend' of nitrox (for the standard entry level nitrox class) is 40% blend, it's depth limit is 80 fsw (exceptional 100 fsw and using 1.4 po2 max).
However, to at of 130 fsw a blend of 28% is best. The average of these is 34% (MOD 100 fsw at 1.4 po2) NOAA I and NOAA II are average best used all around blends of nitrox and readily available.
To say for the "NDL diver" or "NO DECO diver" nitrox with conventional blends (I.E. NOAA I and NOAA II) is advantageous to the sport divers depths (here sport divers depth meaning standard ow max limits of 90 fsw). However for the true benefits of nitrox lies in the decompression realm of less than 50 fsw.
Anothe thing to consider is that nitrox deeper than 2 atm has similar EAD numbers to the ABD (Acutal bottom depth). I.E. a 40% blend at 80 fsw has a MOD of 60 fsw while a 34% blend at 90 fsw has a MOD of 80 fsw.
Ed
Not to talk bad here but the USN manual does NOT state 'practicality' they state facts. Those facts are true (just look at all the experiments done with 100% oxygen rebreathers at shallow depths and the new flying after diving and flying after oxygen breathing)
Benefits from nitrox at depths less than 50 fsw is primarly used for deco. This is highly advantageous. We are not just talking NDL here but total use of nitrox. (BTW for those who don't know 10-70 fsw is the standard deco depths for 0-130 fsw dives)
With out a doubt the most beneficial 'blend' of nitrox (for the standard entry level nitrox class) is 40% blend, it's depth limit is 80 fsw (exceptional 100 fsw and using 1.4 po2 max).
However, to at of 130 fsw a blend of 28% is best. The average of these is 34% (MOD 100 fsw at 1.4 po2) NOAA I and NOAA II are average best used all around blends of nitrox and readily available.
To say for the "NDL diver" or "NO DECO diver" nitrox with conventional blends (I.E. NOAA I and NOAA II) is advantageous to the sport divers depths (here sport divers depth meaning standard ow max limits of 90 fsw). However for the true benefits of nitrox lies in the decompression realm of less than 50 fsw.
Anothe thing to consider is that nitrox deeper than 2 atm has similar EAD numbers to the ABD (Acutal bottom depth). I.E. a 40% blend at 80 fsw has a MOD of 60 fsw while a 34% blend at 90 fsw has a MOD of 80 fsw.
Ed
The Chairman
Chairman of the Board
but if they would only comb their hair right...
Hey all,
At 33 fsw where we double the pressure for double the fun, air gives us the partial pressure of N2 (PPN2) of 1.58 atm which is of course (by definition even-duh) twice the hit at the surface. At 99 fsw the PPN2 is 3.16 atm.
In contrast, an EAN36 mixture gives us a PPN2 of 1.28 atm which is a full thirty points less! Every additional 33 fsw of depth will see the difference widen by another 0.15 atm. So at a depth of 99fsw it gives you a PPN2 of 2.56 atm or an Air Equivalency Depth (AED) of 74 fsw. So I have to agree that the deeper you go the bigger the benefit.
As a caveat, the Maximum operating depth (MOD) of an EAN36 is only 95 fsw, and just up to 113 fsw in an emergency, so please don't plan a dive to 99 fsw on it. The maximum O2 you should plan a safe dive to a 99 fsw would be a 35% EAN mixture.
:all:
Hey all,
At 33 fsw where we double the pressure for double the fun, air gives us the partial pressure of N2 (PPN2) of 1.58 atm which is of course (by definition even-duh) twice the hit at the surface. At 99 fsw the PPN2 is 3.16 atm.
In contrast, an EAN36 mixture gives us a PPN2 of 1.28 atm which is a full thirty points less! Every additional 33 fsw of depth will see the difference widen by another 0.15 atm. So at a depth of 99fsw it gives you a PPN2 of 2.56 atm or an Air Equivalency Depth (AED) of 74 fsw. So I have to agree that the deeper you go the bigger the benefit.
As a caveat, the Maximum operating depth (MOD) of an EAN36 is only 95 fsw, and just up to 113 fsw in an emergency, so please don't plan a dive to 99 fsw on it. The maximum O2 you should plan a safe dive to a 99 fsw would be a 35% EAN mixture.
:all:
In my country military divers use nitox with a maximal po2 until 2,2 ata, with a facial full mask (a case of convulsion they would stay dry). It means they use nitrox at his maximum limits (maximal depth and bottom time).
Well yes I said 2,2 ata and not in a dry chamber...
As a sport diver we can use nitrox of course to improve bottom time or use it on air table to improve security.
But you also have to watch to %age of o2 exposure.
At shallow depts. nitrox is useful if you really want to increases bottom time ( for some professional divers staying several hours down ) the limited factor becomes than the o2 toxicity.
Some scientific divers i know use a twin bottles set of nitrox to stay longer down to be able to perform their research work. But there are some other factors that limit the bottom time : cold, fatigue ( on nitrox tables )
Another use is off course the to use nitrox as a decompression gas ( with high %age of o2)
Well yes I said 2,2 ata and not in a dry chamber...
As a sport diver we can use nitrox of course to improve bottom time or use it on air table to improve security.
But you also have to watch to %age of o2 exposure.
At shallow depts. nitrox is useful if you really want to increases bottom time ( for some professional divers staying several hours down ) the limited factor becomes than the o2 toxicity.
Some scientific divers i know use a twin bottles set of nitrox to stay longer down to be able to perform their research work. But there are some other factors that limit the bottom time : cold, fatigue ( on nitrox tables )
Another use is off course the to use nitrox as a decompression gas ( with high %age of o2)
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