IT IS BAD ENOUGH TO HAVE TO USE THE EAD WHEEL BUT THAT ONLY TAKES YOU TO 21 PERCENT, NOT TO OTHER MIXTURES. IT IS REALLY A PAIN TO HAVE TO USE THE EAD FOR THE FIRST DIVE BECAUSE YOU TANK HAS A 27% MIX TO START.CONSERVATISM IS GREAT WHEN ALL ARE ON DIFFERENT GAS TABLES AND AN END DIVE TIME IS ESTABLISHED. MY DIVE SHOP TELLS ME THAT I CAN NOT GO FROM 36 TO 32 TO 21 MIXES USING THE TABLES. I DONT KNOW IF I BUY THAT. I THINK I CAN USE THE EAD TO CONVERT FROM ONE TABLE TO ANOTHER THROUGH THE 21 TABLE. I WILL ADMIT THAT MOST PROBABLY YOU WOULD GO FROM NITROX TO AIR AS A NORM AND NO THOUGHT BEYOND THAT IS GIVEN. THIS STILL LEVES ME WITH THE CASE OF THE FIRST DIVE BEING ON OTHER THAN 32 OR 36 AND HAVING TO USE THE CONVERSIONS TO THE 21 TABLE TO DO A ROUGH PLAN. I DO KEEP MY TANKS LABLED FOR THE REASONS STATED BY OTHERS AND WITH THE HOME MIXERS AROUND I DONT BLINDLY SHARE TANKS OR EQUIPMENT. I WAS HOPING TO BE ABLE TO HAVE A ,SAY< 27% TABLE TO START WITH AND AVOID THE EAD'S ON THE FIRST DIVE AND THE NUMBER JOCKYING THAT IS THE SEED FOR TROUBLE. ILL CHECK THE OTHER REFERENCES MENTIONED BY SOME OF YOU. THANKS.
dive tables
- Thread starter NAM001
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You can definitely convert between any Nitrox mix and the air tables, and you can also compute the MOD by simply computing the PPO2 of the O2 in the mix at a given depth.
No big deal.
Which shop/agency is telling you otherwise? This one I'd love to hear....
No big deal.
Which shop/agency is telling you otherwise? This one I'd love to hear....
As many things as Genesis and I vehemently disagree on, he is right here (and on most of the actual diving information that he quotes).
MOD is very simple to figure out. Just figure out where your 27 percent (for example) hits a 1.4 ATA. In this 1.4 ATA/.27 will give you roughly 5.18 ATA. Subtract 1 ATA for atmospheric and multiply by 33. This gives you 4.18 x 33 fsw which is roughly 138 fsw MOD at 1.4 ATA.
EAD can be figured by the tables that most agencies use for nitrox training. Figure your EAD and use air tables and you all set.
The only catch may be in figuring your CNS clock, but that was covered in my nitrox training as well and you need to dive pretty agressively to hit a CNS clock problem. This is normally an issue that is hit in tech diving training when using mixes with a higher FO2 to accelerate decompression. It is not a typical issue when diving within NDL's.
MOD is very simple to figure out. Just figure out where your 27 percent (for example) hits a 1.4 ATA. In this 1.4 ATA/.27 will give you roughly 5.18 ATA. Subtract 1 ATA for atmospheric and multiply by 33. This gives you 4.18 x 33 fsw which is roughly 138 fsw MOD at 1.4 ATA.
EAD can be figured by the tables that most agencies use for nitrox training. Figure your EAD and use air tables and you all set.
The only catch may be in figuring your CNS clock, but that was covered in my nitrox training as well and you need to dive pretty agressively to hit a CNS clock problem. This is normally an issue that is hit in tech diving training when using mixes with a higher FO2 to accelerate decompression. It is not a typical issue when diving within NDL's.
Manfred
Registered
There are conversion tables available you can use for any mix.
Padi has them in a kit. You will have to analize your gas to know what percent O2 you have and go from there.
Padi has them in a kit. You will have to analize your gas to know what percent O2 you have and go from there.
chrpai
Contributor
Sorry Charlie, ( lol no pun intended ) but I wouldn't trust that table you quoted farther then I could throw it.
First they use 1.6 for MOD calcs instead of 1.4 and then it has very liberal calculations for No-D time.
For example it says MOD for 36% is 113'. Now lets say you want to dive a Max 1.4 so thats 95'. The chart you quote will give you an EAD of 70' and an NDL of 50 minutes.
Now PADI AIR RDP will only give me 40 minutes at 70' and the Nitrox 36 tables planning for 94 ( rounded to 100 ) will only give me 35 minutes. My Suunto Mosquito will only give me 38 minutes at 94' on 36%.
Doesn't seem like good diving to me....
scubasean
Contributor
I've operated on the premise that more info is generally better than less, especially when my life may depend on the info being shared.
Charlie99
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I gave the URL because it is unique in that it is a REVERSE EAD table.
This eliminates rounding up to the next 10' increment, but at the expense of having weird depth steps in your new table: ie 94' /40 minutes, 81' / 55 minutes, 69' / 80 minutes in the the case of EAN36.
The original poster was looking for tables for EAN other than 32 and 36. This reverse EAD table gives him an easy way to generate those tables.
The table happened to include the Navy (pre-doppler) NDLs and 1.6 MOD for convenience. Use them or ignore them as desired.
Personally, I prefer to stay with the PADI/DSAT table, so I generated a modified table that just covers 30-40%, has PADI NDLs, and adds 1.4ata ppO2 MODs. On the other hand, I also added a 2.0ata PPO2 "emergency depth".
Don't forget that the danger of a CNS hit is determined by both the ppO2 AND the exposure DURATION. At 36%, if you stay within NDL, you will never get close to CNS limits, even with 1.6ppO2 max. In your case though Chris, your Suunto will run up the CNS clock so fast that you need to stay below 1.4 to keep it happy.
An acute PO2 of 1.6 or above is no guarantee of an oxygen toxicity hit, but you are running a real high risk of it if you hit that PO2 for more than a couple of minutes. Ask the widows/widowers of some very experienced divers who thought that they knew more than the Navy on this.
Like everything else, these are theoretical limits based on various conditions and most divers try to stay on the conservative side of them. If you run a severely high PO2, even if you stay in NDL's you are risking a hit. This is all risk. There is no guarantee that you will have a problem, but it is safe bet that sooner or later you will if you keep pushing into PO2 limits.
Yes, the time is a factor. That is shown by the "CNS clock" and is normally reflected on repetitive dives similar to residual nitrogen except the excess oxygen does not off-gas at the same rate. For normal recreational diving, one can do the math and see that unless you are on a live-aboard diving rich nitrox mixes, you probably won't have a problem with it. But it is something to look at.
So don't underestimate either component in avoiding an oxygen toxicity hit. Either one can get a diver into real trouble real fast. Obviously pushing both components at the same time is trying to shake Mr. Murphy's hand and invite him along as your dive buddy.
Like everything else, these are theoretical limits based on various conditions and most divers try to stay on the conservative side of them. If you run a severely high PO2, even if you stay in NDL's you are risking a hit. This is all risk. There is no guarantee that you will have a problem, but it is safe bet that sooner or later you will if you keep pushing into PO2 limits.
Yes, the time is a factor. That is shown by the "CNS clock" and is normally reflected on repetitive dives similar to residual nitrogen except the excess oxygen does not off-gas at the same rate. For normal recreational diving, one can do the math and see that unless you are on a live-aboard diving rich nitrox mixes, you probably won't have a problem with it. But it is something to look at.
So don't underestimate either component in avoiding an oxygen toxicity hit. Either one can get a diver into real trouble real fast. Obviously pushing both components at the same time is trying to shake Mr. Murphy's hand and invite him along as your dive buddy.
Charlie99
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Navy or NOAA? NOAA limit is 45 minutes at 1.6. What is the Navy limit?
What is your personal depth limit if your buddy or another diver is in trouble below your 1.4 MOD?
The Navy had the orginal standards on this, so that is the term that I used.
IANTD preaches 1.4 in cold water and actually swimming/working.
A PO2 of 1.6 is acceptable for decompression hangs when you aren't working. The IANTD standards recommend no higher than a working PO2 of 1.5 regardless of water conditions. Seeing that I live in Michigan, you can guess that I use the 1.4 and 1.6. I use the 1.5 in the Caribbean if I want to take pictures and the fish happens to want to hide just below my 1.4 MOD. I am typically just floating waiting for Mr./Ms. Fishie to come out and give me a good shot anyways in that case.
IANTD preaches 1.4 in cold water and actually swimming/working.
A PO2 of 1.6 is acceptable for decompression hangs when you aren't working. The IANTD standards recommend no higher than a working PO2 of 1.5 regardless of water conditions. Seeing that I live in Michigan, you can guess that I use the 1.4 and 1.6. I use the 1.5 in the Caribbean if I want to take pictures and the fish happens to want to hide just below my 1.4 MOD. I am typically just floating waiting for Mr./Ms. Fishie to come out and give me a good shot anyways in that case.
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