a few nitrox questions...need help please...

[JackSpearo]

I'm doing a few nitrox questions and I need some help... can someone who is good with the nitrox tables PM me and I'll ask them the questions (see if my answer is correct) (it's just a few questions)...

would be very very appreciated!

thanks...

Jack

 

[Blackwood]

Ask on the public boards.

If they are table questions, be sure to specify which tables you are using.

 

[wedivebc]

I'm doing a few nitrox questions and I need some help... can someone who is good with the nitrox tables PM me and I'll ask them the questions (see if my answer is correct) (it's just a few questions)...

would be very very appreciated!

thanks...

Jack

If you post them on the board we can all learn from them

 

[JackSpearo]

here are the probs...

1) Use the CNS "clock" time table to calculate the percentage of oxygen exposure for a dive to 100ft/30m, for 20 minute using EAN32
would the answer be 11 percent?

2) using the SSI combined air/eanx tables plan the following dives to determine the final group after the second dive. Using EAN36, dive no. 1 to 72ft/22m to the maxiumum allowable no-decompression limit, followed by a one hour surface interval. Dive No.2 to 70 ft/21 m, for the maximum allowable no-decompression limit.
would this answer be group G?

3) two divers want to make two dives photographing a shipwreck at 101/31m using ean30. they want 20 minutes bottom time on the first dive and need a two hour surface interval to change film and have lunch. plan the dives using the equivalent air depths table and the SSI doppler no-decompression limits air tables to determine the maximum adjusted no decompression limit for the second dive.
not sure about this one, but i'm guessing 16 percent?

4) using the two dives in the question 3, calculate the CNS "clock" exposures to determine the total exposure for the two dives.
dunno about this one...the multiple choice for this are: 12,16,19,15....

thanks a lot...

Jack

 

[ronbeau]

I'm doing a few nitrox questions and I need some help... can someone who is good with the nitrox tables PM me and I'll ask them the questions (see if my answer is correct) (it's just a few questions)...

would be very very appreciated!

thanks...

Jack

I am more than willing to help you out but I agree with the others. Please post your questions publically so others may get the benefits of your question and the answers you receive.

 

[Meng_Tze]

here are the probs...

1) Use the CNS "clock" time table to calculate the percentage of oxygen exposure for a dive to 100ft/30m, for 20 minute using EAN32
would the answer be 11 percent?

2) using the SSI combined air/eanx tables plan the following dives to determine the final group after the second dive. Using EAN36, dive no. 1 to 72ft/22m to the maxiumum allowable no-decompression limit, followed by a one hour surface interval. Dive No.2 to 70 ft/21 m, for the maximum allowable no-decompression limit.
would this answer be group G?

3) two divers want to make two dives photographing a shipwreck at 101/31m using ean30. they want 20 minutes bottom time on the first dive and need a two hour surface interval to change film and have lunch. plan the dives using the equivalent air depths table and the SSI doppler no-decompression limits air tables to determine the maximum adjusted no decompression limit for the second dive.
not sure about this one, but i'm guessing 16 percent?

4) using the two dives in the question 3, calculate the CNS "clock" exposures to determine the total exposure for the two dives.
dunno about this one...the multiple choice for this are: 12,16,19,15....

thanks a lot...

Jack

So you get the answers on this forum..... what have you learned?

 

[whoji]

So you get the answers on this forum..... what have you learned?

To be fair the OP did state he wanted to cross check his answers to see if they were correct, I take it from this has already answered them.

 

[Meng_Tze]

To be fair the OP did state he wanted to cross check his answers to see if they were correct, I take it from this has already answered them.

Fair enough.

 

[JackSpearo]

pretty please?

 

[Dan Watkins]

1. First you solve for your PPO2 at 100 feet with a FO2 of .32. Your PPO2 is approx. 1.3. According to this table if you stay 20 min. at a PP02 of 1.3, your answer is 11%, you are correct.

2. I don't have the SSI Tables, I only have NAUI sorry.

3. Again, no SSI tables, sorry, but to me it looks like the question is asking how long you can stay at that depth on the second dive and not go into deco. So I think it is asking for a time answer, not a percent answer if I understand correctly. Equivalent Air Depth of 101 feet with EAN30 is an air depth of 85.73 feet. On my NAUI tables I would round up to 90 feet. After a 20 minute dive and a 2 hour surface interval, at an equivelent air depth of 90 feet I would be allowed to stay for 9 minutes on my next dive.

4. 101 feet with a FO2 of .3 yields a PPO2 of 1.22. So I assume you round up to 1.25 to be more conservative. 20 minutes yields 10% on the first dive according to the table linked above. If I remember correctly each hour of surface interval, your % is cut in half so 5% for the first hour, and then down to 2.5% after the 2nd hour. If the NAUI table matches the SSI table and says your next dive is only 9 minutes, that would be roughly 5% rounding up (from the same table linked above), add the 2.5% from the prior dive and its 7.5%. Your multiple choice is 12,16,19,15, so I am guessing the SSI tables may allow for a longer 2nd dive? If not maybe someone else can point out where I went wrong here. My guess is 12 since it is the lowest option.