Hello folks,
I know DIR divers that won't dive in recreational depths w/o 30/30. Is it a safer gas, sure. Some may say its overkill, and others say nothing but a clean body upon exit, throw in O2 while you're at it too. Can you blame someone that wants to put premium gas in their car? Some treat their body's like Ferrari's and others like a Yugo (no offense to Yugo). I also know divers that won't use mix when EAN32 is just fine. Me thinks that the educated diver knows the limits of his gas both in depth and time. In the 60-120' range there are three gas options out there: EAN32, 30/30 and 21/35. Each has pros and cons. This X-over point is similar to pushing your gas requirements while determining the use of single vs doubles. In the 100-150 cf range there's a X-over point between singles and doubles. You can only push your limit so far based on gas, time and depth before you're required to go to the next level (requiring additional equipment and training). I'm holding END and PPO2 at a determined constant since we generally don't ride those hard, but for limited exposure, we can play with them slightly. Just like switching to doubles in order to have enough SUFFICIENT gas reserves toward the deeper end of recreational range, so too is the use of mix in these ranges.
Some considerations (not all inclusive):
-Extended MDL ADV (you get that at the 30-32% Nitrox)
-DECO efficiency (He), if you're approaching MDL or going beyond
-Depth flexibility (you loose that with O2 levels beyond 32% with Nitrox and increase with O2 levels at 21% and lower)
-Environmental conditions (how hard do you have to work?)
-Intended Exposure (time, which is related to depth)
-Access to gas
-Cost (this really should never factor in since we're talking about your life, but if you're just screwing off goign up and down on a skills dive, mix is kinda expensive). Some will disagree-ok.
Other things like depth restrictions on EAN32 kinda work themselves out with MDL time restrictions, so you you can spike PPO2 a little with some depth and lose a little with time. Obviously, you wouldn't want to do a deco dive in the rec range with EAN32. It's doable, but it's not as clean as with mix...from personal experience.
The thinking DIR diver is always making reasoned choices in and out of the water and always creating options. That diver is also hopeful that his teammates can come to an agreement on things like gas selection. The thinking diver also has opinions and some opinions are much stronger than other opinions. So, happy diving!
Sincerely,
H2
I know DIR divers that won't dive in recreational depths w/o 30/30. Is it a safer gas, sure. Some may say its overkill, and others say nothing but a clean body upon exit, throw in O2 while you're at it too. Can you blame someone that wants to put premium gas in their car? Some treat their body's like Ferrari's and others like a Yugo (no offense to Yugo). I also know divers that won't use mix when EAN32 is just fine. Me thinks that the educated diver knows the limits of his gas both in depth and time. In the 60-120' range there are three gas options out there: EAN32, 30/30 and 21/35. Each has pros and cons. This X-over point is similar to pushing your gas requirements while determining the use of single vs doubles. In the 100-150 cf range there's a X-over point between singles and doubles. You can only push your limit so far based on gas, time and depth before you're required to go to the next level (requiring additional equipment and training). I'm holding END and PPO2 at a determined constant since we generally don't ride those hard, but for limited exposure, we can play with them slightly. Just like switching to doubles in order to have enough SUFFICIENT gas reserves toward the deeper end of recreational range, so too is the use of mix in these ranges.
Some considerations (not all inclusive):
-Extended MDL ADV (you get that at the 30-32% Nitrox)
-DECO efficiency (He), if you're approaching MDL or going beyond
-Depth flexibility (you loose that with O2 levels beyond 32% with Nitrox and increase with O2 levels at 21% and lower)
-Environmental conditions (how hard do you have to work?)
-Intended Exposure (time, which is related to depth)
-Access to gas
-Cost (this really should never factor in since we're talking about your life, but if you're just screwing off goign up and down on a skills dive, mix is kinda expensive). Some will disagree-ok.
Other things like depth restrictions on EAN32 kinda work themselves out with MDL time restrictions, so you you can spike PPO2 a little with some depth and lose a little with time. Obviously, you wouldn't want to do a deco dive in the rec range with EAN32. It's doable, but it's not as clean as with mix...from personal experience.
The thinking DIR diver is always making reasoned choices in and out of the water and always creating options. That diver is also hopeful that his teammates can come to an agreement on things like gas selection. The thinking diver also has opinions and some opinions are much stronger than other opinions. So, happy diving!
Sincerely,
H2
