Nitrox question

[dwndeep]

i just finished up my nitrox cert. i have 3 al 80 tanks set up for air use and i just bought a hp120 for nitrox use my question is can use the 120 at say 32% for one dive then switch to the 21% mixes for last 2 dives. i dont have the cash right now to buy 3 hp 120s so im looking at 1 a month for the next 3 months

 

[OE2X]

i just finished up my nitrox cert. i have 3 al 80 tanks set up for air use and i just bought a hp120 for nitrox use my question is can use the 120 at say 32% for one dive then switch to the 21% mixes for last 2 dives. i dont have the cash right now to buy 3 hp 120s so im looking at 1 a month for the next 3 months

Absolutely. Make sure you dive your 32% on your first dive. If you use a computer then make sure to reset it to 21% for your next dives.
If you want to use 32% for your other two dives - it's pretty easy to get your AL80's O2 cleaned and ready to go for nitrox.

 

[Otter]

and....depending on how they fill nitrox, you MIGHT not even need to get them O2 cleaned.....if they use a membrane system or premix.

 

[dwndeep]

thanks otter, i plan on having my 80s o2 cleaned but have a trip for thursday and they are already filled and im picking up the 120 on tuesday filled to ean32.
what is the going rate to have tanks 02 cleaned i assume this also covers the yearly vip

 

[bedmund]

Absolutely. Make sure you dive your 32% on your first dive. If you use a computer then make sure to reset it to 21% for your next dives.

If you dove 21% first, you don't have the same limitations on depth and you could stay diving standard profiles as opposed to looking at doing inverse profiles. Also, the additional O2 at the end of the day in the 32% might help in the off-gassing. (?)

-Bill

 

[Stryker]

Can someone explain to me why you need "special tanks" for nitrox if it is still the same gas inside with just a higher oxygen concentration.... That and why would you need to get a tank O2 cleaned to switch it to nitrox? Thanks!

 

[OE2X]

If you dove 21% first, you don't have the same limitations on depth and you could stay diving standard profiles as opposed to looking at doing inverse profiles. Also, the additional O2 at the end of the day in the 32% might help in the off-gassing. (?)

-Bill

For me I rather do my deep dive first on 32% and lessen my nitrogen loading. All my subsequent dives get progressively shallower (and if I can't dive again on 32%) then 21% is the choice.

I'm not sure what depth you advocate diving 21% on. For me I keep it to under 100'. Where as up to 32% I'll go deeper.

 

[lamont]

Can someone explain to me why you need "special tanks" for nitrox if it is still the same gas inside with just a higher oxygen concentration.... That and why would you need to get a tank O2 cleaned to switch it to nitrox? Thanks!

i just learned there may be a little bit of debate over this, but even if your tanks aren't seeing over 40% O2 the tank neck o-ring should be viton to prevent degradation and should use O2 compatible lube (christo-lube).

if you're seeing 100% O2 you should go through the whole O2 cleaning process to make sure there's no hydrocarbons in the tank or valve that could provide fuel to an O2 fire.

 

[Stryker]

so to clarify this, you are telling me that if you use a low O2 content nitrox mix that it SHOULD be ok to use with a tank you use 21% on also?

 

[OE2X]

so to clarify this, you are telling me that if you use a low O2 content nitrox mix that it SHOULD be ok to use with a tank you use 21% on also?

Yes. Just make sure that any 21% is hyperair or hyperfiltered. You won't compromise your nitrox rating then.

What Lamont said is correct. Most shops that blend will add 100% onto the existing gas in the tank or they will first add hyperair and then blend 100%.