preparing for Nitrox / air dives

[disco1999]

I am planning 2 dives in a quarry water temp: 50f.
The 1st one at 130' and the 2nd one at 90' after 1 hour surface interval.
I have one 119cf steel tank for nitrox mix and the other is a casual 80cf air tank

Question . . . what is the safest setup...? OR does it really matter ? comments ?

1st Dive Nitrox EANx28 / 2nd dive Air
or
1st Dive Air / 2nd dive Nitrox EANx36

 

[Tortuga68]

I would dive EAN28 first. Not really safer but you'll get better bottom times & reduced N2 loading. Plus you're using your bigger tank for the deeper dive

OTOH you'll be right on the MOD for the first dive (I'm assuming EAN36 was a typo in the second option?)

BTW it's either EANx (Nitrox) or EAN28... not EANx28 - the x indicates the variable which is defined by the 28

 

[disco1999]

Thanks for the info, the question was also to decide either to fill with EAN36 or EAN28, so I'll go with 28

If nitrox tank was smaller than the air, would you go with nitrox smaller tank for the deeper dive anyways ?

 

[Bob DBF]

I always go for the bigger tank for deep dives, more air can come in handy. In addition, should I do gas planning, it may be mandatory.


Bob
------------------------------
I may be old, but I’m not dead yet.

 

[DevonDiver]

As Bob said; your gas management will probably dictate the size of cylinder needed for the deeper dive. The mix used would come secondary, unless your dive plan/objective was strict and required a set bottom time that would otherwise be limited by air NDL.

The best bet is to calculate and compare your predicted air consumption/gas supply against the air/nitrox NDLs.

 

[DaleC]

Really? You're asking which tank you should take to 130', a 130cuft or an 80cuft. You're wondering if you should have EAN 36 or 28 for that dive.
I think you should call up your nitrox instructor and ask for your money back.

 

[disco1999]

Really? You're asking which tank you should take to 130', a 130cuft or an 80cuft. You're wondering if you should have EAN 36 or 28 for that dive.
I think you should call up your nitrox instructor and ask for your money back.

I think you read too fast. . . .
It's a 119cuft, not a 130 and
I've never said I wanted to dive @130' with EAN36
and I fully understand MOD, chill man.

 

[Blackwood]

What they said: deeper dive with the bigger cylinder. If partial pressure cleanliness requirements restict the contents, so be it.

BTW it's either EANx (Nitrox) or EAN28... not EANx28 - the x indicates the variable which is defined by the 28

Depends on who you ask. Some people abbreviate Nitrox "Nx" (and trimix "Tx").

 

[disco1999]

Depends on who you ask. Some people abbreviate Nitrox "Nx" (and trimix "Tx").

Thanks for the appropriate replies guys.

In PADI Enriched air diving manual it states "EANx32" "EANx36" throughout the whole book.
I believe both ways is universal

 

[RTee]

Disco...better yet. Do the first dive (130 ft) on EAN 28 using your 119 cft and then do the second one at 90 ft on EAN 36 using your 80 cft if you can get it from a bank (premix) and not partial blending. If this is not possible consider EAN32 which is readily available premix. Such combination will maximize your bottom times.