Is nitrox worth it for deeper rec dives?

[Marie13]

This is going to be my last post since many of you have your facts mixed up. Putting aside the issue of “Is nitrox better to dive?” there are logistics issues.

DRIS banks 32%. Any other nitrox mixes need O2 cleaned tanks. It’s what is specified on their website and what I have been told in the shop. Filling partially with 32% and then diluting with air has never been presented as an option. Period.

The other places I dive on the Great Lakes do not bank nitrox at all (unsure about Toby). So I have the choice of bringing as many tanks as I’ve got dives, filled with banked 32% if that fits planned depths. I only have 6 tanks, 2 of which are now doubled up. The people I carpool with do not appreciate hauling more than 2 of my tanks, especially if they are only bringing 2 or are renting.

Remember, this is not Florida. Our dive season for charters locally generally goes from late May to late September. Charters on either side of that time frame are often blown out. Having to hit other wrecks than planned is very common due to conditions.

It seems the places that do partial pressure fills do have hyper clean air. There are shops in the Chicago area that do not offer nitrox fills at all, do not have hyper clean air, and even charge more for HP tanks.

Screen shot from DRIS’ website.

 

[Storker]

If you are coming up due to getting to your air limit then there is little point in nitrox.

Allow me to disagree. For a middle-aged couch potato like me, surfacing with a lower N2 loading and thus lower decompression stress is a good thing. I don't need to be close to my NDL on every dive I do.

When I used to dive air, it wasn't unusual for me to surface pretty darned close to my NDL. After switching to EAN32 as my standard gas, my typical N2 loading after a dive is somewhere around 50% of what would have put me in deco. I like that. It's a way to introduce some extra conservancy without reducing my bottom time.

 

[JohnnyC]

Filling partially with 32% and then diluting with air has never been presented as an option. Period.

Did you ask? Call them and say, "hey, would you guys fill my tanks to 2000psi with banked 32 and top it to 3000 with air for me?"

I'm sure they would be more than amenable than making you get full 32 fills and bleeding them out in the parking lot only to take them back in and get topped with air. They're nice guys (and gals), I bet they'd do it. Probably wouldn't even charge you extra.

 

[Marie13]

Did you ask? Call them and say, "hey, would you guys fill my tanks to 2000psi with banked 32 and top it to 3000 with air for me?"

I'm sure they would be more than amenable than making you get full 32 fills and bleeding them out in the parking lot only to take them back in and get topped with air. They're nice guys (and gals), I bet they'd do it. Probably wouldn't even charge you extra.

Does me absolutely no good for when I’m traveling.

 

[JohnnyC]

So? It's still information you can use when diving locally and you have the same question.

Bring the two tanks you're allowed to bring and just rent everywhere else and deal with having to compromise.

 

[Marie13]

So? It's still information you can use when diving locally and you have the same question.

Bring the two tanks you're allowed to bring and just rent everywhere else and deal with having to compromise.

I dive HP80s and have the choice of renting either AL80s (yuck) or occasionally HP100s.

I was not aware filling partially with 32% and then diluting was even an option. People here have been acting like I should have known this.


Yammer amongst yourself if you wish, but I will no longer be posting in this thread.

 

[shoredivr]

Does me absolutely no good for when I’m traveling.

In Tobermory, Divers Den will mix whatever Nitrox blend your certifications allow for. Want a 26% for the stern of the Forest City wreck? No problem. They blend though IIRC.

 

[shoredivr]

@Marie13 do you have an app like Multideco? There is a function on it that shows how much O2 and air is needed to get a specific Nitrox fill from a partially full tank. That way you could calculate your gas costs if the shop charges by the cubic foot of O2 on a partial fill. If it’s just a per-tank charge, then you know your answer.

For example, your HP 80 has 1200psi remaining and you want a 28% blend. Fill the boxes in and 133psi of O2 and an air top are needed. That supposes the shop does Blending.

Or, if the shop has banked 32% only, an air top up would give you 24.8% approximately.

Divers Den in Tobermory will fill the rental tanks with whatever mix your certifications allow for.

 

[Jim Lapenta]

I dive HP80s and have the choice of renting either AL80s (yuck) or occasionally HP100s.

I was not aware filling partially with 32% and then diluting was even an option. People here have been acting like I should have known this.


Yammer amongst yourself if you wish, but I will no longer be posting in this thread.

A good nitrox course should have presented this as an option. It's in the materials section on blending nitrox.

 

[Alan Browne]

Marie13 said: I was not aware filling partially with 32% and then diluting was even an option

A good nitrox course should have presented this as an option. It's in the materials section on blending nitrox.

I'll try to remember to post if my nitrox course (2 Feb) presents this. (I'll try to remember to ask if they don't).

It's not explicitly mentioned in the PADI 'Enriched Air Diver' manual that I've been studying.