Nitrox vs. advanced Nitrox

[mania]

Most nitrox tanks I see are marked with O2 % on a piece of tape. No MOD, no date, not testers initials. There are exceptions, but that's the way it's usually done.

I was taught to always write mix and MOD - and this is what I do everytime I'm diving nitrox.
Mania

 

[Wijbrandus]

I rented three 32% tanks over the weekend for an outing.

When I picked them up, the manager analyzed them, and recorded the gas fraction on the tape. That's it.

I asked him for his marker, and marked down the MOD on the tape. He looked at me funny, and said hardly anyone ever does that. Arguably, it's just about impossible to hit the MOD where I live, even on 40%, but it's still a good thing to record IMHO.

 

[StSomewhere]

I was taught to always write mix and MOD - and this is what I do everytime I'm diving nitrox.

Mania, my guess is that we learned from the same agency.

 

[Ana]

I rented three 32% tanks over the weekend for an outing.

When I picked them up, the manager analyzed them, and recorded the gas fraction on the tape. That's it.

I asked him for his marker, and marked down the MOD on the tape. He looked at me funny, and said hardly anyone ever does that. Arguably, it's just about impossible to hit the MOD where I live, even on 40%, but it's still a good thing to record IMHO.

I'm curious about this routine. I understand about good habits and the benefits of always following a sequence. With that said, here is my question:

When you asked for the marker to write down the MOD, did you know it from memory or did you have to look it up?

I now dive pretty much the same profiles every week, so I get the same mixes over and over. I know the MOD for that particular mix and the dive sites have hard botton. Add a computer that hold the previous O2 setting, and it doesn't seem to me like I accomplish much by writting additional data.

I can't remember the exact MOD for each concentration so I won't write a plus or minus depth, if Ineed to know to the closest foot (not sure why) then I've already looked it up at home before going to the shop. Realistically, do you use the MOD info, or is it just a step in your "i'm going diving" routine?

 

[StSomewhere]

The MOD I write down is the max depth *I'm* willing to go on *that* tank, my buddy's tank should show the same thing. I realize that's not a issue for a solo diver, but IMO that's not a bad thing to over communicate for a buddy team.

FWIW, I know the obvious MODs by memory and I also have a laminated card with various MODS and PO2s (I also have an IANTD MOD table with my EAN tables, IIRC). When I get around to doing DIR-F where they advocate standard mixes, this will be less of an issue.

 

[mossym]

I'm curious about this routine. I understand about good habits and the benefits of always following a sequence. With that said, here is my question:

When you asked for the marker to write down the MOD, did you know it from memory or did you have to look it up?

I now dive pretty much the same profiles every week, so I get the same mixes over and over. I know the MOD for that particular mix and the dive sites have hard botton. Add a computer that hold the previous O2 setting, and it doesn't seem to me like I accomplish much by writting additional data.

I can't remember the exact MOD for each concentration so I won't write a plus or minus depth, if Ineed to know to the closest foot (not sure why) then I've already looked it up at home before going to the shop. Realistically, do you use the MOD info, or is it just a step in your "i'm going diving" routine?

it's useful if you're not sure what site you're going to, and you have a stack of tanks in the back, just easy to run along the tanks and pick best mix for the dive you are about to do..but you could just as easy get by with %'s..

 

[jpcpat]

I'm curious about this routine. I understand about good habits and the benefits of always following a sequence. With that said, here is my question:

When you asked for the marker to write down the MOD, did you know it from memory or did you have to look it up?

I now dive pretty much the same profiles every week, so I get the same mixes over and over. I know the MOD for that particular mix and the dive sites have hard botton. Add a computer that hold the previous O2 setting, and it doesn't seem to me like I accomplish much by writting additional data.

I can't remember the exact MOD for each concentration so I won't write a plus or minus depth, if Ineed to know to the closest foot (not sure why) then I've already looked it up at home before going to the shop. Realistically, do you use the MOD info, or is it just a step in your "i'm going diving" routine?

I'm new to Nitrox, and surprised by what I'm reading. My "very" limited experience is with operators that make you sign their log, including the MOD. Both had a chart of MOD's, and so do I. Absent the charts, my dive computer displays MOD when I'm setting the mix.

My course also taught me how to calculate MOD for any mix with a calculator, and why it's important. It only took a few minutes. If you take a course that only teaches cartain mixes, what do you do when your 34% turns out to be 33% or 35%? The difference is only a few feet, and the margin for error between divers is probably bigger than that, but it still scares me. Maybe I an overworried by the posibility of convulsions underwater.

JC

 

[String]

If you take a course that only teaches cartain mixes, what do you do when your 34% turns out to be 33% or 35%? The difference is only a few feet, and the margin for error between divers is probably bigger than that, but it still scares me. Maybe I an overworried by the posibility of convulsions underwater.
JC

Thats why its important to analyse your gas after a fill, work out the MODs etc of the gas and if needed adjust the plan.

Allow some variation for a lean/rich fill in the plan before requesting the fill.

Its also worth noting some analysers are only accurate to roughly 1%.

For those reasons alone i dislike courses that DONT teach the forumlae to calculate MOD and so on for any mix. Its not exactly difficult...