Diving Nitrox with a pony bottle - theoretical

[fsardone]

The non green ones usually have the large stickers labeling the % of o2 in each tank correct?

Usually those are marked with MOD max operating depth. The depth at which the contained gas would yield. 1.6 bar ppO2.

 

[Diver below 83]

Usually those are marked with MOD max operating depth. The depth at which the contained gas would yield. 1.6 bar ppO2.

no I wasn’t talking about the tape where people usually write on MOD. I was specifically talking about the o2% ex “20%” decal on the bottles

 

[tursiops]

no I wasn’t talking about the tape where people usually write on MOD. I was specifically talking about the o2% ex “20%” decal on the bottles

The percentage is nice, and you do see that, but the essential safety info is the maximum depth at which that bottle can be breathed, so if it says 50% it might also say 70 feet, or 80% might say 30 feet, or 100% might say 20 feet.

And it will likely say that in big 4-inch block stick-on letters, not marked on a piece of tape with a Sharpie.

 

[fsardone]

Whate he says ^^^
What i write on a piece of tape is the actual values found out analising the bottle content for example 50.7/21.3 (oxigen/helium) the date of analysis and my initials.
On the bottle, no matter if it is 49 or 51 % oxygen it still says in big numbers 21 (meters we are metric here)

 

[JohnnyC]

no I wasn’t talking about the tape where people usually write on MOD. I was specifically talking about the o2% ex “20%” decal on the bottles

That's not the percentage. That's the MOD. Those decals are depth decals.

The percentage is what gets marked on the analysis tape. That could be something as simple as duct tape or painters tape, to as elaborate as pre-printed tape with fields for each bit of data.

 

[MrBigfins]

That's not the percentage. That's the MOD. Those decals are depth decals.

The percentage is what gets marked on the analysis tape. That could be something as simple as duct tape or painters tape, to as elaborate as pre-printed tape with fields for each bit of data.

I mark both the gas values from analysis as well as the MOD on the tape, especially when diving rented tanks where the same tanks will be filled to various mixes over time

 

[fsardone]

Stages extend the bottom portion of the dive, or are used as a travel gas to get to the bottom (or back up). Anything with extra O2 to accelerate deco is a deco bottle. Stages extend the dive beyond what your back (or side) gas volume is.

The non green ones usually have the large stickers labeling the % of o2 in each tank correct?

All the tanks should be so marked, especially the 50+% deco bottles. People have died from breathing the wrong bottle at the wrong depth.

The percentage is nice, and you do see that, but the essential safety info is the maximum depth at which that bottle can be breathed, so if it says 50% it might also say 70 feet, or 80% might say 30 feet, or 100% might say 20 feet.

And it will likely say that in big 4-inch block stick-on letters, not marked on a piece of tape with a Sharpie.

I mark both the gas values from analysis as well as the MOD on the tape, especially when diving rented tanks where the same tanks will be filled to various mixes over time

@MrBigfins

we are talking about stages/bailout bottles. You are probably referring to back gas bottles.
Please note that even if you rent you stages, you NEED (for your safety and those around you) to have MOD written on them, and have in them a mix that matches.
If unwilling, you should not be diving multiple gasses.

Finally doing what you said for a single gas dive is ok, but reading the thread and the context of the exchange would probably be beneficial.

 

[JohnnyC]

I mark both the gas values from analysis as well as the MOD on the tape, especially when diving rented tanks where the same tanks will be filled to various mixes over time

Your analysis should include FO2, MOD, date, initials, and I like putting pressure on mine. The poster I was responding to was incorrectly assuming MOD decals like those on DIR-rigged stages was an FO2 marking. I'm just pointing out that FO2 goes on the analysis tape.

 

[MrBigfins]

For t

Your analysis should include FO2, MOD, date, initials, and I like putting pressure on mine. The poster I was responding to was incorrectly assuming MOD decals like those on DIR-rigged stages was an FO2 marking. I'm just pointing out that FO2 goes on the analysis tape.

For tanks that I take with me from a fill at a shop I fill tape out close to how you state. Most of my personal experience though is analysis on boat and then I simply mark mod and percentage, log book and tank sign off sheet gets rest of info.

 

[tursiops]

For t

For tanks that I take with me from a fill at a shop I fill tape out close to how you state. Most of my personal experience though is analysis on boat and then I simply mark mod and percentage, log book and tank sign off sheet gets rest of info.

Are you talking about a tank on your back, or a tank that you sling as an additional tank (stage or deco)?