MOD Stickers

[stuartv]

Who leaves the fill station with a gas 10% off from the target?

Do you guys really do this?

I can’t even.

Sadly, not every fill station operator is as good as you guys....

 

[stuartv]

I certainly don't. I give them about 2-3% before I get grumpy.

@stuartv don't confuse MOD stickers with mix stickers, VERY different things

I'm not. If my MOD sticker is for 80% and my actual fill is 78 or 82, I don't mess with the MOD sticker. But, if the mix is off by 10% and circumstances dictate that I roll with it, I want my MOD sticker to match what's in the cylinder.

 

[PfcAJ]

Sadly, not every fill station operator is as good as you guys....

Wtf are they doing?

Plug the numbers into an app and do what the app says.

You don’t need to be some sort of a scholar to fill gas.

It seems like acceptance of shoddy service is now a factor along with being cheap. Double bad.

 

[JohnnyC]

We're seriously having a discussion about removing MOD stickers because a fill monkey can't put the right gas in a tank?!

Standard gases are a great way to minimize variables, dedicated tanks for those standard gases eliminates even more variables, MOD stickers ARE NOT analysis stickers.

 

[tomfcrist]

Wtf are they doing?

Your guess is as good as anyone's. The best part is that the tank monkey is usually a self proclaimed expert...and usually a course director for (Name your random agency here).

We're seriously having a discussion about removing MOD stickers because a fill monkey can't put the right gas in a tank?!

No...Its merely one of the discussion points.

Another discussion point would be valid for rebreather divers carrying bailout gas....Which is almost never the same as the diluent, and standard gasses could conceivably add a ton of deco obligation in a bailout scenario.

Standard gases are a great way to minimize variables, dedicated tanks for those standard gases eliminates even more variables, MOD stickers ARE NOT analysis stickers

Standard gasses for who? The "standard" gasses we speak of are only standard for the WKPP (and its clones)...And even then they aren't standard. IIRC: 190 gas could be 18/45 or 21/35 depending on if its a staged bottom gas or a deco gas. That may not be the case anymore, but it used to be.

But yes...MOD markings are not analysis markings...I concur completely.

 

[PfcAJ]

One can standardize a set of gases for their group without them being identical to gue, Wkpp, etc.

I also question the idea of bailing out to standard gases adds “a ton of deco”.

 

[tomfcrist]

One can standardize a set of gases for their group without them being identical to gue, Wkpp, etc.

I also question the idea of bailing out to standard gases adds “a ton of deco”.

Certainly can, but for the sake of argument, 99% of divers refer to Gues gasses as the “standard”.

As far as additional deco...it depends a lot on the dive, and the available gasses.

 

[boulderjohn]

Certainly can, but for the sake of argument, 99% of divers refer to Gues gasses as the “standard”.

Standard gases were not determined randomly--they make just as much sense for any agency. Unfortunately, they make the most sense for the primary reason they were developed, which was very much dependent upon location--and that means Florida.

If you go back to the days before apps, when we had to calculate gas blends through pure math, this was the process:

1. Determine your planned mix.
2. Determine your planned final pressure.
3. Figure the percentage of helium you wanted to add (very simple math).
4. Do a more complicated mathematical step to determine the percentage of Nitrox you needed to add to the helium to get the planned final mix.
5. Do another more complicated mathematical step to determine the amount of oxygen you needed to add to get that percentage of Nitrox.
6. Add the helium.
7. Add the oxygen. (Steps 6 & 7 could be reversed)
8. Top off with air.

That's a PITA. Fortunately, lots of Florida dive shops have banked EANx 32. That means that if you plan to use mixes that will use EANx 32 for step #4, you have a much simpler (and probably cheaper) process:

1. Determine your planned final pressure.
2. Figure the percentage of helium you wanted to add (very simple math).
   
3. Add the helium.
4. Top off with banked Nitrox.

If you have reserve gas in your tank prior to the next fill, you can make any of the standard gases by simply adding the right amount of helium and then topping off with the banked nitrox. No real math involved.

Pretty darn simple. That's a very attractive reason to use those gases, and it would be attractive to anyone in any agency.

Of course, if you don't have banked EANx 32, you lose all that advantage, and you are left with other reasons for choosing those gases.

 

[tbone1004]

@boulderjohn even if you don't have banked 32, the main benefit of standard gases is the ease of blending. If you have banked anything, just use that plus helium. On the coast of NC and in parts of cave country EAN30 is the most common because of the depths. No problems, just blend EAN30+helium. Sure the gases will end up a bit different, but that's nbd. Same with EAN36.
The other advantage is the narcosis is going to be essentially the same regardless of depth. If you have a personal narcosis tolerance deeper than 100ft, then so be it.
Sure the range of depths may be pretty big, but it is beneficial if you have potentials for multiple depths at the trimix range. If you're diving in nitrox depths though, just learn to do backgas deco and you'll quickly see that any change in nitrox percentage to get "best mix" is only going to change your backgas deco/"safety stop" by a few minutes. Hardly enough to go through the hassle imo

 

[boulderjohn]

If you have banked anything, j

Beleive me, in the midwest and in the Rocky Mountain region, Nitrox diving is so rare that there is no banked ANYTHING. Most of the Colorado shops can't even make it from scratch. The shop for which I used to work uses nitrox only for their instructors in busy instruction days when the instructor is teaching multiple classes. They have a set of nitrox tanks for that purpose, and when they get used up, they call me to find out when I'll have some O2 on hand so I can come over with MY fill whip and put the necessary O2 in their tanks.