Acceptable mix accuracy for Nitrox

[broncobowsher]

I give or take 1% without thinking about it. If you are planning your dives so tight that 1% is going to make a difference you have bigger problems. If not now, they are coming soon.

Add in the tolerance of the analyzer. As for being able to hit within .25%, I will call BS. What analyzer are you using that reads to the hundredth of a percent? Every one I have ever seen tends to dance around a couple of tenths.

 

[Bob DBF]

They used to partial pressure off of a rich banked nitrox, but I get the impression that they've switched to completely partial pressure blending as they no longer fill nitrox in tanks without an O2 clean sticker.

I'd ask, there is more than that one reason to require an O2 clean sticker.


Bob

 

[Johnoly]

...Am I being too picky in wanting it +/- 1% of my requested mix?

That's not the problem.........
You clearly are not bringing enough cupcakes, donuts & treats to the tank fillers. My tanks come out perfect in PSI & Mix all the time.
Tank fillers need to be fed !!

 

[tridacna]

That's not the problem.........
You clearly are not bringing enough cupcakes, donuts & treats to the tank fillers. My tanks come out perfect in PSI & Mix all the time.
Tank fillers need to be fed !!

LIKE LIKE LIKE LIKE LIKE!

Amazing how people who treat us the best get the best fills!!!

 

[tomfcrist]

I’m good with +\- 1% for Nitrox. Most fills are closer to +\- .5%, but I fill everything myself.

 

[jlcnuke]

I've had pressure that was 10% off what I expected, but never seen O2% off by more than 0.5% so far. Granted, I don't have that many nitrox dives yet, but the number is growing..

 

[Manatee Diver]

I've had pressure that was 10% off what I expected, but never seen O2% off by more than 0.5% so far. Granted, I don't have that many nitrox dives yet, but the number is growing..

Getting under fills are pretty normal, particularly with aluminum tanks. Seeing a drop of 200-300 psi with the tank still slightly warm to touch is normal. I've personally stopped worrying about it too much as even with the under fills I finish the dive with over 1,000 psi left in my tanks. But it is awesome when they hit it perfect, but I don't see that except with my steel tanks and shops that don't mind overfilling.

Anyways I've decided that my expectation of +/- 1% isn't being picky when the passing standard for the TDI nitrox blender course has the same standard for oxygen content (I know because I am looking at taking it). I'm going to give the shop one last chance (or whatever is left on my nitrox card), and if they don't hit it, I will permanently go else where.

 

[seeker242]

+/- 1.5%, anything more than that is just a monkey who can't blend.

 

[Barnaby'sDad]

I've had pressure that was 10% off what I expected, but never seen O2% off by more than 0.5% so far. Granted, I don't have that many nitrox dives yet, but the number is growing..

I got one tank that was ~8% off. I’m guessing that they topped the tank off from an air line instead of the banked 32% line. That’s the only way I can think of that you can get a partially filled tank with ~30% down to 24%.

I had less than 10 Nitrox dives/fills when that happened, so I’m going to go out on a limb and guess that it wasn’t that rare of an occurrence (or I just got lucky).

 

[Neilwood]

I personally would accept +/- 1%. Getting that should be pretty easy for a good blender (especially as there are apps that do all the calcs for them).