Acceptable mix accuracy for Nitrox

[Johnoly]

.. Getting that should be pretty easy for a good blender (especially as there are apps that do all the calcs for them).

The phone blending apps are really good. The problem is you have 20 Nitrox tanks that are waiting on a monday morning. Every tank has a different mix in it (and don't ever trust what the owner wrote WAS inside for % on their tank with 800psi left over). Then the 2nd problem is you have 3-4 guys that normally fill the banked bottles and maybe someone got busy with a customer and one of the T's is high/low in the bank but you don't know it when cascading down the T bottle line. Finally throw in the variable that everyone want's something different in their mix because we all dive all over the place(ocean/cave/lake) and it can take time to get it right.

When I was filling a while ago, I would sniff everything before I got started (cust tanks & banks) then fire up the phone app and start pumping them out. We'd run the banks at 38% and then it was easy to top off with air and not be hogging the Nitrox whips to end up at 36% with a healthy fill psi. It's nice having separate banks for nitrox and air but many smaller places just bank Nitrox and then pump air direct from the compressor.

And then one day you go to Amigo's in cave country and just DROOL over his multi-bank system that is like a 31 flavors ice cream shop.

 

[Manatee Diver]

And then one day you go to Amigo's in cave country and just DROOL over his multi-bank system that is like a 31 flavors ice cream shop.

Wayne's setup is awesome.

 

[KentB]

From a shop I think .5% is fair
I blend myself and if my few friends I do fill for ask for 32 I feel bad giving them 31.4 or 32.6 that’s not what they asked for...... I justify it by the fact they don’t pay for it and it’s free so if you wanna complain feel free to go pay at a shop

 

[Scuba Cobra]

From my shop expect +/- 1 %.

where I currently am I have gotten bottles that were up to 5% off before. It's kind of annoying and frustrating as it isn't like the states were I can have them correct it on the spot, and I have to alter my plan around the mixes I get.

 

[Neilwood]

+/- 1% shouldn't really change your dive plan as even going to NDL there is a safety margin built in (plan to 1.4, contingency of 1.6).

More than that, it will start messing up MOD.

 

[Scuba Cobra]

+/- 1% shouldn't really change your dive plan as even going to NDL there is a safety margin built in (plan to 1.4, contingency of 1.6).

More than that, it will start messing up MOD.

I'm not sure if your comment was directed at me, but for the dives I am doing it is an issue. Especially if back gas is off high and deco gas is off low.

 

[Neilwood]

I'm not sure if your comment was directed at me, but for the dives I am doing it is an issue. Especially if back gas is off high and deco gas is off low.

Bear in mind the location of the forum that this is posted in - BASIC SCUBA DISCUSSIONS.

If you are using multiple gases, such as a deco gas, this ceases to be BASIC scuba and becomes ADVANCED scuba (emphasis is mine).

We should only be talking about basic Nitrox in this section of the forum and not AN/DP procedures.

 

[Scuba Cobra]

Bear in mind the location of the forum that this is posted in - BASIC SCUBA DISCUSSIONS.

If you are using multiple gases, such as a deco gas, this ceases to be BASIC scuba and becomes ADVANCED scuba (emphasis is mine).

We should only be talking about basic Nitrox in this section of the forum and not AN/DP procedures.

Ah, my apologies. I missed that.

 

[JohnnyC]

+/- 1% isn't a big deal to me. +/- 5% isn't cool. If I'm getting my tanks filled at a shop, I analyze there and give them the opportunity to fix it.

 

[Manatee Diver]

Just a bit of a follow up.

Went to another local shop, requested 32% without draining the fill dude was able to get me to 31.7%, and filled to 3,800psi so it should settle down to around 3,400-3,500 psi (steel tank). Hopefully they remain consistent for the next 19 fills on my nitrox card.

I will be giving the old shop a chance with one last tank on my nitrox card before I put them on my NFE list, we will see if they can get +/- 1%.