Acceptable mix accuracy for Nitrox

[tridacna]

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%.

Bring a dozen donuts and you’ll get 32% next time.

 

[tridacna]

If someone pays us for 32%, 32% or darn close is what they get. This is not rocket science. Dilligence and simple arithmetic is all that’s needed.

 

[Tug]

Bring a dozen donuts and you’ll get 32% next time.

Don’t forget the beer.

 

[Neilwood]

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%.

31.7 is pretty much bang on IMHO. As others have said a little calculation and diligence and it should be pretty easy.

 

[Manatee Diver]

Follow up part deux.

Dropped off my other tank at the old shop. Marked for my usual 32% but I mentioned that I wanted them to blend it rich. So he gave me their reasoning, by blending it lean it doesn't affect your MOD.

I emphasized that I don't mind topping it off to get the exact mix, but I would rather not need them to completely drain and remix my tanks when they are outside my acceptable range.

 

[faze]

+/- 1% is completely acceptable - anything outside of that calibrate the analyser on a tank of air to read 21% and try again - sorry if it's more than 1% out I would refuse it - something is wrong, I'd be embarrassed as a dive shop operator if I couldn't get within 1% of what I claimed to be selling.

 

[Barnaby'sDad]

Follow up part deux.

Dropped off my other tank at the old shop. Marked for my usual 32% but I mentioned that I wanted them to blend it rich. So he gave me their reasoning, by blending it lean it doesn't affect your MOD.

I emphasized that I don't mind topping it off to get the exact mix, but I would rather not need them to completely drain and remix my tanks when they are outside my acceptable range.

Did they ask what kind of profile/depth you were expecting for the dive you'd be using that tank for? ex. If they knew that you'd be close to your expected MOD with 32%, I get why they'd want to proactively ask about it and suggest going on the lean side.

That being said, if you asked for 32%, requested the tank to be on the rich side, and you picked it up and they filled it on the lean side because they thought they knew better than you...I can see why you wouldn't be happy with that.

 

[Storker]

The accuracy for a standard analyzer is +/- 1.0%. Demanding better than that is stupid.

That said, if a shop couldn't deliver within +/-1%, I'd look for another shop for my fills. So if i asked for 32% I'd accept anything between 31.0% and 33.0%, but not outside those limits.

 

[Manatee Diver]

Did they ask what kind of profile/depth you were expecting for the dive you'd be using that tank for? ex. If they knew that you'd be close to your expected MOD with 32%, I get why they'd want to proactively ask about it and suggest going on the lean side.

I don't really give my profile, heck half the time I don't know my profile as I keep two tanks of 32% in my closet in case I decide to head to out to do a east coast or Keys wreck dive on a whim. I dive there enough and my tanks all have the same thing stenciled on them, so if they know it is me they would realize that I am picky.

That being said, if you asked for 32%, requested the tank to be on the rich side, and you picked it up and they filled it on the lean side because they thought they knew better than you...I can see why you wouldn't be happy with that.

That was the first time I specifically asked for a mix on the rich side, and they delivered at 33%.

 

[Johnoly]

Follow up part deux........... I would rather not need them to completely drain and remix my tanks when they are outside my acceptable range.

Sometimes I have to ask the shop "How long have you been in business" and the answer is amazing. Once saw a new shop owner get rid of all their customers because they wanted to 'start fresh'. What's that slogan about how to make a million dollars owning a dive shop?????