Reminder - Always Personally test your Nitrox Mix

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Flutter

Contributor
Messages
106
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Location
Midwest, USA
# of dives
500 - 999
This is just meant to be a reminder for new Nitrox divers - always personally test your (rental or filled) Nitrox tanks before using them. Don't take someone elses word for it.
My husband & I tested a tank (one of many) on a recent dive trip. We were told it was between 31-33% mix. It tested on our analyzer at 100%. We notified the shop so they could pulled the tank & we got a different one. Some shops don't have analyzers. If you dive Nitrox - buy one & bring it with you. It might save you serious injury. Happy Bubbles!!
:idk:
 
Good catch.. That could have been deadly..
 
Wow. That would have been very, very bad. I'd probably find a new operator to dive with.
 
Normally I don't bother with Nitrox however in Lembeh with NAD the dive profiles dictated that Nitrox gave a significant advantage.
I did not have my own tester but observed the staff testing my tanks on the boat with my gear on it. Every Nitrox tank with gear on was tested and the result logged and signed for by the diver.
I was comfortable with the procedures and would definitely dive with them again.
I agree that if I am going to dive Nitrox on a regular basis I will get my own tester.
 
Scary stuff
 
I don't think I've ever gotten a nitrox tank from a dive op where I was not handed an analyzer or watched the dive shop employee do the analysis right in front of me. I don't think you need to buy your own.
I agree completely that it is foolhardy to take another person's word for something so critical to your own survival. Even being off by a few points can affect your no deco time or MOD dramatically.
 
wow 100% ??? dang, that most likely would have been fatal

The liveaboard I was on tested the tanks in front of us, and you were free to use it to test them yourself.
The dive shop has an analyzer for your use to test tank after they fill it.

I wouldn't trust fills from a shop that didnt have a way to test your nitrox tank after they have filled it
 
. . . Some shops don't have analyzers. If you dive Nitrox - buy one & bring it with you. . . .

I have never encountered that. I would not use such a shop again. I've been under the impression that it's standard procedure for a dive shop that provides tanks to have an analyzer and a tank log that each diver is supposed to fill out and sign.
 
Normally I do not carry an O2 analyser with me on dive trips as usually the supplier of what mix I want provides one and either I analyse it personally or observe one of the staff analyse it and then sign for it.

The only exception has been in Saudi Arabia, where the dive op provided tanks with a theoretical EAN32 but had no analyser as somebody had dropped it off the boat the previous week, needless to say I dived air.

I now carry a Nitroxbuddy with me now on my trips as it is compact and easy to use and also links with my phone (which I always have anyway).

Over the past 10 years though I have never come across a mislabeled mix or one that was out by more than 1%
 
We had a local diver pick up one of his tanks at a reputable dive shop at the coast. It also tested very rich when he tested it. Turned out the filler had thought it was a deco bottle when actually the diver wanted just an air fill for a pony. Filler thought he was doing diver a "favor". This diver worked at a shop that from then on had you test everything including air to make sure it was correct. They had a fill system where you could do all sort of custom mixes.

I also ran across a shop where when I went to check the fill the employee calibrated, after just testing some nitrox, by just setting the meter to 21 without it being attached to any bottle. I recalibrated correctly and it was off by 5%. I no longer get fills there.

Those meters are delicate in the sense that on the common ones you can easily get the setting off by touching the adjustment knob. So not only make sure each tank is tested but also make sure you know the testing device is calibrated. In a couple of situations where the shop was analyzing I have asked them to recalibrate before doing my tanks.

Not that it matters but often dive shops doing a lot of tanks will measure you a few tenths low. They stop as soon as the number quits rising. But if you leave it on the tank longer the reading will often creep up another 0.2 to 0.3 %

---------- Post added February 17th, 2015 at 09:46 AM ----------

Over the past 10 years though I have never come across a mislabeled mix or one that was out by more than 1%

Had one come in 2.5% rich. Same shop that I do not use anymore.
 

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