Diving nitrox when you don't own an analyzer

[divengolf]

Now here is a really good question. When "checking" out a NITROX cylinder you record the O2 contents and most often the pressure. Yet when you get a cylinder with air neither are done. So how many check the pressure with an air cylinder? Conversely how many check the O2 content for an air cylinder that supposedly contains 21%

My personal policy is to always analyze any tank that I'm diving for CO and, if I'm diving air, I'll analyze for O2 if the filling facility has the ability to fill nitrox. So, in practice, I almost always analyze for both O2 and CO. I rarely dive air any more. I'm especially wary of those who do individual tank partial pressure O2 blending. That's an art that is frequently messed up.

 

[Dive-aholic]

if the cell reads 100% with 100% 02 and 21% with air you can assume the readings between are correct.

if you calibrate on air and then get a reading from a tank of 32% all you know is the analyser will read up to 32%.

I've owned a few analyzers over the years and have never seen one calibrated with 21% read 100%. They have all read over 100%.

 

[DiveNav]

Currently I am checking my analyser with air and one of my deco bottles that has 50%

Do you use "air" as in ambient air? Or as in a tank containing air?

Using a tank containing air will give you a more accurate result (as you get similar pressure / temperature as the deco bottle)

 

[Searcaigh]

Hi Alberto,

I use a tank of air, however I found no noticeable difference by just moving the analyser through the air around me

 

[The Chairman]

No, you don't need to own an O2 analyzer, but you do need to analyze your tanks. Any place that provides NitrOx had better provide an analyzer for you to check your own gas and also insist that you do so and record the results for posterity. Anything less would be negligence.

On a side note, I was pretty impressed with Dive-aholic's set up and that he did check every tank for CO. Yes, he made analyze my own tanks for O2 and record it properly. It was a class act.

 

[Chocula]

I received a reply back from the boats owner that they do have an O2 analyzer on board available for me to use. Looks like we will be diving nitrox for this trip.

-Chocula

 

[The Chairman]

Good for you and them!

 

[Agility]

Do you use "air" as in ambient air? Or as in a tank containing air?

Using a tank containing air will give you a more accurate result (as you get similar pressure / temperature as the deco bottle)

provided the tank really contains air, how would you know that if the shop fills nitrox?
it might be a nitrox tank topped up with air after being returned, how would you know?
I prefer ambient air, KISS

 

[Dive-aholic]

provided the tank really contains air, how would you know that if the shop fills nitrox?
it might be a nitrox tank topped up with air after being returned, how would you know?
I prefer ambient air, KISS

Easy. Before I had my own fill station I would go to a shop I knew didn't provide Nitrox and top off my calibration tank there. No question.

 

[Mr Carcharodon]

we have a boat trip scheduled for the end of the month which has EAN32 available. I am not sure how practical this would be without having our own analyzer. .

I can't think of a single boat in Southern California that has nitrox that does not provide an analyzer. Having an analyzer is not an issue at all.