Calibrating Analox O2EII - Not sure I get it

[Caryam]

Hello!

I'm new to the boards and have been diving for just a couple of years. Last year, my fiance and I got certified for diving Nitrox (wow, what a difference!) and for a wedding present this year we received an Analox O2EII analyzer.

We are heading to Aruba next week for some diving, so I'm trying to get up to speed on how to use this particular analyzer. Basically, I'm a bit confused by the Compensation chart they supply.

Honestly, we will be using the Analox just as a way to double-check our tanks, but I'd like to know I'm doing it right.

I've read on these boards that many people don't use the chart at all -- can someone explain the reasoning behind this? If you don't calibrate to the chart, are you just setting it to 20.9? (edited for typo.)

Also, if I'm reading this chart correctly, the only time you need to calibrate to the chart is if the temperature and humidity fall into the green areas. Is this correct?

Thanks in advance for any answers you may have. I have no doubt this is a great piece of equipment, but the directions for calibrating could be worded much better

 

[Pedro Burrito]

You don't have to worry about the chart if you use a reference gas to calibrate your analyzer. The fill station should have a bottle on hand. You can then compare your analyzer to the fill station's analyzer. They both should start at 20.9 (not 2.9).

Did you read the online documentation? It's usually more clear than the instructions that come with the unit. http://www.analox.net/product-docs/manual-13.pdf

Also, your next analyzer purchase should be the CO analyzer. EII CO Carbon Monoxide Analyzer: Analox - Looking after the air you breathe.

 

[Patti Analox]

Wow... Pedro, I couldn't have done it better. Hi Caryam, Pedro is right, the compensation chart only comes into play if 1) you don't have dry tank air, or 2) if it's extremely hot and humid. If you take a look at the chart you'll see most of the adjustments are less than 1%. Essentially you will probably turn the unit on, calibrate it to 20.9 and go. If it hot and raining, I would recomend first putting the analyzer on a tanks of plain air and then calibrating to 20.9. If you don't have a tank of plain air laying around, you can always use the compensation chart and find your starting calibration based on temp and humidity.

 

[Caryam]

Thank you both. I did read the pdf, but I still found it difficult to understand for a novice.

So, as I understand it, if there's a tank of regular air around, I can read from that tank and adjust the calibration setting to 20.9 -- then I'm ready to read my EAN tank.

If I don't have a tank of air around, and the weather is mild, I can just set the calibration to 20.9 and go -- if the weather is hot and humid I can adjust to the chart.

Is that right?

 

[Patti Analox]

Caryam, Yes, that's correct. Please feel free to contact me directly if you have any further questions. I can be reached at 877 723-3247 or patti@analox.net

 

[DandyDon]

 

[elan]

Personally I never calibrate the analyzer with air coming from any tank. The thing is that you never know what is inside unless you measured the content of that tank with an analyzer calibrated with known source. Ambient air's content is known and even if you ignore the chart you will only be tenths of a percent off in the worst case which i not a big deal. If your calibration tank has higher (some nitrox leftovers topped up with air )or lower content(rusting tank sitting for a long time ) you will be father off.

 

[DandyDon]

Personally I never calibrate the analyzer with air coming from any tank. The thing is that you never know what is inside unless you measured the content of that tank with an analyzer calibrated with known source. Ambient air's content is known and even if you ignore the chart you will only be tenths of a percent off in the worst case which i not a big deal. If your calibration tank has higher (some nitrox leftovers topped up with air )or lower content(rusting tank sitting for a long time ) you will be father off.

Well said. I just use air and go.

 

[Caryam]

Thank you all for your input -- that really helps clarify things for me. It sounds like it could be useful to have that Compensation Chart in the event of a truly rainy/muggy day, but that most of the time it would be easiest and safest to just calibrate to ambient air and go. I can see how a few 10ths of a percent off in either direction isn't going to mean much.

I think I'll be more comfortable with it all once I see how that difference plays out in real life -- will a few 10ths of a percent difference at calibration time translate into just a few 10ths of a percent off on my EAN reading?

 

[manni-yunk]

I have an AL30 that I dont dive with anymore and I keep it handy. I fill it with plain air - and bring it with me on my boat. When anyone wants to calibrate their analyzer - its there to use. I think this is the easiest way. takes 3 seconds - and I know what is in the test tank....since I filled it.

Since analyzing is all the tank is used for......it basically lasted all summer.