Nitrox/Oxygen Analyzers

[Doubler]

These are the same analyzers that many shops and dive boats use, the Aggressor fleet has them. Calibrate them in ambient air to 20.9. As far as the $130 goes for the new sensor, didn't a diver just die in the Red Sea because she was given a tank with Nitrox for a very deep dive, I believe 200 feet plus. I would think that my butt is worth $130 replacement charge. The shop there didn't have an analyzer and neither did she. For dive travel, one is most definitely required. If the sensor last 4 years that is $2.70 a month, seems worth it. My 2 cents.

 

[Teamcasa]

Anybody want to chime in that owns the one I linked above? Will it work with ambient air?

Sure.
I have one and it works great. I check every fill and found the mixes differ, regardless of what they were pumping enough to warrant my buying my own.

Many times, I have 500-600 lbs of air and they dump in 32, or I was diving 32 and can only get air on the refill. I would not dive Nitrox without testing the mix myself, with my own tester.

 

[fdog]

Worthwhile investment?

I was looking at this one...
AmoxTec Analox O2EII Nitrox Analyzer

What are some other ways to calibrate? The only one I know of is analyzing regular air at 21%. What if it's just you and a buddy only diving Nitrox and there is no regular air available to calibrate using that method?

$130 to replace the sensor after 4 years... That's nearly half the price of the entire device =-O What are some signs of the sensor going bad, just cross-checking with other devices?

We own one. It's been bulletproof.

As long as you're at sea level and not outside the temp/humidity norms, pulling the green inlet dome and waving it around works fine.

If the temp/humidity are enough to indicate a need for correction from the chart, you either:

A)skew your readings from the chart
B)calibrate from a cylinder absolutely known to have air.

...the latter is the easiest.

If you're at altitude, like diving at Lake Tahoe, calibrating to ambient air (removing the green dome) will also generate errors because of the reduced ppO2. Again, the easiest thing is to calibrate from a known cylinder of air.

Checking for lifespan:

Every 6 months I calibrate to a known cylinder of air. Then, I'll check:

• A cylinder of known 50% O2
• A supply cylinder of Oxygen (100%)
• A supply cylinder of Helium (0%)

If the meter quickly reads correctly (within 20 seconds or so), and makes it to within a % or two of correct readings, I'll sticker the meter and continue using it.

If it has an error of 5% or more I replace the sensor, but, I'm using it for checking technical mixes and need the span of 0% to 100%.

If I was strictly using it for recreational nitrox, which has a narrower span requirement, I'd replace the sensor when it had an errror of 10% at the extremes (Helium and pure Oxygen).

Hope this helps.


All the best, James

 

[tedj101]

While I guess you could do it this way, Analox says there is a simpler way, when the analyzer won't reach the appropriate calibration point, it is time to replace the sensor.

It is a bit odd to find this thread here. Analox has a forum on this board and Michelle answers all questions pretty quickly. Moreover, Analox has video's posted on U-Tube to show how to use the device (including how to calibrate it) and how to change the sensor. Links are on their forum.

Just thought you'd like to know....

<TED>

 

[charlesml3]

didn't a diver just die in the Red Sea because she was given a tank with Nitrox for a very deep dive, I believe 200 feet plus.

I find it very hard to believe a technical diver would let themselves get into this kind of position. She's going down to over 200 feet and doesn't know what's in her tank? This sounds more like fear mongering to me.

At those kinds of depths, she wouldn't be on any Nitrox mix.

-Charles

 

[SkiDiver]

Interesting discussion. My wife and I are going to Bonaire in August and diving with Dive Friends Bonaire using nitrox. I had been planning to buy or build an analyzer, but they say they have nitrox analyzers at all their locations. After reading this thread, I'm reconsidering my plan to buy one.

 

[Web Monkey]

That's really pointing out why it's a good idea to calibrate the tester yourself. It's still not a very compelling reason to buy an analyzer.
-Charles

It was mounted on the wall and she wouldn't let me touch it.

Terry

 

[charlesml3]

It was mounted on the wall and she wouldn't let me touch it.

Then you walk out and find another dive op. Seriously, that's just nonsense. They calibrated the Nitrox analyzer ON NITROX and then wouldn't let you do it properly, and yet you continued on and did the dive with them? Nothing personal, but I think this is on you as much as it's on them.

If they're going to deviate that far from accepted practice (divers analyze their own tanks) then customer should be voting with their feet. They're most likely going to deviate from accepted practices in other areas as well.

-Charles

 

[Web Monkey]

Then you walk out and find another dive op. Seriously, that's just nonsense. They calibrated the Nitrox analyzer ON NITROX and then wouldn't let you do it properly, and yet you continued on and did the dive with them?

No, I tossed it in the back of my car, took it home and bought an O2 analyser.

If they're going to deviate that far from accepted practice (divers analyze their own tanks) then customer should be voting with their feet. They're most likely going to deviate from accepted practices in other areas as well.

Probably, although I don't really care. It's a dive shop that I don't use, so they can do whatever they want.

Terry

 

[Cave Bum]

Where to start...

Humidity plays a role in calibration. If you have big chunk of nitrogen and a little chunk of oxygen and you 'squeeze in' humidity it will take up some space, thus reducing the percentages of the other components. Typically, I see ambient air in North Florida at 50% humidity reading 20.4% on a correctly calibrated analyzer.

To accurately calibrate an analyzer you usually use compressed air directly off the compressor, not out of the air banks or a tank filled from the air bank. Most shops that blend through their compressors will switch between banks before all of the previous mix is out of the lines. In the shop I worked in we'd switch to the air bank to clean out the lines after blending both Nitrox and 10/50 Trimix. (Yes! Free Helium! Kewl!)

But does that really matter? Hummm, not really. What you're trying to do is to determine 'do I have air or Nitrox in my tank and what is the percentage of O2 (within 1%) (in the case of technical shops that might include determining if you have pure O2 and Trimix, also). The resolution tolerance of the readout on an analyzer is only 1.0% anyway which means it's only accurate to that 1 percent.

To be perfectly correct and within the standards, calibrate with pure, dry air directly out of the compressor but in practice you'll probably be fine just waving the analyzer around and setting it 20.9% (or even 20.4% on a humid day).

One more thing, the sensor reads higher if it sees higher pressure. If you wave it around to calibrate it then crank open the tank valve so it's seeing much higher pressure blasted right into the sensor hole the O2 percentage will read higher then it actually is. So if you're working in a shop and the tank you're analyzing in front of a customer doesn't come to a high enough percentage, just crank open the valve some more... That'll take care of it

(That last was a joke, BTW, I'm not really advocating that...)

Another reason to own your own analyzer is you should analyze both when picking up your freashly filled tank and again right before you dive it, at the dive site.