"The Best." Oxygen Analyzer?

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rjack321

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@rjack321, yeah. If you know of another oxygen sensor (other than chromatography) I'd love to hear about it...

Alas other than a mass spectrometery, gas chromatograph or xray florescence, I am at a loss for a field method that isn't at its heart an electrochemical reaction.
 

lowviz

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Accuracy is much more dependent on the age of the sensor than on anything else.
Truth. I calibrate mine with argon and O2. You can see the range shrinking really well this way...

I bought a second O2 analyzer from Caet**** Seadj****. She gave me the dates and specs. We agreed on a fair price. She wanted to be a good 'seller' (back when that was recorded) so she took it to her LDS. It was dead. Horrified, she PM's me. Me: Yeah, I know. The cell is dead, I told you so. It has to be. Same price, same conditions.

I got the most amazing 'buyer review' from her. Too bad we don't do that anymore...
 

ScubaBunga

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I made my own so like it the best...I think many allow you to use either a simple put against tank adapter - where you need to carefully crack the tank or use an adapter to use the bcd hose. When on a boat using the bcd connector is plain simple. Hook it up and turn on the tank. It registers quickly and you don’t have to hold it just right or worry about how much you open the tank. I got an Mk2 for cheap off eBay and a release valve and with an old bcd hose I use it dedicated with my analyzer when on land. Just easy.
I also added an “ok” for when the value stabilizes I get an ok message on screen, and then a quick hit of a button locks the screen so you can walk away from the tank and keep the value.
 

broncobowsher

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I really like the Divesoft professional flow limiter. Screws directly into a DIN valve. Gives a nice steady stream of gas for an analyzer. The crack a valve and shove a ball in I have little faith in getting a good number. Want it to read a little higher, crack it a little more. Little less, slow the flow. It screws in, doesn't take a full reg set like a BC inflator adaptor. Nicest flow limiter I know of.

Then there is the analyzer itself. On the high end of what you are looking for but the Divesoft Solo is more than capable. But if straight Nitrox is all you are ever after there are a lot of more affordable options. I can't help there, I knew Helium was in my future so my first analyzer also did Helium. I never really searched the basic ones. The rebreather cell and an Arduino are a great combo if you are DIY.

Or you could do what we did in 5th grade science class. Put some gas in a vial. Light a tongue depressor on fire and blow it out. Make sure there are still orange glowing embers. Put it in the best tube. If it embers catches fire, there is concentrated oxygen in that sample gas. If the glowing stops, there is a lack of oxygen. If it stays the same, it is air. If it flashes and shots fire out, it was a flammable gas. Cool grade school science but not that practical for getting an exact concentration.
 

JahJahwarrior

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The analyzers we use are very similar to the type used in hospitals to keep patients alive...they are accurate in the sense that consumer GPS is accurate. Sure, military GPS might be more accurate, but consumer GPS is more than enough for day to day. Siemens guy is nerdsplaining, don't pay too much attention to him.

You can see the very minor differences from temperature, humidity and gas pressure/flow yourself, by testing at room temp, storing stuff in cold (fridge, ice water for tank), then storing in heat (car in middle of day for a tiny bit), and with valve open a lot or just a little. It will be small, it won't turn your 32% into 80%.

I would look at the design and size. The home built one will be bigger, bulkier, and possibly more fragile than say, a Palm. But the nicest analyzer I ever owned was a homebuilt one that was built into a pelican case, with an aluminum sheet custom bent and milled out, it was awesome, but big and bulky compared to a tiny handheld unit that I can throw into a case. Traveling on a plane would have been impractical, but for use around home, it was great. I should not have sold it.

I don't want a screw on DIN fitting, because sometimes you have lots of tanks to confirm. A standard rebreather dive has me checking 5 tanks, three of which the regulators only come off for fills, and I don't fill up each dive. I check those with the half ball that you shove into a second stage mouthpiece, or into a valve opening, or with an adaptor (QC fitting screwed into a 1/2" PVC end cap) into an inflator hose.

What is important is to leave room in your budget to also buy a CO analyzer. CO will kill you just like having the wrong o2 percentage.
 

Divin'Papaw

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I use the Analox O2EII and have for years. I first bought it in May 2007. Other than replacing the battery when prompted and O2 sensor when readings become erratic it has been rock solid. The replacement O2 sensor is not cheap (none of them are) but is readily available.

This one: NITROX ANALYSER - O2EII PRO - Analox
 
https://www.shearwater.com/products/swift/

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