Nitrox Analyzer

[CuriousRambler]

It looks good to me. You'd want to read more at that site about how it works, how it calibrates, and the longterm costs of keeping viable.

The cheapest approach is the Portable Carbon Monoxide Detector Meter (CO Inspector) used with heavy duty gallon ziplock bags. I am not going to have mine recalibrated as often as needed for accurate measurements in the PPM range. Think about what a PPM is, 0.0001%! I have it refurbished by the supplier every two years, new sensor & battery, and allow for drift. I use it in my car, hotel rooms, etc. as well as one of my tank testers, but even when new it's not going to be accurate as using a bag is a little clumsy and you will suck in some ambient air. It's an economical first indicator. You have to pack extra bags too as they don't last. Blowing tank air directly into the unit is not accurate as pressure throws it off.

As someone who's interested in getting a CO analyzer for personal use, directing this question at someone who's absolutely done more research than me:

I believe CGA Grade E air (which I understand to be the general basis for most (all?) scuba air quality standards) specifies a maximum of 10ppm CO. I don't disagree that 0.0001% seems insignificant, but let's look at that another way:

If your meter is at best capable of +/- 1PPM accuracy, then you're already only accurate within +/-10% of the accepted "safe" CO limit. THAT seems significant. If you're not accurate to single PPM, how accurate are you? If I know my best case scenario is +/- 10% of the limit, how bad is my worst case scenario? If I drift to +/-7% (keeping in mind I actually have no idea what my precision actually is) then a reading of 3PPM could potentially be at the limit. A reading of 15PPM could be perfectly safe gas.

So how do you deal with this? Do you just treat any reading above 0 as a failed tank? Obviously erring on the side of caution is the easy/smart thing to do. Just curious how you apply "real world" to the technical limitations.

How often do you register 1+ PPM in a dive tank? I sincerely don't know if it's common and acceptable to see 2-3PPM, but treat >10 as a failure, or if the average tank registers <1PPM every day of the year, so you'd fail any non-zero reading. For all I know, achieving less than 3PPM could be cost prohibitive. This is why I hate reading standards and trying to infer the reality

 

[grf88]

This is probably the best CO analyzer to get for longer term use and the one I wish I had bought in the first place, but will be the one I purchase next.
OxyCheq - OxyCheq Expedition CO Analyzer w/ Alarm

 

[NTJB]

Thank you all for the responses and constructive discussion!

Yep. I got mine after a weeklong trip to a dive resort that furnished some unknown analyzer that seemed questionable. It's been so long I don't remember the details, but I know I did not like it as much as the Analox I'd used elsewhere. I like to test my air tanks too as I have seen divers use Nitrox by mistake and many boats don't carry one.

Easy enough. Here's the Analox for $269 Analox O2EII Pro Nitrox Analyzer or there are others.

Here's the sensor for $127 Analox Replacement 02 Sensor. If you get the saver for $17 Analox Sensor Saver Cap it can protect your sensor from unneeded exposure so it lasts for years depending on how many trips & dives you do. I figured that I'd lose the other part without a box to keep it all together, so instead, I got an airtight & water-resistant box. There are many choices on such boxes.

Not now. DAN and the agencies are still avoiding the importance of tank testing for CO as that'd be bad for business, so the demand has not supported the market.

It's more important than the O2 tester to me. Back when PADI required that shops send samples to recognized testing labs, 3% failed and most of those horribly - even tho the shops could take samples only when the compressors at their best. CO deaths are easily hidden in the industry, written off as drownings, etc. and without timely post mortem testing, we really don't know how many diver deaths or even cases of "travelers flu" were actually caused by CO.
The required testing was never enforced tho, and even it has been discontinued as a requirement so no one is doing much to protect against CO hits and deaths. I choose to protect myself.

Most vocal perhaps. I'm no expert, but I know enough to be insulted by the failures of DAN, the agencies, and the dive destinations, so I work at the risk more than some. Many others just consider it an accepted risk to guard against.

Thank you very much. Your posts and signature definitely prompted me to post this thread. Do you think using a bag of tank air is accurate enough to measure PPM? Feels like a lot of room for error compared to something that reads directly from the tank or regulator?

Are there any real-world difference between the Analox O2EII and the Palm D O2 Analyzer? I sort of like the Palm D form factor better and figure I could buy the Palm CO analyzer and share the same BC hose adapter but that's just based on looking at pictures on the internet without any real world experience. Is there sort of a "industry" standard for scuba on these? I'm worried about sourcing the replacement sensor later on, as I tend to relocate every couple years around the globe, and sometimes it's hard to get parts (DGX sells the palm and sensors and ships worldwide, so that's another plus for me).

 

[NTJB]

This is probably the best CO analyzer to get for longer term use and the one I wish I had bought in the first place, but will be the one I purchase next.
OxyCheq - OxyCheq Expedition CO Analyzer w/ Alarm

Which one did you buy first and what don't you like about it?

 

[grf88]

I originally purchased the Analox which is a similar format to their O2 analyzer but they stopped supporting it and replacement sensors became harder to find and almost treble the price they had indicated when they first introduced it. I credit it with saving my son from a very serious outcome when it registered 80ppm on a dive trip. If Analox had continued their support with a reasonable price for replacement sensors I would have happily continued with it.

 

[DandyDon]

I believe CGA Grade E air (which I understand to be the general basis for most (all?) scuba air quality standards) specifies a maximum of 10ppm CO. I don't disagree that 0.0001% seems insignificant,

I did not intend to suggest that any readings are insignificant. I was just trying to illustrate how challenging all of this is.

So how do you deal with this? Do you just treat any reading above 0 as a failed tank? Obviously erring on the side of caution is the easy/smart thing to do. Just curious how you apply "real world" to the technical limitations.

By all means, get one of the $400 tank testers if you can talk yourself into it. My alternative suggestions with the cheaper approach are for the divers who won't spend that much, but might spend $130 as better than nothing. There are some cheaper CO testers sold on Ebay, but I think that they are junk.

How often do you register 1+ PPM in a dive tank? I sincerely don't know if it's common and acceptable to see 2-3PPM, but treat >10 as a failure, or if the average tank registers <1PPM every day of the year, so you'd fail any non-zero reading. For all I know, achieving less than 3PPM could be cost prohibitive. This is why I hate reading standards and trying to infer the reality

A 1ppm reading could be operator error, especially use the bag approach, but when you call the dive is a personal call. Many countries have lower maximums allowed, but 10 ppm is probably safe enough. Yes, I have seen readings over 5 & 10 ppm and I have turned boats.

 

[NTJB]

O2 sensors should last a couple years unless they are used frequently and exposed to harsh environments. They can last much longer (5 years maybe) if used unfrequently, capped when not in use and not exposed to heat and sunlight.

I have this one. Cheap and disposable when it fails

Maxtec

I bought my own because I have my own tanks and like to check before I dive to make sure it was labeled right

If I didn't have my own tanks, and trusted my dive shop analyzer, I wouldn't buy one.

Talk to the shop you rent and get fills from. Do they bank, use a stick or blend. Ask how often they CO test

Forgive my ignorance...what is bank, stick and blend?

Also, as a further question to everyone...why does the Palm 02 require calibration before every use whereas the Oxycheq does not?

 

[grf88]

Forgive my ignorance...what is bank, stick and blend?

Also, as a further question to everyone...why does the Palm 02 require calibration before every use whereas the Oxycheq does not?

All O2 analyzers require calibration before each use it is the Oxycheq CO unit that doesn't not their O2 units. Search for continuous blending of Nitrox and partial pressure blending in answer to your other questions.

 

[GJC]

Forgive my ignorance...what is bank, stick and blend?

Also, as a further question to everyone...why does the Palm 02 require calibration before every use whereas the Oxycheq does not?

Banked nitrox
Nitrox created with a stick that concentrated the O2
Partial pressure blending that mixes O2 from tanks

This should have been mentioned in your nitrox course

 

[grf88]

I maybe should have qualified my post with Most O2 units require calibration before each use. Units like the OxySpy will let you know if calibration is required and can hold calibration for a period of time.