Analyzing your own nitrox tanks
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Instructor_Tom
Contributor
I have this analyzer and picked it up at a local shop for $100.
http://www.tecdivegear.com/scuba-diving-gas-analyzers/59-nitrox-o2-diving-gas-mixture-analyzer.html
They are a throw away unit as the o2 sensor can not be replaced once it starts to fail. As for analyzing tanks. I have seen to many recent incidents where people have died because they where breathing the wrong mix. You should always test your tanks even if diving air from shop that sells nitrox. You should absolutely test it if they do any partial pressure blending. Also always recalibrate back to air after every 2 tanks are tested.
Never trust anyone else to test your tank, even a family member.
T.
Sent from my iPad using Tapatalk HD
http://www.tecdivegear.com/scuba-diving-gas-analyzers/59-nitrox-o2-diving-gas-mixture-analyzer.html
They are a throw away unit as the o2 sensor can not be replaced once it starts to fail. As for analyzing tanks. I have seen to many recent incidents where people have died because they where breathing the wrong mix. You should always test your tanks even if diving air from shop that sells nitrox. You should absolutely test it if they do any partial pressure blending. Also always recalibrate back to air after every 2 tanks are tested.
Never trust anyone else to test your tank, even a family member.
T.
Sent from my iPad using Tapatalk HD
violamama
Contributor
Well, this would just set all my hairs on end. I'm newly Nitrox certified, too, with fewer dives than you. But if I pull up at the dive shop and their equipment (with which they themselves are evaluating their mix?!) is funky combined with them blowing it off... No.
Again, with such little experience I can't say what is "normal" but I can say where my threshold for trust would be. And it's nowhere near "don't worry what the sensor reads".
Incidentally, meeting a guide who is diving with me away from a shop would be a situation in which I would choose to trust her or not. I would be more likely to believe her if she says she has tested it at home than to disregard a "drifting" sensor on the advice of a shop.
My 2c.
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I often think the safety brigade can take things too far to the extreme in a lot if threads I read here, but on this one I am on their side. You MUST be confident that the mix in your tank is what you think it is. If you are not, the safe option would always be not to dive it.
In reality you have to make your own call about the dive based on your own risk assessment which will include factors such as:
A) percentage you think it is out by
B) whether it is a single dive or part if a series of dives
C) type if dive planned
E.g If the shop supplies 32% and you test at between 30 and 33, and it is a 30m dive you, can make your own call as to what adjustments you make to your profile. BUT if the shop says it is 32 and you test at 25 or 39 then that's a very different story!
Most places should have more than one analyzer available if you think the one you are using is faulty ask for a second, however if they are different you really then need to find a third analyzer to figure out which is faulty!
Final word "if your gut tells you something is wrong, it probably is"
In reality you have to make your own call about the dive based on your own risk assessment which will include factors such as:
A) percentage you think it is out by
B) whether it is a single dive or part if a series of dives
C) type if dive planned
E.g If the shop supplies 32% and you test at between 30 and 33, and it is a 30m dive you, can make your own call as to what adjustments you make to your profile. BUT if the shop says it is 32 and you test at 25 or 39 then that's a very different story!
Most places should have more than one analyzer available if you think the one you are using is faulty ask for a second, however if they are different you really then need to find a third analyzer to figure out which is faulty!
Final word "if your gut tells you something is wrong, it probably is"
Dr. Lecter
Contributor
The provision of nitrox probably should, but does not, necessarily include the provision of an analyzer for your use. You should analyze any tank you plan to dive, but unless you've asked for and been promised an analyzer when you booked the dive/tanks...pony up the $200 or $300 for your own 
analyzer.
Or just wing it and hope you don't get 80% instead of 28%. Your life.
Here's the other thing: O2 sensors like to fail in a manner that can make 100% read more like, say, 40%... so just because you can fiddle with the calibration knob and get 21% in air and then get something sensible from the tank, doesn't mean it's truly what you'll be breathing. Most analyzers don't even give you millivolts, which could at least help you validate the %s they're spitting out.
analyzer.Or just wing it and hope you don't get 80% instead of 28%. Your life.
Here's the other thing: O2 sensors like to fail in a manner that can make 100% read more like, say, 40%... so just because you can fiddle with the calibration knob and get 21% in air and then get something sensible from the tank, doesn't mean it's truly what you'll be breathing. Most analyzers don't even give you millivolts, which could at least help you validate the %s they're spitting out.
In OZ its expected that you will witness the analysing of your tanks and sign off. Have never seen it different here, nor anywhere I have dived using Nx or deco mixes. I would NOT use a mix I had not analysed ever. Where LDS use air and Nx I analyse my cylinders regardless of the supposed mix even if air. In particular if I am diving to say 60m. I want to know its air and not some mix greater than 21%
I bought my own Trimix and CO analysers, what is my life worth? More than a paltry $1000. Given I use mixed gases and have already had a bad tank of contaminated gas, testing is the ONLY way to go. If people think I am a fool, well;
"Better to test and they think I am a fool, rather than to not test and die and prove I am a fool"
I bought my own Trimix and CO analysers, what is my life worth? More than a paltry $1000. Given I use mixed gases and have already had a bad tank of contaminated gas, testing is the ONLY way to go. If people think I am a fool, well;
"Better to test and they think I am a fool, rather than to not test and die and prove I am a fool"
Well said.
You should always analyze your cylinders. Do not accept what's on the label. If you can't get an accurate analysis, then don't dive it! If you are getting cylinders from a shop that fills nitrox then you should also analyze air tanks. Otherwise you do not know for certain that air is what's in that cylinder. Do not trust anyone else with your life. It just isn't worth it.
The only new $100 analyzer out there (or rather close to $100) is the El Cheapo but you will need to spend several hours building it. Can you cut nice holes into the casing and solder the connections? I would avoid used analyzers as you will not save any money. The sensor will be used and need replacing soon after you get it. Better to just get a new one and be done with it.
The only new $100 analyzer out there (or rather close to $100) is the El Cheapo but you will need to spend several hours building it. Can you cut nice holes into the casing and solder the connections? I would avoid used analyzers as you will not save any money. The sensor will be used and need replacing soon after you get it. Better to just get a new one and be done with it.
tplyons
Contributor
If I'm diving Nitrox, I have my own analyzer with me.
Scuba diving is an expensive sport, what's another $200 to ensure my safety?
I'm the only one that fills my tanks too, and I still analyze them at the fill station, and shortly before diving them.
Better safe than sorry.
Scuba diving is an expensive sport, what's another $200 to ensure my safety?
I'm the only one that fills my tanks too, and I still analyze them at the fill station, and shortly before diving them.
Better safe than sorry.
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