Analox analyzer

[stuartv]

ps. Here's a portable hygrometer (with temp) for $30, if you really want something to throw in the drybox with your analyzer.

Oasis Digital Hygrometer

 

[tbone1004]

O2 will kill the sensor too soon. Ideally, there should be 2 calibration standards, air and N2 (or any other gas with zero O2). But this will get a bit complicated.

o2 isn't going to kill the sensor that quickly. People run them on rebreathers for hours at a time at a ppO2 of 1.0+ and they still last well over a year. 30-60 seconds at a ppO2 of 1.0 every few weeks isn't going to kill them appreciably faster than nitrox

 

[tarponchik]

o2 isn't going to kill the sensor that quickly. People run them on rebreathers for hours at a time at a ppO2 of 1.0+ and they still last well over a year. 30-60 seconds at a ppO2 of 1.0 every few weeks isn't going to kill them appreciably faster than nitrox

You better ask the manufacturer before making such statements.

 

[tbone1004]

You better ask the manufacturer before making such statements.

why bother? They're galvanic cells, they are used up by oxygen, the more oxygen, the faster they die. In analyzer use, they will die from age before they die from momentary exposure to high O2.
They literally use identical oxygen sensors in rebreathers, and since galvanic sensors measure ppO2 instead of fO2, they are exposured to a ppO2 of at least 1.0 for 3+ hours.
Since it takes less than a minute for calibration, we'll call it a few minutes. If you're diving every day, you'll need to calibrate about once a week. 3 hours=180 minutes=180 calibration cycles. 180 calibration cycles at 1x cycle per week *over calibrating is unnecessary*=3+years of use before you experience the same use that a rebreather would see in a single dive. At daily calibration, that's 6 months of use, before a single dive in a rebreather. Since rebreathers certainly don't burn through their cells in a week of daily diving, which is equivalent to over 3 years of daily calibration of an analyzer with O2, one can infer that calibrating with O2 has no significant bearing on the reduction of sensor life in an analyzer.

care to provide any evidence, studies, manufacturer evidence that proves otherwise? I'm sure literally every technical diver in the world would love to hear it....

 

[stuartv]

@tbone1004 There you go brandishing dangerous logic again!

 

[tarponchik]

why bother? They're galvanic cells, they are used up by oxygen, the more oxygen, the faster they die. In analyzer use, they will die from age before they die from momentary exposure to high O2.
They literally use identical oxygen sensors in rebreathers, and since galvanic sensors measure ppO2 instead of fO2, they are exposured to a ppO2 of at least 1.0 for 3+ hours.
Since it takes less than a minute for calibration, we'll call it a few minutes. If you're diving every day, you'll need to calibrate about once a week. 3 hours=180 minutes=180 calibration cycles. 180 calibration cycles at 1x cycle per week *over calibrating is unnecessary*=3+years of use before you experience the same use that a rebreather would see in a single dive. At daily calibration, that's 6 months of use, before a single dive in a rebreather. Since rebreathers certainly don't burn through their cells in a week of daily diving, which is equivalent to over 3 years of daily calibration of an analyzer with O2, one can infer that calibrating with O2 has no significant bearing on the reduction of sensor life in an analyzer.

care to provide any evidence, studies, manufacturer evidence that proves otherwise? I'm sure literally every technical diver in the world would love to hear it....

You do not know how often the sensor will be used, nor does the manufacturer know. In self-service places like Bonaire everyone calibrates when they grab a tank. This makes it 20-30 times a day. Here comes another reason not to use O2: who will leave an oxygen tank unattended?

 

[tbone1004]

You do not know how often the sensor will be used, nor does the manufacturer know. In self-service places like Bonaire everyone calibrates when they grab a tank. This makes it 20-30 times a day. Here comes another reason not to use O2: who will leave an oxygen tank unattended?

30x/day=~11k calibrations per year obviously a gross exaggeration. 11,000 minutes=183 hours. Average rebreather dive=3 hours which is call it 60 dives. CCR divers in cave country can easily do 200 hours/year on their rebreather, on the same sensors.
This is done at an average ppO2 of call it 1.2 since you'll have say 1.0 at depth, and 1.4-1.6 when on decompression.

1 year is life expectancy of these sensors anyway, and the numbers for the analyzer have been rounded to extreme conservatism since it doesn't actually take 60 seconds for people to calibrate.

People leave O2 tanks unattended all the time. they're all over gyms and hospitals across the US in their medical kits. No reason they need to be "attended", just bungee them to the wall since they're a calibration tank. or better yet, be an intelligent shop, and don't allow all of the f*ckwits at your dive shop to re-analyze your analyzer every minute and a half minutes when it only needs to be done once a week.


try again

 

[tarponchik]

30x/day=~11k calibrations per year obviously a gross exaggeration. 11,000 minutes=183 hours. Average rebreather dive=3 hours which is call it 60 dives. CCR divers in cave country can easily do 200 hours/year on their rebreather, on the same sensors.
This is done at an average ppO2 of call it 1.2 since you'll have say 1.0 at depth, and 1.4-1.6 when on decompression.

1 year is life expectancy of these sensors anyway, and the numbers for the analyzer have been rounded to extreme conservatism since it doesn't actually take 60 seconds for people to calibrate.

People leave O2 tanks unattended all the time. they're all over gyms and hospitals across the US in their medical kits. No reason they need to be "attended", just bungee them to the wall since they're a calibration tank. or better yet, be an intelligent shop, and don't allow all of the f*ckwits at your dive shop to re-analyze your analyzer every minute and a half minutes when it only needs to be done once a week.


try again

I do not know anything about sensors used in rebreathers, so why do you keep bringing them up? I know sensors used in Nitrox analyzers are good for 2 years (at least those I used). So if the sensors are the same, are you telling me that the sensors in rebreathers have only half the lifespan of sensors in Nitrox analyzers, which is my point exactly?

Using oxygen tanks requires following some basic safety rules. In fact, medical personnel are trained to use them. You probably heard the scary word "liability", I am sure. It is one thing you keep it in your dive shop for your own use (although it is still OSHA regulated); it can be very different thing putting it out into public use. But the analyzer manufacturer needs one procedure for all and they came up with the simplest and safest.

 

[tbone1004]

@tarponchik i keep bringing up the sensors used in rebreathers because they are literally identical to those used in analyzers. In fact, those that change their cells out early ~12 months, will usually rotate those old cells into analyzers. These cells have already experienced say 100-200 hours of use at a ppO2 of 1.2 ish, and then go into use as O2 analyzers.

Sensors die when they either become voltage limited, or behave in a non-linear fashion. You don't know that it is suffering from either of those conditions unless you test it both below, and above the circumstances of it's use. In this case, you test at 20%, and at 100% and use between 30-40%. You do'nt know by testing in air if the cell is limited because you have no way to validate the linearity of the cell.

Regarding O2. Allowing customers to calibrate the analyzer is frankly more dangerous than keeping an O2 tank for shop personnel to calibrate with since most people don't know how to properly calibrate, and if they aren't using a cal-gas for it, there is no guarantee that the sensor has been fully purged. O2 is a regular item in dive shops that are filling nitrox, so it's not like it's not already in the building

 

[NAM001]

quite possible, but if you're going for a cal gas, it may as well be one that you know dead nuts is spot on. Me personally? I will either do single calibration to air, or dual calibration to air+o2

In most cases i would agree. Here in south east texas its 90+f and 90 rh I dont push the MOD so i have a lot of forgiveness in my methods.