Testing your breathing Gases Prior to Diving

[thez_yo]

You know, I got on a boat once, where the dives were 80' and above, and heard (paraphrasing - I haven't been on a boat in a while):

"We just got a new membrane system. If any of you who have an analyzer get a reading, could you give it to us so we could let everyone know what we're pumping out at?"

The more I think about it, the less I want to dive nitrox before I buy an O2 analyzer. I got certified for EANx last November, btw. Most of my dives are in the 15-20'ish range in the past 6 months, so I put the money towards a CO analyzer first because that one makes me more nervous right now. If I've already paid a couple of $K combined on stuff that's collectively considered 'life support equipment' e.g. regulators, what's another couple hundred to make my dive even more relaxed/less nervous. There's a middle ground between 'nope' and 'paranoid' - trust, but verify.

 

[D. Martin]

When I travel overseas, then I'll worry about analyzing rental tanks.

The whole point of this silly thread is somebody thinks that paranoia is a solution to safe diving.

This is not a paranoid knee jerk reaction however it's your choice, no one can make you analyze a tank . As for myself and my family we analyze . Here is a scenario you should think about although you test with a O2 analyzer you get a reading of 15% now you must ask yourself what is the rest of the tank filled with? Is it nitrogen ,helium ,carbon monoxide ,carbon dioxide. Or is it just hypoxic from an oxidation problem which can not only happen with steel but also happen when aluminum develops corrosion. I suggest that some of you revisit your basic chemistry books there is only 100% volume in any tank if air is a standard 19.9- 20.9% what is the on a normal tank it must be nitrogen ,co2 , and other trace gases . However you still don't know for sure what you are breathing you are assuming that you know, and all know what assumption makes out of all of us, except in this case you would rather be an ass than DEAD!

 

[Dr. Lecter]

another point in analysis - Never calibrate the analyzer using a tank. Even if you believe its air. There can be anything in the tank - you have no way of knowing.

Instead use ambient air which has known percentage of O2.

Not the brightest idea, though given the inherent lack of accuracy of available O2 testers, probably NBD. Calibrating from a known air tank at the same flow rate as the tank you'll be testing fixes two potential issues that can throw off your reading: humidity and effect of moving gas on the O2 sensor.

If you simply must reassure yourself that the calbration tank hasn't magically changed from air to something else, or you haven't previously confirmed it's actually air, do an initial calibration in ambient and then go to the air tank.

 

[DBailey]

This is not a paranoid knee jerk reaction however it's your choice, no one can make you analyze a tank . As for myself and my family we analyze . Here is a scenario you should think about although you test with a O2 analyzer you get a reading of 15% now you must ask yourself what is the rest of the tank filled with? Is it nitrogen ,helium ,carbon monoxide ,carbon dioxide. Or is it just hypoxic from an oxidation problem which can not only happen with steel but also happen when aluminum develops corrosion. I suggest that some of you revisit your basic chemistry books there is only 100% volume in any tank if air is a standard 19.9- 20.9% what is the on a normal tank it must be nitrogen ,co2 , and other trace gases . However you still don't know for sure what you are breathing you are assuming that you know, and all know what assumption makes out of all of us, except in this case you would rather be an ass than DEAD!

Overkill and sensationalism for standard air fills in rental tanks. I mitigate the risks by getting my fills from reputable shops and renting from reputable operators on trips.

You can analyze if you want too, but I think it is overkill for a miniscule risk.

 

[guruboy]

Not the brightest idea, though given the inherent lack of accuracy of available O2 testers, probably NBD. Calibrating from a known air tank at the same flow rate as the tank you'll be testing fixes two potential issues that can throw off your reading: humidity and effect of moving gas on the O2 sensor.

If you simply must reassure yourself that the calbration tank hasn't magically changed from air to something else, or you haven't previously confirmed it's actually air, do an initial calibration in ambient and then go to the air tank.

Might as well bring your own mini tank of "calibration air" along...

 

[Dr. Lecter]

Might as well bring your own mini tank of "calibration air" along...

I test my tanks at home where all the various doubles, singles, and deco bottles are stored, so finding a tank of air to calibrate off isn't a problem. For testing rental tanks while traveling or whatever, I'll agree that the minor improvement in accuracy provided by a better calibration isn't offset by the hassle of bringing calibration gas. Though I think you'd be hard-pressed to find a dive location where there wasn't a bottle of air you could use.

However, the recent fatality that inspired this thread could have been prevented by testing with an O2 analyzer that only functioned in 50% increments. Nice calibration issues--worrying about whether to calibrate in air or on a tank, on dry air or trying to compensate for humidity, or with or without flow rate--are unnecessary to figure out that you have much less or much more than 20.9% O2 in a tank...it becomes obvious pretty quickly.

But for making MOD or deco calculations, I like knowing that I'm diving 29%(ish) rather than 25%(ish) and 76%(ish) rather than 80%(ish), because it can matter.

 

[guruboy]

So how much does a tester(s) cost to test for O2, Helium, CO, and whatever other gasses people use?

 

[pensacolaracer]

So how much does a tester(s) cost to test for O2, Helium, CO, and whatever other gasses people use?

If you are even the least bit electrically and mechanically inclined, you can make your own for under 140 bucks. Oxycheq has the kits.


Sent from 115 FSW.

 

[guruboy]

If you are even the least bit electrically and mechanically inclined, you can make your own for under 140 bucks. Oxycheq has the kits.


Sent from 115 FSW.

The DIY kit appears to be O2 only.

 

[pensacolaracer]

That is correct. I know of no DIY helium and co testers as of now.

I have 2 home built o2 testers and they work great. I also have a he tester that ran about 700 and a co tester that was 300.

O2 is what matters in the tank... It's what will keep you alive... In the proper amounts for depth.

C0 is also an issue but that's been covered ad nauseam in other threads.

2 deaths that I know of in the last year due to improper o2 content in a tank. The other was a tech instructor a few months ago on the Hydro Atlantic.

When I first started diving and only used air, I didn't analyze, because I didn't know what I didn't know.

Now, EVERY tank gets analyzed prior to use and if I fill a tank for a buddy, I won't let them put the reg on the tank until its analyzed. I guess in just an ******* like that.


Sent from 115 FSW.