Nitrox class

[Storker]

In theory you need to check a tester before every check... But, In the real world... If I take tester, Any tester off the shelf and it gives me the reading I believe it should, I'm good...

I don't know about the analyzers you've been using, but all the ones I've used have a calibration knob that's very easily turned. In fact, just taking the analyzer out of its box will most likely move the calibration knob. So I don't feel comfortable trusting an analyzer if I haven't checked that it shows ~20.9% O2 in air before I hold it close to my tank valve to record my tank's O2 content. Which means that I always check my analyzer's reading before testing my tank.

 

[JerseyJames]

In theory you need to check a tester before every check... But, In the real world... If I take tester, Any tester off the shelf and it gives me the reading I believe it should, I'm good... If I put a volt meter on a 6 volt battery and the meter reads 6.01 good... If it reads 22volts, Well I may need to look at it.. If I hook up a 32% nitrox tank and I get 31.99% good... If I get 42% I'm going to check that out.. But let's face the facts... If they are filling from banked nitrox at 32% at a dive shop you'll be getting 32% nitrox... If they are blending, that's a whole new ball game...

Jim...

Always analyse and calibrate first! Even from banked nitrox. The previous fill will determine the true blend and you can't be sure of that (if you're hiring). Always calibrate and analyse (in the real world)


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[tbone1004]

why should it be combined with AOW? We combine with OW and issue a Nitrox Diver card thru NAUI. Saves a whole lot of money, and like I said in post #3,
Learn to calculate MOD, EAD, and Best Mix. One formula, simple algebra, shuffle the equation around depending on which variable you need to find. Explain why PO2's matter for O2 toxicity and why a diver would choose different PO2's. Explain PN2's so you can find EAD and how to use it for use with air tables.
Learn how to use an O2 analyzer, and emphasize importance of analyzing your tank ideally as soon as you pick it up, and before you get in the water because people should own O2 analyzers....
Brief explanation of the dangers of high pressure O2 as it relates to personally owned tanks when getting partial pressure fills.

All can be done in maybe an hour? Shouldn't add any cost to the OW course in my opinion, but then that would mean less money for the agencies and shops, so can't have that happening

 

[boulderjohn]

My answer was meant to post #25. Would you like to comment on that post(#25)?

I see no exoneration for dividing one topic in two courses - Nitrox and Advanced Nitrox. I had the Nitrox with SSI and Adv. Nitrox with TDI. The content was identical in both agencies and both courses. Nothing more than a ripoff.

Don't know anything about SSI and TDI. But there is day and night differences between PADI's Basic Nitrox and IANTD's Adv Nitrox. The Adv Nitrox includes 50% deco mix for light deco with a backmount twin set throw in as well. You can get away with a single tank with H-valve as alternative. Whatever it is, two independent 1st stages are required for the course.

OK, I am not sure exactly what I am commenting on, but I'll give it a shot. I only know specifically the content of the PADI and TDI courses I have taught, so my response will attempt to be generic and theoretical.

The key ideas related to nitrox, especially concerns about oxygen toxicity, are generally the same whether you are talking about recreational nitrox or technical nitrox. In terms of pure academics and dive planning, there are some differences, though, so I would not expect the courses to be completely the same. The PADI course I took 15 years ago was much more comprehensive than it is now, and that is because the course designers realized a lot of what was in the course then was not necessary. For example, we spent a lot of time on avoiding pulmonary oxygen toxicity using the DSAT oxygen exposure tables. In doing so, I saw that it would be close to impossible for a recreational diver to get into trouble with pulmonary oxygen toxicity. I assume the course designers figured that out, too, because it is no longer part of the course. On the other hand, it is still taught in the technical courses, where longer dives with higher levels of oxygen exposure make it more possible (although still highly unlikely). In the PADI tech courses, students are required to calculate oxygen exposure over time using tables and arithmetic.

As I said in my earlier response, I believe the key difference between the two is the fact that you are only using one tank with one gas and one regulator at the recreational level, and you are using at least two tanks with two gases at the tech level. A tech diver must be able to plan dives for two or more gases and make a safe switch to the appropriate gas while holding a decompression stop. That means the tech course involves skills that are entirely unnecessary at the recreational level. One course is mostly academic; the other is mostly skill. Since there is not all that much that needs to be added academically to a nitrox course at the tech level, I would expect a stand alone, generic tech nitrox course would not be a whole lot different from a generic recreational one. For that reason, it makes sense to me to combine a technical nitrox course with a decompression procedures course, either by having students take both classes at once (as TDI allows) or by putting the nitrox content into the decompression course (as PADI does).

 

[tursiops]

why should it be combined with AOW? We combine with OW and issue a Nitrox Diver card thru NAUI.

Fine, make Nitrox an endorsement on either OW or AOW, anything that makes it less of a big deal. I agree, an hour is about right. I cal it an endorsement so it is NOT a separate certification.

I am really committed to the calibration training....the previously expressed opinion above that calibration does not matter is a serious recipe for disaster. That doesn't mean you need to calibrate before every use, but certainly at each turn-on and after it is bumped. That is just the way the analyzers work, not an arbitrary training-agency rule. It is physics, not policy or politics.

I watched a fellow and his wife at a wall-mounted analyzer in Bonaire. He had the hose attached to her tank, and asked her what percentage she wanted. She said she'd been on 32 most of the time, how about trying 36? So he turned the calibration knob until it showed 36, and she said thanks. He did his tank the same way. They moved away from the analyzer, set their computers, and went diving. Jeez.

 

[oldschoolto]

OK... Let's look at this again... If you want to calibrate at every tank check.. Go ahead... But I don't and have no problem doing so... I have a large number of tools and testers that I use.. I don't send out my torque wrench before torquing down the cylinder heads... Even when I was building 3000hp nitro motors... If I'm checking ohm' s with my ohms meter I have a good idea if it's right or way off.. (Broken) I will test a test light before looking for dead power.. I don't send out my Shadow graft scale before balancing rods and pistons... And If I test a Nitrox tank in Bonaire ( only place I dive it ) the tester tells me I got 32% in a tank that should have 32%... I'm good with that... Or should I ask for a 100% O2 tank and then a 50% O2 and then a air tank to make sure it's right on the money..

Because God forbid I got 31.5 % and not 32% in the tank to dive the Himla Hooker for 20 minutes at 90' average depth....

Jim....

 

[tursiops]

OK... Let's look at this again... If you want to calibrate at every tank check.. Go ahead... But I don't and have no problem doing so... I have a large number of tools and testers that I use.. I don't send out my torque wrench before torquing down the cylinder heads... Even when I was building 3000hp nitro motors... If I'm checking ohm' s with my ohms meter I have a good idea if it's right or way off.. (Broken) I will test a test light before looking for dead power.. I don't send out my Shadow graft scale before balancing rods and pistons... And If I test a Nitrox tank in Bonaire ( only place I dive it ) the tester tells me I got 32% in a tank that should have 32%... I'm good with that... Or should I ask for a 100% O2 tank and then a 50% O2 and then a air tank to make sure it's right on the money..

Because God forbid I got 31.5 % and not 32% in the tank to dive the Himla Hooker for 20 minutes at 90' average depth....

Jim....

Firstly, calibrating before each tank is NOT what I said.
Secondly, I told my Bonaire story because it illustrates EXACTLY to problem you do not what to admit. If tghe person who analyzed before you screwed around with the calibration, you have no idea how to interpret the output of the analyzer. If you will believe whatever it says, why do you sue it? If you believe it only when it shows 32, what do you do when it shows 31 or 33, or 30 or 34? Call it 32 anyway? Maybe you don't dive near NDLs or do repetitive dives, I don't know. But why you are playing Russian roulette, I don't know either. Hey, people die or get the bends from bad Nitrox analysis. I guess you are immune.

 

[Storker]

If you want to calibrate at every tank check.. Go ahead...

Excluded middle, hyperbole. There's a difference between on the one hand checking the calibration before using an analyzer and on the other hand obsessively calibrating the instrument with certified mixes between tanks.

I don't and have no problem doing so... I have a large number of tools and testers that I use.. I don't send out my torque wrench before torquing down the cylinder heads... Even when I was building 3000hp nitro motors... If I'm checking ohm' s with my ohms meter I have a good idea if it's right or way off.. (Broken) I will test a test light before looking for dead power.. I don't send out my Shadow graft scale before balancing rods and pistons... And If I test a Nitrox tank in Bonaire ( only place I dive it ) the tester tells me I got 32% in a tank that should have 32%... I'm good with that... Or should I ask for a 100% O2 tank and then a 50% O2 and then a air tank to make sure it's right on the money..

Like I said, all nitrox testers I've operated have an easily turned calibration adjustment knob which more likely than not needs a bit of twiddling to show 20.9% for air when the analyzer is taken out of its case. None of the torque wrenches, multi-meters or timing lights I've used (and there has been a few of them) have had a calibration feature which is as easily meddled with.

 

[oldschoolto]

Excluded middle, hyperbole. There's a difference between on the one hand checking the calibration before using an analyzer and on the other hand obsessively calibrating the instrument with certified mixes between tanks.



Like I said, all nitrox testers I've operated have an easily turned calibration adjustment knob which more likely than not needs a bit of twiddling to show 20.9% for air when the analyzer is taken out of its case. None of the torque wrenches, multi-meters or timing lights I've used (and there has been a few of them) have had a calibration feature which is as easily meddled with.

Yes, You are right.. But I'm saying is in Bonaire at dive friends they bank their Nitrox... So if you test the tank and it should be 32% Nitrox and the tester shows 32% then why should I calibrate it ? Or think it wrong.. If I was at a place where they are blending ,I would be more inclined to recalibrate it... If and its not in my future, I was doing a deep multiple gas tri-mix with deco... You bet your ass I would be calibrating the testers...

Jim...

 

[NAM001]

The volumn of the bank is not important. if the bank was filled with a faulty meter then the bank is wrong no matter if it is a tank or a 40 tank bank system. I cal my meter then read the half a dozen tanks and then check the meter is still calibrated when done. I don't calibrate prior to every reading but every session of reading tanks, before and after. If I set it down I recheck calibration. Its just the right thing to do. Now if you have a wall mounted unit and long hoses that go to he tanks it may be different in that a bump would not change the cal knob setting. On a trip to coz I asked for 32 what I got on my meter was 30 theirs read 32. I get to stateside and checked it against several others and it still read same as the others with slight +/- .1 or so. Never trust a shop or any one to verify your gas. I have on an occasion trusted the reading s of others but in that case my tank was filled at the same time as the others. 3 other tanks read 32 so I trusted mine to be 32 also. The dive was not one that pushed the limits. And I was there when the tanks were filled and watched them use multiple meters to check the gas content as it went toe the octopus supplying the tanks. That is not a common situation for most.