Loose rules in Fort Lauderdale, FL

[Wookie]

This thread is getting sidetracked with a lot of competing posts, but really there is one topic that I want to clarify.

Tarponchik, you do realize that dive shops have 100% oxygen (well maybe 99.5%). That it comes from gas suppliers, that there are various grades, and that it is meticulously checked and verified because it needs to be at certain quality in order to be used by welders, hospitals, etc?

Also, that some dive shops mix the 100% O2 with air in order to create a combination of nitrox from 21% - 100%?

Some of your posts just seem to be all over the place, I just want to confirm this fundamental fact and then take things step by step.

I can't imagine any analysis coming back at 99.5%. 99.5% would be from an oxygen generators for home medical use. Medical and OBA is more on the order of 99.999 or 99.9995%. Even diver grade is 99.995%. Welding grade isn't analyzed, but the cylinders are evacuated before they are filled from a liquid O2 source (medical and OBA are triple vacuumed) on the same rack as medical and OBA so you can be pretty sure that even welding grade is the same purity as medical and OBA grade.

 

[tarponchik]

This thread is getting sidetracked with a lot of competing posts, but really there is one topic that I want to clarify.

Tarponchik, you do realize that dive shops have 100% oxygen (well maybe 99.5%). That it comes from gas suppliers, that there are various grades, and that it is meticulously checked and verified because it needs to be at certain quality in order to be used by welders, hospitals, etc?

Also, that some dive shops mix the 100% O2 with air in order to create a combination of nitrox from 21% - 100%?

Some of your posts just seem to be all over the place, I just want to confirm this fundamental fact and then take things step by step.

I've said it already: I trust the guy at the air pump.

 

[tarponchik]

So what do you do? Stay under 13' on every dive because your tank might contain 100% and you don't trust any analyzer? I guess you could take a sample from each tank and send it off for lab analysis.


Test with the shop's analyzer, then test with your own. If the results between the two differ then you figure out where the problem is. If there isn't a difference in the results, I'm plenty happy trusting that confirmed result. If you have an analyzer with multipoint calibration like a cootwo that also checks CO then so much the better.

No, of course not. I've already checked that it's Nitrox, not air. I love to use Nitrox on 60-90 ft dives but I do not go deeper. On air I went down as deep as 180 ft, no problem.

 

[boulderjohn]

No, of course not. I've already checked that it's Nitrox, not air. I love to use Nitrox on 60-90 ft dives but I do not go deeper. On air I went down as deep as 180 ft, no problem.

Let me see if I understand your personal limits.

1. You will dive nitrox from 60-90 feet, no problem. If you are talking about 32%, then you are willing to go to a partial pressure of 1.2 there--not too dangerous.
2. You will dive air at 180 feet, meaning you are willing to go to a partial pressure of 1.36 there--not too dangerous.
   
3. You will not dive nitrox at 100 feet. If you are talking about 32%, then you are NOT willing to go to a partial pressure of 1.28 there--too dangerous.
4. You will not dive nitrox at 100 feet. If you are talking about 30%, then you are NOT willing to go to a partial pressure of 1.2 there--too dangerous.
   
5. You will not dive nitrox at 100 feet. If you are talking about 28%, then you are NOT willing to go to a partial pressure of 1.12 there--too dangerous.

Are those all accurate?

 

[stuartv]

Let me see if I understand your personal limits.

1. You will dive nitrox from 60-90 feet, no problem. If you are talking about 32%, then you are willing to go to a partial pressure of 1.2 there--not too dangerous.
2. You will dive air at 180 feet, meaning you are willing to go to a partial pressure of 1.36 there--not too dangerous.
   
3. You will not dive nitrox at 100 feet. If you are talking about 32%, then you are NOT willing to go to a partial pressure of 1.28 there--too dangerous.
4. You will not dive nitrox at 100 feet. If you are talking about 30%, then you are NOT willing to go to a partial pressure of 1.2 there--too dangerous.
   
5. You will not dive nitrox at 100 feet. If you are talking about 28%, then you are NOT willing to go to a partial pressure of 1.12 there--too dangerous.

Are those all accurate?

My understanding is that tarponchik's issue is not the ppO2. It's that he/she doesn't trust the gas analyzer to be accurate even to +/-20%. But he/she DOES trust the person filling tanks to actually put air in when they say they only put air in.

ps. I analyze my tanks even when I requested an Air fill.

pps. If an analyzer tells you a tank has 30% O2 in it and you think it could be off by, say, +/- 10%, then why would you trust it when it says 21%?

 

[tarponchik]

Let me see if I understand your personal limits.

1. You will dive nitrox from 60-90 feet, no problem. If you are talking about 32%, then you are willing to go to a partial pressure of 1.2 there--not too dangerous.
2. You will dive air at 180 feet, meaning you are willing to go to a partial pressure of 1.36 there--not too dangerous.
   
3. You will not dive nitrox at 100 feet. If you are talking about 32%, then you are NOT willing to go to a partial pressure of 1.28 there--too dangerous.
4. You will not dive nitrox at 100 feet. If you are talking about 30%, then you are NOT willing to go to a partial pressure of 1.2 there--too dangerous.
   
5. You will not dive nitrox at 100 feet. If you are talking about 28%, then you are NOT willing to go to a partial pressure of 1.12 there--too dangerous.

Are those all accurate?

1. Yes
2. Once a day
3. If I do multiple dives
4-5 Irrelevant.

 

[kensuf]

Ken, I trust you know your stuff, but this kind of comment always makes me cringe a bit. To truly master technical concepts, most adults need several components: Good instruction, repetition, review, and so good experience. Opportunities to teach back these concepts really improve retention too. My point is.. calling out an instructor because a former student goes off the reservation seems a bit harsh.

I don't know the poster in question, or said instructor. Just my point of view.

You're right, I was bad and let my emotions take control of the keyboard. Apologies to the instructor.

 

[CptTightPants21]

I can't imagine any analysis coming back at 99.5%. 99.5% would be from an oxygen generators for home medical use. Medical and OBA is more on the order of 99.999 or 99.9995%. Even diver grade is 99.995%. Welding grade isn't analyzed, but the cylinders are evacuated before they are filled from a liquid O2 source (medical and OBA are triple vacuumed) on the same rack as medical and OBA so you can be pretty sure that even welding grade is the same purity as medical and OBA grade.

Yes, meant 99.995.

 

[boulderjohn]

4-5 Irrelevant.

Why irrelevant? You are using the word "nitrox" to refer to all situations, but you really only seem to be talking about 32% nitrox. Do you believe there is no such thing as nitrox made to any other percentage of oxygen, or do you never dive under any circumstances where such mixes are available to you?

It seems to me that this would be a different way of phrasing your position:

1. You only dive air or nitrox 32--no other mixes.
2. If it is air, you aren't worried about the accuracy of meters, so you will take it to a 1.4 PO2.
3. If it is nitrox 32, you will only take it to a 1.2 PO2.

Is that what you are really saying?

 

[runsongas]

Please do me a favor, go through analyzer adds like this one, or this one, or that one, etc. and find one add where accuracy or precision are disclosed.

did you look up the manual?

Palm oxygen Analyzer

MO2-865 O2 EII Pro Technical Manual.pdf