Nitrox Analyzer - How many use one?

[Patoux01]

If there is water in a steel tank, rusting will occur which will change some of the O2 to iron oxide. If I ever get a lower number on the second test, I will empty the tank, pull the valve and inspect. That is one reason.

I'm pretty sure that's not gonna change anything, but I can't be bothered doing the maths.

 

[swimlikethefish]

I test twice for two reasons.
1. It provides reassurance that what is written is what is actually in the tank. The last thing I want is to oxtox because I was lazy and forgot to peel the tape between fills or made an error.
2. It allows me to verify my sensor or the shop sensor is correct. I change mine every 18 months just for safety sake. But if their sensor read differently from mine it would throw a red flag.

Without getting to involved in the science behind it. A 1% error would be survivable when diving a ppo2 of 1.4 but might not be when you are at a ppo2 of 1.6. This is why we dive with a ppo2 of 1.4. This 1.4 number represents what your maximum depth can be while diving higher levels of oxygen aka nitrox. This depth is what we refer to as MOD or maximum operating depth. These are all things you WILL learn when you TAKE a nitrox course.

 

[Storker]

What is the thought on the two tests?

1. O2 cells are consumables. You're not guaranteed to notice a failing cell. The risk of two cells failing simultaneously is a lot less.
2. People screw up, even I do sometimes. Two analyses makes me more certain that the label is correct. If you want to see what can happen, read up on Carlos Fonseca's death.

So, another case of "two is one and one is none". Or, what @swimlikethefish said.

 

[Patoux01]

Without getting to involved in the science behind it. A 1% error would be survivable when diving a ppo2 of 1.4 but might not be when you are at a ppo2 of 1.6. This is why we dive with a ppo2 of 1.4. This 1.4 number represents what your maximum depth can be while diving higher levels of oxygen aka nitrox. This depth is what we refer to as MOD or maximum operating depth. These are all things you WILL learn when you TAKE a nitrox course.

Yikes. Please get in the science behind it. If you're 1% off, you're gonna be like 1m off in MOD. Where it *might* become an issue is *if* you're somehow able to reach past CNS times, which are also largely conservative.

Some organizations happily let you use 1.6 as bottom mix.

 

[Skulmoski]

Always; I always use an analyzer. I use my dive club analyzer when I get fills from my dive club. I use the dive company's analyzer when I use their cylinders. I do not dive enough to justify my own analyzer.

GJS

 

[swimlikethefish]

Yikes. Please get in the science behind it. If you're 1% off, you're gonna be like 1m off in MOD. Where it *might* become an issue is *if* you're somehow able to reach past CNS times, which are also largely conservative.

Some organizations happily let you use 1.6 as bottom mix.

You must remember the audience. The is an a basic discussion. And I did say, you might not be safe with an error at 1.6. I'm not saying immediate death, but the possibility does exist as the science can not say at what ppo2 you will tox out. You might be able to take a chamber ride, dry, at 1.7, 1.8, or even higher. But, I would not want to take that risk while underwater.

Example, take a diver with a 30% mix with a ppo2 of 1.4 and a mod of 121. He goes to a wreck and isn't aware of his depth and his computer goes beep beep. He looks and is at 131 feet. That is recoverable. Now same diver with the same mix diving a ppo2 of 1.6 with a mod of 142. Same scenario but this time his depth is 152 before he realizes. There isn't any margin of error. He would now be at a 1.7+, for a basic scuba discussion that is a big NO. Even if this were an advanced scuba discussion, I would still say NO.
There is no exact ppo2 number you can show me that science says is the limit. You might be able to dive a 1.8 and the next guy might tox at that. You just never know.

 

[scubadada]

How many of you guys use an analyzer to check LDS fills before a dive?

It depends, there are many different situations. (representative examples)

I generally don't retest these before diving:
1. The tank is filled, I analyze, label, and log it. (Jupiter Dive Center, Reef Divers Little Cayman, Red Sea Aggressor)
2. The tank is filled, it is analyzed in front of me and I log it (Ocean Frontiers, Subway Watersports)
3. The tank is filled, it has been analyzed, labeled personally and vouched for by someone I know and trust (many of the cylinders I use locally in SE FL)

I always test or retest all other cylinders. I will often use an analyzer that is available, I have my own Analox analyzer with me if there is none available

 

[Patoux01]

You must remember the audience. The is an a basic discussion.

To the contrary, I damn well know where we're posting, and that's why things should be explained, and that "let's not get too technical"-bs should stay at the door, IMO. It's a formulation that is very comparable to "trust me I'm right".

And again, some agencies allow 1.6 as bottom mix.

 

[Storker]

I do not dive enough to justify my own analyzer.

To each their own. I took my nitrox cert because I'm past 50 and definitely not in the same shape I was when I was 25, so I have an increased risk of DCS. Also, it seems as if I'm one of those who bubble easily, because if I do two deep-ish, long-ish dives in one day, I want to be in my bunk before 8pm. And nitrox is one of the many tools to reduce that decompression stress. Since my club offers ean fills at the same price as regular air fills, standardizing on ean(ca)32 instead of air seemed like a no-brainer. A clubmate of mine likes to be able to go to 40m, so he has standardized on ean28 for basically the same reasons.

My first gear purchase after my nitrox class was an analyzer. I don't trust gadgets and I don't trust myself enough to rely on one analyzer.

 

[Wookie]

I always use an analyzer every dive. Air or nitrox. To go on with post 22 above, I dive at 1.6 PPO2 and deco at 2.0 PPO2.