Gas analysis and team diving...

A DIR diver in another thread:

It had been analyzed, but not by me. It had actually been analyzed that day.

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Decided to break this off from the other thread... and removed the diver's name to protect Lynne's identity. (Ooops! :cool2

Are you OK diving tanks you didn't analyze? Not asking in an accusatory fashion, just interested under what situations you're ok with that. I'm assuming Peter - or someone else you trust implicitly - analyzed it?

So to those of us who trust that our teammates will do right by us underwater - do you/would you trust their gas analysis?

I go back and forth on this issue situationally. For local diving I do my own blending so de facto I'm usually the only one who analyzes my gas. However, I wouldn't trust anyone elses analysis of my gas here at home. We all own multiple tanks, change mixes from one dive/day to the next, top off tanks with clean air if we're in a rush, etc. We also do partial pressure blending, so at any point in time a partially full tank could be partially full of anything from 0% 02 to 100% 02. Just too much that can go wrong here.

On vacation with my usual trusted buddy we typically analyze our own tanks for the most part, if only from a "division of labor" standpoint since there's often only one analyzer.

However in places like Bonaire when we're throwing a dozen tanks in the back of a truck and the logistics/likelihood of keeping them seperated is low - and we're filling from a station with banked 32% - as long as I've analyzed one of the tanks in the batch or have generally been standing around as my buddy has been analyzing, I'm willing to accept his call out of "these are all 32%" as a good analysis. Similarly, on a liveaboard we might analyze each other's tanks, but rarely, and thinking back it's only ever been if the other was standing right there saying "Dude... look... 32%."

Other than that one buddy, in that type of controlled situation, I don't take anyone's analysis as true.

As Reagan said "Trust... but verify."

Working on a boat I'm often surprised at how many people will accept MY analysis. We don't do fills on the boat - strictly BYOB - but I'll frequently offer my own tanks to a customer who might need them (a rebreather diver with a gear crap-out or someone who finds that a slow leak left them with empties) or a transfill to someone who doesn't have enough gas for a second dive.

In all those cases no has ever questioned my analysis... though I'll tell them "I believe these are filled with 28% but you should analyze them to confirm." I've actually gone to telling them "You know, I have no idea what's in them... here's an analyzer" and they'll look at the tape and say "Say's 28% right here - thanks!"

Guess I must just have one of those faces that people trust!

It comes down to two things:

1) If I wouldn't dive with you, I definitely wouldn't trust you to analyze my tanks. So I'd analyze them again. Takes 2 mins.

2) If I didn't truly know you analyzed the tanks and you weren't around to confirm that you indeed did put the tape on it... I'd analyze the tanks.

All that being said, have I dove with tanks that I've not personally analyzed? Yep. Was I 100% sure of what was in the tanks. Yep.

I'll through out an interesting scenario for you here...

You're picking up 12 rental tanks and they are being filled from the local dive shop's EANx32 bank. It's a technically oriented and trusted shop. One you've done business with before and have no 2nd thoughts of referring other divers to.

It's first thing in the morning, you arrive and they are just starting to fill the rental tanks you want - filling 4 tanks at a time in front of you while you wait. Time is getting short to make the boat. Pressure isn't an issue because they are doing slight overfills.

Here's the question:

a) Do you skip analyzing completely since it's coming right out of the bank and after all it's a trusted technical dive shop?

b) Do you analyze a couple tanks and leave it at that since your running out of time?

c) Do you analyze each and every tank and risk making the boat wait?

pickens_46929:

Here's the question:

a) Do you skip analyzing completely since it's coming right out of the bank and after all it's a trusted technical dive shop?

b) Do you analyze a couple tanks and leave it at that since your running out of time?

c) Do you analyze each and every tank and risk making the boat wait?

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"Trust, but verify!"

The simple answer is: I'd take the risk and analyze them on the boat.



But, assuming I didn't have my own analyzer...

If they're filling them 4 at a time from banked gas, I'd analyze one tank from each set of four... the last set while the other three were being loaded. Wouldn't take any extra time.

But even if it would take extra time I'd rather risk missing the boat ride out... than risk taking a helicopter ride back.

Ironically, your scenario seems to actually beg the original question about trusting other people's analysis. Since you're picking up 12 rental tanks I'm guessing some of them are for other people. Should they trust your analysis? Especially if you tell them you didn't actually do one because you were running late?

PS - do you know a "technically oriented" shop that will let you leave without analyzing tanks and filling out log sheets? I don't.

RJP:

"Trust, but verify!"

The simple answer is: I'd take the risk and analyze them on the boat.



But, assuming I didn't have my own analyzer...

If they're filling them 4 at a time from banked gas, I'd analyze one tank from each set of four... the last set while the other three were being loaded. Wouldn't take any extra time.

But even if it would take extra time I'd rather risk missing the boat ride out... than risk taking a helicopter ride back.

Ironically, your scenario seems to actually beg the original question about trusting other people's analysis. Since you're picking up 12 rental tanks I'm guessing some of them are for other people. Should they trust your analysis? Especially if you tell them you didn't actually do one because you were running late?

PS - do you know a "technically oriented" shop that will let you leave without analyzing tanks and filling out log sheets? I don't.

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plenty

LiteHedded:

plenty

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Yeah, down where you are I guess if they're willing to fill your tanks to 7,000psi they're willing to look the other way on log sheets.

:shocked2:

Since I fill them, I usually end up analyzing my tanks, usually my wife's and sometimes others. If they are standing in the garage I will tell them the analysis and that's basically good enough for them. Ditto if I loaded them in the truck with dated analysis tape yesterday. Basically my garage door is the gateway between gawd knows what contents and known gas. I will not load a tank which isn't full, analyzed today or yesterday and dated as such on the tape, and if its a stage of some sort got the correct MOD label.

On vacation in MX we sometimes analyze each other's tanks if its convenient. Generally at the cenote. I may just have my back turned to the analyzer at the moment or getting something of theirs from the car etc. My initials are as good as theirs in those cases. Every tank gets analyzed & taped though.

My answer is simple -- I veryify, or my wife verifies, any mixed tank I breathe. (BTW, "I veryify" may mean I am watching someone else physically handle the analyzer.)

Perhaps the more interesting question is why I don't, and I suspect this is true of most, analyze every tank I breathe? Especially when on a trip, I don't analyze tanks that are "air" -- but why not? (Neither do I analyze for CO -- which might be a bigger issue.)

I make a point to always analyze my own tanks or watch my buddy analyze them (hook up the analyzer, start the gas flow, and I look at the readout) if I'm doing something else like checking the pressures off all the tanks. Even then, I write down the analysis and initial it.

Common sense plays in here. If you know the person and know they don't cut corners, who cares. If you don't know the diver well, clearly you need to verify it yourself.

I usually analyze my own gas, only exception is if I'm doing something else at the fill station.

even if I know them really well I want to see it myself