Do you analyze?

[Line Squirrel]

No shop names please.

[icestac]

I analyze -- although sometimes I only remember AFTER I have carried my tanks down to the water when I go to set my computer. sonofa*****!

~Jeff

[RN]

My wife and I dive a lot together and even though one of us may be hooking up the analyzer, we always eyeball the readout for out own tanks. We usually even eyeball each other's readout. My wife is also the one who programs our computers (while I lug tanks to the water...something wrong with that...), but I still verify that she set the right numbers. Not that it really matters because we've either cut tables for new locations or already have a profile for the caves we've been to. I just don't want to have to listen to my computer beeping the whole time because the nitrox percentage was accidently set at 52 instead of 32 and now it thinks I'm violated MOD (those numbers on the He are way too small).

[aainslie]

I'm a lot more casual about this than I should be. Thanks for the reminder that being casual is a bad idea...

[Oister]

In the NE we analyze when we pickup fills at the shop. I was shocked @ how things worked in cave country. I ordered an O2-He analyzer after my 10 min blending class @ the roadside 24-hour self-service fill station.

[sem824]

my son and I got to the site and realized we had forgotten to analyze. I went and bought a hand held before I would dive. (I had wanted one anyway, so it was a good excuse to - though I wish I had not paid retail!)

[PacketSniffer]

I may bend a rule here or there but I never bend this one. I always analyze everything.

With my trimix analyzer out for repair (He sensor...OUCH$) on a recent trip, I borrowed my buddy's analyzer to find something in one of my rebreather cylinders that I didn't expect because they were relatively new cylinders (but never used). It wouldn't have killed me that day but it reinforced the reason why I analyze. I've read enough of the stories in the accident forums as well to not be complacent on this one at all.

Another one...

During my RB training dives, I asked to borrow an analyzer at a popular cavern training location that supplies gas. The man behind the counter turned to give me the look of complete amazement. He said, "...for air???" I said, "yes". :yawinkle:

[swadiver]

twice with two different analyzers

[jj1987]

I've been lazy before from shops I trust. Here in Orlando I ALWAYS do it, but in cave country, I think I've gotten complacent and lazy because frankly I trust the shops, this thread kinda makes me re-evaluate things, I guess even the best of shops have people who make mistakes.

[Bill Rotella]

My life to me and my family is too important to mess up. I would recommend reading some of the IUCRR reports regarding toxing and death. Not analyzing is like playing russian roulette with an advanced dive.

[OutlawCaver]

I mix my own gases, although I use the LDS for air, 32, 36 or 100 top offs. All of my tanks are numbered and tracked in a gas analysis chart that I keep in my van. Trimix & 50/50 gets analyzed at least 5 times prior to a dive over a five day period. At least twice during this process, I use two seperate oxygen sensors with a flow meter and a high resolution voltmeter. I calibrate the sensors with 100% O2, 100% He and dry filtered air. I input these 3 calibration points into a linear regression program using one of my TI 83, 84 or 89 calculators. I then sample the unknown gas and enter it's oxygen sensor output into the linear regression formula to achieve my FO2.

Although, this may seem excessive, my life, and that of my buddies, is well worth the effort. It is a far superior way of getting accurate analysis over a broad range of oxygen fractions using 3 calibration points versus the typical single calibration point offered by commercial oxygen sensors.

Since I am rarely starting with empty cyclinders, I run calculations for what FO2 & FHe I plan to finish with and then mix by partial pressure (pp) method using a bench digital pressure gauge. Experience has shown me that van der Waal forces can effect my final gas outcome fractions. In essence, oxygen and helium do not act like ideal gases. Oxygen is slightly more compressable than air and helium slightly less compressable than air. Therefore, I knock off about 2% of the calculated oxygen pressure and then add about 2% more helium pressure than calculated.

I analyze FHe, although this is much less critical than FO2, since +/- 5% helium has very little impact on deco schedules for the duration/depth dives I conduct.

I have found that gas homogeneity of heliox or trimix mixtures, is not achieved, for at least a day after my final top offs.

I also confirm manifold crossovers are open each time I analyze.

The day before a dive I label all tanks with appropriate MODs on the sides and bottom of the cylinders.

In case you are wondering, I neither iron or fold my underwear and socks. I am only anal about breathing gases.

I would be glad to show &/or demonstrate, to anyone interested, my mobile calibration system that fits into a oversized briefcase.

[MORGAN]

This is the type of thread I really enjoy. The opportunity to see what other people are doing and why they're doing it is extremely valuable.

I analyze my gas all the time except when I don't.

I'm not mix certified, so the only gases I use are air, nitrox, and 100% O2 in my deco bottle.

I don't analyze air or 100% 02.

I analyze partial pressure blended nitrox every time.

When I get a one-time fill, or any fill from a shop that I'm not very familiar with, I analyze every time.

IF I'm changing my fO2, such as adding air to nitrox to increase my MOD, I analyze every time.

When I'm diving in cave country, and getting repeated fills of banked nitrox from a shop I'm very familiar with, I tend to analyze the first fill of the day, and then slack off, lapsing into indolence and sloth, and not analyze subsequent fills the same day from the same banks. I know that this is not the thing to do, but I sometimes do it anyway.

Reading this thread has gotten me thinking that I need to throw off my laziness and complacency and go back to analyzing every gas I breathe, every time.

Mike

[Slüdge]

Vince, I thought I was going to get razzed for analyzing nitrox three times!

[icestac]

In case you are wondering, I neither iron or fold my underwear and socks. I am only anal about breathing gases.

I would be glad to show &/or demonstrate, to anyone interested, my mobile calibration system that fits into a oversized briefcase.

Good job! I'd like to see a picture of your setup if you have one. I'll have to go scrounge up one of my old TI calculators. They may even still have some games on them :)

BTW - Nothing wrong with ironed and folded underwear... just go easy on the starch.

~Jeff

[flyczek]

I'll admit to slacking off on analyzing banked 32 from a trusted shop. I might analyze the first fill, but not the second.

Interesting thread, it does make you rethink your procedures.

[flyczek]

Here's an experience I've had that raised questions in my mind:

As per manufacturers instructions, I keep my sensor in the fridge when it isn't going to be used for awhile. So the other day, when I needed to do some analysis, I got the sensor out and allowed it to sit about an hour before use. I calibrated, then analyzed, the percentages lined up with my target mix.

Later that day I analyzed what should have been the same mix, another tank I filled with the same mix on a different fill whip, and I noticed a significant variation in readings (>2%). I wasn't sure if this was from the sensor still warming or if it was from changes in air temp or humidity, or something else. I decided to recalibrate and try again.

I grabbed an air tank and recalibrated, but the reading was so far off, it made me question if I really had air in that tank. I didn't want to use a "known mix" to calibrate off of, because even though I mixed, analyzed and labeled it myself, I could have made an error. I thought about calibrating using my O2 bottle, but then I wasn't sure if that would be an accurate way to calibrate and whether it should read 98, 99 or 100. Finally, I grabbed a air mattress pump and used that to push air through the sensor, as I knew that would really be air.

So what do you guys use to calibrate with? Anyone else keep their sensor in the fridge when not in use?

[RN]

Before I moved to N. Florida and was travelling here from the desert every few months, I noticed a significant difference in readings from my analyzer depending on where I was. The analyzer I had at the time was self calibrating to air by waving it back and forth for about 30 seconds. I quickly realized the humidity in N. Florida threw the readings off a lot! Refridgerated air will cut down the humidity and do the same thing. The longer your analyzer is exposed to humid air, the more "off" it will be. My analyzer stays in a storm case now (actually it was built into a storm case).

[BabyDuck]

yay! just found my analyzer - it had been mia after the move.

love my little pink box...

[Lamar English]

I analyze every time, without exception. What you don't know can kill you!
People screw up sometimes; like the young F-Tard who accidently filled my 120' nitrox deco bottle with pure O2... Had I not analized my gas, I would be dead and Diepolder's would surely be closed.

Wake up!

[cavediver256]

I analyze every time, without exception. What you don't know can kill you!
People screw up sometimes; like the young F-Tard who accidently filled my 120' nitrox deco bottle with pure O2... Had I not analized my gas, I would be dead and Diepolder's would surely be closed.

Wake up!Well put Lamar.....I don't know of anyone I would trust that much with my life. Accidents do happen, and the only dumb accident is one that could have been prevented !!!! Analyze your gas people !!!!

[swadiver]

as a frequent recepient of outlaw caver's mixes, i appreciate very much his fastidiousness when it comes to mixing and analyzing our breathing gasses. i know that this is a very time consuming process, but when we hit the nest or diepolder or even JB, i know that i do not have to worry about what i be breathing. now if only the rest of his pathetic life was so ordered!

however, as safe and accurate they are, i have wondered about that nefarious odor of only MY mixes

[Moonfuzzy]

Even with air or O2, if you are not analyzing you are assuming they are connected to the right whips and the correct knobs are on - you could be getting helium instead or O2 etc. You are also assuming that nothing evolved in your tanks since you used them - I wonder if that would show up on my testing if something strange did happen in there?

[lamont]

i do my own fills. typically i like to analyze at the shop and at the divesite right before diving.

i've caught myself doing fills where i've left the O2 open with the air (now i tend to run through an automatic check to ensure that everything is off before i open anything up to prevent that, but it could still happen). since the bank pressure of the 21% was so high and the O2 pressure was so low it didn't seem to cause much of a difference. buddies of mine have done that mistake when the pressures were closer to equal and have gotten really crazy mixes.

sometimes it takes awhile for helium mixes to settle out as well -- although typically this happens to me when everything i do goes through the booster and flow rates are really, really slow (e.g. changing half-full 30/30 into 21/35 or something silly like that). normally i put a few hundred psi of air in fairly quickly at the very end which seems to promote bulk mixing in the tank and i don't need to let it settle overnight.

[traveler]

The O2 and He we buy from gas suppliers is required to meet extremely high purity standards and is subject to a series of controls intended to ensure you get what you pay for. I see divers omit analyzing their O2 bottles fairly often, and while I understand the temptation in my opinion it's a very bad idea...

A gas supplier (not a dive shop) I used to use in Ohio delivered bottles of pure N2 to a nursing home, rather than the O2 that was ordered. A series of errors involving repainted bottles and inappropriate use of valve adapters allowed the nursing home to plumb it into their supplemental O2 system, killing several residents throughout the building.

So now I analyze my oxygen, just like everything else. I calibrate to dry compressed air, so don't expect it to read exactly 100.0%, but the difference between pure O2 and anything else is quite apparent. Such errors may be extremely rare, but the ultimate opportunity to prevent the consequences rests with me, the guy who's about to breathe it.

BTW, a friend made up some decals for calibration bottles, "Air - do not breathe". :)

[LCF]

I analyze all Nitrox, and all cylinders which come from a facility that fills Nitrox or mix. (For example, on this last trip to Mexico, I got doubles with air in them from Aquanauts -- but they come from the same fill station that does all the Nitrox, so I analyzed them, too.)

We have a couple of local shops that only fill air, and I wouldn't analyze tanks from them.

[Dsix36]

I analyze all tanks before I leave the shop with them. I then analyze them again at home.

I don't have a helium analyzer just yet, but it is in the works. So for right now it is just the O2 that gets checked a second time.

[megahurts]

I have never forgotten the first dive in the Extended Range class that our team did at Forty Fathom's.

We failed to analyze our O2.......Dan said (actually yelled) now you're both dead.

We have never forgotten this and we ALWAYS analyze our gas independently. We forgot the analyzer once.....so we didn't dive.

[Rubis]

Ever since I got to CCR I analyze everything (even air or O2) without exception.
Before I used to be sloppy with O2 sometimes.

[carlcz]

I have gotten complacent with analyzing air at shops that I trust. Not anymore, just too important. Thanks for reminding me folks!

[rjack]

I continuous blend at home (except 50%). Sometimes I label tanks with what they are supposed to have in them just to maintain inventory. In these case I don't use a decimal point and I use a % symbol.

But before a tank gets into the truck it gets analyzed. This includes O2 although I'm not very anal about calibrating for that, 98, 99, 102% are all good to me. As long as I can tell its not 50% or He or something like that.

My biggest potential source of error is on 50%. Al40s get pretty hot during fills and to avoid much overfilling I usually top them off the next day. 1100psi of O2 but only (net) 1600psi of air gives a rich mix. Forgetting to top off isn't common but it happens.

When travelling I or my wife analzyes every tank (e.g. I haul to the car, she analyzes). Generally the mixes are low but we've had some 'hot' ones too. e.g. 41% instead of 32%EAN. Proving to me that you are rolling the dice if you don't analyze every tank. Stupid way to die too.