O2 Analyzer without decimal

[boulderjohn]

We have a home in Cyprus, at 650 meters above sea level. If I were to analyze at home, then at sea level, there may be a difference? Haven't actually tried it yet...

You should never calibrate and then go a long period of time without recalibrating.

I have no idea why you would calibrate at home and THEN go to altitude to test your tanks. I do a whole lot of diving at different altitudes, and I always calibrate on site before doing the dives.

Alternatively, if you are planning to go to altitude and dive immediately, you could calibrate and analyze at home and then go to the dive site. I personally do not trust my tank markings for more than a day or so. It's too easy to make a mistake. I can name several divers who trusted their memories of what was in their tanks, and their names are well known because they were wrong.

 

[Capt Jim Wyatt]

I can name several divers who trusted their memories of what was in their tanks, and their names are well known because they were wrong.

and dead because of it.

 

[PR_SMITH]

You should never calibrate and then go a long period of time without recalibrating.

I have no idea why you would calibrate at home and THEN go to altitude to test your tanks. I do a whole lot of diving at different altitudes, and I always calibrate on site before doing the dives.

Alternatively, if you are planning to go to altitude and dive immediately, you could calibrate and analyze at home and then go to the dive site. I personally do not trust my tank markings for more than a day or so. It's too easy to make a mistake. I can name several divers who trusted their memories of what was in their tanks, and their names are well known because they were wrong.

Please read the post again; my house in Cyprus is at 650m above sea level. I was speculating on what the difference in readings would be at sea level. I also mentioned that I have yet to try it. I don't live there full time yet and my compressor, etc are still in Canada.

I always retest any tank immediately prior to any dive and never said anything different.

I lost a friend who refused to analyze a tank prior to a dive, and he swore he knew the contents. He switched to said tank at 90ft, which happened to contain 100% o2. R.I.P. I wasn't there, and I had been I would have refused to get in the water with unknown gas.

 

[broncobowsher]

Oxygen analyzers use the same oxygen cells as a rebreather. Research how that read at pressure.

Short answer, they don't read percent. They read partial pressure of O2. So changes in elevation (and barometric pressure) will change the readings. The higher the pressure, the higher the reading. the lower the pressure, the lower the reading.

I'm pretty sure the DiveSoft trimix analyzer has a baro sensor in it. I don't know of any others that do. That might be more for the Helium sensor anyway.

 

[Sevenrider860]

Oxygen analyzers use the same oxygen cells as a rebreather. Research how that read at pressure.

Short answer, they don't read percent. They read partial pressure of O2. So changes in elevation (and barometric pressure) will change the readings. The higher the pressure, the higher the reading. the lower the pressure, the lower the reading.

I'm pretty sure the DiveSoft trimix analyzer has a baro sensor in it. I don't know of any others that do. That might be more for the Helium sensor anyway.

You are correct. The DiveSoft analyzer has a temperature and barometric sensor. The Analytic Industries Trimix 4001 analyzer has temperature, barometric and relative humidity sensors.

I think the temperature sensor in the DiveSoft is used for warnings when you may be at the extremes of the O2 sensor. In the AI unit, the temperature and RH sensor are used to compensate the O2 value (i.e. 20.0% at 90 degrees and 90% RH).

 

[The Chairman]

That said, never use a tank you haven't analyzed yourself.

So, it's a moot point. Again, if being off by a percent or even two really impacts your dive, you're planning it way, way, way too close. I will jot down integers, MOD, and initials on a sticker... or not. Often, I am measuring the mix spring side, so it gets plugged into my PDC before I have a chance to forget. Since I always have 32 programmed into my Shearwater, anything from 31 to 33 gets put in as 32. I've been diving since 1969, and have never been bent diving like this.

I do see too many divers measuring their mix while it's fresh off the compressor and hot. Best to let it mellow to ambient temps before you measure.

 

[jadairiii]

So, it's a moot point.

Not really, as I prefaced, if diving with a group or team, and your job is analyzing the tanks, the other divers will want to see that number to the decimal.

And if I see my buddy's tanks marked without the decimal I will call him/her on it, and possibly re-analyze the cylinders. I dont analyze (normally) my buddy's tanks, but I do confirm the mix via the analyzation stickers.

Not to mention, the OP's question was sort of a "why?" the decimal, and the "why" is more for marking cylinders than programing your computer.

 

[The Chairman]

and your job is analyzing the tanks

No. Only I analyze my tanks and then only my tanks. That's the whole problem right there.

Dive only the tanks that YOU have analyzed is one of the most important tenets of diving with NitrOx. I do it like my life depends on it. I made that mistake only once, and it could have ended in tragedy. The guy who had analyzed my tanks was the guy who had just certified me on NitrOx. He should know, right? On descent, I felt that I had a cold coming on with weird dizziness and I aborted my dive after I hit 60ft or so. I didn't even try the second dive. When I got back home, I analyzed the tank elsewhere. The tank had 100% 0₂. Yeeesh! Since then, I have never let anyone, anytime analyze my tanks, and I won't do it for them, either.

But you do you. I'm going to stay safe.

 

[Scubagermany]

I would never rely on anyone to perform a task such as analyzing my tank for me. Many people tend to be total idiots.

Since its me writing the percentage on the tank a decimal is really not necessary.

Furthermore, how big is the possibility of an error when I hold the analyzer in front of the outlet and try to make it tight with said hand? I dont know for sure but I am certain it is way more than 0.1 percent.

I dont dive Tec deep (which does not matter with EAN anyway) but what difference does it make if you have 32 or 33 percent in your tank? You should never plan your dive in a way that this 1 % could make it unsafe....

 

[Gone for diving]

You know its correct when you see 32.10345%.
Whoever tested it cared and definitely was not lazy.

You test it yourself, that way, you can blame yourself before you blackout,

You don't want your buddy to blame himself for the rest of his life.