Now that would be injecting some actual information into this argument. Way to ruin the onslaughtnessum:
Anyone ever hear of tank rolling after mixed gas fill??
- Thread starter bruehlt
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rat314
Registered
"QUOTE"
If I'm not mistaken, temperature and relative humidity will affect most O2 sensors, but I don't think that the temperate drop from the tank cooling will raise the reading from 30% to 40%
I work in the Medical field, delivering Oxygen and can verify that Humidity will effect an O2 analyzer dramatically. In fact, O2 analyzers are both Humidity and Temperature sensitive.
We are required to bring our test equipment inside our offices each night to prevent damage to the Fuel Cell's. Wall temperature can rise as much as 20-30 degress F during the fill process of a medical grade "E-Cylinder" So due to this, we are required by JCAHO (Joint Commision of Accredited Hospital Organaztions) and per the instuctions for use of our Servo-Mex analyzers.
We have to allow any cylinders we fill to return to an ambient temperature between 71-86 degrees F before analyzing the contents.
If I'm not mistaken, temperature and relative humidity will affect most O2 sensors, but I don't think that the temperate drop from the tank cooling will raise the reading from 30% to 40%
I work in the Medical field, delivering Oxygen and can verify that Humidity will effect an O2 analyzer dramatically. In fact, O2 analyzers are both Humidity and Temperature sensitive.
We are required to bring our test equipment inside our offices each night to prevent damage to the Fuel Cell's. Wall temperature can rise as much as 20-30 degress F during the fill process of a medical grade "E-Cylinder" So due to this, we are required by JCAHO (Joint Commision of Accredited Hospital Organaztions) and per the instuctions for use of our Servo-Mex analyzers.
We have to allow any cylinders we fill to return to an ambient temperature between 71-86 degrees F before analyzing the contents.
Armydiver
Guest
Please pay your $10 for the nitrox at the front counter, wile I drop your $300 tank on the floor and kick it around. ????????? I dont think so.
rat314:
How much will the reading be affected? If the temp is 30f higher, will air read as pure 02 or more like 25%. My guess is that even with the temperate drop, it will still be in the ballpark. Got any numbers to support the method?
I agree with Mike on this one. When I mix bottles of 50%, with slow flow rates, I get similar results.
OP
bruehlt
Contributor
Good replies - its nice to see that I'm not the only one that doesn't believe in this fallacy....
DWJ
Contributor
Sideband:
saw that one coming
bruehlt:
Lots of people don't believe it. Then again, lots of people haven't spent much time blending the types of mixes where it's most commonly seen.
Still, seeing is believeing. It's easy to show that a mix with a large volume of, say, oxygen, topped with a small volume of another gas/mix (like air) added very slowly does not mix by itself instantly. It's also easy to compare the results obtained by letting the mix sit for different periods of time to the results you get when you immediately agitate the tank and analyze. Admitedly you aren't likely to see this when blending mixes like 32% or 36%. Try blending some 80% as I described (add the air at about 60 psi/ minute or so) and let me know what you see...and no I don't dive 80% these days and there's no blending issues with streight O2. LOL
It's a simple enough experiment. Try it...oh, just use something common like an AL 80. There's no need to confuse things with tricky geometries.
Xanthro
Guest
MikeFerrara:
It would seem to me that this would only be possible if the pressure inside the tank was so high, that the added gas to top off the tank couldn't overcome the pressure to mix the blend.
I'll take your word that you've seen it, thought I would tend to believe in theory such a thing would be very rare to near impossible. Though, it wouldn't be the first time I've seen a practical application contradict a theoritical one.
The person you saw kicking a cylinder around might have been ME! I have be playing with this theory for about a month now and still find it interesting. I too throw out my BS flag when I first saw this done but the more research I do into Pressure and Mixing gasses the more probable this becomes. For the Type I and II Nitrox I have never really seen more than a 1 and 1/2 percent difference which is almost within the +/- range of the sensor and user error.
See my thread on this topic EANx Shaken or Stirred
See my thread on this topic EANx Shaken or Stirred
Xanthro:
Thanks for taking my word because while I might not be able to eplain the science in this case I'm not telling lies. And...I've dealt with this many a night when trying to get packed to go diving. LOL
However, as an electronics guy (I should say former electronics guy) I've seen real life deviate from theory many times and dramatically at that. We calculate to get close and then go measure to find out what's going on with all the things that we didn't include in our model.
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