james croft
Contributor
I shake my tank until the marble rattles around freely for 45 seconds. When I took my Nitrox class we were taught to roll them around. Thought that was sort of silly.
Anyone ever hear of tank rolling after mixed gas fill??
- Thread starter bruehlt
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Wayward Son
Contributor
I didn't say that it served an actual purpose. I dunno for a fact that it does. Just that I have seen shops that blend in the tank do this.
pants!:
I've tried this and it does make a small improvement, although it isn't as effective as letting them sit overnight. Shooting air in at higher speeds isn't recommended when blending over 40%. When I mix 50%, I flow the air at slow rates and if I measure the tank right away, it will read roughy 30%. If I spin it a few times, it will read in the 40's. Again, I think that there is some truth, but to be effective, you'd probably have to spin it pretty quickly for several minutes.
I usually let my (partial pressure) mixes sit for a few hours before I measure.
teknitroxdiver
Contributor
Have you compared the difference in measurements when you spin for a few minutes versus letting it sit for the same amount of time? Not that I have, I'm just curious as to the difference...do it easy:
doos
Registered
This is done frequently with industrial gas mixtures (for fire suppression, etc), if the cyilders have been sitting for a long period of time in excessivly cold temperatures (ie sitting outsied for a Canadian winter), especially if the gasses have very different partial pressures, densities, etc. I really doubt it's required for a scuba tank that was just filled.
teknitroxdiver:
I suppose using a control tank would make the result more meaningful. I think the one time I tried this, there might have been 15-20 minutes from initial measure to final measurement, although I wasn't spinning it the entire time. I would guess that I spun it for about 1 minute. If I believe these numbers, than I would guess it has some merit, but next time I'm mixing two sets of 50%, I'll run a controlled experiment.
Do it easy,
Did the thought ever occure to you that due to the temp increase that is created during the fill may have an impact on the reading your getting right after the fill vs a few mins later when the tank may have cooled just a bit?
Did the thought ever occure to you that due to the temp increase that is created during the fill may have an impact on the reading your getting right after the fill vs a few mins later when the tank may have cooled just a bit?
GeekDiver:
I would guess that the temperature change from going from 3000 psi to ambient will cool the gas much more than the few degrees it will drop from just sitting there.
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%
Anyone have any info on this? Or maybe any experience with partial pressure blending in a water bath?
teknitroxdiver
Contributor
How did draining to ambient enter the equation?do it easy:
I sincerely doubt that shaking does anything at all. This is not a liquid where shaking it would do any good. Paint sprays actualy have liquid in them that is why you should shake them. The reason for the diffrent readings are probably due to the temperature of the gas (more active molecules appear more frequently on sensors).
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