You don't! I said, "I experienced this "Phenomenon" with high % O2 mixes. I
doubt
anyone is putting high % O2 mixes in their twins!...............Or are they???

Jim Cobb wrote:

> So, how do you roll a set of doubles?
>
>    Jim
>
> Sender: Jeff Waugh  Date: 4/8/99 11:13 PM
>
> >     I'm not sure about the temperature actually being that much of an
> >influence
> >on the ending reading. I have found that generally low O2 % mixes such as
> >"deep"
> >Tri-Mix'es generally homogenize to the final desired analysis over a
> >period of a
> >few hours.
> >     I've found that high O2 mixes that if filled with O2 and topped with
> >air and
> >allowed to sit without agitation, can render an inaccurate analysis a day
> >later.
> >At that point, a simple "roll" around the garage will suffice to get you
> >what you
> >were looking for!
> >
> >Jim Cobb wrote:
> >
> >> I don't know about you guys but I think the problem we are dealing with
> >> here is the temperature of the mix rather than stratification. As the mix
> >> cools off the reading becomes more accurate.
> >>
> >>    Jim
> >>
> >> Sender: Steve Hogan  Date: 4/8/99 6:53 PM
> >>
> >> >
> >> >I have run into this and have modified my mixing procedures
> >> >so that after I add the O2 to the helium I wait 1 day (I
> >> >usually mix at night so waiting around is not appealing)
> >> >before measuring the O2 % (O2 & He). It is not hard to figure
> >> >out what percentage I expect after mixing O2 with He.
> >> >Next step is to add air, wait a few hours (usually doing
> >> >something else) and then measure again.
> >> >I fill about 50 psi/min so I expect to not get much mixing from
> >> >Brownian motion.
> >> >
> >> >Steve
> >> >
> >> >-----Original Message-----
> >> >From: Patricia Disler [mailto:pdisler@io*.ne*]
> >> >Sent: Friday, April 09, 1999 1:14 PM
> >> >To: S I L E N T I M M E R S I O N
> >> >Cc: techdiver@aquanaut.com
> >> >Subject: Re: Trimix Question
> >> >
> >> >
> >> >
> >> >
> >> >
> >> >At 09:16 AM 4/8/99 -0700, you wrote:
> >> >>Frank,
> >> >>
> >> >>>Not me, but I do let the filled tanks rest a day before analyzing. An if
> >> >>>you want to tell me
> >> >>>thats not neseccary I recommend that you try this: Fill oxygen, top with
> >> >>>air, wait a minute,
> >> >>>analyze mix, turn the tank so that the valve faces ground, wait another
> >> >>>minute and than
> >> >>>re-analyze the mix.
> >> >>
> >> >>And it's the same... or not?
> >> >>When filling a tank the temperature and pressure are high which in turn
> >> >>gives a high diffusion coefficient. Makes the mix homogeneous almost
> >> >>instantaneoulsy (couple of seconds).
> >> >>What kind of differences do you get?
> >> >>What kind of analyser do you use, are you sure the hoses are drained when
> >> >>using a regulator or something?
> >> >>
> >> >>Regards,>
> >> >>THOMAS
> >> >
> >> >I have witnessed Nitrox mixtures take a while to fully homogenize. Several
> >> >years ago while mixing 80/20, (Yeah I know don't start) it came out 63% O2
> >> >approx 30 min after the very s-l-o-w top off to fill pressure. Yes I
> >> >checked the calibration of the aynalizer (Teledyne TD-50). Each time I
> >> >would check the O2 reading would climb. I did this over a period of
several
> >> >hours. Later it was right on 80%.
> >> >I'd have to say stratification can and does occur, esp. if there is not
> >> >enough turbulence during top off.
> >> >I have never seen this with Trimix as the fill rates are much higher.
> >> >However I suppose it could occur if they too were topped slowly.
> >> >At any rate I never seem to dive my gas until they show the correct
> mixture.
> >> >
> >> >
> >> >
> >> >"SILT HAPPENS"JD   JEFF DISLER
> >> >  SAFE CAVING       NSS 26000
> >> >--
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> >> >
> >>
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