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Kevin, Stop it. Your making sense again. Blend a couple, keep some *very* simple notes, you will get the feel. Its an art, not a science (sounds cool, huh?). Scott ----- Original Message ----- From: "Kevin Connell" <kevin@nw*.co*> To: <techdiver@aquanaut.com> Sent: Tuesday, March 28, 2000 1:20 PM Subject: Re: Trimix fudge factors > Hey guys, I hate to break this to you, but mixing isn't rocket > science. Fudge factors have more to do with your personal gauge and with > the T in PV=NRT (tank overheating) than they have to do with > compressibility and real gas laws. > > That combined with the fact that the O2 is really the only critical > pressure, and you are doing that as a delta pressure in the midrange of the > gauge means that if you're getting your mixes wrong, you're not doing it right. > > Next we'll be hearing about how oxygen analyzers have to be on a flow meter > to be accurate. > > At 01:09 PM 3/28/2000 +0200, <Bjorn.Forshei@kv*.co*> wrote: > >Capitan, > >You may download a demo version of GASMIX 5.0 on Cobb's Trimix page. It's > >not a full version, but you will find the compressibility (Z) factors for > >He, O2 and N2 there for any pressure. As you see, Z may be below or above > >unity, depending on type of gas and pressure. A fudge factor to compensate > >for compressibility factors may thus not always work. The reason it works > >anyway is probably because the main thing to compensate for is temperature > >(hotfill), and not compressibility factors. > > > > > >I've enclosed a listing from GASMIX, for Trimix 18/50, 2640 and 3500 psig, > >for both Ideal and Real gas. The "Real gas" gas model should be > >theoretically most accurate. > > > >-b- > > > > > > > >****************************************************** > >* * > >* Trimix from Helium + Oxygen + Air * > >* * > >****************************************************** > > > > Gas Model = Ideal Gas > > Narcotic Oxygen = No > > Registred User = Bjorn Forshei > > > > > > Filling Data... > > > > Goal contents : 18.00 [%] O2 > > 50.00 [%] He > > 32.00 [%] N2 > > 2640.00 [psi] > > > > The bottle to be filled is empty > > > > Filling Sequence : Helium -> O2 -> Air > > HELIUM fill pressure : 1320.0 [psi] > > Intermediate O2 cont.: 0.00 [%] > > OXYGEN fill pressure : 1572.0 [psi] > > Intermediate O2 cont.: 16.03 [%] > > AIR fill pressure : 2640.0 [psi] > > Final O2 contents : 18.00 [%] > > > > You have now mixed Trimix : 18.0 / 50.0 > > > > > >****************************************************** > >* * > >* Trimix from Helium + Oxygen + Air * > >* * > >****************************************************** > > > > Gas Model = Real Gas > > Narcotic Oxygen = No > > Registred User = Bjorn Forshei > > > > > > Filling Data... > > > > Goal contents : 18.00 [%] O2 > > 50.00 [%] He > > 32.00 [%] N2 > > 2640.00 [psi] > > > > The bottle to be filled is empty > > > > Filling Sequence : Helium -> O2 -> Air > > HELIUM fill pressure : 1319.5 [psi] > > Intermediate O2 cont.: 0.00 [%] > > OXYGEN fill pressure : 1557.3 [psi] > > Intermediate O2 cont.: 16.03 [%] > > AIR fill pressure : 2640.0 [psi] > > Final O2 contents : 18.00 [%] > > > > You have now mixed Trimix : 18.0 / 50.0 > > > > > > > > > >****************************************************** > >* * > >* Trimix from Helium + Oxygen + Air * > >* * > >****************************************************** > > > > Gas Model = Ideal Gas > > Narcotic Oxygen = No > > Registred User = Bjorn Forshei > > > > > > Filling Data... > > > > Goal contents : 18.00 [%] O2 > > 50.00 [%] He > > 32.00 [%] N2 > > 3500.00 [psi] > > > > The bottle to be filled is empty > > > > Filling Sequence : Helium -> O2 -> Air > > HELIUM fill pressure : 1750.0 [psi] > > Intermediate O2 cont.: 0.00 [%] > > OXYGEN fill pressure : 2084.1 [psi] > > Intermediate O2 cont.: 16.03 [%] > > AIR fill pressure : 3500.0 [psi] > > Final O2 contents : 18.00 [%] > > > > You have now mixed Trimix : 18.0 / 50.0 > > > > > > > > > > > > > >****************************************************** > >* * > >* Trimix from Helium + Oxygen + Air * > >* * > >****************************************************** > > > > Gas Model = Real Gas > > Narcotic Oxygen = No > > Registred User = Bjorn Forshei > > > > > > Filling Data... > > > > Goal contents : 18.00 [%] O2 > > 50.00 [%] He > > 32.00 [%] N2 > > 3500.00 [psi] > > > > The bottle to be filled is empty > > > > Filling Sequence : Helium -> O2 -> Air > > HELIUM fill pressure : 1723.2 [psi] > > Intermediate O2 cont.: 0.00 [%] > > OXYGEN fill pressure : 2031.8 [psi] > > Intermediate O2 cont.: 16.03 [%] > > AIR fill pressure : 3500.0 [psi] > > Final O2 contents : 18.00 [%] > > > > You have now mixed Trimix : 18.0 / 50.0 > > > > > >-- > >Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. > >Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'. > > > ---------------------------------- > Kevin Connell <kevin@nw*.co*> > > NW Labor Systems, Inc > http://www.nwls.com > > Res tantum valet quantum vendi potest. > (A thing is only worth what someone else > is willing to pay for it) > > ---------------------------------- > > -- > Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. > Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'. -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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