It occurs to me that with the oxygen molecule SLIGHTLY smaller than
the nitrogen molecule that the oxygen molecule is probably lost at a
great rate than the nitrogen molecule (the stated reason for using
nitrogen in this thread). Therefore, if we add air to the tire we
are increasing the nitrogen to oxygen ratio in the tire. It would
therefore follow that if we add air to our tire often enough we would
eventually get to the nearly 100% nitrogen valhalla, making this
discussion moot.
--- In Diesel-RVs@yahoogro
>
> OK, since you opened the door in this discusion, I'll throw some
more stuff
> into the equation. Membrane permeability and molecule size. Both
have
> significant effects on what is going on here.
>
> I'm not going to go further except to say most of us have no real
interest
> in going further and I am not going to refresh my memory and delve
into them
> any further. Besides I gave all those books away when I
> retired!!!!!
>
> Jim
> James Godward
> On the Road From
> Belgrade, MT
> ~
> ----- Original Message -----
> From: "R.Jordan McDowell" <allstarlocks@
> To: <Diesel-RVs@yahoogro
> Sent: Wednesday, January 02, 2008 8:27 PM
> Subject: RE: [Diesel-RVs] Re: 07 Toyota/Nitrogen
>
>
> > Jerry,
> >
> > Ah ha! A pithy question and one that cuts to he crux of this
biscuit.
> >
> > Like most of these discussions the group is busy comparing apples
to
> > something-not-
goal is not
> > to solve the problem - it is to argue. Get 3 Americans together
in the
> > same
> > place and they will argue about something and of the 3, 1 of them
will
> > argue
> > for the sport of it. There are about 5000 members on this list.
Don't you
> > know that a bunch of them (me included sometimes) just enjoy a
good ol'
> > disagreement. Throw in the 15% of posts generated because the
responder
> > didn't really understand the original question (which I did just
this
> > morning - about the external propane tank hookup) and the many
paths a
> > conversation follows and, especially with a subject like this,
not much is
> > ever agreed upon.
> >
> > The value in this group is when X quits working or needs
replacement and
> > the
> > vast amount of experience here answers "Do "Y" and replace "Z"
and it will
> > be fixed - and it is.
> >
> > pV=nRT is sometimes called Boyles (or Boyles-Mariotte) Law ,but
is more
> > accurately named the "Ideal Gas Law", because it assumes ideal
conditions.
> > One of those conditions is that (assuming the amount of gas
remains the
> > same) when you compare changes in pressure to changes in
temperature, then
> > the volume will remain constant (or change volume and compare
pressure and
> > the temperature is the constant) to make the equation work. No
one would
> > argue that the inside of a tire is an ideal environment in any
sense.
> >
> > And we haven't even talked about partial pressures. Basically
different
> > gases will generate a pressure that is proportional to the total
pressure
> > as
> > the amount of that gas is to the total amount of all the gases in
the
> > container. For instance if I mix 1/2 Argon atoms and 1/2 Helium
atoms in a
> > constant volume container at a total of 60 lbs/sq inch, the Argon
alone
> > will
> > generate 30 lbs/ sq inch and the Helium will do the same. If I
change the
> > mixture to 2/3 Argon and 1/3 Helium, the partial pressure of the
Argon
> > will
> > be 40 lbs/si and the Helium will be 20 lbs/si for a total
pressure in the
> > container of 60 lbs/si..
> >
> > So what do I care about partial pressures, you ask? Well.... what
if one
> > of
> > the gases were water vapor (it is) and what if that gas could
change from
> > a
> > gas to something else (solid or liquid) in the normal
circumstances we
> > encounter? It does. Have we not seen liquid water and, especially
this
> > time
> > of year, solid water (aka ice). Well the Ideal Gas Law does not
apply to
> > liquids and solids. So, as we drive, and solids warm up to
liquids, or
> > liquids warm up and (evaporate) turn back to gas inside the tire,
Boyles
> > Law
> > becomes more of a rule, really, and unenforceable at that.
> >
> > Finally, a word about the container, which was what your question
> > addressed.
> > A tire, viewed in cross section will flex and extend repeatedly
as it
> > rolls
> > and, in doing so, will generate heat of it's own. This interferes
with
> > Boyles (by now) Suggestion which considers temperature as a
variable only
> > as
> > a function of the properties of the gas (not the tire). Whereas
Boyle says
> > the temperature will decrease if the pressure is decreased (and
the amount
> > of gas stays the same) the tire says that if you decrease the
pressure
> > more
> > flexing will occur and the temperature will rise. Poor old Boyle.
> >
> > Anytime we compare the ideal to real life there are
discrepancies - that's
> > why test pilots get hazardous duty pay. And. that's why these
type of
> > arguments can be entertaining, but not usually productive. That
said, I do
> > not dismiss this whole discussion. The guy who ran NASCAR and the
guys
> > here
> > that ran a fleet of diesel trucks - guys like that offer a solid
dash of
> > real life and real value. And the guys who are physicists and
chemists
> > have
> > a lot to offer on the ideal side of the coin.
> >
> > So, I was being a bit facetious with my post - but I was NOT
poking fun at
> > anyone.
> >
> > BTW - I bet my lunch money that someone will argue that Americans
do NOT
> > argue for just the fun of it - thus proving my point.
> >
> > Best Regards,
> >
> > Jordan
> >
> >
> > -----Original Message-----
> > From: Diesel-RVs@yahoogro
RVs@yahoogroups.
> > Behalf Of hazegraydynasty
> > Sent: Wednesday, January 02, 2008 8:00 PM
> > To: Diesel-RVs@yahoogro
> > Subject: [Diesel-RVs] Re: 07 Toyota/Nitrogen
> >
> >
> > I don't claim to know anything about this stuff (and usually
refrain
> > from posting on this subject), but I do have a question for you
smart
> > guys:
> >
> > If it's as simple as pV=nRT...
> >
> > Why does a tire that's 10 - 15 pounds low run 30 - 40* high?
> >
> > Cheers/Jerry
> >
> >
> >
> > --- In Diesel-RVs@yahoogro
> > wrote:
> >>
> >> I'm pretty sure I have my facts straight. I spent wayyyy too much
> >> time in school to mess up the basic stuff too bad. If you are so
> >> certain something I wrote here is wrong, please back it up with
> >> facts, references to textbooks, scientific journals and the like,
> > or
> >> mathematical evidence.
> >>
> >> Les
> >>
> >> --- In Diesel-RVs@yahoogro
> >> >
> >> > Go back to school Les!
> >> >
> >> >
> >> > -----Original Message-----
> >> > From: Diesel-RVs@yahoogro
> >> RVs@yahoogroups.
> >> > Behalf Of lshields20
> >> > Sent: Wednesday, January 02, 2008 1:46 PM
> >> > To: Diesel-RVs@yahoogro
> >> > Subject: [Diesel-RVs] Re: 07 Toyota/Nitrogen
> >> >
> >> >
> >> >
> >> > I "think" the air loss through migration is mostly in one's
> >> > imagination. If nitrogen did "migrate" through the tire more
> > slowly
> >> > than oxygen does, what would happen? Some oxygen would migrate
> >> through
> >> > the tire leaving the nitrogen behind. Add plain air to make up
> > and
> >> the
> >> > process repeats. After several such episodes, what do you have
> > left
> >> in
> >> > the tire? It would be nearly pure nitrogen. The process called
> >> gaseous
> >> > diffusion and is one method that can be used to enrich uranium
for
> >> > fissile purposes.
> >> >
> >> > Loss through the valve stem is much greater than through
> > the "pores"
> >> > in the rubber.
> >> >
> >> > I must have the best set of Michelins ever made on my 2004
Dutch
> >> Star.
> >> > For the first two years I owned it, I never added air (and I do
> >> check
> >> > them frequently). I have added air about twice since then. Both
> >> times
> >> > were to compensate for me reducing pressure while traveling in
the
> >> > south, then adding air to make up during cold months up north.
> >> >
> >> > I highly suspect the transition between summer and winter is
the
> >> main
> >> > reason people find they need to add a couple pounds to their
> > tires.
> >> > The ambient temperature change between summer (say 80 degrees)
and
> >> > winter (say 20 degrees) is enough to cause a several pound
change
> > in
> >> > pressure. At least a pound a month from summer to winter.
> >> >
> >> > I don't believe Costco is run by idiots. I think it is run by
very
> >> > good marketing people. If a store can provide a perceived value
> >> > (whether or not it is an actual value) when selling a commodity
> > item
> >> > (a particular tire is pretty much the same no matter where you
buy
> >> > it), people are more likely to buy where they get the perceived
> >> value.
> >> >
> >> > Les
> >> >
> >> > >
> >> > > Then why does Costco fill all the tires they sell with
> > nitrogen.
> >> You
> >> > > cannot buy nitrogen from them--it is only something they
> > provide
> >> at no
> >> > > cost for their new tires. I don't believe that Costco is run
by
> >> idiots.
> >> > > There must be some value. In my case, the only difference
I've
> >> seen
> >> > is a
> >> > > much, much lower of air loss due to migration. But that is a
> > very
> >> > > worthwhile difference for me.
> >> > >
> >> > > Bob Clerc
> >> > > @ Casa Grande, AZ
> >> > >
> >> >
> >> >
> >> >
> >>
> >
> >
> >
> >
> > ------------
> > Off-topic posts will be removed.
> > Please sign with your name (real or online name) and include the
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> > you have.
> >
> > To unsubscribe from this group, send an email to
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> >
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
> >
> > ------------
> > Off-topic posts will be removed.
> > Please sign with your name (real or online name) and include the
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> > you have.
> >
> > To unsubscribe from this group, send an email to
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> >
> > Yahoo! Groups Links
> >
> >
> >
>
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