OT: Nitrogen filled tires

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Duh! Because then they wouldn't be able to to charge the idiots $100.00
for air!

The fact that they are doing it suggests there are enough people
willing to believe in this . . . I saw an ad (disguised as news) on
the local TV news that said a gas station was supplying police with
nitrogen for "free" and singing the advantages - and by the way you
can get a fill for $10 a tire.

Other than the tank demurrage, the average person with a garage could
buy a regulator and fill their own tires with N2 for less.

 

[Richard Henry]

CarTalk is likely full of shit. It does NOT cost that much ($100 per
fill) to have a ten Lb tank of Nitrogen at 3000 psi on each truck, with a
regulator and means for the driver to maintain his tires with it.

Car Talk did not say it costs $100. A CT reader asked if it was worth
$100 charged by a local service. CT said no.

 

[Richard Henry]

Perhaps the beads of the rim oxidize less on the Nitrogen filled
series, and thereby leak down less, making the stats for those vehicles
batter. Maybe even the valves degrade less.

So, if that is the reason, then I believe the study.
Perhaps...Maybe...

From the FleetOwner article:

"Drexan is Canada's largest distributor of Parker Hannifin Corp.'s
TireSaver nitrogen generator, which was used for the fleet's study."

Therefore I am skeptical.

 

[John Larkin]

The static pressure of R-12 is almost the same as the ambient temp when
around 70F. This is one way of telling how full your R-12 tank is. It
is no longer in use in the US.

At other temps, I am sure it isn't linear, but the stuff changes
pressure a LOT with temperature.

Only if liquid is present, or it's close to liquifying, which means it
isn't following the universal gas laws. If a lower molecular weight
freon were used, or maybe some other gas like SF6, it would behave
just like air or nitrogen, but would leak slower. It's a tradeoff
between high molecular weight (leaks less) and low (follows gas law
more closely under pressure/temperature situation.) Too bad the
methane series is all explosive.

Interesting stuff:

http://en.wikipedia.org/wiki/Sf6


John

 

[John Larkin]

KaBang!

Yes, but only if you ever mix it with air in the tire. Pure propane is
fine.

It would also liquify if it got cold enough, but that wasn't a problem
in New Orleans.

John

 

[John Larkin]

Even the sulfur part sounds bad, but he is right as far as rubber and
metals go.

http://en.wikipedia.org/wiki/Sf6


John

 

[Martin Griffith]

http://en.wikipedia.org/wiki/Sf6


John

This is quite fun, the last few seconds applies to this thread

Martin

 

[ChairmanOfTheBored]

"Drexan is Canada's largest distributor of Parker Hannifin Corp.'s
TireSaver nitrogen generator, which was used for the fleet's study."

Therefore I am skeptical.

So much for "double blind". I guess they thought that we would be
doubly blind.

 

[ChairmanOfTheBored]

Only if liquid is present, or it's close to liquifying, which means it
isn't following the universal gas laws.

It is most certainly a LOT of liquid at that pressure.

A 30 Lb tank of R-12 is ALL liquid (save a bit of head space), and the
pressure reading is what is used to determine tank fill level by some in
the industry.

This is a "read vapor pressure" thing.

Many truck tires are at 90psi or higher so freon is not likely a very
good media to fill them with.

 

[Jim Yanik]

Yes, but only if you ever mix it with air in the tire. Pure propane is
fine.

It would also liquify if it got cold enough, but that wasn't a problem
in New Orleans.

John

since most people would not know there was propane in the tire,they could
easily add compressed air to reinflate it. That's the hazard.

 

[ChairmanOfTheBored]

Yes, but only if you ever mix it with air in the tire. Pure propane is
fine.

Bwuahahahaha! It is also known to be an excellent refrigerant media,
but we don't see the industry using it for that either.

So is ammonia, but leaky systems prove that it is not a good thing to
use toxic or volatile mediums in such places.

BTW freon (the chlorinated types) turns into a very nasty toxic gas
above a certain temperature. That is why all torch based system
servicing had to be done on evacuated systems in the old days (just a few
years back). I think it becomes Phosgene gas... one breath of that and
sigh-o-nara sucka!

It would also liquify if it got cold enough, but that wasn't a problem
in New Orleans.

It liquefies even easier (read higher temp) under pressure.

 

[redbelly]

Yes, but only if you ever mix it with air in the tire. Pure propane is
fine.

It would also liquify if it got cold enough, but that wasn't a problem
in New Orleans.

John

Those must be low pressure bicycle tires. At 100 psig, for example,
propane will liquify at about 65 F or lower, according to this table:

http://www.engineeringtoolbox.com/propane-vapor-pressure-d_1020.html

On the other hand, a propane-filled auto tire at say 30 psig would
stay a gas down to around 5F.

Mark

 

[John Larkin]

It is most certainly a LOT of liquid at that pressure.

A 30 Lb tank of R-12 is ALL liquid (save a bit of head space), and the
pressure reading is what is used to determine tank fill level by some in
the industry.

This is a "read vapor pressure" thing.

Many truck tires are at 90psi or higher so freon is not likely a very
good media to fill them with.

Well, then R-12 isn't a good choice for filling tires.

John

 

[John Larkin]

since most people would not know there was propane in the tire,they could
easily add compressed air to reinflate it. That's the hazard.

It wasn't, because it was my bicycle.

John

 

[John Larkin]

Bwuahahahaha! It is also known to be an excellent refrigerant media,
but we don't see the industry using it for that either.

Propane is used as a refrigerant, in which case it's called HC-290.
Google it.

John

 

[ChairmanOfTheBored]

Well, then R-12 isn't a good choice for filling tires.

John

Ooops! That should READ... REED vapor pressure! :-]

 

[ChairmanOfTheBored]

Propane is used as a refrigerant, in which case it's called HC-290.
Google it.

John

Perhaps in military or specialized industry situations, but not likely
in consumer goods/systems.

It is a VERY GOOD refrigerant. It is also dangerous in leaky systems,
and most systems where it is used have leak detection built into them as
well.

 

[Don Klipstein]

It wasn't, because it was my bicycle.

John

Theft retaliation? Gets me going!...

How about this: 3-speed bike, which usually has hand caliper brakes on
both wheels, but the rear brake can be a coaster brake instead. Sturmey
Archer made both coaster brake and non-coaster-brake versions of their
3-speed internally geared rear hubs, mostly without the coaster brake.

Make one with a coaster brake and both front and rear brake levers, and
rear caliper brakes. Possibly not seen by unauthorized riders: The rear
brake cable does not actuate the rear caliper brake, but pulls the pin out
of the hand grenade under the seat.

Sounds a little too risky, dangerous and extreme to actually fly, but I
don't think highly of thieves.

Less extreme would be an unusual but actual brake setup, along with fake
usual-type brakes that do nothing but maybe sound a burglar alarm. Put a
warning label on the handlebars: WARNING - ATYPICAL BRAKES - UNAUTHORIZED
RIDERS CAN CRASH! I'm sure some lawyers and maybe a few laws can cause
problems with even that...

Safer still would be a burglar alarm, though I'm afraid that in many
areas the thief would then only get a slap on the wrist. Starting now to
think of a "dye grenade" to paint a thief some glary bright color, like
they boobytrap bank robbers with, but that may not be much of a deterrent
in some neighborhoods or social circles where it is socially acceptable to
be a thief.

Anyone think of any electronic solutions that won't get me jailed or
sued but cause a bike thief to become a former bike thief?

- Don Klipstein ([email protected])

 

[Don Klipstein]

On Fri, 21 Sep 2007 14:23:24 -0700, John Larkin


Whenever my tires get low, I bring it in (no appointment, no charge)
and they suck all the old N2 out and refill with fresh N2, and I drive
away.

They claim the tire pressure is less affected by the tire temperature,
too, which may account for the 3% fuel savings in that article.

PV = nRT for any gas, right?

John

"suck out the _old_ N2..."

I have that done twice a year to my wife's car. When I get back home
it'll be past time to replace the summer air with winter air[*]. If
we get an early snow storm, I'll be a dead man. :-(
.
Bwahahahahahaha!

Must be Slowman's kid ;-)

[*] The air gets changed along with the rubber; no additional
charge. ;-)

I put Helium in my tires so the car floats.

Yeah, right...

All four tires add up to a grand total of one pound of less downward
force, and that only at sea level. Whoopie!

I heard track bikes at the Olympics at least sometimes have their tires
filled with helium, and inflated to aproaching the breaking point (as high
as 300 PSI) to minimize rolling resistance. Takes away maybe 25 grams of
mass at that pressure. For acceleration purposes, this counts almost
double being at the edge of the wheels - consider both translational and
rotational kinetic energy.

At the olympic level, just several milliseconds will occaisionally make
a difference between winning and losing a velodrome event, or between 2nd
and 3rd place. Racers will sometimes pay 10's of dollars to $100 more for
a helmet that weighs an ounce or two less.

- Don Klipstein ([email protected])

 

[mpm]

Anyone think of any electronic solutions that won't get me jailed or
sued but cause a bike thief to become a former bike thief?

.....electronic aiming? (i.e., a target acquisition system)

Elsewhere in this thread "SF6", "Freon" and "New Orleans" were all
mentioned.

Circa 1990 - The Tower site at -90.024782, 29.919968, South of the
City, (Now owned by American Tower) had 3 Full Power Class-C FM's and
a 5-MW ERP TV on it (CH-59? or maybe Ch.62?). The 3-FM's were on a
master antenna fed by a single run of continuous 9-inch coax. (Yes,
coax - NOT rigid transmission line - like a normal engineer would do).

Anyway, the point: That line used Freon to prevent arcing in the line
with all 3 FM's at full power. It switched to something else when
Freon got hard to come by (and expensive!) for that application (But
did not switch to SF6.) Not sure what ultimately became of it, but I
do know we put solar shields on the line and painted it white in an
effort to help keep the solar loading down, with pretty good results
as I recall....

It was such a weird coax - I never really got a straight answer
whether or not it could handle the power with just dry nitrogen. The
Freon decision was made before my time.....

It's a LeBlanc & Royle 1049' T-bar tower.
Definately worth checking out on Google maps if you're into that sort
of thing...

-mpm