Re: Starving people refuse to eat food aid
trag
> Strobe <Str...@nyc.Beep!Beep!.com> wrote:
> > If you don't need your car for a month, you can just ignore it. If
> > you ignore your horse and cart for a month, you've got a dead horse.
>
> I thought cars would refuse to start if they aren't used for a while.
> (Presumably this is easier to fix than a dead horse.)
I think this was more of a problem when cars had carburetors. There
were many tiny tubes, passages and jets which could clog up when
gasoline evaporated leaving behind a varnish-like residue.
I'm not sure if fuel injectors have this problem, but being sealed,
rather than sitting on top of the engine right under a giant opening
just one layer of paper from the air, I doubt that they do.
On my 1978 motorcycle, if I let it sit too long, I open the drain
plugs on the carburetors to drain the residual fuel--if any. Perhaps
fill them with gasoline and then drain them. Then I spray canned
carburetor cleaner (the nasty solvent laden kind) into the carbs
through the overflow tubes. Then let them sit for a day. Then open
the drain plugs again to remove the nasty brownish result. This
works about as well as a $150 carburetor job.
Of course, with a great deal of idleness, rubber tires and belts will
rot, oil will lose its volatiles and turn to sludge, batteries will
lose their charge and their ability to hold a charge, insulation will
become brittle and protons will eventually decay...
Dimensional Traveler
I've been told that gasoline also degrades over time, so if you let the
vehicle sit too long you'd need to replace the fuel.
--
"Dude. They've gone fractal."
Dorothy J Heydt
Yes. but there are ways of handling that. Hal keeps a supply of
gasoline in the emergency storage (to run the generator, should
it be needed), and he adds a driblet of some kind of preservative
to it. This preserves it for one year, he tells me, after which
he pours it into the car and puts fresh stuff into storage.
--
Dorothy J. Heydt
Vallejo, California
djheydt at hotmail dot com
Should you wish to email me, you'd better use the hotmail edress.
Kithrup is getting too damn much spam, even with the sysop's filters.
Cryptoengineer
> In article <4b2965c9$0$1593$742ec...@news.sonic.net>,
My 15 year old lawn tractor sits in the shed from sometime in
November, till sometime in March or April. Generally, I just drive it
in, turn if off, and walk away.
In the spring I usually have to jump start it, but it has never
refused to start. Every couple of years, I take it in to the dealer
for a tuneup.
pt
Wayne Throop
: Yes. but there are ways of handling that. Hal keeps a supply of
: gasoline in the emergency storage (to run the generator, should
: it be needed), and he adds a driblet of some kind of preservative
: to it. This preserves it for one year, he tells me, after which
: he pours it into the car and puts fresh stuff into storage.
I wonder if that's because of differential evaporation of fractions
of the gasoline, or accumulation of water being hydrophilicized into
it over time, or something else I haven't thoguht of. The addative
could be a bit of alcohol, which could keep water from causing mischief,
but would eventually be overwhelmed, and you couldn't add more, hence
that'd explain the goings-on.
Hmm.
Wayne Throop thr...@sheol.org http://sheol.org/throopw
Strobe
>On Dec 13, 1:31 pm, "Keith F. Lynch" <k...@KeithLynch.net> wrote:
>> Strobe <Str...@nyc.Beep!Beep!.com> wrote:
>> > If you don't need your car for a month, you can just ignore it. If
>> > you ignore your horse and cart for a month, you've got a dead horse.
>>
>> I thought cars would refuse to start if they aren't used for a while.
>> (Presumably this is easier to fix than a dead horse.)
>
>I think this was more of a problem when cars had carburetors. There
>were many tiny tubes, passages and jets which could clog up when
>gasoline evaporated leaving behind a varnish-like residue.
I used to have that problem, too.
Then I stopped buying cheap gasoline. . .
>I'm not sure if fuel injectors have this problem, but being sealed,
>rather than sitting on top of the engine right under a giant opening
>just one layer of paper from the air, I doubt that they do.
>
>On my 1978 motorcycle, if I let it sit too long, I open the drain
>plugs on the carburetors to drain the residual fuel--if any. Perhaps
>fill them with gasoline and then drain them. Then I spray canned
>carburetor cleaner (the nasty solvent laden kind) into the carbs
>through the overflow tubes. Then let them sit for a day. Then open
>the drain plugs again to remove the nasty brownish result. This
>works about as well as a $150 carburetor job.
Dang! That's alot of money.
>Of course, with a great deal of idleness, rubber tires and belts will
>rot, oil will lose its volatiles and turn to sludge, batteries will
>lose their charge and their ability to hold a charge, insulation will
>become brittle and protons will eventually decay...
Hey, it was only supposed to be for a month!
Keith F. Lynch
> trag <tr...@io.com> wrote:
>> Of course, with a great deal of idleness, rubber tires and belts
>> will rot, oil will lose its volatiles and turn to sludge, batteries
>> will lose their charge and their ability to hold a charge,
>> insulation will become brittle and protons will eventually decay...
> Hey, it was only supposed to be for a month!
They don't make protons like they used to.
When my mother returned home after four months' hospitalization, her
car wouldn't start, and had to be towed to a service station, which
was able to get it working again. I'm not sure what was wrong with it.
--
Keith F. Lynch - http://keithlynch.net/
Please see http://keithlynch.net/email.html before emailing me.
Wayne Throop
: When my mother returned home after four months' hospitalization, her
: car wouldn't start, and had to be towed to a service station, which
: was able to get it working again. I'm not sure what was wrong with it.
I would expect a dead battery coupled with water in the gas tank.
Ours was a multi-car family when I was growing up, fluctuating between
two and three, and the older cars tended to see less and less use, and
then finally got sold. Once upon a time, the eldest car hadn't been run
in more than a year, and a buyer gave a price contingent on it starting
and running. It took my father a couple hours of charging the battery,
treating it for congealed crankcase oil (with kerosene iirc) and flushing
fuel lines (with alcohol iirc), and a change of spark plugs (I think he
just steel-wire-brushed the existing ones, but I'm not sure; he wasn't
putting much money in it, or any consumables he didn't already have on
hand), but got it running. This is somewhat easier than restarting
a horse or mule after a similar time left in a garage. And that's a
tired old car at the end of its lifetime, mind. One of the newer cars,
had it sat that long, would be considerably easier, I expect.
I think that's the last one that got sold to somebody else; after that,
they normally went to the eldest child, in turn.
Dimensional Traveler
> : "Keith F. Lynch" <k...@KeithLynch.net>
> : When my mother returned home after four months' hospitalization, her
> : car wouldn't start, and had to be towed to a service station, which
> : was able to get it working again. I'm not sure what was wrong with it.
>
> I would expect a dead battery coupled with water in the gas tank.
>
> Ours was a multi-car family when I was growing up, fluctuating between
> two and three, and the older cars tended to see less and less use, and
> then finally got sold. Once upon a time, the eldest car hadn't been run
> in more than a year, and a buyer gave a price contingent on it starting
> and running. It took my father a couple hours of charging the battery,
> treating it for congealed crankcase oil (with kerosene iirc) and flushing
> fuel lines (with alcohol iirc), and a change of spark plugs (I think he
> just steel-wire-brushed the existing ones, but I'm not sure; he wasn't
> putting much money in it, or any consumables he didn't already have on
> hand), but got it running. This is somewhat easier than restarting
> a horse or mule after a similar time left in a garage. And that's a
> tired old car at the end of its lifetime, mind. One of the newer cars,
> had it sat that long, would be considerably easier, I expect.
>
heavily 'chipped, that last may not be true.
Wayne Throop
:: between two and three, and the older cars tended to see less and less
:: use, and then finally got sold. Once upon a time, the eldest car
:: hadn't been run in more than a year, and a buyer gave a price
:: contingent on it starting and running. It took my father a couple
:: hours of charging the battery, treating it for congealed crankcase
:: oil (with kerosene iirc) and flushing fuel lines (with alcohol iirc),
:: and a change of spark plugs (I think he just steel-wire-brushed the
:: existing ones, but I'm not sure; he wasn't putting much money in it,
:: or any consumables he didn't already have on hand), but got it
:: running. This is somewhat easier than restarting a horse or mule
:: after a similar time left in a garage. And that's a tired old car at
:: the end of its lifetime, mind. One of the newer cars, had it sat
:: that long, would be considerably easier, I expect.
: Dimensional Traveler <dtr...@sonic.net>
: Given how hard its getting to work on newer vehicles because they are
: so heavily 'chipped, that last may not be true.
That'd be true if you were trying to alter the fuel mixture, the
timing, or other stuff like that there, but the remedies were all
well within routine user maintenance even on the latest vehicles.
Recharge the battery, flush the crankcase, replace the gasoline and
drain and flush the fuel lines. Maybe the "drain and flush the
fuel line" might be harder to do on a modern car, but that'd be just
because things are packed in their tighter, and so it's more difficult
to reach the fiddly little parts... and there's so many fiddly parts
it might be hard to find the right line. But nothing chip-managed
was done in the above scenario.
In the old days, you could alter the fuel mixture and timing by ear using
a couple wrenches. Nowdays, not a chance. Well, maybe a chance, but
certainly the old simple, familiar mechanical distributor and carburator
just aren't really there anymore. JBut there's still a battery, a gas
tank, and a crankcase, with terminals and fill and drain ports easily
reachable.
I more had in mind that the younger cars in the family stable back then
(all of them pre-digital-everything) wouldn't have had so much gunk in
the crankcase to make the sludge worse, similarly with the gas tank,
and the batteries would be in better shape, going into the idle period.
And therefore, sitting for a year, they wouldn't be in as bad a shape.
Though then too, on really modern cars, all those items are more resistant
to the problems they used to be heir to.
cryptoguy
> :: Ours was a multi-car family when I was growing up, fluctuating
> :: between two and three, and the older cars tended to see less and less
> :: use, and then finally got sold. Once upon a time, the eldest car
> :: hadn't been run in more than a year, and a buyer gave a price
> :: contingent on it starting and running. It took my father a couple
> :: hours of charging the battery, treating it for congealed crankcase
> :: oil (with kerosene iirc) and flushing fuel lines (with alcohol iirc),
> :: and a change of spark plugs (I think he just steel-wire-brushed the
> :: existing ones, but I'm not sure; he wasn't putting much money in it,
> :: or any consumables he didn't already have on hand), but got it
> :: running. This is somewhat easier than restarting a horse or mule
> :: after a similar time left in a garage. And that's a tired old car at
> :: the end of its lifetime, mind. One of the newer cars, had it sat
> :: that long, would be considerably easier, I expect.
>
> : Given how hard its getting to work on newer vehicles because they are
> : so heavily 'chipped, that last may not be true.
>
> That'd be true if you were trying to alter the fuel mixture, the
> timing, or other stuff like that there, but the remedies were all
> well within routine user maintenance even on the latest vehicles.
> Recharge the battery, flush the crankcase, replace the gasoline and
> drain and flush the fuel lines. Maybe the "drain and flush the
> fuel line" might be harder to do on a modern car, but that'd be just
> because things are packed in their tighter, and so it's more difficult
> to reach the fiddly little parts... and there's so many fiddly parts
> it might be hard to find the right line. But nothing chip-managed
> was done in the above scenario.
>
> In the old days, you could alter the fuel mixture and timing by ear using
> a couple wrenches. Nowdays, not a chance. Well, maybe a chance, but
> certainly the old simple, familiar mechanical distributor and carburator
> just aren't really there anymore. JBut there's still a battery, a gas
> tank, and a crankcase, with terminals and fill and drain ports easily
> reachable.
One advantage of the 'chipped' cars is that they are more fuel
flexible. My current car, has a sticker in the gas cap that says
'Premium Fuel Preferred', and that's what I usually put in it. A
couple times I've hit the wrong button, and filled it up with
regular.
It ran just fine; it just doesn't have the higher end performance that
I bought it for. In the new cars, the fuel/air system adapts for fuel
quality in real time. An older sporty car would be much more finicky,
put regular in it, and it might be unusable.
pt
Sea Wasp (Ryk E. Spoor)
>
> One advantage of the 'chipped' cars is that they are more fuel
> flexible.
Back in the day I drove a non-chipped car, and I never saw any problem
using whatever fuel came to hand. Never understood why ANYONE paid those
higher prices.
--
Sea Wasp
/^\
;;;
Live Journal: http://seawasp.livejournal.com
John Francis
cryptoguy <treif...@gmail.com> wrote:
>
>One advantage of the 'chipped' cars is that they are more fuel
>flexible. My current car, has a sticker in the gas cap that says
>'Premium Fuel Preferred', and that's what I usually put in it. A
>couple times I've hit the wrong button, and filled it up with
>regular.
>
>It ran just fine; it just doesn't have the higher end performance that
>I bought it for. In the new cars, the fuel/air system adapts for fuel
>quality in real time. An older sporty car would be much more finicky,
>put regular in it, and it might be unusable.
I doubt it. In my time I've driven a few cars that were happiest with
premium grade fuel (the worst being my Triumph Vitesse, which ran best
with 101 octane, or five-star as it was known in those days).
Putting something lower in just caused excessive "pinking". It wasn't
something you'd want to do for too long (and it was best if you didn't
open the throttle too wide), but the car was drivable.
John Francis
Sea Wasp (Ryk E. Spoor) <sea...@sgeinc.invalid.com> wrote:
>cryptoguy wrote:
>
>>
>> One advantage of the 'chipped' cars is that they are more fuel
>> flexible.
>
> Back in the day I drove a non-chipped car, and I never saw any problem
>using whatever fuel came to hand. Never understood why ANYONE paid those
>higher prices.
That probably just shows that you didn't drive any kind of performance car.
There's rarely a problem putting higher-octane fuel in a car designed to run
on the cheap stuff (such as, say, my old Morris Minor, or later Mustang GT).
Drive something with a high-compression engine and you soon find that there
is a reason why you want high-octane fuel (which, counter-intuitively, is
harder to ignite) - you get pre-detonation from simply compressing the fuel
charge in a hot engine. This is not a good thing.
Wayne Throop
: Back in the day I drove a non-chipped car, and I never saw any problem
: using whatever fuel came to hand. Never understood why ANYONE paid
: those higher prices.
Because for sports cars, you could get knocking and other problems
if you use lower octane, onaccounta more finicky timing, compression,
and fuel mixtures. For most cars, though, it didn't tend to matter.
Sea Wasp (Ryk E. Spoor)
> In article <hgdlvb$pj6$1...@news.eternal-september.org>,
> Sea Wasp (Ryk E. Spoor) <sea...@sgeinc.invalid.com> wrote:
>> cryptoguy wrote:
>>
>>> One advantage of the 'chipped' cars is that they are more fuel
>>> flexible.
>> Back in the day I drove a non-chipped car, and I never saw any problem
>> using whatever fuel came to hand. Never understood why ANYONE paid those
>> higher prices.
>
> That probably just shows that you didn't drive any kind of performance car.
>
My car had stellar performance: I went out, I started it, it got me
where I wanted to go along with all my stuff, and did so while keeping
me in comfort. This is the function of a car. :)
James
> : "Sea Wasp (Ryk E. Spoor)" <seaw...@sgeinc.invalid.com>
> : Back in the day I drove a non-chipped car, and I never saw any problem
> : using whatever fuel came to hand. Never understood why ANYONE paid
> : those higher prices.
>
> Because for sports cars, you could get knocking and other problems
> if you use lower octane, onaccounta more finicky timing, compression,
> and fuel mixtures. For most cars, though, it didn't tend to matter.
I drove a car with an "Up level" engine for 5 years. It did have a
higher compression engine, overhead cams etc. The manual stated mid
grade octane. It was however new enough that it was chipped and would
run without problems on regular gas, for what was a minor loss of fuel
economy. My understand is that there is a knock sensor that adjusts
timings and settings.
So it was with eager anticipation one night that I pulled into a gas
station where the pumps were not running for regular fuel, and they
didn't sell a mid grade. Instead they were selling Premium for the
Regular price. I had hoped to see a little better performance or
slightly better fuel ecomomy but sadly no. While the car was capable
of adjust down for regular fuel, it wouldn't adjust up for premium,
presumably because there is no knock to sense.
James
trag
> On Wed, 16 Dec 2009 10:16:34 -0800 (PST), trag <t...@io.com> wrote:
> This
> >works about as well as a $150 carburetor job.
>
> Dang! That's alot of money.
The motorcycle in question has *four* carburetors.
Mike Ash
"Sea Wasp (Ryk E. Spoor)" <sea...@sgeinc.invalid.com> wrote:
> cryptoguy wrote:
>
> > One advantage of the 'chipped' cars is that they are more fuel
> > flexible.
>
> Back in the day I drove a non-chipped car, and I never saw any problem
> using whatever fuel came to hand. Never understood why ANYONE paid those
> higher prices.
Because some cars need the stuff, and some don't. Yours evidently
didn't, but that doesn't mean anything about others.
If you have a "normal" car and put premium fuel in it because you think
it's better, then you're being silly. However, if you have a car that
actually benefits from it, then it's not silly at all.
--
Mike Ash
Radio Free Earth
Broadcasting from our climate-controlled studios deep inside the Moon
R H Draney
>
>In article <hgdlvb$pj6$1...@news.eternal-september.org>,
> "Sea Wasp (Ryk E. Spoor)" <sea...@sgeinc.invalid.com> wrote:
>
>> cryptoguy wrote:
>>
>> > One advantage of the 'chipped' cars is that they are more fuel
>> > flexible.
>>
>> Back in the day I drove a non-chipped car, and I never saw any problem
>> using whatever fuel came to hand. Never understood why ANYONE paid those
>> higher prices.
>
>Because some cars need the stuff, and some don't. Yours evidently
>didn't, but that doesn't mean anything about others.
>
>If you have a "normal" car and put premium fuel in it because you think
>it's better, then you're being silly. However, if you have a car that
>actually benefits from it, then it's not silly at all.
Whether owning the kind of car that benefits from it is silly is left as an
exercise for the reader....r
--
A pessimist sees the glass as half empty.
An optometrist asks whether you see the glass
more full like this?...or like this?
John Francis
R H Draney <dado...@spamcop.net> wrote:
>Mike Ash filted:
>>
>>In article <hgdlvb$pj6$1...@news.eternal-september.org>,
>> "Sea Wasp (Ryk E. Spoor)" <sea...@sgeinc.invalid.com> wrote:
>>
>>> cryptoguy wrote:
>>>
>>> > One advantage of the 'chipped' cars is that they are more fuel
>>> > flexible.
>>>
>>> Back in the day I drove a non-chipped car, and I never saw any problem
>>> using whatever fuel came to hand. Never understood why ANYONE paid those
>>> higher prices.
>>
>>Because some cars need the stuff, and some don't. Yours evidently
>>didn't, but that doesn't mean anything about others.
>>
>>If you have a "normal" car and put premium fuel in it because you think
>>it's better, then you're being silly. However, if you have a car that
>>actually benefits from it, then it's not silly at all.
>
>Whether owning the kind of car that benefits from it is silly is left as an
>exercise for the reader....r
That rather depends on whether you drive because you have no reasonable
alternative (so it becomes at best routine, and at worst a chore), or
purely for pleasure.
Keith F. Lynch
>> her car wouldn't start, and had to be towed to a service station,
>> which was able to get it working again. I'm not sure what was
>> wrong with it.
> I would expect a dead battery coupled with water in the gas tank.
How would water get in the gas tank?
David DeLaney
>Wayne Throop <thr...@sheol.org> wrote:
>> "Keith F. Lynch" <k...@KeithLynch.net> wrote:
>>> When my mother returned home after four months' hospitalization,
>>> her car wouldn't start, and had to be towed to a service station,
>>> which was able to get it working again. I'm not sure what was
>>> wrong with it.
>
>> I would expect a dead battery coupled with water in the gas tank.
>
>How would water get in the gas tank?
Obviously the tiger melted.
Dave "butter might also have been involved" DeLaney
--
\/David DeLaney posting from d...@vic.com "It's not the pot that grows the flower
It's not the clock that slows the hour The definition's plain for anyone to see
Love is all it takes to make a family" - R&P. VISUALIZE HAPPYNET VRbeable<BLINK>
http://www.vic.com/~dbd/ - net.legends FAQ & Magic / I WUV you in all CAPS! --K.
R H Draney
>
>Wayne Throop <thr...@sheol.org> wrote:
>> "Keith F. Lynch" <k...@KeithLynch.net> wrote:
>>> When my mother returned home after four months' hospitalization,
>>> her car wouldn't start, and had to be towed to a service station,
>>> which was able to get it working again. I'm not sure what was
>>> wrong with it.
>
>> I would expect a dead battery coupled with water in the gas tank.
>
>How would water get in the gas tank?
Condenses out of the air trapped therein...even in Phoenix there's such a thing
as relative humidity....r
John F. Eldredge
> Wayne Throop <thr...@sheol.org> wrote:
>> "Keith F. Lynch" <k...@KeithLynch.net> wrote:
>>> When my mother returned home after four months' hospitalization, her
>>> car wouldn't start, and had to be towed to a service station, which
>>> was able to get it working again. I'm not sure what was wrong with
>>> it.
>
>> I would expect a dead battery coupled with water in the gas tank.
>
> How would water get in the gas tank?
Generally, by humidity from the air condensing on the inside of the gas
tank if the outside temperature goes down. Since water won't mix with
gasoline, and is denser than gasoline, it will tend to sink to the bottom
and thus be sucked in by the fuel pump. A small amount of water will
tend to make the engine misfire or stall, but you can then restart the
engine (thus pumping more gasoline into the engine). A sufficiently
large amount will mean that the fuel tank will need to be emptied and
fresh gasoline put in.
--
John F. Eldredge -- jo...@jfeldredge.com
"Reserve your right to think, for even to think wrongly is better
than not to think at all." -- Hypatia of Alexandria
Keith F. Lynch
> Keith F. Lynch wrote:
>> How would water get in the gas tank?
> Generally, by humidity from the air condensing on the inside of the
> gas tank if the outside temperature goes down. Since water won't
> mix with gasoline, and is denser than gasoline, it will tend to
> sink to the bottom and thus be sucked in by the fuel pump. A small
> amount of water will tend to make the engine misfire or stall, but
> you can then restart the engine (thus pumping more gasoline into the
> engine). A sufficiently large amount will mean that the fuel tank
> will need to be emptied and fresh gasoline put in.
Why wouldn't gasoline vapors displace the air and its humidity?
Presumably the opening to the outside is only just barely large
enough to keep the pressure in the tank from the gasoline vapors
from increasing without bounds. And to replace gasoline with air
at the rate gasoline is consumed in a running engine.
John F. Eldredge
> John F. Eldredge <jo...@jfeldredge.com> wrote:
>> Keith F. Lynch wrote:
>>> How would water get in the gas tank?
>
>> Generally, by humidity from the air condensing on the inside of the gas
>> tank if the outside temperature goes down. Since water won't mix with
>> gasoline, and is denser than gasoline, it will tend to sink to the
>> bottom and thus be sucked in by the fuel pump. A small amount of water
>> will tend to make the engine misfire or stall, but you can then restart
>> the engine (thus pumping more gasoline into the engine). A
>> sufficiently large amount will mean that the fuel tank will need to be
>> emptied and fresh gasoline put in.
>
> Why wouldn't gasoline vapors displace the air and its humidity?
> Presumably the opening to the outside is only just barely large enough
> to keep the pressure in the tank from the gasoline vapors from
> increasing without bounds. And to replace gasoline with air at the rate
> gasoline is consumed in a running engine.
Well, for one thing, as you just said, air is pulled into the gas tank as
fuel is pulled out. If my understanding is correct, the filler cap has a
one-way valve so that it will let air in when the external pressure is
higher than the air pressure in the gas tank, but won't let gas vapors
out (which would be a fire hazard) if the pressure in the tank is higher
than the air pressure outside.
Keith F. Lynch
> Well, for one thing, as you just said, air is pulled into the gas
> tank as fuel is pulled out. If my understanding is correct, the
> filler cap has a one-way valve so that it will let air in when the
> external pressure is higher than the air pressure in the gas tank,
> but won't let gas vapors out (which would be a fire hazard) if the
> pressure in the tank is higher than the air pressure outside.
If gas vapors aren't let out, won't the pressure increase until the
tank bursts? What *is* the vapor pressure of gasoline, anyway?
I know that gas cans intended to be hand carried are always vented.
David Scheidt
:John F. Eldredge <jo...@jfeldredge.com> wrote:
:> Well, for one thing, as you just said, air is pulled into the gas
:> tank as fuel is pulled out. If my understanding is correct, the
:> filler cap has a one-way valve so that it will let air in when the
:> external pressure is higher than the air pressure in the gas tank,
:> but won't let gas vapors out (which would be a fire hazard) if the
:> pressure in the tank is higher than the air pressure outside.
:If gas vapors aren't let out, won't the pressure increase until the
:tank bursts? What *is* the vapor pressure of gasoline, anyway?
depends on where you are, and what season it is. Summer gas, in the
US, in places where ozone is a problem, is less than 7.8 psi (at some
specified temperature which escapes my memory.). winter gas is
higher.
:I know that gas cans intended to be hand carried are always vented.
Like so many things you know, this isn't true. Gas cans on sale in
the US are not vented.
--
sig 48
John F. Eldredge
Well, to be specific, they usually have a vent that you would open while
pouring gas out of the can, in order to get a smooth flow instead of
"glug, glug, glug". However, that vent has a snap-on cap, and is
generally snapped closed while carrying the gas can.
I did learn the hard way, years ago, to leave the vent cap open when
storing a can of gasoline. I left a mostly-empty can sitting in an
unheated shed in cold weather, and came back to discover that the can had
imploded as the vapor pressure of the gasoline went down.
Fuel caps on a car may well have some degree of overpressure venting, but
I know for sure that they retain some pressure. When you take the fuel
cap off in order to put more gasoline into the car, you hear a hiss of
pressure equalizing and smell gasoline vapor, indicating that the
pressure inside the tank was higher than that outside the tank.
Wayne Throop
: Why wouldn't gasoline vapors displace the air and its humidity?
I doubt gasoline vapor'a partial pressure is high enough.
David Scheidt
:On Sat, 19 Dec 2009 22:24:46 +0000, David Scheidt wrote:
:> In alt.folklore.urban Keith F. Lynch <k...@keithlynch.net> wrote: :John
:> F. Eldredge <jo...@jfeldredge.com> wrote: :> Well, for one thing, as you
:> just said, air is pulled into the gas :> tank as fuel is pulled out. If
:> my understanding is correct, the :> filler cap has a one-way valve so
:> that it will let air in when the :> external pressure is higher than the
:> air pressure in the gas tank, :> but won't let gas vapors out (which
:> would be a fire hazard) if the :> pressure in the tank is higher than
:> the air pressure outside.
:>
:> :If gas vapors aren't let out, won't the pressure increase until the
:> :tank bursts? What *is* the vapor pressure of gasoline, anyway?
:>
:> depends on where you are, and what season it is. Summer gas, in the US,
:> in places where ozone is a problem, is less than 7.8 psi (at some
:> specified temperature which escapes my memory.). winter gas is higher.
:>
:> :I know that gas cans intended to be hand carried are always vented.
:>
:> Like so many things you know, this isn't true. Gas cans on sale in the
:> US are not vented.
:Well, to be specific, they usually have a vent that you would open while
:pouring gas out of the can, in order to get a smooth flow instead of
:"glug, glug, glug". However, that vent has a snap-on cap, and is
:generally snapped closed while carrying the gas can.
No. They don't. They used to, but they haven't for years.
:Fuel caps on a car may well have some degree of overpressure venting, but
Quite a lot. It's an air-pollution requirement, an dhas beenfor
decades in the US.
--
sig 101
John F. Eldredge
> In alt.folklore.urban John F. Eldredge <jo...@jfeldredge.com> wrote: :On
> Sat, 19 Dec 2009 22:24:46 +0000, David Scheidt wrote:
>
> :> In alt.folklore.urban Keith F. Lynch <k...@keithlynch.net> wrote:
> :> :I know that gas cans intended to be hand carried are always vented.
> :>
> :> Like so many things you know, this isn't true. Gas cans on sale in
> the :> US are not vented.
>
> :Well, to be specific, they usually have a vent that you would open
> while :pouring gas out of the can, in order to get a smooth flow instead
> of :"glug, glug, glug". However, that vent has a snap-on cap, and is
> :generally snapped closed while carrying the gas can.
>
> No. They don't. They used to, but they haven't for years.
This must be a recent change, then; I bought my most recent gas can two
years ago, and it has a snap-on cap.
Charles Wm. Dimmick
> Wayne Throop <thr...@sheol.org> wrote:
>> "Keith F. Lynch" <k...@KeithLynch.net> wrote:
>>> When my mother returned home after four months' hospitalization,
>>> her car wouldn't start, and had to be towed to a service station,
>>> which was able to get it working again. I'm not sure what was
>>> wrong with it.
>
>> I would expect a dead battery coupled with water in the gas tank.
>
> How would water get in the gas tank?
Gasoline is slightly hygroscopic. Gasoline containing ethanol is very
hygroscopic.
cryptoguy
What's more, gasoline is usually stored in underground tanks, and
pumped up to fill the cars. In summer, it's often a lot colder than
the ambient temperature, and thus (1) doesn't vaporize much itself,
and (2) presents a cold, hygroscopic surface to the humid air in the
tank.
Gas stations sell small bottles of isopropyl alcohol that you can add
to your tank, which makes the gas much more miscible with the water.
The mixed-in water can even boost performance slightly, under certain
circumstances.
pt
David DeLaney
>> John F. Eldredge <jo...@jfeldredge.com> wrote: :On
>> Sat, 19 Dec 2009 22:24:46 +0000, David Scheidt wrote:
>> :Well, to be specific, they usually have a vent that you would open
>> while :pouring gas out of the can, in order to get a smooth flow instead
>> of :"glug, glug, glug". However, that vent has a snap-on cap, and is
>> :generally snapped closed while carrying the gas can.
>>
>> No. They don't. They used to, but they haven't for years.
>
>This must be a recent change, then; I bought my most recent gas can two
>years ago, and it has a snap-on cap.
Mine, I believe, has one that you can screw open a little and screw closed
again, but I think it doesn't specifically have a snap-on. But yes, the
second-hole-wanted theory DOES get invoked when trying to pour gas, just as it
would for large juice cans or oldstyle no-pop-top beer cans.
Dave
Richard Casady
wrote:
>: "Keith F. Lynch" <k...@KeithLynch.net>
>: Why wouldn't gasoline vapors displace the air and its humidity?
>
>I doubt gasoline vapor'a partial pressure is high enough.
7 PSI at 100 F. Half that for Avgas.
Casady
Keith F. Lynch
> thr...@sheol.org (Wayne Throop) wrote:
>> I doubt gasoline vapor'a partial pressure is high enough.
> 7 PSI at 100 F. Half that for Avgas.
I'd think that was high enough to exclude air, assuming the vent hole
is very small. And I don't see why it wouldn't be. It need only
admit air fast enough to replace gas as it's used, and to vent vapor
-- if at all -- before the pressure gets dangerously high. Which even
the full 7 PSI probably is not if the tank is solidly built.
David DeLaney
>> thr...@sheol.org (Wayne Throop) wrote:
>>> I doubt gasoline vapor'a partial pressure is high enough.
>
>> 7 PSI at 100 F. Half that for Avgas.
>
>I'd think that was high enough to exclude air, assuming the vent hole
>is very small. And I don't see why it wouldn't be. It need only
>admit air fast enough to replace gas as it's used, and to vent vapor
>-- if at all -- before the pressure gets dangerously high. Which even
>the full 7 PSI probably is not if the tank is solidly built.
... Air is 15 PSI, most places. Even up high, like Los Alamos, it's still
around 11 PSI. 15 > 7. If you had only the 7 PSI inside your tank from the
gas partial pressure, you'd get a Giant Sucking Sound (tm) from any little
pinhole, and usually wouldn't be able to unscrew the cap at all if the tank was
airtight.
Hatunen
<k...@KeithLynch.net> wrote:
>Wayne Throop <thr...@sheol.org> wrote:
>> "Keith F. Lynch" <k...@KeithLynch.net> wrote:
>>> When my mother returned home after four months' hospitalization,
>>> her car wouldn't start, and had to be towed to a service station,
>>> which was able to get it working again. I'm not sure what was
>>> wrong with it.
>
>> I would expect a dead battery coupled with water in the gas tank.
>
>How would water get in the gas tank?
In weather with temperatures changes, when the temp goes down,
the gas tank devlops a slight vavuum drawing in humid outside are
through any small cracks or bypassing the filler cap. Once in the
tank the humdity condenses out, and the water goes to the bottom
of the tank. This is pretty small potatoes, but repeat oftern
enough and quite a bit of water can collect at teh bottom where
the outlet is.
Driving fairly often, the small amount of trapped water is sucked
through the fuel injectors or carburetor rather swiftly and you
hardly notice it. Get enough water at the bottom so that the fuel
line fills with water, you got trouble.
--
************* DAVE HATUNEN (hat...@cox.net) *************
* Tucson Arizona, out where the cacti grow *
* My typos & mispellings are intentional copyright traps *
Hatunen
wrote:
>Keith F. Lynch filted:
>>
>>Wayne Throop <thr...@sheol.org> wrote:
>>> "Keith F. Lynch" <k...@KeithLynch.net> wrote:
>>>> When my mother returned home after four months' hospitalization,
>>>> her car wouldn't start, and had to be towed to a service station,
>>>> which was able to get it working again. I'm not sure what was
>>>> wrong with it.
>>
>>> I would expect a dead battery coupled with water in the gas tank.
>>
>>How would water get in the gas tank?
>
>Condenses out of the air trapped therein...even in Phoenix there's such a thing
>as relative humidity....r
That's Phoenix for you...
Hatunen
<k...@KeithLynch.net> wrote:
>John F. Eldredge <jo...@jfeldredge.com> wrote:
>> Well, for one thing, as you just said, air is pulled into the gas
>> tank as fuel is pulled out. If my understanding is correct, the
>> filler cap has a one-way valve so that it will let air in when the
>> external pressure is higher than the air pressure in the gas tank,
>> but won't let gas vapors out (which would be a fire hazard) if the
>> pressure in the tank is higher than the air pressure outside.
>
>If gas vapors aren't let out, won't the pressure increase until the
>tank bursts? What *is* the vapor pressure of gasoline, anyway?
No. Please look up "vapor pressure". The gasoline would have to
be boiling to create that kind of pressure.
Hatunen
<k...@KeithLynch.net> wrote:
>Richard Casady <richar...@earthlink.net> wrote:
>> thr...@sheol.org (Wayne Throop) wrote:
>>> I doubt gasoline vapor'a partial pressure is high enough.
>
>> 7 PSI at 100 F. Half that for Avgas.
>
>I'd think that was high enough to exclude air, assuming the vent hole
>is very small. And I don't see why it wouldn't be. It need only
>admit air fast enough to replace gas as it's used, and to vent vapor
>-- if at all -- before the pressure gets dangerously high. Which even
>the full 7 PSI probably is not if the tank is solidly built.
This whole water-in-the-gas-tank thing mostly happens when the
car is left parked too long. During driving, any condensate will
be slow and small enough that it will simply pass through the
engine with scarcely a hiccup.
Keith F. Lynch
> In weather with temperatures changes, when the temp goes down,
> the gas tank devlops a slight vavuum drawing in humid outside are
> through any small cracks or bypassing the filler cap.
I'm still not clear on why the gasoline's vapor pressure doesn't more
than counteract this slight vacuum.
David DeLaney
>> In weather with temperatures changes, when the temp goes down,
>> the gas tank devlops a slight vavuum drawing in humid outside are
>> through any small cracks or bypassing the filler cap.
>
>I'm still not clear on why the gasoline's vapor pressure doesn't more
>than counteract this slight vacuum.
Because it takes rather longer for the gasoline to evaporate than it does for
the air to rush in from outside, essentially. If you decreased the pressure
inside and DIDN'T let air in from outside, and the gasoline vapor wasn't at
its full value yet, more would eventually evaporate. But if you decrease the
pressure enough, the gasoline vapor alone won't push it back up above 7PSI
(value taken from earlier in the thread, may not be correct).
[postponed paragraph that, when I looked back up, didn't actually answer the
original question, but instead answered a precursor to it:]
Because it counts as _part_ of atmospheric pressure.
The 15 PSI is made up of all the partial pressures of the individual gases.
... aaaand, taking a look at Wikipedia on partial pressure and vapor pressure,
there doesn't seem to be a simple explanation in there. Basically, if your gas
tank starts full of air at 15PSI, and you fill it halfway with gasoline,
that'll drive out half the air just from volume considerations - if it all
stayed in it'd get compressed to 30PSI, pV=nRT. Then the gasoline says "hey,
there's no gasoline vapor in this mixture" and starts evaporating, but the
pressure still stays at 15PSI if there's a connection to the outside. What
I can't find is the math to show whether that gasoline vapor evaporates to
make the FULL 7PSI component of the 15PSI, or whether the presence of other
gases inhibits it...]
Keith F. Lynch
> Because it takes rather longer for the gasoline to evaporate than it
> does for the air to rush in from outside, essentially.
Thanks. It sounds like the vent hole is larger than it needs to be.
> What I can't find is the math to show whether that gasoline vapor
> evaporates to make the FULL 7PSI component of the 15PSI,
Yes, if that's the correct vapor pressure at that temperature.
> or whether the presence of other gases inhibits it...
No. Gases are mostly empty space. Unless the pressure is extremely
high or there's a chemical reaction, every gas is acting like the
other gases aren't even present.
Similarly, hot summer air doesn't "hold" water like a sponge. To a
good first approximation there would be exactly as much water vapor
floating around if all the oxygen, nitrogen, argon, CO2, etc., were
removed.
And when you open the valve to a scuba tank or a tire, air hisses
out not because something is pushing it, but due to sheer statistics.
Every molecule, inside and outside, is moving randomly at about the
same speed. More molecules happen to be going from the interior
to the exterior only becuase there are more in the interior. It's
perfectly possible for air to leak *into* a punctured tire, inflating
it. It's just very, very unlikely.
Hatunen
<k...@KeithLynch.net> wrote:
>Hatunen <hat...@cox.net> wrote:
>> In weather with temperatures changes, when the temp goes down,
>> the gas tank devlops a slight vavuum drawing in humid outside are
>> through any small cracks or bypassing the filler cap.
>
>I'm still not clear on why the gasoline's vapor pressure doesn't more
>than counteract this slight vacuum.
I can't really explain partial vapor pressures very well in a
Usenet post. In essence, the vapor pressure is a function of
temperature. For instance, the vapor pressure of water is low
until the water gets hot. The vapor pressure of water is one
atmosphere at 100C, which is why it boils at that temperature.
Look at the graph at
http://en.wikipedia.org/wiki/File:Water_vapor_pressure_graph.jpg
Unfortunately the pressure is expressed in torr, but we an still
get the idea from looking at the 100C point, where the vapor
pressure is approximately 760 torr (it's actually millimeters of
mercury as shown on a mercury barometer). But the vapor perssure
at 40C is about 75, or one-tenth of an atmosphere. if you wer to
boil water (100C) in a container to drive off all the air, then
seal the container and allow it to cool down to 40C (which would
be a pretty warm day) the pressure in the container would drop to
0.1 atmospheres, resulting in what we would generally call a
"vacuum". The water vapor does not fill up the container to make
it one atmosphere in the container, and if you puch a small hole
in the container outside air will . Nor do the fuel vapors in a
gas tank expand to exclude outside air.
Keith F. Lynch
> "Keith F. Lynch" <k...@KeithLynch.net> wrote:
>> I'm still not clear on why the gasoline's vapor pressure doesn't
>> more than counteract this slight vacuum.
> I can't really explain partial vapor pressures very well in a
> Usenet post.
No need, I already understand it just fine. David DeLaney answered
me yesterday: The vent hole is simply much larger than I thought
it would be, so pressure never builds up in gas cans.
cryptoguy
> On Tue, 22 Dec 2009 03:19:33 +0000 (UTC), "Keith F. Lynch"
>
> <k...@KeithLynch.net> wrote:
> >> In weather with temperatures changes, when the temp goes down,
> >> the gas tank devlops a slight vavuum drawing in humid outside are
> >> through any small cracks or bypassing the filler cap.
>
> >I'm still not clear on why the gasoline's vapor pressure doesn't more
> >than counteract this slight vacuum.
>
> I can't really explain partial vapor pressures very well in a
> Usenet post. In essence, the vapor pressure is a function of
> temperature. For instance, the vapor pressure of water is low
> until the water gets hot. The vapor pressure of water is one
> atmosphere at 100C, which is why it boils at that temperature.
>
>
> Unfortunately the pressure is expressed in torr, but we an still
> get the idea from looking at the 100C point, where the vapor
> pressure is approximately 760 torr (it's actually millimeters of
> mercury as shown on a mercury barometer). But the vapor perssure
> at 40C is about 75, or one-tenth of an atmosphere. if you wer to
> boil water (100C) in a container to drive off all the air, then
> seal the container and allow it to cool down to 40C (which would
> be a pretty warm day) the pressure in the container would drop to
> 0.1 atmospheres, resulting in what we would generally call a
> "vacuum". The water vapor does not fill up the container to make
> it one atmosphere in the container, and if you puch a small hole
> in the container outside air will . Nor do the fuel vapors in a
> gas tank expand to exclude outside air.
On warm, humid days, the amount of water vapor in the atmosphere
increases to the point where the density of the air is significantly
reduced. Water (mol weight 18) is much less dense than Nitrogen (mol
weight 28, or Oxygen (mol weight 32).
Both planes and balloons have to take this into account.
pt
Keith F. Lynch
> On warm, humid days, the amount of water vapor in the atmosphere
> increases to the point where the density of the air is significantly
> reduced. Water (mol weight 18) is much less dense than Nitrogen
> (mol weight 28, or Oxygen (mol weight 32).
> Both planes and balloons have to take this into account.
So do weather forecasters.
I wonder how weather would differ if water vapor were heavier than air.
Richard Casady
Never heard of an airplane pilot making any kind of calculation
involving it. It isn't on an E6B slide rule. The pilots all think it
is insignificant. Instructors and the literature, not to mention the
flight test examiners never heard of it. Pilots do calculate
temperature effects.
Casady
Ralph Jones
<richar...@earthlink.net> wrote:
[snip]
>>
>>On warm, humid days, the amount of water vapor in the atmosphere
>>increases to the point where the density of the air is significantly
>>reduced. Water (mol weight 18) is much less dense than Nitrogen (mol
>>weight 28, or Oxygen (mol weight 32).
>>
>>Both planes and balloons have to take this into account.
>
>Never heard of an airplane pilot making any kind of calculation
>involving it. It isn't on an E6B slide rule. The pilots all think it
>is insignificant. Instructors and the literature, not to mention the
>flight test examiners never heard of it. Pilots do calculate
>temperature effects.
>
Try this:
http://wahiduddin.net/calc/calc_da.htm
rj
Hatunen
<k...@KeithLynch.net> wrote:
>cryptoguy <treif...@gmail.com> wrote:
>> On warm, humid days, the amount of water vapor in the atmosphere
>> increases to the point where the density of the air is significantly
>> reduced. Water (mol weight 18) is much less dense than Nitrogen
>> (mol weight 28, or Oxygen (mol weight 32).
>
>> Both planes and balloons have to take this into account.
>
>So do weather forecasters.
>
>I wonder how weather would differ if water vapor were heavier than air.
There would be little or no precipitation.
Richard Casady
<k...@KeithLynch.net> wrote:
>Hatunen <hat...@cox.net> wrote:
>> In weather with temperatures changes, when the temp goes down,
>> the gas tank devlops a slight vavuum drawing in humid outside are
>> through any small cracks or bypassing the filler cap.
>
>I'm still not clear on why the gasoline's vapor pressure doesn't more
>than counteract this slight vacuum.
Because the pressure in the tank goes down when the temperature goes
down. That is what vapor pressure is: the pressure in the tank if
sealed.
Casady
Richard Casady
>On Sat, 19 Dec 2009 21:11:16 +0000 (UTC), "Keith F. Lynch"
><k...@KeithLynch.net> wrote:
>
>>Wayne Throop <thr...@sheol.org> wrote:
>>> "Keith F. Lynch" <k...@KeithLynch.net> wrote:
>>>> When my mother returned home after four months' hospitalization,
>>>> her car wouldn't start, and had to be towed to a service station,
>>>> which was able to get it working again. I'm not sure what was
>>>> wrong with it.
>>
>>> I would expect a dead battery coupled with water in the gas tank.
>>
>>How would water get in the gas tank?
>
>In weather with temperatures changes, when the temp goes down,
>the gas tank devlops a slight vavuum drawing in humid outside are
>through any small cracks or bypassing the filler cap. Once in the
>tank the humdity condenses out, and the water goes to the bottom
>of the tank. This is pretty small potatoes, but repeat oftern
>enough and quite a bit of water can collect at teh bottom where
>the outlet is.
>
>Driving fairly often, the small amount of trapped water is sucked
>through the fuel injectors or carburetor rather swiftly and you
>hardly notice it. Get enough water at the bottom so that the fuel
>line fills with water, you got trouble.
Go to the car parts house and buy a racer's fuel jug, five gallons,
wide mouth. Go to the sprint or Indy car track and buy methanol for a
couple of bucks a gallon. You can put in a ultrasonic bath and clean
all the tar and carbon out of a pipe. If you put I cup or two in the
gas it will absorb quite a bit of water. If you buy a tankful of
ethanol blend it will absorb pints of water.
Ralph Jones
<richar...@earthlink.net> wrote:
[snip]
>
>Go to the car parts house and buy a racer's fuel jug, five gallons,
>wide mouth. Go to the sprint or Indy car track and buy methanol for a
>couple of bucks a gallon. You can put in a ultrasonic bath and clean
>all the tar and carbon out of a pipe. If you put I cup or two in the
>gas it will absorb quite a bit of water. If you buy a tankful of
>ethanol blend it will absorb pints of water.
Indeed. It's highly preferable to buying "fuel line antifreeze", which
is a 6-ounce can of methanol sold in auto parts stores for the price
you'd pay for a gallon at the hardware store...
rj
Keith F. Lynch
> Indeed. It's highly preferable to buying "fuel line antifreeze",
> which is a 6-ounce can of methanol sold in auto parts stores for the
> price you'd pay for a gallon at the hardware store...
Wooden it be cheaper to distill your own? :-)
Keith F. Lynch
> "Keith F. Lynch" <k...@KeithLynch.net> wrote:
>> I wonder how weather would differ if water vapor were heavier
>> than air.
> There would be little or no precipitation.
I'm skeptical. Water would still evaporate. And as much water has
to come out of the air as goes into the air. Perhaps more of the
precipitation would be on or near the ocean.
Richard Casady
DeLaney) wrote:
>... Air is 15 PSI, most places. Even up high, like Los Alamos, it's still
>around 11 PSI. 15 > 7. If you had only the 7 PSI inside your tank from the
>gas partial pressure, you'd get a Giant Sucking Sound (tm) from any little
>pinhole, and usually wouldn't be able to unscrew the cap at all if the tank was
>airtight.
These days all the tanks are airtight. You can tell by the hiss when
you open them. The 7 psi is at 100F and 100% humidity. It is the
specification for the stuff. Avgas is 3 1/2. Reid Vapor Pressure it is
called. Winter blend gas contains pentane which boils at 95 F. For
easy starting. In the summer the winter stuff tends to boil in the
lines under the hood.
Casady
John Francis
Richard Casady <richar...@earthlink.net> wrote:
>
>Go to the car parts house and buy a racer's fuel jug, five gallons,
>wide mouth. Go to the sprint or Indy car track and buy methanol for a
IndyCaras don't run on methanol any more; they've switched to ethanol.
David DeLaney
>Hatunen <hat...@cox.net> wrote:
>> "Keith F. Lynch" <k...@KeithLynch.net> wrote:
>>> I wonder how weather would differ if water vapor were heavier
>>> than air.
>
>> There would be little or no precipitation.
>
>I'm skeptical. Water would still evaporate.
>And as much water has
>to come out of the air as goes into the air. Perhaps more of the
>precipitation would be on or near the ocean.
No. Instead, much of the bottom layer of the air would be water vapor. Hope
we'd learn how to breathe it.
Dave "obSF: The Nitrogen Fix" DeLaney
Keith F. Lynch
> Keith F. Lynch <k...@KeithLynch.net> wrote:
>> Hatunen <hat...@cox.net> wrote:
>>> "Keith F. Lynch" <k...@KeithLynch.net> wrote:
>>>> I wonder how weather would differ if water vapor were heavier
>>>> than air.
>>> There would be little or no precipitation.
>> I'm skeptical. Water would still evaporate.
> Yes, but the vapor would not RISE.
Not on perfectly windless day. But given any wind at all, there will
be plenty of mixing. When CO2 erupted out of a lake in Africa, it
stayed low long enough to suffocate plenty of people. But then it
spread out and mixed with the rest of the atmosphere.
The atmosphere doesn't consist of layers of oxygen, nitrogran, carbon
dioxide, water vapor, etc. There's plenty of mixing.
Richard Casady
<k...@KeithLynch.net> wrote:
>The atmosphere doesn't consist of layers of oxygen, nitrogran, carbon
>dioxide, water vapor, etc. There's plenty of mixing.
If you have a basement furnace with propane fuel you may find out what
non plenty mixing means. Propane is exactly as dense a carbon dioxide,
of course. It has been known to blow boats to bits. Things mix but not
always fast enough as you said. Once mixed there is not the slightest
tendency to form layers. Entropy. Mixtures don't unmix because
disorder always increases. This is related to the reason perpetual
motion machines cannot work. Thermodynamics it's called and it isn't
all that complicated, the fancy name notwithstanding.
Casady
Keith F. Lynch
> "Keith F. Lynch" <k...@KeithLynch.net> wrote:
>> The atmosphere doesn't consist of layers of oxygen, nitrogran,
>> carbon dioxide, water vapor, etc. There's plenty of mixing.
> If you have a basement furnace with propane fuel you may find out
> what non plenty mixing means. Propane is exactly as dense a carbon
> dioxide, of course. It has been known to blow boats to bits.
> Things mix but not always fast enough as you said.
Indeed. Most basements don't have much wind, unlike the outdoors.
> Once mixed there is not the slightest tendency to form layers.
And the same would be true if water vapor were heavier than air.
Perhaps someday a planet with water oceans and a hydrogen atmosphere
will be discovered, and we can see this for ourselves.
> Entropy. Mixtures don't unmix because disorder always increases.
> This is related to the reason perpetual motion machines cannot work.
> Thermodynamics it's called and it isn't all that complicated, the
> fancy name notwithstanding.
Now explain why a mixture of oil and water *do* unmix.
Richard Casady
<k...@KeithLynch.net> wrote:
>> Entropy. Mixtures don't unmix because disorder always increases.
>> This is related to the reason perpetual motion machines cannot work.
>> Thermodynamics it's called and it isn't all that complicated, the
>> fancy name notwithstanding.
>
>Now explain why a mixture of oil and water *do* unmix.
>--
Entropy again things roll down hill, never up. The water rolls
downhill and the oil is left behind. The center of gravity is lower
with the water on the bottom. Minimum potential energy.
Casady
Keith F. Lynch
>>> Entropy. Mixtures don't unmix because disorder always increases.
>>> This is related to the reason perpetual motion machines cannot work.
>>> Thermodynamics it's called and it isn't all that complicated, the
>>> fancy name notwithstanding.
>> Now explain why a mixture of oil and water *do* unmix.
> Entropy again things roll down hill, never up. The water rolls
> downhill and the oil is left behind. The center of gravity is lower
> with the water on the bottom. Minimum potential energy.
Now explain why a mixture of gases *do not* unmix.
An explanation that can explain any observation explains no
observation.
Feynman once showed his students that a Coke can on a sunny windowsill
was warm on the shady side and cool on the sunny side. He challenged
them to explain it. Most of them came up with plausible-sounding
explanations.
The correct explanation, which none of them came up with, is that he
had turned the can around just before the students entered the room.
Canth
<k...@KeithLynch.net> wrote:
>Richard Casady <richar...@earthlink.net> wrote:
>> "Keith F. Lynch" <k...@KeithLynch.net> wrote:
>>> The atmosphere doesn't consist of layers of oxygen, nitrogran,
>>> carbon dioxide, water vapor, etc. There's plenty of mixing.
>
>> If you have a basement furnace with propane fuel you may find out
>> what non plenty mixing means. Propane is exactly as dense a carbon
>> dioxide, of course. It has been known to blow boats to bits.
>> Things mix but not always fast enough as you said.
>
>Indeed. Most basements don't have much wind, unlike the outdoors.
>
>> Once mixed there is not the slightest tendency to form layers.
>
>And the same would be true if water vapor were heavier than air.
>
>Perhaps someday a planet with water oceans and a hydrogen atmosphere
>will be discovered, and we can see this for ourselves.
>
>> Entropy. Mixtures don't unmix because disorder always increases.
>> This is related to the reason perpetual motion machines cannot work.
>> Thermodynamics it's called and it isn't all that complicated, the
>> fancy name notwithstanding.
>
>Now explain why a mixture of oil and water *do* unmix.
A system tends toward minimum energy. Normally, maximising entropy by
mixing reduces the energy of the system & is the preferred state.
However, with an oil water mixture, there is considerable energy in
the surface tension of the water-oil boundary. A finely divided
mixture of oil & water has a huge surface area for the water-oil
boundary and far more energy stored in it than the reduction in
entropy produced. The system therefore tends to minimise the surface
area of the boundary, even though this reduces the entropy.
AS! ds++:+++ a++ c+++ p++ t+ f-- S+ p+ e++ h++ r++ n++ i+ P+ m++ M
R H Draney
>
>Richard Casady <richar...@earthlink.net> wrote:
>> Entropy. Mixtures don't unmix because disorder always increases.
>> This is related to the reason perpetual motion machines cannot work.
>
>Now explain why a mixture of oil and water *do* unmix.
ObGrammar: sometimes it do, but other times they doesn't....r
--
A pessimist sees the glass as half empty.
An optometrist asks whether you see the glass
more full like this?...or like this?
Hatunen
<k...@KeithLynch.net> wrote:
>Richard Casady <richar...@earthlink.net> wrote:
>> "Keith F. Lynch" <k...@KeithLynch.net> wrote:
>>> Richard Casady <richar...@earthlink.net> wrote:
>>>> Entropy. Mixtures don't unmix because disorder always increases.
>>>> This is related to the reason perpetual motion machines cannot work.
>>>> Thermodynamics it's called and it isn't all that complicated, the
>>>> fancy name notwithstanding.
>
>>> Now explain why a mixture of oil and water *do* unmix.
>
>> Entropy again things roll down hill, never up. The water rolls
>> downhill and the oil is left behind. The center of gravity is lower
>> with the water on the bottom. Minimum potential energy.
>
>Now explain why a mixture of gases *do not* unmix.
I'm sorry, but it cost me several years of college and a whole
bunch of physics courses to find that out and I'd be very
surprised if anyone could explain that to you in a Usenet post.
>An explanation that can explain any observation explains no
>observation.
>
>Feynman once showed his students that a Coke can on a sunny windowsill
>was warm on the shady side and cool on the sunny side. He challenged
>them to explain it. Most of them came up with plausible-sounding
>explanations.
I have his lectures; which one did he do that in? Was there Coke
in the can?
>The correct explanation, which none of them came up with, is that he
>had turned the can around just before the students entered the room.
Shame on you. And him, if true.
Keith F. Lynch
> "Keith F. Lynch" <k...@KeithLynch.net> wrote:
>> Now explain why a mixture of gases *do not* unmix.
> I'm sorry, but it cost me several years of college and a whole bunch
> of physics courses to find that out and I'd be very surprised if
> anyone could explain that to you in a Usenet post.
I already know the answer. And why it doesn't apply at extreme
altitudes, at which the air composition *does* vary with altitude.
I was curious whether others also knew.
>> An explanation that can explain any observation explains no
>> observation.
>> Feynman once showed his students that a Coke can on a sunny
>> windowsill was warm on the shady side and cool on the sunny side.
>> He challenged them to explain it. Most of them came up with
>> plausible-sounding explanations.
> I have his lectures; which one did he do that in?
I think it was in one of his biographies. I'll try to find it.
> Was there Coke in the can?
I think so.
>> The correct explanation, which none of them came up with, is that
>> he had turned the can around just before the students entered the
>> room.
> Shame on you. And him, if true.
Why shame on *me*? And why shame on him? He was making an important
point: An explanation that can explain any observation explains no
observation.
Hatunen
<k...@KeithLynch.net> wrote:
Rubbish. It was a trick.
R H Draney
>
>On Tue, 29 Dec 2009 03:33:42 +0000 (UTC), "Keith F. Lynch"
><k...@KeithLynch.net> wrote:
>
>>Hatunen <hat...@cox.net> wrote:
>>> "Keith F. Lynch" <k...@KeithLynch.net> wrote:
>>>> Feynman once showed his students that a Coke can on a sunny
>>>> windowsill was warm on the shady side and cool on the sunny side.
>>>> He challenged them to explain it. Most of them came up with
>>>> plausible-sounding explanations.
>>
>>> I have his lectures; which one did he do that in?
>>
>>I think it was in one of his biographies. I'll try to find it.
>>
>>> Was there Coke in the can?
>>
>>I think so.
>>
>>>> The correct explanation, which none of them came up with, is that
>>>> he had turned the can around just before the students entered the
>>>> room.
>>
>>> Shame on you. And him, if true.
>>
>>Why shame on *me*? And why shame on him? He was making an important
>>point: An explanation that can explain any observation explains no
>>observation.
>
>Rubbish. It was a trick.
He was making an important point, the same point he'd made on any number of
other occasions: "Feynman is a smartass"....r
Thomas Prufer
>Rubbish. It was a trick.
Yup.
I assume (and hope) that he was doing it to teach them to be aware of tricks,
and say "bullshit" in the face of authority. (Though he may have been a
smartass, but perhaps then the students learned to be beware of smartasses?)
Just see how many sites there are, backed with shiny authorities with titles
made of pretty bits and bytes, selling cars that run on water, magnetic fuel
ionizers, and all the other stuff that tramples all over "conservation of
energy". There seem to be enough out there that aren't convinced enough to make
it worthwhile...
Thomas Prufer
Charles Wm. Dimmick
Reminds me of a lab exercise I would occasionally use on my Historical
Geology students towards the end of the semester. I provided them with a
number of published articles that were supposed to have the answers to a
series of geologic questions I asked in reference to maps of a
particular area. The articles gave conflicting answers to the questions,
sometimes radically conflicting. Grades were based on how well they
handled the conflicts.
Charles
Lon
How dare you attempt to teach them the value of thinking!
Curiosity impels me to query whether or not more modern students were
less able to handle this set of conflicting written opinions than less
modern ones.
Thomas Prufer
On Thu, 31 Dec 2009 06:24:52 -0500, "Charles Wm. Dimmick" <cdim...@snet.net>
wrote:
>Reminds me of a lab exercise I would occasionally use on my Historical
>Geology students towards the end of the semester. I provided them with a
>number of published articles that were supposed to have the answers to a
>series of geologic questions I asked in reference to maps of a
>particular area. The articles gave conflicting answers to the questions,
>sometimes radically conflicting. Grades were based on how well they
>handled the conflicts.
Sounds like you have found a use for Ed Conrad's posts?
Thomas "though may be at the beginning of the semester" Prufer
Charles Wm. Dimmick
> Charles Wm. Dimmick wrote:
>> Reminds me of a lab exercise I would occasionally use on my Historical
>> Geology students towards the end of the semester. I provided them with
>> a number of published articles that were supposed to have the answers
>> to a series of geologic questions I asked in reference to maps of a
>> particular area. The articles gave conflicting answers to the
>> questions, sometimes radically conflicting. Grades were based on how
>> well they handled the conflicts.
>
> How dare you attempt to teach them the value of thinking!
>
> Curiosity impels me to query whether or not more modern students were
> less able to handle this set of conflicting written opinions than less
> modern ones.
A bit of background is necessary to put this in context. Although
Historical Geology was a freshman-level course, it had as a prerequisite
Physical Geology. We taught three sections of Physical each year, with
about 60 students in each section. We taught one section of Historical
each year, with an average of 16-18 students. Most of the students
taking Physical Geology were there only to fulfill a science requirement
in their program, and many took it because it sounded as though it would
be easier than Chemistry or Physics, or because all the freshman Biology
courses were filled. Of those who went on to take Historical Geology,
about half were taking it because they were Earth Science majors or
minors. The other half were taking it because they found geology
interesting after the first course. So it was a select group, not a
captive audience. And because they had had either me or Dr. Baskerville
for the first course they knew what to expect in terms of hard work and
standards. About 15% of the students taking Physical flunked the course.
Hardly anyone ever flunked Historical Geology. It was a real delight to
teach. The students were learning how to think like a geologist, how to
come to sound conclusions with fuzzy and inadequate data. [And also to
be willing to revise the conclusions when more data appeared. In one of
my upper-level courses I had a continuing exercise involving a
hypothetical buried structure where new drill-hole data would appear
each week and they would draw a new sketch of the likely shape of the
structure.]
charles