Strong Gasoline Smell

[RS4U]

Hi everyone,

Here is another strange happening I had on the road to Italy from Switzerland:
I was zipping up on the Nufenen Pass (2478m high) [img]images/graemlins/FIREdevil.gif[/img] when just before reaching the pass at about 2400m a very strong gasoline smell came in the cockpit. [img]images/graemlins/062802drink_prv.gif[/img]
I stopped the car looked under the hood, nothing special except lots of heat. Then, I heard some noise at back of the car. After a closer listening I could clearly hear the gasoline boiling in the tank [img]images/graemlins/confused.gif[/img]
So I opened the lid and went for a small walk until the fuel cooled down... Going down on the other side of the pass the smell was luckily gone.
This was a very hot summer day (~32C at the bottom off the pass) and with the altitude the gas boiling point must have come down quite a lot (made a calculation for water and found that at 2478m the water boiling point is at 16C less than at sea level)
I did a quick search on the net to see if any one had experienced the same thing, but found nothing on boiling car gasoline in high altitude driving. The only thing that came is the vaporlock which occurs in the engine and not in the gas tank.
Could it be that my after market exhaust is dissipating more heat than the original one?

I was wandering if any of you had experienced the same thing?

Cheers

[Jon]

very strange, living in yorkshire it has never happened to me!

[donrs4]

wow!
Yes, your explanation sounds plausible. definitely fueling up in such hot conditions at higher altitudes is very annoying as the gas pump keeps switching off, claiming the tank is full (which it is not yet, far off even), but the vapors trigger the sensor in the nozzle and thus stop the flow of gas to the tank.
So, I could quite imagine your story.
Have to keep that in mind.


You live in Switzerland, RS4U?

d.

[RS4U]

Hi,

Yes, I live in Switzerland (in the French part)

Last night I broke a rim a in a small pothole. Hope it won't be too expensive [img]images/graemlins/frown.gif[/img]

Greetings,

[toasty]

Hi Mate,

I've held off replying to your post as I usually wait for Dippy to post, then I disagree with him over some minor technicality [img]images/graemlins/tongue.gif[/img] [img]images/graemlins/tongue.gif[/img]

It's a interesting phenomenon that you describe, and certainly boiling points do decrease as altitude increase.

I think you may have made an error for the boiling point of water at 2478m above sea level. I actually make it 92C and here's how:

To compute the air pressure (p) for each altitude, I used the formula
p = poe-ay

where
p = pressure in Pascals (Pa)
po = pressure at sea level = 1.013x105 Pa
a = 1.16x10-4 m-1
y = altitude (m)

Gives:
Altitude (m) Pressure (mm-Hg) Temp. °C
0 759.85 100.0
2478 572.65 92

This formula assumes temperature and acceleration of gravity are constant over the range of altitudes.

From here you need a table of vapour pressures for water, luckily I had one of these to hand [img]images/graemlins/smirk.gif[/img]

More simply you can approximate based on an empirical relationship and simply say that Raising or lowering the pressure by about 28 mmHg will change the boiling point by 1°C, so in this case the atmospheric pressure has gone down by 181mmHg which would suggest a drop of about 6.5C.

As for gasoline/petrol, well it is more volatile than water and has a lower boiling point to start with, but it's dificult to say exactly what the boiling point is as petrol is a mixture of lots of different chemicals and so tends to have a boiling point 'range' rather than a specific temperature, however it is usually accepted to be around 70C ish

It's quite difficult therefore to estimate how altitude will affect its boiling point (since the boiling point range is between 37C to 180C for the components) ... and my chemistry isn't great, but I'll have a go and report back. [img]images/graemlins/smile.gif[/img]

[tanoga]

To compute the air pressure (p) for each altitude, I used the formula
p = poe-ay

where
p = pressure in Pascals (Pa)
po = pressure at sea level = 1.013x105 Pa
a = 1.16x10-4 m-1
y = altitude (m)

Gives:
Altitude (m) Pressure (mm-Hg) Temp. °C
0 759.85 100.0
2478 572.65 92

[img]images/graemlins/jawdrop.gif[/img]

Jesus Christ what I know is that if a buy 2 pints of [img]images/graemlins/beerchug.gif[/img] at £2 a pint and I hand over a £5 note I will get £1 change. [img]images/graemlins/hoho.gif[/img]

[PhilT]

To compute the air pressure (p) for each altitude, I used the formula
p = poe-ay

where
p = pressure in Pascals (Pa)
po = pressure at sea level = 1.013x105 Pa
a = 1.16x10-4 m-1
y = altitude (m)

Gives:
Altitude (m) Pressure (mm-Hg) Temp. °C
0 759.85 100.0
2478 572.65 92

[img]images/graemlins/jawdrop.gif[/img]

Jesus Christ what I know is that if a buy 2 pints of [img]images/graemlins/beerchug.gif[/img] at £2 a pint and I hand over a £5 note I will get £1 change. [img]images/graemlins/hoho.gif[/img]

My thoughts exactly.... Dan, what you been smoking? [img]images/graemlins/hatthing.gif[/img]

[toasty]

Jesus Christ what I know is that if a buy 2 pints of [img]images/graemlins/beerchug.gif[/img] at £2 a pint and I hand over a £5 note I will get £1 change. [img]images/graemlins/hoho.gif[/img]

Fair play Karl, I might be good with numbers but I couldn't take a few tin cans, an old kitchen sink and some hosepipe and build some of the stuff you produce. [img]images/graemlins/grin.gif[/img]
You must be a wizard on the lathe mate. [img]images/graemlins/thumbs.gif[/img]

As for smoking Phil, not me, but I did get bitten by a snake or some other gremlin on the weekend and still have the bite mark to prove it, perhaps the venom had an effect on me! [img]images/graemlins/laugh.gif[/img] [img]images/graemlins/laugh.gif[/img]

[Jon]

on the smoking front....in my student days we once built a pipe out of a household radiator, a funnel with chicken wire as a gauze and two in line windescreen washer motors to suck the mix through....cooled the smoke down and force fed it into your lungs under pressure....coma tackle!!!! [img]images/graemlins/tongue.gif[/img] [img]images/graemlins/tongue.gif[/img] [img]images/graemlins/tongue.gif[/img] [img]images/graemlins/tongue.gif[/img] [img]images/graemlins/roflmao.gif[/img] [img]images/graemlins/roflmao.gif[/img] [img]images/graemlins/roflmao.gif[/img] [img]images/graemlins/roflmao.gif[/img] [img]images/graemlins/crucified.gif[/img]

[Taipan]

petrol is a mixture of lots of different chemicals and so tends to have a boiling point 'range' rather than a specific temperature, however it is usually accepted to be around 70C ish

OT.

Toasty, I don't know how accurate the 70c is but NO WAY would I try to check that [img]images/graemlins/shocked.gif[/img]

I mean you've got people putting a few liters of petrol in a pot on the gas stove and checking when it starts doing bubbles ?!?!? And then what happens ? [img]images/graemlins/flamethrower.gif[/img]

Eric

[RS4U]

After some research I found that only gaseous hydrocarbons burn, consequently if the air is cold, then the fuel has to be very volatile. But when summer comes, a volatile fuel can boil and cause vapour lock, as well as producing high levels of evaporative emissions. So, the oil companies modifies the gasoline between winter and summer.
Maybe I got an old winter mixture. [img]images/graemlins/062802drink_prv.gif[/img]

[jonp]

To answer the first Q, I have had strong Gas smells in the summer - nothing coul be found, nad have not had it since

J

[img]images/graemlins/audiS4black.gif[/img]