So I read that gasoline evaporates at 140 F, but then what is that strong gasoline odor that is clearly smell-able even at cold air temperature, if not gasoline vapor?
Or is that the difference between “evaporate” and “vaporize?”
Who says the gasoline components have zero vapor pressure at lower temperatures? Obviously they don’t, and the American standard of Reid vapor pressure is in fact measured at 100 °F.
Liquids evaporate at any temperature. That’s why you can hang wet clothes out to dry.
“Vaporize” is a blanket term that covers evaporation and boiling. It’s technically incorrect to say that gasoline vaporizers only above a specific temperature.
Also, gasoline is a mixture so it does not have a specific boiling point.
Experiment: put some water in a bowl. Measure the depth of the water. Let the water sit in the bowl at room temperature for a few days.
Is there more or less water in the bowl than before? If there’s less, where did it go?
The answer is that water (and other liquids) are always evaporating, at least a little bit. Temperature measures the average amount of heat (molecules zipping around) in a container, but some molecules will always be zipping around a bit more than others, and some zip around enough to become vapor. As noted above, this phenomenon is called vapor pressure. The boiling point of a liquid (100C for water at sea level) is the temperature at which the vapor pressure of the liquid is equal to the atmospheric pressure around it.
Complicating matters, since gasoline is a mixture of different liquids, they all have different partial pressures and will evaporate at different rates. So the smellocules in gasoline vapor may not be statistically representative of actual gasoline.
It may be worth pointing out that this 140 F figure is wildly misleading from a safety point of view. According to this table, the flash point of gasoline is -45 F. You really do not want to be smoking your cigarette next to a gasoline tank just because the weather is only 100 F.
First thing you should do is never read that site again, it’s full of garbage.
Second thing is that “gasoline” is not one substance, but a blend of short-chain hydrocarbons with widely varying boiling points. Gasoline’s “boiling point” is given as anywhere between 100-400 F depending on the specific mix of components.
Third is that gasoline’s flash point (the temperature at which it emits ignitable vapors) is -45 F. This is why it still can work in an ice cold engine.
Fourth is you should never read that site again, it’s full of garbage.
Well now, the topic at hand seems to be a common mistake, I don’t see why the site is …
read … read … restore conductivity, wha? {click}
Oh my science …
Put your nose over the sugar bowl. Can you smell something? Is it the scent you’ve come to associate with sugar? What temperature is reported for the vaporization of table sugar? The answers are much the same as for gasoline – made more egregious given sugar is a solid at room temperature.
It appears to be one of those sites that exist to drive ads where random people post clickbait to try to skim off some of the ad money.
Take a look at Russel Ade’s biography. Tell me where you see scientist in any of it.
If you look at his recent publications, this - I swear by Og - is the latest: 12-21-2012 What are Your Predictions? The Cosmic Vagina. Is it as bad as you might think? Hoo boy, is it. :smack:
From what I understand, most of the vapor you see coming out of gasoline is butane, which is one of the most volatile components in it. It’s also why gas can go stale: all the most volatile elements evaporate and leave the less powerful stuff behind.
Winter-blended gasoline has more butane in it to ensure your engine can create a combustible mixture when it’s -50F; this is why people in International Falls, MN are able to drive to work on January mornings. Here’s some info I posted in a thread earlier this year about the flash point for various hydrocarbons:
Octane (C8H18) flash point: 55 F
Heptane (C7) flash point: 25 F
Hexane: -15 F
Pentane: -56 F
Butane: -76 F
Propane: -155 F
Ethane: -297 F
Methane: -306 F
Pentane and the heavier hydrocarbons will evaporate at low temps, but not in large enough amounts by themselves to create a flammable mixture. When you first turn the key on those frosty mornings, butane is the lead singer and the heavies are just the backup singers.
In hotter climates, relatively little butane is blended in. It’s not needed for cold-starts in these conditions, and the warm weather would just increase evaporative emissions, contributing to smog.
FWIW, the worst that’ll happen is a small “woof” and burbling flame at the opening of the filler neck; you might get local first- or second-degree burns, but you’re not going to turn the gas station into a smoking crater. This is because the fuel-air mixture inside the tank is too rich to burn. Good example here: she starts the tank fill, gets in/out of her car (accumulating a static charge), and then when she touches the dispenser the static spark lights the combustible gaseous mixture near the opening of the fuel filler neck. After flickering for a bit, the fire emanating from the fuel filler neck actually snuffs itself out. Tank no go boom.
Here’s another such incident. Still no tank explosion, although this fire is sustained because the dispenser is still pouring fuel into the tank, causing an incombustibly-rich mixture of air and fuel vapor to be displaced out of the filler neck, where it mixes with ambient air and creates a combustible mixture. They put the fire out with an extinguisher, but they could have stopped it with less drama if they had just shut off the pump, either by hitting an e-stop button or by manually tripping the paddle that the dispenser nozzle pushes when you hang it back on the pump.
Really bad things don’t happen unless you panic and pull the dispenser nozzle out while it’s still dispensing fuel,, like this guy did. The fire underneath his truck grows so quickly that I’m pretty sure the nozzle was still dispensing fuel after he dropped it and ran.
Seconding what others have said here, the article the OP linked to is utter horseshit.
Is the sugar really vaporizing or is that just sugar dust that’s light enough that even moving the container sets it airborne?
I never knew that sugar had a scent–like salt, it seems utterly smelless to me.
this is also why it’s perfectly safe to place electric fuel pumps inside the gas tank. even if the pump or associated wiring were to fail, there is (or should be) no oxygen inside the tank to allow the fuel/vapors to ignite.
Sugar has very little smell to me. Those times where I deliberately have tried to smell it I have to get much closer to it than to the paper it is in or I will smell the paper instead.
Sucrose is odorless. The “sweet” smell associated with baked goods comes from a milieu of other molecules.
Does this mean Anton Chigurh needed a different distraction?