boiling gas?

[timberlinetree]

Yesterday I frogot the long hose for spraying. I just kept the quad running and pulling ahead. In the afternoon it started getting hot and could really fell the heat coming from the engine. When I shut it off I could hear a noise like an overcharged battery which I thought it was. Nope it was coming from the gas tank and fumes and drips of gas coming out the vent tube. When I loosen the gas cap it would stop. Tighten and it sounds like I'm boiling water for spaghetti. It was a little scary and today I will remember the hose. Can gas boil?

[petefrom bearswamp]

This used to happen to me in hot weather with my old super XL 12 chain saw.

[thenorthman]

Short answer, Yes.

Long answer hopefully not from the engine getting too warm,  The vent tube is there to let off excess vapor and to allow for expansion/shrinkage as well as to let air into the tank so you don't get vapor locked (which sucks when your 7 years old and 20 miles from home).

If it is boiling gas yer not in much more danger then not boiling gas, just going to have more vapor, so sparks and what not are slightly more of a concern.

Really the big issue here is the motor getting so hot, if its air cooled only then putting all day is really bad for them, they need to be moving a certain minimum speed to allow air to travel across those cooling fins.  If its water cooled then you have bigger concerns.

[BargeMonkey]

 I just looked in my MSDS to see what gas will boil @, it says from 160-400 F but "gasoline" is such a broadly used term. Gasoline spec differs by zone in the U.S, and by season. The gas we would bring to Portland, and Newhaven was formulated differently due to pollution standards, and who was buying it. Gasoline is flammable down to -40, the trick is to keep out of the "lower or upper explosive level", LEL & UEL.
What you heard was gas vapor building up, basically pressuring your tank and blowing out of the vent, turning back to a liquid as it cooled and condensed when it hit the outside air. You should try that with a 10" vapor line loading 15-18k bbl per hour off a ship on a barge sometime, in a lightning storm.
Google "B125 barge explosion" and watch the video of her going off in staten island, thats what 70kbbl of gas looks like going boom. The irony is, the first barge you see in the video was the 105, she went to africa 4yrs ago and the video is also online of her blowing up loading crude oil. I had almost 10yrs in as a tankerman, all set with that.

[mad murdock]

Is your vent line clear? If it is hot outside, Northman has a good point , going slow and running all day is not good for an aircooled engine, without some sort of external fan or something to increase airflow around the cylinder fins to carry heat away. My gator has a fan mounted on it for this very purpose, that can be selected on or off with its own switch on the panel.

[luvmexfood]

Any liquid can boil when it reaches a certain temp. Then it gets a little technical but it will start ommiting gases, depending on its chemical composition, which may or may not be flammable. Plus if you had the gas cap on it may sort of act like a pressure cooker. That was never covered in firefighter school or I missed it. My best guess as a firefighter with over 23 years experience is you were lucky. My main training was in Aircraft and Hydrocarbon fires. Jet fuel and avgas.

[Ed_K]

x2 on the super xl 12 my kawasaki triple would do it in summer city traffic too.

[snowstorm]

x2 on the super xl 12 my kawasaki triple would do it in summer city traffic too.

kawi triple? 500 or 750? i remember riding a 500 once the front wheel didnt want to stay on the ground

[mesquite buckeye]

Gas for our gas powered water pump boils all afternoon at the saguaro hill in the summer. Sometimes it starts hard when it is doing that. :(

[CCC4]

timberlinetree, what model 4 wheeler and what year? If you are talking about an older air cooled motor with a metal gas tank, gas will definitely boil when lugging one around all day, there just isn't enough air flow. Like mentioned above, the gas tank pressure was probably over riding your gas tank vent...is your a vent in the cap? I have had bikes build so much pressure on a gas cap vent that the bail which aides in spillage reduction, gets pushed to the top shutting off ventilation completely.

If it is a new model quad with FI, I would get it checked out if it was me.

[BargeMonkey]

Gas for our gas powered water pump boils all afternoon at the saguaro hill in the summer. Sometimes it starts hard when it is doing that. :(

Yeah anytime anyone ever complains about being a$$ deep in snow and cold I want you to think about this post. No way. I wish it never got above 70 year round.

[timberlinetree]

Wow never new gas could boil. I probably shouldn't have been spaying like I was with an air cooled Yamaha wolverine but the temp/ oil light wasn't coming on and had to keep working. It works so much better when we have the long hose so we can shut it off and spot spray 75' instead of the 15' which would kill the starter starting/stopping. I think I won't take up smoking any time soon. :D

[Ianab]

Anything will boil if it gets hot enough.  :D  Boiling point of Tungsten is 10,706F. You don't see that very often.  :D

Also that's how a refinery works. They heat up the Crude Oil, and different compounds boil out at different temperatures.

Naphtha come off first.
Petrol.
Kerosene
Diesel
Fuel Oil
Road Tar etc.

Then each different range is condensed into separate tanks.  OK it's a bit more complex than that, but that's the basic idea.

Another handy thing is that Ethanol boils at 173F, compared to water at 212F. A very handy fact if you want to make some fire water.  ;)

Like BargeMonkey says, the lighter compounds in gasoline may start boiling at only 160F, while the heavier compounds may stay liquid to ~400F. It's a mix of dozens of different chemicals. but the boiling will start at the low end with the lighter compounds gassing out first. The 160F isn't out of the question for parts of a chainsaw... Even a water cooled engine will be running ~180F.

Ian

[chuckthompson]

I used to ride an old Yamaha motorcycle, in the woods quite a bit.  Air cooled engine (of course) with an aluminum gas tank.  It would boil the gas when you were just putting along.  Made it hard to re-start after stopping (500 single cyl).  But, I never did blow up!

[Ianab]

What will be happening in a metal gas tank in that situation is the gas at the bottom will be bubbling, then the vapour hits the cooler top surfaces, and most of it will re-condense and run back into the bottom again. Like a pot on the stove with a lid on it. Very little steam (fuel vapour) comes out the vent, but the vent is enough to stop any pressure build up.

Ian