Hidden Danger

[Ianab]

I think the danger with filling on / in the vehicle is that the whole vehicle may be holding a static charge that could cause a spark + the vapour that overflows the can as you fill it. It's not actually LIKELY to catch fire... but it COULD. Then you have a plastic can of burning petrol, in the back of a pickup full of petrol, sitting in a gas station... also full of petrol. 

By placing the can on the ground you remove the charge that the vehicle could hold. The gas can by itself isn't big enough to carry enough charge to cause ignition. Even if pumping the fuel generates static the can isn't big enough to build up a dangerous spark.

The diesel tank welding would be hairy though. The heavier diesel would be SURE to leave a residue inside the tank, even more so than petrol. It's harmless at normal temps but once you heat it with a welding torch it's going to vapourise some of it and become flammable.

Cheers

Ian

[Furby]

Saw a fellow at the gas station just yesterday filling not one but two plastic tanks in the back of his SUV. : :

[woodbowl]

That was probably me again Furb.  : :

[Corley5]

I've got a 100 gallon diesel tank from TSC that sprung a leak where the mounting tab is attached at the bottom.  A local welding shop welded it up with an inch or so of deisel still in it    I just stopped to see if they could/would fix it and I was going to leave it with them if they could figuring they'd want to flush it out or something.  They welded it right then.  I waited outside at a distance  ;) ;D.  Cost twenty five bucks.  Lots cheaper than a new tank  8) 8)   

[DanG]

Betcha they woodna done that if it had been empty.  The liquid in the tank absorbs the heat long before it gets to any oxygen to enable combustion.

[Raphael]

  Like using a cutting torch to get the hanging straps off a car's gas tank.  Got half a tank of gas in it then it's not a problem but if it's empty BOOM!!!
  Of course more often than not you're pulling these things because of a leak so the torch option goes away, and I hope nobody is dumb enough to use a torch on the straps of a plastic gas tank.

[OneWithWood]

So answer me this - how come the gas cans don't go boom when you put them back in the bed, sloshing the gas around inside and sliding them over the liner?

Sounds like a topic for Mythbusters . . .

[Ianab]

Maybe 999,999 times out of 1,000,000 it wont catch fire....

But if a million people do it, one poor schmuck is gonna luck out. :D

Ian

[Gary_C]

There are a number of reasons for the dangers of filling gas cans.

The first reason is that any fluid flowing in a hose can build up static electricity. I believe that all fuel hoses now are required to have a grounding wire built into the hose so there can be no difference in static charge between the ends.

You can also have static charges on your body. People that work around flammable solvents are supposed to wear conductive shoes or wear a simple grounding clip and test the conductivity of their shoes every day.

Your vehicle can also carry a static charge since it is insulated from the ground by the tires.

The safest method of filling gas cans would be to place the metal safety can on the ground, attach the grounding wire from the fill point to the can, keep the nozzle in contact with the can, and only use a dead man valve, not an automatic. That is essentially what OSHA requires in the workplace.

As far as the cigarette into the glass of gas, he knew that LIQUIDS WILL NOT BURN nor explode, only vapors. Even gasoline must be vaporized and mixed with the proper amount of oxygen to burn or explode.

[Gary_C]

Welding any fuel tank without following safe cleaning proceedures is like playing russian roulette with all but two chambers loaded. Regardless of any small degree of difference in diesel or gasoline it is just plain stupid.

There are three things need for combustion or an explosion. The first is fuel and leaving any in the tank is the first mistake. The second is oxygen and and you can only hope there is not enough in the tank to create a mixture that is above the LEL or lower explosive limit. The third is ignition and the weld metal will be above the 400-500 degree auto ignition temperature of either gasoline or diesel.

So either way, you are guaranteed two out of three or four out of six.