Ned Simmons wrote:



Yeah, I worked on the automation for the powder metal
gerotors in an early Bosch submersible fuel pump. Freaked
me out til I realized the motor is always supposed to be
submerged. But what happens when you run out of fuel? A
fuel gage can be designed to operate with limited current -
I think the limit is in the neighborhood of 1-10mA for most
intrinsically safe stuff at low DC voltages - but of course
that's not going to run a fuel pump. Is it assumed the pump
will always be submerged, or is it really that difficult to
get the vapor in the tank within explosive limits? If so,
can you weld with abandon on a tank as long as it's got a
bit of gasoline in it?

Ned Simmons

It's pretty common practice to weld on fuel oil tanks by filling them
all the way and weld a quick patch on. As long as your floor is clean
you don't have to worry much about a fire, and if it does burn it'll
advance quite slowly.

Gasoline, being as volatile as it is, will burn on a clean floor and
spread as rapidly as we all know it can. A pint of fuel oil on the floor
below where you're welding is no big deal, a pint of gasoline would be
exciting, especially if you burned a hole below the liquid in the tank.

I've had very good results welding gas tanks by rinsing them out with a
few gallons of hot water and a big squirt of dishsoap. If you're
feeling careful, a hard purge with CO2 before welding is a good idea.
The good thing about dishsoap in the tank is that once you fill it gas
the leftover water will mix with the gas and go on through.

I was cutting scrap one day at a little scrapyard, heard a mighty
hissing behind me, it really made me jump. I looked and there was a
flat-type GM fuel tank standing with the neck up, orange flame standing
about two inches out the pipe with a thick black smoke streaming off the
flame. The guy had said they had all the tanks picked up, I never saw it
in the weeds.. really put the respect of gas tanks into me.

Saw another that a friend set off, the thing looked like a beach ball,
remarkably round shape to it. Lucky guy that day.

Another friend of mine had a truck tank (gas) that someone had robbed
the cap from get a spark in it while he was cutting on a truck next to
it. It hosed his back with blazing rancid old gas, he had Carharts on
and got to the hose about 20' away and ran it down his back.. went home
and got in the tub, realized he was getting seriously uncommon amounts
of skin peeling off the backs of his legs, went to the hospital and
spent some ****ty length of time laying on his belly, month and a half
or two months, I forget now. Ugly scars on the calves, thighs, ass, up
his back, didn't get the backs of the knees or right below his ass.. he
said his jeans didn't even scorch.

I got heaps of respect for gas tanks and empty fuel oil tanks and empty
barrels.. the whole universe of empty stuff.

John