On Mon, 11 Jul 2011 17:20:22 -0700 (PDT), "
wrote:

On Jul 11, 5:57Â*pm, Ignoramus24437 ignoramus24...@NOSPAM.
24437.invalid wrote:
I have a 22 gallon (or so) fuel tank that originally had gasoline in
it.

I want to use it for diesel.

I would like to drill it and install a through-hull fitting, which
would be for the fuel return line. Ideally, I would like to braze the
fitting in place also.

My question is how do I drill it and braze, so that it would not
explode.

The tank has not had gasoline in it for a couple of weeks.

Today, I recently set it up with the fuel cap open, turned it over so
that the fuel fill hole pionts down, and set it out so that it would
becmoe quite hot under the sun.

Would it be correct to assume that after a few days I could purge it
with compressed air, and then drill and braze it, without exploding?

Would purging with argon be a good idea?

i

A long time ago, I took a course in Vacuum Tube Technology. I figured
it would a last chance to learn about vacuum tubes. The course was
taught by Renee Rogers who worked at Varian. And had nothing to do
with ordinary vacuum tubes.

Klystrons, BWO's, TWT's, multigun CRT's, Yes. Triodes No.

But what I really learned was how Renee figured out what was causing
production problems. You have a hypothesis and then you put numbers
on it and see if it still could be true.

So how much gasoline vapor do you think could be in the tank. The
equivalent of a drop of gasoline? Two drops of gasoline? Can you
smell any gasoline fumes?

Then how much energy is in say two drops of gasoline? if it was
combined with the optimum amount of air, how much energy would there
be. Then if it were combined with 22 gallons of air? The
flammability limits for 100 octane gasoline is 1.4 % at the lower
limit and 7.6 % at the upper limit ( per Wiki ).

I have not done the math, but my guess is that you have no problem.

Dan


My guess is you are PROBABLY right - but would I bet my life on it?
Nope. There could be several times more gas than you calculated for,
and when that gas evaporated out of the rust/scale holding it in the
tank it could stratify, producing a pretty lethal 14:1 type mix at
exactly the wrong place - producing a fairly serious whollop.

Remember, gasoline containd THREE TIMES the energy per unit of mass as
compared to TNT. (or close enough for our discussion)