[KYHAM] Re: BPL, Ham radio and the EOC

[wa4qal at ix.netcom.com]

Blake Bowers wrote:
> I am pretty familiar with BLEVE, as presently a
> Fire Chief, having been in the fire service since the
> 70's, being an instructor in handling propane
> emergencies, and my son teaches the class as
> a state certified instructor.  I fail to see how
> BLEVE has anything to do with lifting a propane
> tank however.

One of the concerns with lifting a filled propane tank
is that if the lifting mechanism gives way, the tank
will probably fall, and possibly rupture.  If the tank
does rupture, liquid propane will be expelled at a 
fairly rapid rate, since the propane in the tank is 
under pressure.  This liquid propane will almost
immediately vapourize, since the boiling point of
propane is well below the average ambient temperature.
This will form a propane vapour cloud, which will be
mixed with air.  Any ignition source in the proximity
of the cloud, or below the cloud, since propane vapour
is heavier than air, could cause it to ignite, which will
then form a fuel-air explosive mixture.  Even if the
cloud doesn't ignite, the propane may create an 
asphixiation hazard.  One additional hazard is that the
flash evaporation of the propane liquid will severely
chill the remaining material, possibly causing frostbite
injuries if it happens to have spilled on anyone.

Years ago, I was out trimming up some trees that had
been downed by a storm.  While moving some of the
limbs, I dropped one, and it bounced and kicked so that
it hit my upper leg rather hard (No, this isn't a story 
about how even firewood can be handled dangerously,
although it obviously can be.).  It just so happens that
the end of the limb hit my pants pocket where I had a 
butane lighter.  The impact cracked the plastic lighter body,
allowing the butane fuel to be squirted out.  I immediately
noticed a severe and painful cold feeling on my leg, caused 
by the sudden evaporation of the small quantity of butane
that the lighter had contained.  Fortunately, I was smart
enough to stay well away from any ignition sources until 
the cloud had dissipated.  Also, note that the quantity of
butane in a lighter is relatively small, and that butane boils
at a higher temperature than propane, so a couple of 
hundred gallon spill of liquid propane could get rather, umm,
interesting.

> Propane is even used as vehicle fuel now.  Again,
> handled properly, it is safe. 
> While Diesel may be "the safest combustion
> fuel" that does not mean that properly
> handled propane, gas, or even nuclear
> fuel is unsafe.

Any fuel can be handled safely or unsafely.  Diesel
fuel has the advantage that it's relatively hard to 
ignite, due to its low vapour pressure, and is relatively
inert otherwise.  Spills of it can still contaminate 
ground water, and you could always slip on it (since
it is quite "oily"), but it doesn't take many special 
precautions to handle it.  

Radioactive fuel is also fairly easy to handle as long
as you know how to do it safely.  Then, again, I wouldn't
want to go juggling raw Plutonium pellets.

> I stand by my statements.  I have also been
> in the telecommunications industry for years,
> and have experience with hundreds of gensets,
> diesel, and propane.

The biggest issue is knowing how to handle the material
properly.  I'm reminded of the infamous Kingman, Arizona
incident where a railway worker cross threaded the coupling
on a rail car tanker of propane (or, was it LP gas?  They're
both about the same.).  When he opened the valve, due to
the cross-threaded fitting, the propane began leaking out.
He next violated protocol by trying to tighten the coupling
with a steel wrench (instead of a brass or Aluminum one),
without turning off the valve and waiting for the cloud to dissipate.
The steel sparked, igniting the leaking propane.  At that point,
he realized what a problem he had created and promptly left
the scene.  Unfortunately, the local fire department responded,
and tried to extinguish the blaze.  The flames from the leaking
coupling was impinging on the tank, which weakened it, along
with boiling more of the propane in the tank, which increased
the pressure.  Eventually, the tank ruptured, producing a BLEVE
fireball that was approximately a half mile in diameter, and 
tossing half of the railway tank car (which was made from 
approximately one inch thick steel!!!) a mile and a half!  
Unfortunately, quite a few members of that fire department were 
killed.  :-(

Any fuel can be handled safely or unsafely.  However, some fuels
require more care than others, and some are less forgiving of
the ocassional mistake than others.  And, since we're all only
human, mistakes will eventually be made, especially when we're
tired, worried, and sleep deprived, as is likely to happen in a 
disaster setting (or during field day).

Dave
WA4QAL