Hi Doc,
Enjoyed your informed response. Please don't think I'm being critical or
nitpicking here, because I assure you I am not. But I'm retired from Shell Oil
Company after a 30 year career, part of which was managing our rail fleet for
two years. During that time, I learned more than I ever wanted to know about
"BLEVE"s and it scared the crap out of me. It actually is an acronym for
"Boiling Liquid Expanding Vapor Explosion". I've seen films of gas cars
containing 33,000 gallons of pressurized gas catching fire in a derailment
situation, and eventually exploding. The resulting BLEVE was akin to an atomic
bomb going off, mushroom cloud and all. The resulting carnage and devastation
was impossible to imagine. Most of the films were from news crews taping "a
big fire". One, in Houston, TX back in the late sixties, resulted in the total
evaporation of the cameraman up on a fire truck ladder. Shot up there to get a
better view.
So you're quite right to be extremely cautious around any pressurized flammable
gas container. But the direction of the BLEVE is a lot more nebulous than many
would like to think. The key is where is the heat source coming from to create
the over pressurization and the tank structural degradation, and the
construction of the tank itself. Most probably, the explosion, if it occurs,
will be a total envelopmental pattern around the tank, most probably not off
the end caps at all. If you look at the construction of a cylindrical tank,
you have a preformed one-piece bottom and top section, plus a rolled and,
possibly, welded middle tube section. The weakest link, to me, is the
longitudinal section, with the longest length of unreinforced steel. Remember,
weld points are stronger than the elements they join. And not the end caps as
your hazmat responder indicated. Consider also that the explosion would be
generated through the expanding gases to all surfaces of the tank str
ucture.
If it were me, I'd certainly press him for more details on his theory.
Especially if you're going to have to be on the scene! Rule number one: Don't
put your communications setup in a place where it can be disintegrated.
As to your last point, not having gas on the property is obviously the safest
solution. :) But, always a but, when installed properly, gas tanks are as safe
as your electrical system, and they can coexist quite nicely. And your
question about keying a1500 watt amp at the same time there is a tiny leak from
a gas line and a weak arcing point in your feedline or at the grounding panel
for your cables prior to entry to the shack system, AND you can't smell the
leak, can only say that one can create a catastrophe-in-the-making on just
about any subject, including getting electrocuted while sitting on the toilet
while using your electric razor and dropping the razor into the bowl, thus
creating a "possible" electrical jump connection to one of your most private
parts, then moving to the heart and causing massive cardiac failure. Possible,
but I don't expect to read about it in my lifetime. "Mathematical possibility"
vs. "real world dynamics."
Even the little propane tank on my grill makes
me nervous, so I am probably a bit more nervous
around those "big white bombs" than most!
That said, I learned when I worked for the Office
of Emergency Management that the key concern
from a tank is the direction of the "blevy".
This was illustrated for me by our lead hazmat
responder who described driving up to the scene
of a huge propane tank with a fire under it. He
exclaimed that they had set up their command post
in direct line with one end of the tank -- the
hottest end -- and would have been obliterated
had the tank "blevied" and sent that end ... and
many superheated shards ... flying their way.
So, if the "ends" are the top and bottom I
suppose you are in less danger then if they
are pointed at the house.
I will not own property with gas of any sort
running under or near it, but that is my "thing"!
I wonder if there is a risk of keying the KW
amp at the same time there is a tiny leak from
the tank and a weak arcing point in your
feedline or at the grounding panel for your cables
prior to entry to the shack? Mathematically
unlikely for sure ... ;-)
--
Thanks! & 73, doc kd4e http://bibleseven.com
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