On Tue, 02 Dec 2003 05:08:07 GMT, Kent Fowler
wrote:

Dave, let me put it this way and then I am ending my part in this
thread. . I hate to see folks get hurt/burned/killed by taking
chances they did not have have to. I have known people who were maimed
or killed by doing just that. And in my opinion, you took a pretty
scary chance and I think you were lucky the conditions weren't right
to have an accident.

I respect that.
However, my opinion was that there was very little risk involved.
And it seems that more and more people are coming up with examples
where people deal with similar situations in every day life, where it
is not only considered safe, but also routine.

I would have filled the tank with water
through the valve to eliminate the vapor space then used the torch. I
wouldn't have stuck even a match to it until that vapor space was
gone. Why take the chance????

Because someone else would probably argue that there will always be a
chance that you *thought* the tank was full of water, but really
wasn't.

I work with
hydrocarbon reactions using super high pressures and elevated
temperatures every day. I know the physics. I know the math. I also
know what can happen if one little thing goes wrong.

You know the math and physics, but what about the chemistry?
I've seen first hand how chemical reactions can become explosive. If
the temperature is wrong. If the chemical ratios are wrong. If the
pressure is wrong. etc. I agree, one little thing going wrong can
cause major problems.

But we are comparing apples and oranges.
I wasn't dealing with high pressures. I didn't have high
temperatures. The propane wasn't going to react with anything inside
the tank.

I certainly wouldn't try this with an acetylene tank, because
acetylene is not very stable by itself, and can detonate violently
with no oxygen present.

Dave

On Tue, 02 Dec 2003 07:27:20 -0600, David A. Webb
wrote:

On Tue, 02 Dec 2003 05:08:07 GMT, Kent Fowler
wrote:

Dave, let me put it this way and then I am ending my part in this
thread. . I hate to see folks get hurt/burned/killed by taking
chances they did not have have to. I have known people who were maimed
or killed by doing just that. And in my opinion, you took a pretty
scary chance and I think you were lucky the conditions weren't right
to have an accident.

I respect that.
However, my opinion was that there was very little risk involved.
And it seems that more and more people are coming up with examples
where people deal with similar situations in every day life, where it
is not only considered safe, but also routine.

I would have filled the tank with water
through the valve to eliminate the vapor space then used the torch. I
wouldn't have stuck even a match to it until that vapor space was
gone. Why take the chance????

Because someone else would probably argue that there will always be a
chance that you *thought* the tank was full of water, but really
wasn't.

No, because you at least eliminated most of the vapor space.

I work with
hydrocarbon reactions using super high pressures and elevated
temperatures every day. I know the physics. I know the math. I also
know what can happen if one little thing goes wrong.

You know the math and physics, but what about the chemistry?
I've seen first hand how chemical reactions can become explosive. If
the temperature is wrong. If the chemical ratios are wrong. If the
pressure is wrong. etc. I agree, one little thing going wrong can
cause major problems.

Know the chemistry very well. Worked a propylene oxide unit for 5
years. Used direct oxygenation of hydrocarbons in the process. Have
been working oxo-alcohols and plastisizers units for the last 25
years. Chemistry is a part of my every day job.

But we are comparing apples and oranges.
I wasn't dealing with high pressures. I didn't have high
temperatures. The propane wasn't going to react with anything inside
the tank.

I didn't say it would. But it certainly might have reacted with a
spark or a flame, which is the point of this dialog.

I certainly wouldn't try this with an acetylene tank, because
acetylene is not very stable by itself, and can detonate violently
with no oxygen present.

Dave

On Mon, 01 Dec 2003 19:16:41 -0600, Richard J Kinch
wrote:

Bob Engelhardt writes:

I've been meaning to do the chemistry to show that there simply is not
enough energy from the propane in an empty tank to do any harm. But I
haven't gotten around to it (what else is new?).

Yeah, do that chemistry. You essentially have 5 gallons of steam at, what,
3000 deg F? Fair bit of pressure, that, and too quick for the overpressure
device to respond.

The theoretical maximum pressure would be less than 130psi.

Someone, please check my math.

For experimental purposes, the tank size doesn't matter.
But in order to do the math easier, we need some real numbers.
Math is easier if things are metric, so lets keep it simple.

My 100lb propane tank looks like it would hold 10 gallons of water.
So lets round up to 50 liters.

The reaction for combustion of propane is:

C3H8 + 5O2 - 3CO2 + 4H2O

One mole of propane requires 5 moles of oxygen.

The ideal gas law states that one mole of an "ideal gas"
takes up 22.4 liters volume.

So 22.4L of propane reacts with 112L O2.

But, oxygen only makes up 21% of air.

So, 22.4L of propane needs 533.3L air.

Or a ratio of 1L propane to 23.8L air.

Or, for our tank, roughly 2L propane and 47.6L air.

So lets change our tank to fit the gas.

2L propane and 47.6L air in a 49.6L tank.

After burning, the propane produced 6L CO2 and
8L H2O vapor.

So now the tank contains:
8L H2O vapor
37.6L Nitrogen
6L CO2

Or, it would if the tank would expand to keep the pressure at zero.

Since we are looking for peak pressure, we don't care what happens
when everything cools and the steam condenses.

So we will assume everything in the tank is now at 3500F, which is the
maximum temperature a propane in air flame will get.

Lets go to the ideal gas law PV=nRT

P = Pressure, and is what we are looking for.
V = Volume. In our case, the volume inside the tank is 49.6 L
n = the number of moles of gas. We have 51.6L which is 2.3 moles.
R = a constant = 0.0821 L*Atm/Mole*K
T = Temperature in Kelvin = 2200K

So, P x 49.6L = 2.3M x (0.0821 L*Atm/Mole*K) x 2200K

Which means P = 8.38 atmospheres.

1 atmosphere = 14.7 psi.

Therefore, the theoretical maximum pressure inside the tank would only
be 123 psi.

Dave

On Tue, 2 Dec 2003 01:22:13 -0600, "Tim Williams"
wrote:

Hey Kent. I gotta real heart-stopper for 'ya. Earlier today I was
drilling a 'decomissioning' hole in a disposable propane tank (later
to be cut up for use as a small crucible, but that's another story),
well I figured I'd pop two so I can have a little fun with the 1atm
gas left sitting inside.. Grab a straw and a lighter and blow flames!

You'll be interested to know that, no matter how hard I tried to get
oxygen into the bottle, I never got internal combustion.
Need to pump up you pecs, Need a little more lung power, Tim.
Also need to redesign your lungs to not quite put so much CO2 instead
of O2. Would go a long way to making a more spectacular pop. See, I
do know the chemistry.

Another neat trick is taking your air+propane torch set lean, put it
down the neck of an empty milk jug, blast it for 10 seconds (until it's
full of propane), then light it off (use something long BTW). Fwooom!
To add to the enjoyment, you can pick up the jug and then light it off -
rocket propulsion!

No matter what setting, rich nor lean, have I had any faster than a
slow burn. The HDPE jug remains intact, though slightly warm.

You might want to try that with a 100 gallon tank such as Dave has.
But tell your mother to up your health insurance first. Hospitals
specializing in burns are rather expensive.

BTW... anyone with a propane foundry can try a similar cute trick. Put
some loose leaves in the furnace, turn on the gas, then light it from
the top (I 'spose you could do it from the bottom too).

Tim

Don Bruder wrote:

Perhaps all of these are true. Perhaps none of them are. That isn't
important. What is important is that he got it done, and, regardless of
how or why, he got it done without getting hemself damaged or dead in
the process.

In my opinion, what is important is that people realize the fact that
he got away with it doesn't in and of itself make it a good idea, or
safe. Without getting into the specifics of the valve removal this
can be discussed as a matter of philosophy. i.e. doing something
risky and getting away with it for a while doesn't make it either safe
or a good idea. Its good to be lucky, but it isn't a good idea to
depend on it over the long term.

They flew the shuttles with burnt O-rings that were not supposed to
burn for quite a long time before they lost the Challenger. They flew
with 11 times the foam falling off, when none at all was supposed to
fall off, after they changed the adhesive that they used to have for
several years before they lost the Columbia. In both cases the logic
was that because it worked a few times it was safe. History has
shown, with tragic outcomes, the flaw in that logic, though it seems
to be a lesson that is very hard to learn.

The deal is that a contemplated course of action should be shown to be
safe, or have acceptable risk vs payback, or one doesn't proceed. One
does not have to show something to be unsafe to avoid proceeding. The
difference is profound.

Doing risky things and getting away with it is a matter of chance. Do
it once, you have a better chance of dying from other causes than if
you do that same risky act a lot. People pass over the yellow line
and may get away with it. People cut in and out of traffic on
freeways at high speeds and get away with it. People who do these
things a lot usually don't. There are similarities.

Shop safety is much the same. I file on the lathe by holding my right
arm over the work with the file handle in my left hand to avoid having
my arm over the chuck. Most folks I know do it the other way. I
suspect this is probably because they are right handed and want the
file handle in their right hand. I'm right handed, but with practice
it doesn't matter. The chuck, in my experience, is more likely to be
able to grab the arm or clothes because:

a) its bigger in diameter and closer to the arm than most of the work
on the lathe

b) it can have grabby things sticking up like chuck jaw ends that are
usually not there on the work. They can be, in which case maybe the
chuck end is safer in that instance, but usually the work where the
right arm is smooth.

Similarly, when using a lathe dog between centers, I don't want my arm
over it, even if it is the "safety" type with a recessed setscrew.
People file with their arm over the chuck a lot, but I don't think it
is as safe as doing it the other way.

Its called risk management. Its a personal choice.

You pick your pony, you take your ride.

Fitch

In article ,
Fitch R. Williams wrote:

Don Bruder wrote:

Perhaps all of these are true. Perhaps none of them are. That isn't
important. What is important is that he got it done, and, regardless of
how or why, he got it done without getting hemself damaged or dead in
the process.

In my opinion, what is important is that people realize the fact that
he got away with it doesn't in and of itself make it a good idea, or
safe. Without getting into the specifics of the valve removal this
can be discussed as a matter of philosophy. i.e. doing something
risky and getting away with it for a while doesn't make it either safe
or a good idea. Its good to be lucky, but it isn't a good idea to
depend on it over the long term.

Now there's a revelation... (please imagine my eyes rolling)

The guy never claimed his method to be "safe". In fact, it seem to me
that he was worried that it might not be safe, so he was taking
umtpy-four different precautions. In the end, he claimed it got the job
done.

Look, NOTHING is "safe". Getting out of bed in the mornign has been
proven to be fatal in certain situations. Risk assessment (and
acceptance) is something we all do every day. I KNOW I can get in my car
to head for work only to wake up in the hospital (or not wake up at
all...) because SOMETHING (I won't even make a feeble attempt to
enumerate all the "somethings that are possible) went wrong. Maybe I was
driving too fast. Or too slow. Maybe there's a drunk heading for me
around the next bend. Maybe the wheels fly off the car and I go into the
drink - whatever! I accept that there's an element of risk to *EVERY
STINKING THING I DO*, and it's not for you or anyone else to tell me I
may or may not do something because *YOU* think the risk is too high.
Ony I can make that decision as to how much risk is too much, so I'd
thank you and your cronies who are intent on protectng me from myself to
keep your nose in your own business.

The deal is that a contemplated course of action should be shown to be
safe, or have acceptable risk vs payback, or one doesn't proceed. One
does not have to show something to be unsafe to avoid proceeding. The
difference is profound.

Likewise, as I just said, *I* decide what risk is acceptable for *ME*,
regardless of what you or anybody else thinks. Yours is to assess *YOUR*
risk and act on that assessment. Yours *IS NOT* to to assess my risk and
tell me "you can't".

Its called risk management. Its a personal choice.

And then here, you come into 100% full agreement with me. Yet you still
try to preach that your decision regarding a risky activity is the only
one that's right. Come on, guy, which is it? Is it my decision, but only
if *YOU* think the risk is low enough? And where's the boundary between
"You go ahead and make your choice" and "Oh, no you don't! That's too
dangerous!"?

You pick your pony, you take your ride.

Interesting analogy, since I'm primarily a horseman. And I agree...
*YOU* pick *YOUR* pony and *YOU* take *YOUR* ride.
*I* pick *MY* pony, and *I* take *MY* ride.

So long as you don't try telling me "That one's too dangerous for you"
(or vice-versa) we'll both get along just fine.

The instant you start trying to "pick my pony" for me, we're going to be
at odds.

--
Don Bruder - --- Preferred Email - SpamAssassinated.
Hate SPAM? See http://www.spamassassin.org for some seriously great info.
I will choose a path that's clear: I will choose Free Will! - N. Peart
Fly trap info pages: http://www.sonic.net/~dakidd/Horses/FlyTrap/index.html

On Tue, 02 Dec 2003 16:12:34 GMT, Fitch R. Williams
wrote:

In my opinion, what is important is that people realize the fact that
he got away with it doesn't in and of itself make it a good idea, or
safe. Without getting into the specifics of the valve removal this
can be discussed as a matter of philosophy. i.e. doing something
risky and getting away with it for a while doesn't make it either safe
or a good idea. Its good to be lucky, but it isn't a good idea to
depend on it over the long term.

....

Doing risky things and getting away with it is a matter of chance.

My grandfather might say there is too much risk involved in using a
microwave oven. After all, if it can cook a chicken from the inside
out, what is it doing to your body?

I know people who are afraid of CD players because the laser could put
your eye out.

So... is it really "risky" if I use a microwave oven or play music?

I'm sure we can all come up with things that many intelligent people
believe are true, but are absolutely not. Parking the car facing away
from the wind will make it easier to start in the morning. Hot water
freezes faster than cold. Octane boost in my fuel tank will make my
car go faster.

But, following the exact steps I outlined, where is the risk?

To say that the tank could have exploded in my face "just because"
isn't good enough for this particular argument.
Sort out the fear from the facts.

Sure, someone could have snuck in and filled the tank with gunpowder,
behind my back, and it could have exploded as soon as I started to
heat the bung, but other than that I don't see the risk.


Dave

On Tue, 02 Dec 2003 16:38:44 GMT, Don Bruder wrote:

The instant you start trying to "pick my pony" for me, we're going to be
at odds.

Whoa.

I don't mind the argument, but lets keep the emotions down a little.

I don't think he was trying to tell you whether or not you could do
anything. He was just saying that in his opinion, my ability to
accept risk is greater than his. My argument is that it isn't,
because I don't believe the risk is truely present.

I considered the whole "it is not safe to drive to work" issue,
but I thought it was better to stick to the issue.
"If what I did was risky, please explain how"

Maybe people will develop a better understanding of how risky this
really was. Heck, I might even learn something.

Dave

Kent Fowler wrote:


The reason I pointed you toward bleve is to see the result of a
vapor explosion.




And what kind of idiot will blow down a tank in the presence of an
ignition source?




--

Mark

N.E. Ohio


Never argue with a fool, a bystander can't tell you apart. (S. Clemens,
A.K.A. Mark Twain)

When in doubt hit the throttle. It may not help but it sure ends the
suspense. (Gaz, r.moto)

Kent Fowler wrote:


As far as the hairspray thing. I'll say this. I work with
hydrocarbon reactions using super high pressures and elevated
temperatures every day. I know the physics. I know the math. I also
know what can happen if one little thing goes wrong.




Inside a petro chem plant which are generally held together with bubble
gum and bailing wire.


A PC plant is not a 100 pound cylinder.

Kent , your impressing me that your the type of person who no one else
can be right or you can't be wrong, no matter what.





--

Mark

N.E. Ohio


Never argue with a fool, a bystander can't tell you apart. (S. Clemens,
A.K.A. Mark Twain)

When in doubt hit the throttle. It may not help but it sure ends the
suspense. (Gaz, r.moto)

Don Bruder wrote:

And then here, you come into 100% full agreement with me. Yet you still
try to preach that your decision regarding a risky activity is the only
one that's right.

I never said anything about your choices anyplace. I specifically
said I wasn't going to discuss the valve removal - I agree its been
discussed to death. I don't know anything about the chemistry of that
stuff, and I didn't discuss it. I don't see that I had a decision in
that posting anyplace other than the discussion of how I use a lathe
file, and why, which you can do with as you please.

What I said, as a matter of philosophy, applies regardless of
circumstance. The physics of risk taking are pretty simple - if you
do something that is risky enough, often enough, it will have a bad
outcome. The corollary to that is that the fact that if one took a
chance, committed a risky act, and didn't have a bad outcome, doesn't
make the act safe. The fact that a person took a chance and it didn't
have a bad outcome isn't the important lesson. The important lesson
is that the lack of a bad outcome doesn't make an act safe. My
intention was to make that point. I provided examples to illustrate
it.

The bottom line is that taking a risk, assessing a risk, is a personal
decision. The outcome depends on chance. Nothing I wrote is
inconsistent with that.

Fitch

David A. Webb writes:

The theoretical maximum pressure would be less than 130psi.

Someone, please check my math.

Hard to predict precisely, but roughly speaking, you have on the order
of a doubling in molar volume (the molar ratio after combustion by your
analysis is 7:1, but the explosive limits are almost the inverse at 10
to 15 percent propane in air), and a 10-fold rise in absolute
temperature, so the ultimate pressure would be the product, which is to
say, upwards of 20 times the original pressure, or 20 atm, or upwards of
300 psi. Of course there is a sub-sonic shock wave as well.

The question is whether the rupture strength of a 20 lb propane tank can
contain an explosive rise from 1 atm to 10 or 20 atms of pressure. If
so, then one would be skeptical that these things *ever* explode.

Have these tanks actually exploded, say, in fires? It seems like the
reports that claim explosions were actually tanks that leaked into a
confined space that then mixed with air and exploded, not that the tank
itself ruptured or exploded.

There was a suicide case locally a few years ago where a guy tried to
deliberately explode several 20 lb tanks indoors by lighting fires
underneath them. He only succeeded in making an explosive mix in the
room, which was devastating, but the tanks themselves survived intact.

Fitch R. Williams writes:

. They flew
with 11 times the foam falling off, when none at all was supposed to
fall off, after they changed the adhesive that they used to have for
several years before they lost the Columbia.

No, not the adhesive, the foam itself. Environmentalism forced a change of
the foaming process from using a CFC agent to something more
"environmentally friendly" (and structurally inferior). If someone is
claiming otherwise, it betrays a political agenda. Environmentalism
destroyed Columbia.

In article , Fitch R. Williams
says...


They flew
11 times [with] the foam falling off, when none at all was supposed to
fall off, after they changed the adhesive that they used to have for
several years before they lost the Columbia. In both cases the logic
was that because it worked a few times it was safe. History has
shown, with tragic outcomes, the flaw in that logic, though it seems
to be a lesson that is very hard to learn.

Ah. Now here is the man who probably knows the inside
story. I read the article in the "National Review" about
the failed safety culture at nasa, and the various
managers (Ham, etc.) who were second-guessing the engineers.

Was that article pretty much accurate?

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

In article ,
Richard J Kinch wrote:

David A. Webb writes:

The theoretical maximum pressure would be less than 130psi.

Someone, please check my math.

Hard to predict precisely, but roughly speaking, you have on the order
of a doubling in molar volume (the molar ratio after combustion by your
analysis is 7:1, but the explosive limits are almost the inverse at 10
to 15 percent propane in air), and a 10-fold rise in absolute
temperature, so the ultimate pressure would be the product, which is to
say, upwards of 20 times the original pressure, or 20 atm, or upwards of
300 psi. Of course there is a sub-sonic shock wave as well.

The question is whether the rupture strength of a 20 lb propane tank can
contain an explosive rise from 1 atm to 10 or 20 atms of pressure. If
so, then one would be skeptical that these things *ever* explode.

Have these tanks actually exploded, say, in fires? It seems like the
reports that claim explosions were actually tanks that leaked into a
confined space that then mixed with air and exploded, not that the tank
itself ruptured or exploded.

anecdotal evidence time:

Back in September, I went out to feed the horses one morning, and in the
process, discovered that my landlord's house was on fire. Half an hour,
maybe 45 minutes later, when the FD got there (no fault or blame put to
them - even driving like an utterly insane bat out of hell, I can't make
it from the house to the nearest fire station in less than 35 minutes in
my car - they responded as fast as was physically possible, considering
the distance and terrain between them and the fire) the house was
essentially totally engulfed. It was a hot fire - the hottest I've ever
seen personally - It did a damn good job of trying to torch trees a
hundred feet away. When it was done, the fire left almost nothing but a
smoking crater where the basement used to be - Other than one small
section of bathroom wall, *EVERYTHING* burned. Glass melted and flowed
like water - I can go down to the site and pick up frozen "rivers" of
glass that would fool just about anybody into thinking they were actual
flowing water. Ceramic countertop tiles, and concrete tile roofing
slumped, cracked, and shattered. Concrete block walls in the basement
scaled and blistered and cracked. A coin collection was turned into a
blob of mixed metal, with only a very few recognizable coins in it.
Aluminum engine blocks on lawn equipment stored in the basement in
preparation for the soon-to-be-coming winter rain were reduced to
puddled lumps with barely recognizable partially melted steel chunks
sticking out of them. An entire woodworking shop - table saw, radial arm
saw, drill press, jointers, planers, routers, you name it, if it can be
used for woodworking, it was probably there - some still in the boxes
from Sears 'casue there hadn't been time or room to get them all
unpacked and set up yet, was destroyed. The cast iron table of the
jointer was twisted and warped like warm taffy. We still haven't found
(or at least, if we have, we don't recognize it) the table saw's table.
The motor was found - as a steel-shelled blob of melted copper. Several
rifles and shotguns got hot enough that the barrels slumped flat. A
fiberglass boat 30 feet away went up in smoke, and the aluminum heads on
the inboard engine melted into slag. The pickup truck 20 feet beyond the
boat had the paint blistered and plastic trim melted and distorted.
Another car near the truck had taillights and bumper melted, and
blistering to the paint job. *EVERYTHING* flammable in the house was
turned into either ash or charcoal chunks. As I say, it was a *VERY* hot
fire. Several of the firemen said it was possibly the hottest, worst
fire they'd ever attended. Usually, at least *SOMETHING* is left. Not in
this case.

Anyway, to the point of this post:

Four propane tanks, one full, one partial, two brand new (less than a
week old, and not yet been filled for the first time since being bought
to replace the recently outlawed pair without the overfill prevention
gizmo) were in the fire. All of them were the (I think) 5 gallon size -
They don't *QUITE* fit into a standard plastic 5 gallon hydraulic fluid
bucket. I guess that would probably make them 20 pounders.

The only visible damage to any of the tanks that could be seen is the
soot and charred paint, and the tracks of shiny metal where the aluminum
valve-wheels melted and dribbled down the sides. No sign of rupture or
expansion, no sign of warping, no sign of *ANY* sort of damage, other
than the char and melted valves. The partial one was on the front deck,
attached to the gas grille (which, other than the cast-iron grates, was
unrecognizable when we found it) and it provided one helluva show when
the overpresure valve let go - a 20 foot tounge of flame and soot that
roared like a ****ed off dragon and blasted out across the yard, lasting
for almost a full minute. I don't know for sure what the full one,
living down in the basement, did, but I'd bet it contributed
substantially to the heat.

Aside from the melted valve wheels, any of these four tanks could have
been repainted, and by looking at them, nobody would ever know they'd
been anywhere near a fire of any size, let alone in one that reduced all
but about a roughly 10 by 10 foot section of bathroom wall in a 50-ish
by 30-ish foot house to ash, charcoal, and broken dreams. (since the
fire, I have personally punched all four tanks to prevent exactly that
sort of thing from happening - As they sit now, they won't hold
atmosphere, let alone pressure. Leastwise, I figure a jagged 6 inch hole
smashed in the side of each one should be adequate to make it impossible
to pass them off as servicable.)

And before anybody asks if the cause of the fire is known, no, it isn't.
The hot water heater (electric) is the "most likely suspect", but
there's no conclusive evidence to pin the blame for certain. The arson
investigator said he could find nothing to suggest that it was
deliberate, and has closed the books on the investigation. Everybody
that was supposed to be in the house was gone at the time, and I managed
to get two of the three dogs that were inside safely out. (No sign of
the third - due to where she was last seen, it's almost certain she was
trapped on the other side of a wall of flames from where I made entry
and found the other two hiding - with the hallway ceiling falling in
flaming chunks, and a solid sheet of flames beyond that, I wasn't about
to try going down the hallway to hunt for a dog)

--
Don Bruder - --- Preferred Email - SpamAssassinated.
Hate SPAM? See http://www.spamassassin.org for some seriously great info.
I will choose a path that's clear: I will choose Free Will! - N. Peart
Fly trap info pages: http://www.sonic.net/~dakidd/Horses/FlyTrap/index.html

In article ,
Richard J Kinch wrote:

David A. Webb writes:

The theoretical maximum pressure would be less than 130psi.

Someone, please check my math.

Hard to predict precisely, but roughly speaking, you have on the order
of a doubling in molar volume (the molar ratio after combustion by your
analysis is 7:1, but the explosive limits are almost the inverse at 10
to 15 percent propane in air), and a 10-fold rise in absolute
temperature, so the ultimate pressure would be the product, which is to
say, upwards of 20 times the original pressure, or 20 atm, or upwards of
300 psi. Of course there is a sub-sonic shock wave as well.

The question is whether the rupture strength of a 20 lb propane tank can
contain an explosive rise from 1 atm to 10 or 20 atms of pressure. If
so, then one would be skeptical that these things *ever* explode.

Have these tanks actually exploded, say, in fires? It seems like the
reports that claim explosions were actually tanks that leaked into a
confined space that then mixed with air and exploded, not that the tank
itself ruptured or exploded.

anecdotal evidence time:

Back in September, I went out to feed the horses one morning, and in the
process, discovered that my landlord's house was on fire. Half an hour,
maybe 45 minutes later, when the FD got there (no fault or blame put to
them - even driving like an utterly insane bat out of hell, I can't make
it from the house to the nearest fire station in less than 35 minutes in
my car - they responded as fast as was physically possible, considering
the distance and terrain between them and the fire) the house was
essentially totally engulfed. It was a hot fire - the hottest I've ever
seen personally - It did a damn good job of trying to torch trees a
hundred feet away. When it was done, the fire left almost nothing but a
smoking crater where the basement used to be - Other than one small
section of bathroom wall, *EVERYTHING* burned. Glass melted and flowed
like water - I can go down to the site and pick up frozen "rivers" of
glass that would fool just about anybody into thinking they were actual
flowing water. Ceramic countertop tiles, and concrete tile roofing
slumped, cracked, and shattered. Concrete block walls in the basement
scaled and blistered and cracked. A coin collection was turned into a
blob of mixed metal, with only a very few recognizable coins in it.
Aluminum engine blocks on lawn equipment stored in the basement in
preparation for the soon-to-be-coming winter rain were reduced to
puddled lumps with barely recognizable partially melted steel chunks
sticking out of them. An entire woodworking shop - table saw, radial arm
saw, drill press, jointers, planers, routers, you name it, if it can be
used for woodworking, it was probably there - some still in the boxes
from Sears 'casue there hadn't been time or room to get them all
unpacked and set up yet, was destroyed. The cast iron table of the
jointer was twisted and warped like warm taffy. We still haven't found
(or at least, if we have, we don't recognize it) the table saw's table.
The motor was found - as a steel-shelled blob of melted copper. Several
rifles and shotguns got hot enough that the barrels slumped flat. A
fiberglass boat 30 feet away went up in smoke, and the aluminum heads on
the inboard engine melted into slag. The pickup truck 20 feet beyond the
boat had the paint blistered and plastic trim melted and distorted.
Another car near the truck had taillights and bumper melted, and
blistering to the paint job. *EVERYTHING* flammable in the house was
turned into either ash or charcoal chunks. As I say, it was a *VERY* hot
fire. Several of the firemen said it was possibly the hottest, worst
fire they'd ever attended. Usually, at least *SOMETHING* is left. Not in
this case.

Anyway, to the point of this post:

Four propane tanks, one full, one partial, two brand new (less than a
week old, and not yet been filled for the first time since being bought
to replace the recently outlawed pair without the overfill prevention
gizmo) were in the fire. All of them were the (I think) 5 gallon size -
They don't *QUITE* fit into a standard plastic 5 gallon hydraulic fluid
bucket. I guess that would probably make them 20 pounders.

The only visible damage to any of the tanks that could be seen is the
soot and charred paint, and the tracks of shiny metal where the aluminum
valve-wheels melted and dribbled down the sides. No sign of rupture or
expansion, no sign of warping, no sign of *ANY* sort of damage, other
than the char and melted valves. The partial one was on the front deck,
attached to the gas grille (which, other than the cast-iron grates, was
unrecognizable when we found it) and it provided one helluva show when
the overpresure valve let go - a 20 foot tounge of flame and soot that
roared like a ****ed off dragon and blasted out across the yard, lasting
for almost a full minute. I don't know for sure what the full one,
living down in the basement, did, but I'd bet it contributed
substantially to the heat.

Aside from the melted valve wheels, any of these four tanks could have
been repainted, and by looking at them, nobody would ever know they'd
been anywhere near a fire of any size, let alone in one that reduced all
but about a roughly 10 by 10 foot section of bathroom wall in a 50-ish
by 30-ish foot house to ash, charcoal, and broken dreams. (since the
fire, I have personally punched all four tanks to prevent exactly that
sort of thing from happening - As they sit now, they won't hold
atmosphere, let alone pressure. Leastwise, I figure a jagged 6 inch hole
smashed in the side of each one should be adequate to make it impossible
to pass them off as servicable.)

And before anybody asks if the cause of the fire is known, no, it isn't.
The hot water heater (electric) is the "most likely suspect", but
there's no conclusive evidence to pin the blame for certain. The arson
investigator said he could find nothing to suggest that it was
deliberate, and has closed the books on the investigation. Everybody
that was supposed to be in the house was gone at the time, and I managed
to get two of the three dogs that were inside safely out. (No sign of
the third - due to where she was last seen, it's almost certain she was
trapped on the other side of a wall of flames from where I made entry
and found the other two hiding - with the hallway ceiling falling in
flaming chunks, and a solid sheet of flames beyond that, I wasn't about
to try going down the hallway to hunt for a dog)

--
Don Bruder - --- Preferred Email - SpamAssassinated.
Hate SPAM? See http://www.spamassassin.org for some seriously great info.
I will choose a path that's clear: I will choose Free Will! - N. Peart
Fly trap info pages: http://www.sonic.net/~dakidd/Horses/FlyTrap/index.html

jim rozen wrote:

Ah. Now here is the man who probably knows the inside
story. I read the article in the "National Review" about
the failed safety culture at nasa, and the various
managers (Ham, etc.) who were second-guessing the engineers.

Was that article pretty much accurate?

Yes.

Fitch

Arg... didn't intend to double-post that. First try (that reported
failure) must have actually gotten everything right except the final
"all done, over and out" part before chucking the error at me.

--
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I will choose a path that's clear: I will choose Free Will! - N. Peart
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On Tue, 02 Dec 2003 17:32:16 GMT, Mark
wrote:



Kent Fowler wrote:


The reason I pointed you toward bleve is to see the result of a
vapor explosion.




And what kind of idiot will blow down a tank in the presence of an
ignition source?

I've seem a few that would, fortunately they didn't make their
probation period.

Don Bruder writes:

anecdotal evidence time

That's quite a tale, thank you.

In article , Don Bruder wrote:
In article ,
Richard J Kinch wrote:
David A. Webb writes:
The theoretical maximum pressure would be less than 130psi.
Someone, please check my math.

Hard to predict precisely, but roughly speaking, you have on the order
of a doubling in molar volume (the molar ratio after combustion by your
analysis is 7:1, but the explosive limits are almost the inverse at 10
to 15 percent propane in air), and a 10-fold rise in absolute
temperature, so the ultimate pressure would be the product, which is to
say, upwards of 20 times the original pressure, or 20 atm, or upwards of
300 psi. Of course there is a sub-sonic shock wave as well.

The question is whether the rupture strength of a 20 lb propane tank can
contain an explosive rise from 1 atm to 10 or 20 atms of pressure. If
so, then one would be skeptical that these things *ever* explode.

Have these tanks actually exploded, say, in fires? It seems like the
reports that claim explosions were actually tanks that leaked into a
confined space that then mixed with air and exploded, not that the tank
itself ruptured or exploded.

anecdotal evidence time: .... Anyway, to the point of this post:

Four propane tanks, one full, one partial, two brand new (less than a
week old, and not yet been filled for the first time since being bought
.....
The only visible damage to any of the tanks that could be seen is the
soot and charred paint, and the tracks of shiny metal where the aluminum
valve-wheels melted and dribbled down the sides. No sign of rupture or
expansion, no sign of warping, no sign of *ANY* sort of damage, other
than the char and melted valves. The partial one was on the front deck,
attached to the gas grille (which, other than the cast-iron grates, was
unrecognizable when we found it) and it provided one helluva show when
the overpresure valve let go - a 20 foot tounge of flame and soot that
roared like a ****ed off dragon and blasted out across the yard, lasting

when a 500 or 1000 gal residential tank vents it scares ten years out
of you. all the folks i knew in the NM volunteer fire dept's said
that if you didn't get a hose on it early, you had to just leave it
alone and stand clear. but worse danger is an overfill that
vents, the valve does not close until the tank is empty. you need
to stay a _long_ way away from that one.
for almost a full minute. I don't know for sure what the full one,
living down in the basement, did, but I'd bet it contributed
substantially to the heat.

Aside from the melted valve wheels, any of these four tanks could have
been repainted, and by looking at them, nobody would ever know they'd
been anywhere near a fire of any size, let alone in one that reduced all
but about a roughly 10 by 10 foot section of bathroom wall in a 50-ish
by 30-ish foot house to ash, charcoal, and broken dreams. (since the
fire, I have personally punched all four tanks to prevent exactly that
sort of thing from happening - As they sit now, they won't hold
atmosphere, let alone pressure. Leastwise, I figure a jagged 6 inch hole
smashed in the side of each one should be adequate to make it impossible
to pass them off as servicable.)

And before anybody asks if the cause of the fire is known, no, it isn't.
The hot water heater (electric) is the "most likely suspect", but
there's no conclusive evidence to pin the blame for certain. The arson
investigator said he could find nothing to suggest that it was
deliberate, and has closed the books on the investigation. Everybody
that was supposed to be in the house was gone at the time, and I managed
to get two of the three dogs that were inside safely out. (No sign of
the third - due to where she was last seen, it's almost certain she was
trapped on the other side of a wall of flames from where I made entry
and found the other two hiding - with the hallway ceiling falling in
flaming chunks, and a solid sheet of flames beyond that, I wasn't about
to try going down the hallway to hunt for a dog)

On Tue, 02 Dec 2003 17:44:39 GMT, Mark
wrote:



Kent Fowler wrote:


As far as the hairspray thing. I'll say this. I work with
hydrocarbon reactions using super high pressures and elevated
temperatures every day. I know the physics. I know the math. I also
know what can happen if one little thing goes wrong.




Inside a petro chem plant which are generally held together with bubble
gum and bailing wire.

Been in a lot of petrochem plants and refineries, have you? Do you
actually work in one?


A PC plant is not a 100 pound cylinder.

A 100 pound cylinder can get you burned or dead.

Kent , your impressing me that your the type of person who no one else
can be right or you can't be wrong, no matter what.

Nope, I've been wrong on lots of occasions. My wife usually proves me
wrong at least once a day and I admit it. . But I will never, ever
change my opinion on this one. I think you need to go back and re-read
all the posts. I suggested he query the chief instructor at the Texas
A and M fire school as to his opinion. Does this sound like I think I
am right all the time? Or his local fire chief. Again, does this
sound like I think I am the only one who is right?? The response I
got was:

1. Fire Chiefs don't know **** about tanks and vessels with
hydrocarbons in them and he wouldn't ask a fire chief about anything.

2 Firemen don't know **** be cause they like to err on the side of
caution and really don't understand because they don't have a physics
or a chemical engineering degree and would do something else beside be
a fireman if they had said degrees.

3 And obviously believes that only degreed people have the mental
capacity to understand the fire triangle.

And you accuse ME of being block headed? I think you must have us
mixed up. I' m the guy who won't take a torch to a propane tank with
out it being cleared first.

In article o19zb.282721$9E1.1469883@attbi_s52,
Loren Coe wrote:


when a 500 or 1000 gal residential tank vents it scares ten years out
of you. all the folks i knew in the NM volunteer fire dept's said
that if you didn't get a hose on it early, you had to just leave it
alone and stand clear. but worse danger is an overfill that
vents, the valve does not close until the tank is empty. you need
to stay a _long_ way away from that one.

That would match...
The first question after "Is anybody inside?" was "Any propane bulk
tanks? Where?" ("Yes, out back, big pig, about 500 gallons, maybe half
full, I think")

First place the hoses went was back to the pig, about 20, maybe 25 feet
from the back wall. The back wall of the house (in fact, it was the
section of bathroom wall that I mentioned was the only thing left
standing in the end) was the only part that wasn't actively burning at
that point, although everything inside, and the entire front, was
blazing away merrily. They put a man with a handline on it, and there
he, or someone like him, stayed for the next 6 hours or so, until the
final bits that were left of the house finally collapsed into the
basement.

--
Don Bruder - --- Preferred Email - SpamAssassinated.
Hate SPAM? See http://www.spamassassin.org for some seriously great info.
I will choose a path that's clear: I will choose Free Will! - N. Peart
Fly trap info pages: http://www.sonic.net/~dakidd/Horses/FlyTrap/index.html

..Apparently:.........................

Yours is not to reason. Why?

Welcome back Fitch. VBG

XXXXXXXXXXXXXXXXXXXXXXXXXXXX

On Tue, 02 Dec 2003 16:38:44 GMT, Don Bruder wrote:

In article ,
Fitch R. Williams wrote:

Don Bruder wrote:

Perhaps all of these are true. Perhaps none of them are. That isn't
important. What is important is that he got it done, and, regardless of
how or why, he got it done without getting hemself damaged or dead in
the process.

In my opinion, what is important is that people realize the fact that
he got away with it doesn't in and of itself make it a good idea, or
safe. Without getting into the specifics of the valve removal this
can be discussed as a matter of philosophy. i.e. doing something
risky and getting away with it for a while doesn't make it either safe
or a good idea. Its good to be lucky, but it isn't a good idea to
depend on it over the long term.

Now there's a revelation... (please imagine my eyes rolling)

The guy never claimed his method to be "safe". In fact, it seem to me
that he was worried that it might not be safe, so he was taking
umtpy-four different precautions. In the end, he claimed it got the job
done.

Look, NOTHING is "safe". Getting out of bed in the mornign has been
proven to be fatal in certain situations. Risk assessment (and
acceptance) is something we all do every day. I KNOW I can get in my car
to head for work only to wake up in the hospital (or not wake up at
all...) because SOMETHING (I won't even make a feeble attempt to
enumerate all the "somethings that are possible) went wrong. Maybe I was
driving too fast. Or too slow. Maybe there's a drunk heading for me
around the next bend. Maybe the wheels fly off the car and I go into the
drink - whatever! I accept that there's an element of risk to *EVERY
STINKING THING I DO*, and it's not for you or anyone else to tell me I
may or may not do something because *YOU* think the risk is too high.
Ony I can make that decision as to how much risk is too much, so I'd
thank you and your cronies who are intent on protectng me from myself to
keep your nose in your own business.

The deal is that a contemplated course of action should be shown to be
safe, or have acceptable risk vs payback, or one doesn't proceed. One
does not have to show something to be unsafe to avoid proceeding. The
difference is profound.

Likewise, as I just said, *I* decide what risk is acceptable for *ME*,
regardless of what you or anybody else thinks. Yours is to assess *YOUR*
risk and act on that assessment. Yours *IS NOT* to to assess my risk and
tell me "you can't".

Its called risk management. Its a personal choice.

And then here, you come into 100% full agreement with me. Yet you still
try to preach that your decision regarding a risky activity is the only
one that's right. Come on, guy, which is it? Is it my decision, but only
if *YOU* think the risk is low enough? And where's the boundary between
"You go ahead and make your choice" and "Oh, no you don't! That's too
dangerous!"?

You pick your pony, you take your ride.

Interesting analogy, since I'm primarily a horseman. And I agree...
*YOU* pick *YOUR* pony and *YOU* take *YOUR* ride.
*I* pick *MY* pony, and *I* take *MY* ride.

So long as you don't try telling me "That one's too dangerous for you"
(or vice-versa) we'll both get along just fine.

The instant you start trying to "pick my pony" for me, we're going to be
at odds.

Hey Richard,

On Tue, 02 Dec 2003 12:21:34 -0600, Richard J Kinch
wrote:

BIG SNIP

There was a suicide case locally a few years ago where a guy tried to
deliberately explode several 20 lb tanks indoors by lighting fires
underneath them. He only succeeded in making an explosive mix in the
room, which was devastating, but the tanks themselves survived intact.


Hmmmmm..... I had not heard that story, but I did see a full 20
(22??) pound tank that sat in a fire. Sort of. Actually, there was a
Coleman stove being used to boil water for some hot dogs. It was
sitting on the end of a picnic table, with the tank sort of tucked
under the end of the table. Somehow, the 3 foot long rubber supply
hose brass fitting at the stove end broke off, and the propane coming
out of the hose caught fire and pointed at the ground about 6" from
the base of the tank. Everybody ran like hell. Me too! But all
that happened was that as the tank got heated up, the safety valve
opened to release the internal pressure, the venting fuel escaped
right into the flame path, and as soon as the venting had accomplished
its purpose the safety valve snapped shut, in about 3 or 4 seconds.
As soon as there was enough more heat applied, it did it again.
Quite a load BrrrrrrrrrROOOAAARR each time. It cycled through this
for maybe five minutes before somebody got a garden hose and sprayed
it all down, about the same time I think it was empty. Would it have
been more dramatic if the flame or heat had burned or melted either
the safety valve seat, or the diaphragm of the regulator? I don't
know.

By the way, the safety vent "nozzle" was about a foot away and at the
same level and pointed perpendicular right at the seat of the picnic
table. A nice piece of 2 X 12. It cut about a foot square off of
that quite handily, like a big axe would have. Never even "caught
fire". Amazing!

Take care.

Brian Lawson,
Bothwell, Ontario.

On Tue, 02 Dec 2003 23:41:51 GMT, Kent Fowler
wrote:

Nope, I've been wrong on lots of occasions. My wife usually proves me
wrong at least once a day and I admit it. . But I will never, ever
change my opinion on this one. I think you need to go back and re-read
all the posts. I suggested he query the chief instructor at the Texas
A and M fire school as to his opinion. Does this sound like I think I
am right all the time? Or his local fire chief. Again, does this
sound like I think I am the only one who is right?? The response I
got was:

1. Fire Chiefs don't know **** about tanks and vessels with
hydrocarbons in them and he wouldn't ask a fire chief about anything.

2 Firemen don't know **** be cause they like to err on the side of
caution and really don't understand because they don't have a physics
or a chemical engineering degree and would do something else beside be
a fireman if they had said degrees.

3 And obviously believes that only degreed people have the mental
capacity to understand the fire triangle.

And you accuse ME of being block headed? I think you must have us
mixed up. I' m the guy who won't take a torch to a propane tank with
out it being cleared first.

Ya know... I don't mind people questioning me, or even calling me
stupid, but I do get ****ed when assholes put words in my mouth and
mis-quote me.

Just because I said that a fire chief will tend to error on the side
of caution does not imply I believe they don't know ****.

I chose my words carefully because I know some firemen, and I didn't
want to generalize and say that ALL of them overreact to potential
fire hazards, or anything that remotely smells like one. But you ask
any one of them, and that one will be likely to admit that most
firemen will overreact.

Actually, ALL of the firemen I know do overreact to fire hazards.
And why do you suppose that is? Maybe because like any profession,
there is a certain amount of psychology involved in the person who
likes the authority to do their job. I'm sure everyone here would
agree that most police are cops because they wanted a job where they
could flex their muscle, and flaunt their authority.
Heck, YOU even got all rialed up because you think you know something
about chemical reactions, but you aren't smart enough to realize that
propane needs something to react with before it will do anything. Why
did you get all rialed up? Because you have a job in the field.

I never once said that only "degreed people" would understand the fire
triangle. All I said was that I know some pretty ignorant firemen,
(note, I did not say stupid) and I am not going to take the word of
one as fact until they have something to back it up.

And they shouldn't take offense at that. I'm not taking your word for
it, because you aren't backing up your statements with facts either.

Can you explain how the fire triangle applies in this case?
There was no oxygen inside the tank.

Dave

I understand that that your reasoning was sound. It was well thought
out and well calculated. It also required the courage of conviction in
your reasoning.
And I'm sure NASA would be eager for your talents.

On Wed, 03 Dec 2003 01:41:09 GMT, David A. Webb
wrote:

On Tue, 02 Dec 2003 23:41:51 GMT, Kent Fowler
wrote:

Nope, I've been wrong on lots of occasions. My wife usually proves me
wrong at least once a day and I admit it. . But I will never, ever
change my opinion on this one. I think you need to go back and re-read
all the posts. I suggested he query the chief instructor at the Texas
A and M fire school as to his opinion. Does this sound like I think I
am right all the time? Or his local fire chief. Again, does this
sound like I think I am the only one who is right?? The response I
got was:

1. Fire Chiefs don't know **** about tanks and vessels with
hydrocarbons in them and he wouldn't ask a fire chief about anything.

2 Firemen don't know **** be cause they like to err on the side of
caution and really don't understand because they don't have a physics
or a chemical engineering degree and would do something else beside be
a fireman if they had said degrees.




3 And obviously believes that only degreed people have the mental
capacity to understand the fire triangle.

And you accuse ME of being block headed? I think you must have us
mixed up. I' m the guy who won't take a torch to a propane tank with
out it being cleared first.

Ya know... I don't mind people questioning me, or even calling me
stupid, but I do get ****ed when assholes put words in my mouth and
mis-quote me.

Just because I said that a fire chief will tend to error on the side
of caution does not imply I believe they don't know ****

"So, as far as I'm concerned, being a fire chief doesn't make a person
the final authority on risks of tank explosions."

Your words................. Sure sound to me like you have a pretty
low opinion of the chiefs. BTW, who is the "final authority" on tank
explosions in your humble opinion???? You?

I chose my words carefully because I know some firemen, and I didn't
want to generalize and say that ALL of them overreact to potential
fire hazards, or anything that remotely smells like one. But you ask
any one of them, and that one will be likely to admit that most
firemen will overreact.

Actually, ALL of the firemen I know do overreact to fire hazards.
And why do you suppose that is? Maybe because like any profession,
there is a certain amount of psychology involved in the person who
likes the authority to do their job. I'm sure everyone here would
agree that most police are cops because they wanted a job where they
could flex their muscle, and flaunt their authority.

A psych dude now??

Heck, YOU even got all rialed up because you think you know something
about chemical reactions, but you aren't smart enough to realize that
propane needs something to react with before it will do anything.

As I said, a spark or flame will make it react nicely. You do know
that fire is a chemical reaction?? And I do know lots about reactions,
a lot more than you.

..


I never once said that only "degreed people" would understand the fire
triangle. All I said was that I know some pretty ignorant firemen,
(note, I did not say stupid) and I am not going to take the word of
one as fact until they have something to back it up.


"I know that most firemen are extremely over reactive to people asking
questions about fire. Their passion sometimes gets in their way of
logic. I don't know any firemen with a degree in physics or
chemistry, probably because anyone with a degree in physics or
chemistry would be in a different career. Maybe forensics
investigator, or something of the sort, but not fire chief."

Your words............................... You think because they don't
have a degree they don't know **** or else you wouldn't have even
brought it up. Why does a fireman have to have a degree in order to
understand what he is dealing with?
.. You also said " their passion gets in the way of their logic." Sure
sounds like you're saying they don't know **** if thats the way you
think they think.

And they shouldn't take offense at that. I'm not taking your word for
it, because you aren't backing up your statements with facts either.

Such as??

Can you explain how the fire triangle applies in this case?

Heat, fuel, air

There was no oxygen inside the tank.

Your arguement about it being 100% vapor sucks wind after leaving
the valves open overnight.

Beecrofters words..........................not mine, but I happen
to agree with him.

Don Bruder wrote:



snipped


a 20 foot tounge of flame and soot that
roared like a ****ed off dragon and blasted out across the yard, lasting
for almost a full minute. I don't know for sure what the full one,
living down in the basement, did, but I'd bet it contributed
substantially to the heat.

Great telling of that tale, and my sympathies for your losses. But I can't avoid
commenting on just one thing...

IIRC it's not legal to store filled propane tanks inside a house. At least not
here in Taxachusetts. But, I could be wrong about that, or it may be different
where you are.

Did you get any static about that propane tank in the basement from the FD or the
insurance company?

I keep my second 20 pound barbeque tank outside, chained to a deck post.

Jeff

--

Jeff Wisnia (W1BSV + Brass Rat '57 EE)

"If you can smile when things are going wrong, you've thought of someone to blame
it on."

David A. Webb wrote:

To say that the tank could have exploded in my face "just because"
isn't good enough for this particular argument.
Sort out the fear from the facts.

I have no opinion at all about what you did. I wouldn't have done it,
but only because I haven't a clue whether it is safe or not. It is a
fuel container, and due diligence would have me deciding it was unsafe
unless I could prove it was safe to myself.

You thought it was safe and removed the valve. Good for you.

If I needed a valveless propane tank for whatever reason, I'd probably
buy a new unfilled one simply because they aren't that expensive, and
spending the time doing the research to prove the risk was very small
compared to the gain wouldn't be worth it to me.

It was to you. That's fine with me.

My only point was that if someone does something (anything - pick a
pony) that is perceived as risky, and doesn't have a bad outcome, that
is not proof that it was a safe thing to do. The definition of "Safe"
being that the risk taken was small compared to the gain.

Whew! I didn't think it was that complicated. But then NASA
management didn't get it either. I don't think they do yet.

Fitch

In article ,
Jeff Wisnia wrote:

Don Bruder wrote:



snipped


a 20 foot tounge of flame and soot that
roared like a ****ed off dragon and blasted out across the yard, lasting
for almost a full minute. I don't know for sure what the full one,
living down in the basement, did, but I'd bet it contributed
substantially to the heat.

Great telling of that tale, and my sympathies for your losses. But I can't
avoid
commenting on just one thing...

IIRC it's not legal to store filled propane tanks inside a house. At least
not
here in Taxachusetts. But, I could be wrong about that, or it may be
different
where you are.

To the best of my knowledge, the only restriction on filled propane
tanks here (Kali-fornicates-ya) is that they're not permitted inside a
public building like a store or restaurant. On private property, in a
private residence, as far as I know, you can do anything you want with
them. Keep in mind that's "As far as I know"... There may be something
on the books that says it's a no-no. I honestly haven't made any attempt
to find out.

Did you get any static about that propane tank in the basement from the FD or
the
insurance company?

From neither, as far as I've heard. The FD, arson investigator, and the
insurance guy all had to kick it aside, step over it, or trip over it to
go inside and look around the next morning, as it had been sitting just
inside the basement door. I don't recall any of them even looking at it
funny, let alone commenting on it.

From the way the place burned, I'd say that the tank inside couldn't
have made any significant contribution to the fire - That corner was one
of the very last places to catch, and by the time the tank had a chance
to "came into play", the rest of the house was essentially already gone.

In general, I'd tend to agree that it's a bad idea to store tanks
inside, but in this case, I doubt that the tank being there had any
significant impact on either damage (total destruction is total
destruction) or the start of the fire.

--
Don Bruder - --- Preferred Email - SpamAssassinated.
Hate SPAM? See http://www.spamassassin.org for some seriously great info.
I will choose a path that's clear: I will choose Free Will! - N. Peart
Fly trap info pages: http://www.sonic.net/~dakidd/Horses/FlyTrap/index.html

One fine evening I showed up for my shift as a telegrapher on the CNR
railroad in Prince Rupert. Mere moments after signing the register a whole
bunch of emergency vehicles converged on the rail yard. Seems like a highway
propane tanker carrying (if I recall correctly) some 20,000 pounds of
propane had had a belly valve sheared off while in the process of being
loaded on a barge. The back-up valve had instantly frozen and was
inoperative.
This meant that the entire load was venting; on the ground (in liquid form
and no way to stop it), and as it evaporated it flowed into the harbour and
the rail yard. My first decision was to evacuate the station - everyone but
myself was (by my not inconsiderable authority) ordered out - pronto!
I stayed as it was my responsibility to do so.
I had a passenger train due in and had to stop that train (200 plus
passengers) before it came anywhere near this incident. If you have ever
seen a train apply brakes at night you will understand why that was
imperative as the track passed within fifty feet of the leaking tanker.
My office was at the other end of the yard from the tanker, about half a
mile away, and on the second floor of the station. I could smell the
propane marker and couldn't see the rails for the white fog of propane and
water vapour. To make things just a little more interesting there were two
'pup' trailers in close proximity to this damaged trailer and each of them
contained 15 tons of dynamite complete with several cases of blasting caps
(totally against regulations).
At the end of the night I had three trains sitting outside of town - two
freights and the passenger - we hired buses to get the people into town. The
coast guard went silently nuts trying to keep all the boat traffic clear.
To this day the gentle citizens of Prince Rupert do not know how close they
came to being a second 'Halifax disaster'.
I went home after my shift and got really drunk!
Still get the chills thinking about it; thirty years after the fact.
Regards
Ken (sitting here in sunny Honduras listening to the rain come down for the
fourth straight day)

On Tue, 02 Dec 2003 19:47:19 GMT, Don Bruder wrote:

and I managed
to get two of the three dogs that were inside safely out. (No sign of
the third - due to where she was last seen, it's almost certain she was
trapped on the other side of a wall of flames from where I made entry
and found the other two hiding - with the hallway ceiling falling in
flaming chunks, and a solid sheet of flames beyond that, I wasn't about
to try going down the hallway to hunt for a dog)

I personally want to thank you for going the distance and rescuing the
two.

Gunner

Antiquis temporibus, nati tibi similes in rupibus
ventosissimis exponebantur ad necem.

On Wed, 03 Dec 2003 03:45:05 GMT, Kent Fowler
wrote:


And I do know lots about reactions, a lot more than you.


Wow, you sound pretty sure of yourself. Care to back it up?
What are your qualifications?

You seem to be pretty proud of yourself for working in a petrochemical
plant, but I have yet to hear what you actually do.
For all I know, you are a custodian. (or maybe a fireman?)

What is your education?
Do you have an associates degree?
How many chemistry, math, or physics classes have you taken?

Even though you can't back up your opinions about the LP tank, you
should be able to back up your statement of general knowledge.

Dave

"Fitch R. Williams" wrote:
... something ... that is perceived as risky ...
^^^^^^^^^

Well, there you go - it's in the eye of the beholder. Dave didn't
_perceive_ it as risky. You're not really talking to each other - Dave
says "So me the risk" and Fitch says "It's not worth the risk for me".

And of course one doesn't just perceive risk: "yes" or "no", one
perceives the _degree_ of risk. Then compares it to the "reward"
involved. Which is what Fitch is saying (I hope I'm not misquoting),
but it's also what everybody does naturally, all the time. Including
Dave - he did perceive _some_ level of risk (there's some level of risk
in _everything_), but he didn't perceive it as significant.

Bob

(Isn't it wonderful how an RCM debate like this can go on and remain
(mostly) civil, polite even?

(Kevin Beitz) wrote in message . com...
Our local junk-yard cut up the old PL tanks everyday... They take a
hammer and bust off the old valve and light the escaping gas and start
the cutting immediately... So far no problems... I watched them do
this... I would not like to do it...

Automobile and light airplanes have fuel level senders in their
tanks. These are wirewound potentiometers that vary the current flow
to the fuel gauge. In many of them the float works a copper reed back
and forth, with a small graphite runner on its tip that runs on the
resistance wire. This takes place in a metal can with large holes in
it, so that all is immersed in fuel or fuel vapours.
The graphite wears out. The copper runs on the wire, chews it up,
and makes sparks. IN A FUEL TANK. IN FLIGHT. I have never heard of an
airplane blowing up due to this. The combustible mixture of gasoline
is 8% to 18%, and the mixture in the tank is much, much richer than
that.
We frequently find these senders worn out in our airplanes. I'm
never nervous working on the system unless we drain all the fuel to
remove a tank, and then I get really careful, as the mixture in the
tank drops into the combustible range. I prefer leaving a least a bit
of fuel in it and keeping the cap on as much as possible.
The most dangerous place is at the filler neck when the cap is off
and vapours are mixing with the atmosphere, which is why we once in a
while hear of fires caused by static sparks during fuelling. Airplanes
can accumulate considerable static in flight, or even on the ground
during a thunderstorm, or the fueller can make his own sparks in cold
weather by rubbing his jacket on the wing while refuelling. So we
ground everything.


Dan

Richard J Kinch wrote:

No, not the adhesive, the foam itself. Environmentalism forced a change of
the foaming process from using a CFC agent to something more
"environmentally friendly" (and structurally inferior). If someone is
claiming otherwise, it betrays a political agenda. Environmentalism
destroyed Columbia.

I heard that, too, but was not able to find a link that didn't look like
tinfoil cap folks posted it. I'm not disputing it, just can't find a
good link - do you have one?

In article , Dan Thomas says...

The graphite wears out. The copper runs on the wire, chews it up,
and makes sparks. IN A FUEL TANK. IN FLIGHT.

Heck that's nothing. Nearly every car on the road today
has a brush type electric motor that runs the fuel pump,
immersed in either liquid gasoline, or gas vapor.

I suppose from the resounding lack of booms, it probably
works.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

Russ Kepler writes:

No, not the adhesive, the foam itself. Environmentalism forced a
change of the foaming process from using a CFC agent to something
more "environmentally friendly" (and structurally inferior). If
someone is claiming otherwise, it betrays a political agenda.
Environmentalism destroyed Columbia.

I heard that, too, but was not able to find a link that didn't look
like tinfoil cap folks posted it. I'm not disputing it, just can't
find a good link - do you have one?

Yes. I wrote about this February 4, 2003, just several days after the
disaster on Feb 1st, based on Greg Katnik's analysis from 1997, and before
the culpability of the foam insulation was being promoted:

http://groups.google.com/groups?q=co...author%3Akinch

Amazingly, if you Google '"greg katnik" nasa' you get only 212 hits today.

This is the key document:

http://quest.arc.nasa.gov/people/jou...s87-12-23.html

Which I herewith quote in its entirety below:

STS-87 is Home! The Post-Flight Inspection Begins

by Greg Katnik
December 23, l997

STS-87 rolled to a stop; the mission was complete! That statement would be
true for the flight of the Columbia, however a new mission began when the
wheels of the Columbia came to a stop -- the post flight inspections. My
division is responsible for the overall analysis of these inspections and
we insure that all changes made, due to these inspections, do not affect
other areas that may jeopardize the flight-worthiness of the shuttle. This
division does not focus on one specific area, but analyzes all information
and ensures that all aspects are kept in balance.

Immediately after the Columbia rolled to a stop, the inspection crews began
the process of the post flight inspection. As soon as the orbiter was
approached, light spots in the tiles were observed indicating that there
had been significant damage to the tiles. The tiles do a fantastic job of
repelling heat, however they are very fragile and susceptible to impact
damage. Damage numbering up to forty tiles is considered normal on each
mission due to ice dropping off of the external tank (ET) and plume re-
circulation causing this debris to impact with the tiles. But the extent of
damage at the conclusion of this mission was not "normal."

The pattern of hits did not follow aerodynamic expectations, and the
number, size and severity of hits were abnormal. Three hundred and eight
hits were counted during the inspection, one-hundred and thirty two (132)
were greater than one inch. Some of the hits measured fifteen (15) inches
long with depths measuring up to one and one-half (1 1/2) inches.
Considering that the depth of the tile is two (2) inches, a 75% penetration
depth had been reached. Over one hundred (100) tiles have been removed from
the Columbia because they were irreparable. The inspection revealed the
damage, now the "detective process" began.

During the STS-87 mission, there was a change made on the external tank.
Because of NASA's goal to use environmentally friendly products, a new
method of "foaming" the external tank had been used for this mission and
the STS-86 mission. It is suspected that large amounts of foam separated
from the external tank and impacted the orbiter. This caused significant
damage to the protective tiles of the orbiter. Foam cause damage to a
ceramic tile?! That seems unlikely, however when that foam is combined with
a flight velocity between speeds of MACH two to MACH four, it becomes a
projectile with incredible damage potential. The big question? At what
phase of the flight did it happen and what changes need to be made to
correct this for future missions? I will explain the entire process.

The questions that needed to be answered we

what happened?
what phase of flight did it happen in?
why did it happen?
what corrective action is required?
At this point, virtually every inch of the orbiter was inspected and all
hits were documented and mapped to aid in visualizing the damage. Maps were
constructed of the lower surface, the left and right surfaces and the top
surface of the orbiter. At this point, a "fault tree" was created. The
fault tree provides a systematic approach in considering all possibilities
of what may have happened. Everything that is on the fault tree is
considered to be legitimate until it is totally ruled out. Some of the
considerations were where the damage occurred -- in the OPF, in the VAB, or
on the pad before launch. These were quickly eliminated because an
inspection at T-3 ("t minus three") hours takes place on each mission and
everything was normal.

After these and many other considerations were eliminated, the focus was
placed on the ascent, orbit and re-entry phase of the mission. Because of
the fore and aft flow characteristics of the damage sites, and the angle of
penetration, the ascent phase seemed most likely. The orbit phase of flight
was eliminated because the characteristics of these types of hits (most
likely meteorites or space debris) occur in a random pattern and direction.
Re-entry was eliminated because the "glazing and re-glassifying" of the
tiles due to heat upon re-entry (a normal process) indicated that the
damage had occurred prior to this phase. The fault-tree was now pointing to
the ascent phase.

The pictures that were taken by cameras mounted in the orbiter umbilical
began to give the first clues. These cameras are designed to turn on during
the solid rocket booster (SRB) separation, and turn off after the
separation is complete, thereby recording the event. This process occurs
once again when the external tank separates from the orbiter. The initial
review of these photographs did not reveal any obvious damage to the
external tank. No foam missing, no "divots" (holes) and no material loss.
Everything appeared normal.

The SRBs were then focused on for the answers. After inspection of the
SRBs, no clues were found. In fact, the solid rocket boosters looked to be
in great condition. Where to now? The external tank photographs were
magnified and reviewed once again. This time some material loss was noted,
but not in a significant degree. The attention was now focused on the crew
cabin cameras. These cameras gave more of a side view of the external tank
as it tumbled back to Earth. These photographs revealed massive material
loss on a side of the external tank that could not be viewed by the
umbilical cameras!

Where are we now? One of the questions had now been answered. The ascent
phase of flight was when the damage occurred. With the information provided
by the photography and the mapped flow of damage, a logical reason could be
established as to "what" happened. It was determined that during the
ascent, the foam separation from the external tank was carried by the
aerodynamic flow and pelted the nose of the orbiter and cascaded aft from
that point. Once again, this foam was carried in a relative air-stream
between MACH two and MACH 4!

Now the big question -- why? The evidence of this conclusion has now been
forwarded to Marshall Space Flight Center (MSFC) because this is the design
center for the external tank. MSFC will pursue the cause of damage. Here
are some descriptions of some of the considerations:

The primer that bonds the tank foam to the metal sub-stream was defective
and did not set properly. This was eliminated as a cause because the
photography indicated that the areas of foam loss (divots) did not protrude
all the way down to the primer.
The aerodynamics of the roll to "heads up." The STS-87 mission was the
first time this maneuver had ever been completed.
The STS-86 mission revealed a similar damage pattern but to a much lesser
degree than STS-87. The STS-86 tile damage was accepted ruled as an
unexplained anomaly because it was a night launch and did not provide the
opportunity for the photographic evidence the STS-87 mission did. A review
of the records of the STS-86 records revealed that a change to the type of
foam was used on the external tank. This event is significant because the
pattern of damage on this flight was similar to STS-87 but to a much lesser
degree. The reason for the change in the type of foam is due to the desire
of NASA to use "environmentally friendly" materials in the space program.
Freon was used in the production of the previous foam. This method was
eliminated in favor of foam that did not require freon for its production.
MSFC is investigating the consideration that some characteristics of the
new foam may not be known for the ascent environment.
Another consideration is cryogenic loading, specifically hydrogen (-423
degrees Fahrenheit) and oxygen (-297 degrees Fahrenheit). These extreme
temperatures cause the external tank to shrink up to six (6) linear inches
while it is on the pad prior to launch. Even though this may not seem much
when compared to the circumference of the external tank, six inches of
shrinkage is significant.
This is where the investigation stands at this point in time. As you can
imagine, this investigative process has required many hours and the skills
of many men and women dedicated to the safety of the shuttle program. The
key point I want to emphasize is the process of investigation, which is
coordinated amongst many people and considers all possibilities. This
investigation has used photography, telemetry, radar coverage during the
launch, aerodynamic modeling, laboratory analysis and many more technical
areas of expertise.
As this investigation continues, I am very comfortable that the questions
will be answered and the solutions applied. In fact, some of the solutions
are already in progress. At present the foam on the sides of the tank is
being sanded down to the nominal minimum thickness. This removes the outer
surface, which is tougher than the foam core, and lessens the amount of
foam that can separate and hit the orbiter.

jim rozen wrote:
... a brush type electric motor that runs the fuel pump,
immersed in either liquid gasoline, or gas vapor.
....

I once found an in-tank fuel pump at the dump. It ran upright, with the
inlet at the bottom, the impeller section, and the motor on top. The
fuel flowed from the inlet, through the impeller, THROUGH THE MOTOR, and
out the end cap of the motor! "Through the motor" means across the
brushes. I couldn't believe it. As long as you have gas, it's OK, but
if you run out and start sucking air too, ??? There must have been a
low-fuel shut-off for the pump.

Bob