Hot grass fire at Sun-N-Fun

Dave S wrote:

Sometime shortly after the catalytic converters were mandated, heat
shields were also mandated that are _supposed_ to
prevent this fire problem....

The heat shield cuts down on radiant heat from the CC, but if the
heatshield itself is hot enough and TOUCHES the tall dry grass, then you
still have a fire.

Seems like if there's ANY air gap at all between the CC and shield
that there would be a HUGE difference in temperature between the two.
If there's no air gap, then it's not a shield, really.

Mark Hickey

Mark Hickey wrote:
Dave S wrote:

Sometime shortly after the catalytic converters were mandated, heat
shields were also mandated that are _supposed_ to
prevent this fire problem....

The heat shield cuts down on radiant heat from the CC, but if the
heatshield itself is hot enough and TOUCHES the tall dry grass, then you
still have a fire.

Seems like if there's ANY air gap at all between the CC and shield
that there would be a HUGE difference in temperature between the two.
If there's no air gap, then it's not a shield, really.


I'd worry that tall grass could get caught and wadded between the two
while driving.

--

FF

wrote)
I'd worry that tall grass could get caught and wadded between the two
while driving.


During the Minnesota Twins World Series parade, in 1987, a few of the
convertibles caught fire from just that - paper, toilet paper, confetti,
etc. dragged along under the cars.

In 1991 the players sat/stood in the beds of 4x4 pickup trucks.


Montblack

Shoot, Uncle John, I don't know how things are up north of us by you, but in
Northern California you couldn't light the grass on fire with a propane
torch and a tank full of gasoline.

83" of rain so far this year, and still pounding down.

I just talked with a guest who is coming in from NorCal, and he says
the flying there has absolutely SUCKED for the last five months. Very
unusual.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Thats kinda reminds me how I disposed of some old gunpowder. Dumped it
in the outdoor fireplace and touched it off. The flame built up slowly,
but it eventually had a flame about 10' high the diameter of the pile of
powder. Very impressive, but too expensive to repeat!

John

John T wrote:
Thats kinda reminds me how I disposed of some old gunpowder. Dumped it
in the outdoor fireplace and touched it off. The flame built up slowly,
but it eventually had a flame about 10' high the diameter of the pile of
powder. Very impressive, but too expensive to repeat!

John


That's smokeless powder, try it with black powder Here's an
experiment: put a tablespoonful of black powder in an ash tray. Touch it
off with a blowtorch held at arm's length. The powder will burn fast
enough to extinguish the blowtorch.

Dan, U.S. Air Force, retired

"Dan" wrote in message news:bwZZf.362$iF3.333@dukeread01...
John T wrote:
Thats kinda reminds me how I disposed of some old gunpowder. Dumped it
in the outdoor fireplace and touched it off. The flame built up slowly,
but it eventually had a flame about 10' high the diameter of the pile of
powder. Very impressive, but too expensive to repeat!

John


That's smokeless powder, try it with black powder Here's an
experiment: put a tablespoonful of black powder in an ash tray. Touch it
off with a blowtorch held at arm's length. The powder will burn fast
enough to extinguish the blowtorch.

Dan, U.S. Air Force, retired

I sure hope that you meant demonstration rather than experiment; because I'd
be way too scared to try anything like that on an experimental basis.
Peter

BTW, the USAF must have been an entertaining place. :-)

Dan wrote:
John T wrote:
Thats kinda reminds me how I disposed of some old gunpowder. Dumped it
in the outdoor fireplace and touched it off. The flame built up
slowly, but it eventually had a flame about 10' high the diameter of
the pile of powder. Very impressive, but too expensive to repeat!

John


That's smokeless powder, try it with black powder Here's an
experiment: put a tablespoonful of black powder in an ash tray. Touch it
off with a blowtorch held at arm's length. The powder will burn fast
enough to extinguish the blowtorch.

Dan, U.S. Air Force, retired

On Sat, 08 Apr 2006 13:24:55 GMT, Dave S
wrote:

Sometime shortly after the catalytic converters were mandated, heat
shields were also mandated that are _supposed_ to
prevent this fire problem....



The heat shield cuts down on radiant heat from the CC, but if the
heatshield itself is hot enough and TOUCHES the tall dry grass, then you
still have a fire.

Dave
And any mechanic knows the heat sheilds often do not last more than a
few years before they come loose and rattle. Then they can either be
clamped on, welded on, or allowed (or helped) to fall off.

A minor missfire can also cause the converter to overheat. Imagine
what happens if the engine "diesels" on shut-down. My wife drove our
Corolla to visit her family in Windsor, and the cruise stuck, holding
the throttle partly open. When she shut it off(in neutral) it
"dieseled" and the cat must have flashed white hot, as it caused the
carpet on the floor above the converter to start on fire. The carpet,
a corner of the seat, and the console had been consumed by the smokey
fire before her sisterinlaw and nephew got the hose out and turned on.
We salvaged the car and got a few more years out of it, but if IT had
been on dry grass on a breezy day, that would have been the end of it.

*** Free account sponsored by SecureIX.com ***
*** Encrypt your Internet usage with a free VPN account from http://www.SecureIX.com ***

clare at snyder.on.ca wrote

A minor missfire can also cause the converter to overheat. Imagine
what happens if the engine "diesels" on shut-down.

We salvaged the car and got a few more years out of it, but if IT had
been on dry grass on a breezy day, that would have been the end of it.

Yep. I had an Olds that was suddenly having intermittent loss of almost all
power, then it would be fine. I was driving it one day and hit a bump, and
heard a strange "ker-thump" (that's technical car talk g) then it lost all
power.

Long to short, I started thinking about the 'ole potato in the tailpipe, and
how it behaved like that. I cut into the pipe downstream of the converter,
and saw that all of the pellets had melted into a perfectly molded lump,
just the shape of the back part of the cat. shell. When I hit the bump, the
lump rolled into the outlet, and shut off the exhaust gas flow. Really
lucky to trouble shoot that one!

It is hard to say how hot it had gotten to melt the pellets, like that.
Certainly hot enough to start a fire.
--
Jim in NC