"Gould 0738" wrote in message
...

Well, first off it would need to be the correct type of fire extinguisher.
Some
extinguishers are charged with halon (which is no longer legal to mfg in
the US
but is imported or recycled from other extinguishers) and a diesel will
run
like crazy on halon.

How will it do that?


And, I'm aware of emergency shut downs that have been accomplished with
CO2
extinguishers, etc. I just thought those were cases where it was
impractical to
cut off the fuel supply.

I would suspect that in an emergency situation you don't have time to be
considering which method is best. If you are going to set up an emergency
shutdown sceanario, use the method that is known to work in all situations.



Wouldn't putting a postive stop to the fuel supply from the injector pump
be a
more certain solution?

Shutting off the fuel will eventually shut it down. The farther away the
shut off valve is from the injection pump the longer the engine will run
after you close the valve. It might not be a wise idea to reach across a
runaway engine to work a valve at the injection pump, you certainly wouldn't
want to be that close if the engine self destructed. If the seas are rough
and/or the engine is overheating (a possible reason it has gone into
runaway) you may not be able to safely get that near the engine.

A CO2 extinguisher can be aimed at the intake from a reasonable distance.
Even if you displaced only 50% of the air I would expect it to throttle the
engine enough so that it lost enough power to break the run away cycle.

I had a diesel car one time that would occasionally go into run away. When
this happened, I could turn the key off and it would keep on going, which
meant that the solenoid valve either didn't work or wasn't in the path of
the current fuel supply. The gas pedal didn't have any effect one way or the
other. The engine was also billowing clouds of black smoke.

I assumed that it was somehow running off crankcase fumes. This problem
never occurred at low power situations, only after long stretches of freeway
running. If it was a problem in the injection pump then it was somehow
bypassing both the fuel metering (gas pedal) and electric shut off valve. I
could easily stop the run away by simply stepping on the brake and loading
the engine down until the RPMs dropped significantly, then it would return
to normal.

Considering my experience, I would be most concerned about the case of the
engine running off of an alternate fuel supply. Shutting down the air supply
is the only option. It would be a good dual purpose device as well,
suitable for shutting down run away engines or putting out a fire. Rig it
with a release cable to the helm station and you wouldn't need to enter the
engine room to do either.


Rod