Re: Capacitor Explosion

In a message dated 96-07-03 00:54:59 EDT, you write:

>  Scott Meyer's excellent post just suggested safety shields for the 
>  capacitor (among some excellent other safety ideas).  I think he's onto a 
> good
>  train of thought!  Perhaps the cylindrical CP capacitor could be installed

> inside
>  a larger diameter PVC pipe section with end caps welded on as a
>  housing.  If you were to fill the void between the two tubes with
>  shipping pellets or something,  that might work.  Also leaving a breathing

> hole 
>  (1/4 inch dia?) in the outer containment vessel would act as a slow
>  release port, dissipating the pressure energy shock if the capacitor went 
> into 
>  grenade mode.  You'd have to have a perforated breathing vent tube so 
>  that any number of styrofoam pellets could not conspire to seal off 
>  the vent in the case of internal overpressure.
>  Food for thought.
>  Happy (and safe) Coiling!, rwstephens

This is interesting.  When I originally built my rotary gap, I also built a
wooden housing for it to run in.  I was concerned about the wheel exploding
and the enclosure also shields the uv.  When I received the first C.P.
capacitor, my first reaction was to worry about it exploding.  For its first
installation, I built a wooden cradle to hold it and a wooden box to sit over
the top with slots in the ends for the connections.  I thought if it blows,
at least the box would contain the parts.

When I recently rebuilt the primary interconnections (replaced all the hook
up wire for the cap, gaps and primary with 3/8" copper tubing) I remounted
the cap and eliminated the containment box.  When the capacitor exploded, it
broke one end off and would have sent it many feet across the driveway except
the roll around cart the system is mounted on is enclosed with galvanized
steel roof flashing which is connected to the main RF ground to act as a
strike shield.  The bolt on the end of the cap did make quite a dent in the
steel where it hit between the top and bottom piece of flashing.

Ed Sonderman