I suspect the X is initially weaker than the glue holding the can on, so
rapid pressure increase will break open there. Perhaps over the 30
minutes heat weakened the glue to the point of it being the weak point
for a gradual pressure buildup.

Dr Skip


On 02/25/2018 08:36 PM, Bob Blick wrote:
> By mistake I put an electrolytic capacitor in backwards. A very generic 1=
00uF, 50V cap exposed to 16V with the equivalent of about 700 ohms in serie=
s with it. It lasted about 30 minutes, then went off with a bang. You can m=
aybe see the damaged heatshrink where the can hit an immovable object.
>
> Please note the scored cross on the top of the can. Isn't that supposed t=
o split and protect me from its rapid self-disassembly? Yes, I was right th=
ere, close at hand, trying to figure out why all the voltages were wrong. P=
erhaps their die for the venting "X" was worn out after 20 million caps. I =
guess that's what I get when I pay USD 0.03 for caps off of Aliexpress inst=
ead of USD 0.11 at Digi-Key :)
>
> I guess I learned a lesson in false economy today. I didn't lose an eye, =
but I'm going to change my buying habits a little. Obviously I made a mista=
ke putting the cap in wrong, but if I'd used a quality cap perhaps I'd have=
 only been startled with a scary hiss instead of a projectile. Take heed! H=
ow many lives do you really have?
>
> Cheerful regards,
>
> Bob
>
>
>
>

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