Pottng SMPS's containing electrolytic capacitors

[treez]

Hello,
The following LXV200 SMPS is potted. However, it must contain electrolytic capacitors. So how have they managed to pot it?..because electrolytic capacitors are not meant to be potted because the potting seals up the explosion vents in the electrolytic capacitor casing.

LXV200-105S power supply
http://amtex.com.au/power_pdf/LXV200.pdf


(the "LED frequently asked questions" section says that LXV200 series power supplies are potted)

 

[Audioguru]

Hee, hee.
When I was 14 I made chasers with neon light bulbs and 90V batteries and potted them in clear plastic. They looked good and worked well.
Then the first one BLEW UP and made a big mess, luckily nobody was injured. I told everybody I made them for to get rid of them.
They had no vent holes.

 

[FvM]

Interesting question. Safety vents aren't provided as an end in itself. Their purpose is to avoid injury of persons by capacitor explosions in case of massive overpressure. The essential requirement is that no particles can be pojected out of an instrument. If an instrument case is able to contain an explosion, there's no safety issue.

Many SMPS vendors have potted AC/DC modules that include electrolytic capacitors, they all have the same problem. I'm not sure if and how the safety of these modules has been verified. But either the potting can be shown to withstand the expectable overpressure, or it's designed such that the overpressure can be released gradually.