"Potting" is not normally used as a way of providing intrinsically safe operating..

to quote Steve...

Look up "Intrinisically safe" "NAMUR" "flame proof" "explosion proof"

In intrinsically safe equipment, great care is taken to ensure that only minute amounts of energy are stored within the system, so little in fact that the energy stored CANNOT trigger an explosion in the specified conditions....

Potted solid state relays can do just as much damage when they let go,as unpotted..
The swichgear used in mines and on refinery's is usually made of heavyweight castings with large flanges around the casings,and designed to be able to withstand an internal explosion without egress.