Re: Safe smoke and fire seal, triple seal
As a 20 yr. firefighter, here's my personal solution. Put safe in basement on a 4 inch riser. Have a floor drain in relatively close proximity. Finally install a fire sprinkler head above or close to your safe.
With city water pressure, an average sprinkler head will flow 25 gpm give or take. Floor drain will take care of that, if it can't quite keep up, the 4 inch riser buys some more time. Hopefully fire will be kept in check.
If the fire dept. arrives and pulls hose they'll usually put out most fires with a couple hundred gallons of water. If the fire is really ripping and the house it a total loss, then yes heat and a hell of alot of water are in order. This is what pictures and a good insurance policy are for.
In 20 years I can honestly say I've only been to a few fires where we filled the basement in which case the owner/occupants lost everything. In times like that just about any safe is FUBAR too.
Keeping your safe on the lowest possible level if you have a basement is a must. As mentioned above, heat rises. Also having a 600 - whatever pound safe on your floor joists isn't the best option, and it's a damn poor idea if I'm the one on the hose line trying to put out your fire in the room below your safe. This senario has the makings of a bad day.
Try to keep the fire load - anything combustible and not needed out of your safe room if you can. The less there is around your safe that can burn the better.