Re: Safety Q's - Powder storage/fire extinguisher
Powder MUST be stored in a pressure release type container. Something which will vent a LOT of gas once it starts to burn.
It will blow a safe (and likely the wall it's attached to) or any tight container.
I use a metal unit which will blow the doors with low internal pressure. Wood is good. Anything heavy and not able to vent is a bomb casing.
If you keep a lot of powder then use mutiple containers away from each other. Put enough powder in one spot and light it and the gas speed/flame front will speed up until it detonates (not technically correct but descriptive enough @1:30 AM). that's why burning off powders is done in a line and with very limited lengths.
You won't fight a fire which has hit your storage container. You just get out. Your local fire guys will likely do the same buy try some high pressure water to get it under control.
You can use fibreglass blankets and make an enviroment which is far less likely to light but it your house is going up...
I would use normal fire precautions as we all should have, store it correctly and make sure you are insured
Just so we are clear about this, a few cans of powder in your safe is enough to blow the safe and your wall. I've got pics here of it happening. Didn't do the house much good at all.