Old (and new) fire safe insulation material

[MartinHewitt]

I am now in George Price's book at the chapter where he describes the fire insulation based on alum and wood dust. The alum is releasing crystal water somewhere in the range of 60°C - 200°C. The argument is, that humidity inside the safe prevents that the temperature goes above 100°C. For this the water released by the alum must go through some openings of the safe interior lining and condense there. Water has a high enthalpy of vaporization and bound to alum probably even more. So yes the water released from alum is cooling the safe filling. If it is then going to the inside of the safe and condensing there it is in fact moving the energy (of the cooling of the wall) to the interior and heating it up. That doesn't sound that helpful, but Price was convinced of it. So did I miss something and the water inside the safe helps to cool it? Is alum still used for fire protection?

[bitbuster]

Don't know if it's still used. Wonder if that's what the Sentry safes used. I do know that alum and borax make a superb cockroach killer.

[huxleypig]

Ha, so you took up the suggestion of George Price's book, eh? Good work, great book. There is a lot of coverage about fire safe fillings and theory and it is a subject that I have long thought about. The merits of some of the theories seem a little crazy to me too. I find the whole concept of sacrificial water, and vents, and everything else fascinating.

[MartinHewitt]

Yup, I did. I have just for the free and mostly old PDFs out there an ebook reader. The other three safe books I mentioned I read already. Price's book I had already downloaded, but really forgotten. Because of this book I know now that the security is provided only by a quarter up to a halve inch of steel and the other, much thicker part of the safe walls are just for fire safety without any burglar protection. A wheel grinder should have it hence open in no time.