Booby trap flour explosion

[Pursuivant]

Originally Posted by Fred Brackin

A flammable gas or aerosolized liquid would almost certainly be easier to arrange. If the PCs aren't using a magical light source they'll be bringing the ignition source in with them too. :)

One RL way to trigger a dust explosion is to light a candle in a chimney or similar enclosed area, suspend a bag of flammable dust well above it with a tiny hole in the bag so that dust slowly leaks out. The updraft created by the candle's heat keeps enough dust suspended until you get to a critical point where it can explode. It's far lower than optimum REF, but it's reliable enough that it can, in theory, be used as a booby trap.

The huge advantage, of course, is the time required for the dust to build up to the point that deflagrates, turning it into a crude booby trap rather than an elaborate suicide method.

The same holds true for attempts to fill an area with gas or aerosolized liquid. It's devilishly tricky to get the physics right, so gas or vapor explosions are extremely unreliable, often not working at all or working entirely too well.

[Fred Brackin]

Originally Posted by Pursuivant

The huge advantage, of course, is the time required for the dust to build up to the point that deflagrates, turning it into a crude booby trap rather than an elaborate suicide method.

The same holds true for attempts to fill an area with gas or aerosolized liquid. It's devilishly tricky to get the physics right, so gas or vapor explosions are extremely unreliable, often not working at all or working entirely too well.

It would seem to me that the huge disadvantage is that an organic like flour will either cake or decay if kept long enough to be a tomb booby trap. I'd go for a light fraction petroleum like naptha for that purpose.

[David Johansen]

Try as I might, a young me never could pull off a flour explosion. sigh

[Anthony]

Originally Posted by Fred Brackin

It would seem to me that the huge disadvantage is that an organic like flour will either cake or decay if kept long enough to be a tomb booby trap. I'd go for a light fraction petroleum like naptha for that purpose.

For solids, there's coal dust (which is noted for explosions, though looking at mine safety stuff they say most coal dust explosions are triggered by methane explosions).

[Fred Brackin]

Originally Posted by David Johansen

Try as I might, a young me never could pull off a flour explosion. sigh

Whereas I assisted in the successful construction and use of an alcohol mortar that fired tennis balls. The volatility of the alcohol helped significantly in the fuel/air mix and ignition but is probably too volatile for long term trap use.

[Anthony]

Originally Posted by Fred Brackin

Whereas I assisted in the successful construction and use of an alcohol mortar that fired tennis balls. The volatility of the alcohol helped significantly in the fuel/air mix and ignition but is probably too volatile for long term trap use.

Depends on the trap maker's capabilities. Blow a glass bottle, fill it with your chosen volatile (I suggest naphtha), seal with molten glass, and if it doesn't shatter immediately it might well be good for millennia.

[Anaraxes]

Originally Posted by Pursuivant

A Food/Air College spell to make an optimized grain dust explosion would be a vicious Area Effect spell, guaranteed to make the Food college a lot more popular among battle mages.

Air College mages could do the same thing, without being restricted to using only grain dust and alcohol. Aerosolized lantern oil, to update a D&D classic for an example. And that Air spell would also work on flour and alcohol, along with pitch, turpentine, etc. Mages in higher-tech worlds would even find it hard to get away from any useful flammable materials.

[The Colonel]

Originally Posted by Anthony

For solids, there's coal dust (which is noted for explosions, though looking at mine safety stuff they say most coal dust explosions are triggered by methane explosions).

IIRC the Flakwaffe spent a long time trying to create a usable anti-aircraft weapon using coal dust and never got anywhere. I think the project was paperclipped but that to generated no progress.

Personally I've only ever created a free dust explosion using non-dairy whitener - the UK's most severe dust explosions that I am aware of (at least in recent times) used custard powder and wood flour.

As noted above, gases and vapours are far easier to detonate - a tomb trap might use a metal/acid mixer to generate a hydrogen cloud, which is has the widest explosive range that I'm aware of, and is colourless, odourless, burns with a clear flame and is prone to self igniting. Industrial hydrogenation chemistry is particularly interesting.

[Prince Charon]

Originally Posted by Anthony

Depends on the trap maker's capabilities. Blow a glass bottle, fill it with your chosen volatile (I suggest naphtha), seal with molten glass, and if it doesn't shatter immediately it might well be good for millennia.

That'd be a heck of a thing for an archaeologist to be surprised by.

[Pursuivant]

Originally Posted by Fred Brackin

It would seem to me that the huge disadvantage is that an organic like flour will either cake or decay if kept long enough to be a tomb booby trap. I'd go for a light fraction petroleum like naptha for that purpose.

Even a light fraction petroleum product would eventually have the volatile portions of the product evaporate, leaving behind nothing or just a tarry mess. For a DF-style trap to survive, the explosive/combustible material needs to be carefully sealed up. Magic or a physical trigger is used to break the container and spray the contents when it's triggered.

Ideally, you also want a regenerative trap. One idea might be to trap methane, from a methane seep or something like swamp gas from decaying vegetation, in a sealed corridor. Adventurers open the sealed door, gas mingles with oxygen and light sources ignite the methane-air mix for a satisfyingly deadly firedamp explosion. Counterweighted doors then swing close and seal themselves up, allowing a new gas buildup to deal with the next party of delvers.