Charcoal-boosted Flash

[BlueComet24]

As I understand it, ordinary perchlorate/aluminum flash produces little gas when it deflagrates. 70/30 KClO₄/Al flash should produce KCl and Al₂O₃ when it burns, maybe with a bit of gaseous chlorine or oxygen too. This makes me wonder if flash could be made more powerful while maintaining relative safety (i.e. not using chlorates, sulfur, or magnesium) by adding some charcoal to boost gas production, perhaps in a ratio of approximately 60/30/10 KClO₄/Al/charcoal (or less charcoal). If this is viable, it would (if I'm correct) produce a flash powder that not only is more powerful, but also cheaper and a slightly better option than regular 70/30 for our European friends who don't have easy access to perchlorate.

I do not plan to try this just yet because I vaguely recall reading something about charcoal sensitizing flash. At this point, I'm not sure if I remember correctly (it was quite some time ago), but I'd thought I'd ask the more experienced pyros just to be sure. I've looked at many flash and report compositions, and none that I found use KClO₄ with a metal and charcoal. I'm wondering why this would be; if it's a safety issue (which I doubt), or if my hypothesis is wrong and charcoal wouldn't benefit flash's brisance. Either way, I'm interesting in knowing how this would work, along with adding other gas-producing agents such as hexamine.

[schroedinger]

Th reason is that charcoal/kp burns a lot slower then metall fueled ones.

But why do you think flash produces no gasses? Some types may be a negative explosives, but this is based on the chemical volume, at room temperature, but flash burnsat 2-3k ºC, where even KCl is gassoues.

[Sparx88]

It's the sulfur that creates the majority of the gaseous emittance in BP. This also occurs when using sulfur in a flash comp, also providing a lower ignition point. If you were to -detonate- a measure of 75/15/10 standard BP and the same measure of sulfurless 80/20 BP, the sulfurless -detonates- almost 1000ms faster than standard BP (350-500ms). Though the opposite it seems, happens when lighting a loose pile of the 2 side by side during deflagration.

 

So I deduce that staying with tested and proven sulfur as a flash enhancer, I am most probable to be in good hands as long as I can keep them.

[Fulmen]

It's the sulfur that creates the majority of the gaseous emittance in BP

Not the case, according to Davis' COPE CO2, CO and N2 are the principal gaseous components (95%).

[Mumbles]

Most of the sulfur ends up as potassium sulfide or potassium sulfate. Off hand, I honestly don't know if normal or sulfurless BP has a higher gas production. Intuition says normal BP, but that is just a guess. It also burns faster in my experience, which is also a factor.

 

This would be an interesting experiment though. There is a KP variant in Shimizu that is just perchlorate and charcoal. It's not very fast in the open or enclosed, but it is a nice burst particularly for large shells. There are a myriad of factors at play here. Yes, adding charcoal will increase gas production. However, it comes with the tradeoff of reducing the energy output of the composition. Aluminum releases roughly 2x as much energy per gram when it burns as carbon. This will lower the temperature and lower the reaction rate. Power is a combination of total force and the time it takes to deliver. While increasing the gas production would increase the force, the slower reaction and less overall energy would decrease it.

 

I don't think you're going to be saving any perchlorate however. Adding in a fuel, and reducing the oxidizer doesn't make any sense. To keep things in balance, you'd want to substitute the aluminum with charcoal.

 

I think the result you want would probably be better accomplished by adding in nitrate. It'll replace the perchlorate and increase the gas production. Nitrate is a somewhat slower and less effective oxidizer than perchlorate, but at the temperatures involved, it shouldn't affect things much, especially in a blend with perchlorate. I was thinking in terms of potassium nitrate. Ammonium nitrate would generate a lot more gas, but also brings in other issues. Ammonium perchlorate would be the ideal common solution, but it's more expensive and harder to source in many instances and probably wouldn't be an effective solution.

[Sparx88]

Oh yah, I forgot, mumbles nailed it. To add sulfur or other fuels to a classic 70/30, you would want it something like this 70/25/5. We know what happens with over or under fueled comps right. If charcoal has to be used, with sulfur, I would try something that looks like this 70/24/3/3..... I'm out of perc so I can't. Would be interesting to see what improvement comes of it.

[Sparx88]

Not the case, according to Davis' COPE CO2, CO and N2 are the principal gaseous components (95%).

 

Those components are the offspring of the reaction and if you remove the main source, you have less volume of gases. It's well known at least round here where I'm at that classic bp 75/15/10 has considerably more gases being produced and quite a few actually. You will never get sulfurless to perform the same whether in pyro, muzzleloading or cannons...because it's the sulfur that makes things GO supercharged. I did the testing for that over 20 years ago when I got my first HR .58 cal muzzy.

Sulfur Dioxide 95% of of gases produced by burning sulfur is SO2. The others fill in the rest in various amounts.

Sulfur Trioxide

Hydrogen Sulfide

Carbon Dioxide

Edited April 3, 2016 by Sparx88