Ignition temp of black powder/flash powders...

[gunner1]

I hope this is the right forum for this question. What are the generally accepted ignition temps for black powder and flash powder? I see alot of videos where people are using hot glue guns to seal their pyrotechnic devices and I always cringe. I know that when 1.3 and 1.4 fireworks are shipped in from China they come in steel containers that sit out in the sun and bake for hours, but that temp probably doesn't even reach 200 degrees.

[pyrojig]

A simple internet search on wickapedia will get you basic answers. Hot melt glue generally is not even close enough to reach dangerous temps. For auto ignition,But that's for the standard comps...not sensitive alternates with additives etc . Always work with the thought , what if .,and have a back door get away plan if something goes unpredicted.sadly with more energetic materials, that option rarely gets exercised when it goes terribly wrong...usually death or dismemberment are the result .

[gunner1]

A simple internet search on wickapedia will get you basic answers. Hot melt glue generally is not even close enough to reach dangerous temps. For auto ignition,But that's for the standard comps...not sensitive alternates with additives etc . Always work with the thought , what if .,and have a back door get away plan if something goes unpredicted.sadly with more energetic materials, that option rarely gets exercised when it goes terribly wrong...usually death or dismemberment are the result .

To be honest, I did do a google search but the only stuff I found was types of FP, how to make FP, stuff like that.

[NeighborJ]

You need to search the decomposition temps of each chem. For example,sulfer, KNO3,and cellulose or Al and KCLO4

[gunner1]

You need to search the decomposition temps of each chem. For example,sulfer, KNO3,and cellulose or Al and KCLO4

Thanks for the tip. The combination of chemicals doesn't alter the decomposition temp of the individual chemicals?

[NeighborJ]

That is correct.

[Arthur]

IMO (and only that!) you should only use hot melt to fix inert components, tubes, disks, etc, there should be NO live compound near hot glue.

[Mumbles]

You need to search the decomposition temps of each chem. For example,sulfer, KNO3,and cellulose or Al and KCLO4

 

 

Thanks for the tip. The combination of chemicals doesn't alter the decomposition temp of the individual chemicals?

 

 

That is correct.

 

 

 

Elements can't decompose. That's a property of being an element. So you're saying that traditional 75/15/10 black powder, nitrate flash powder, and sulfurless BP all have the same ignition temperature? Also that H3, chlorate flash, chlorate/sulfur all have the same ignition temperature?

[NeighborJ]

No, that's ridiculous. A sulfer bearing compound in theory can ignite at 239.4°f and a charcoal comp without sulfer and no other fuel with a lower temp of decomposition can ignite at 451°f.

 

Of coarse there are other factors at play which usually raise the ignition temps or at least raise the BTU amount needed to get to the ignition temp.

 

Just to clarify the fuels ignition temp is what determines the ignition temp of the entire comp. Once the fuel ignites, the temperatures get hot enough to drive the rest of the reaction. That being said, there can still exist the possibility of the fuel with the lowest ignition temp not having a high enough % to effectively be used to ignite the rest but I dont take this into account for this (safety issue). I err on the side of caution and assume that each fuel will have the same potential for ignition.

Edited June 28, 2018 by NeighborJ

[Baldor]

So... Forget theory and rely in proven empiric data. And use some common sense. BP, around 450ºC for autoignition. Or a single spark.

 

Disconnect the hot glue gun before apply it to anything near a live composition, it will retain heat for enough time and the heating element will not fail in this moment. Is the best advise possible regarding hot glue.

[justvisiting]

Gunner1, your concern about hot glue is warranted, but for a different reason. There have been quite a few cases now of hot glue guns shorting out in use and spraying sparks out. As far as I remember, so far, it's only been close calls. It's only a matter of time before a tragic accident occurs due to the use of hot glue guns with live pyro items.

[MadMat]

I get the feeling your looking for something like a kindling temperature for black powder/flash. I don't think you going to find anything like that and if you did, it wouldn't be all that helpful because things like physical shock also come in to play. It certainly stands to reason that as the temperature increases, these compounds become more sensitive to physical shock, flash more so than black powder. So, there is a temperature where these compounds would autoignite, but if they are being handled or physically manipulated, they would "go off" way before that temperature is actually reached.

But yes, it stands to reason that a plugged in hot glue gun should NOT be put into contact with black powder/flash powder ect.

[NeighborJ]

There are hot glue guns which remain hot when plugged into there base but are completely disconnected from a electrical source when it is removed for use. This style of gun IMO poses no threat of ignition to any normal pyrotechnic comp. The danger they pose is the possibility of flammable comp building up on the base contacts. It is important to keep them under some type of dust cover, away from your work and clean frequently.

 

Other types of guns can be used in this manor but it requires unplugging before approaching your work, put the plug end in your pocket so as to not inadvertently forget to unplug or create a pathway for static discharge. The act of making or breaking contacts to turn it on or of also is a possible ignition source.

 

Long story short, the heat from the glue poses little to no threat, it's how the gun is used which determines the level of risk it poses.

[greenlight]

This graph on ignition of black powder might help from chemistry of pyrotechnics:

Grade of powder, purity of chemicals used, ratio of ingredients, etc, would all alter the result of course.

Edited June 29, 2018 by greenlight

[greenlight]

Here's a list of ignition temperatures from the same book that should be helpful too. It doesn't include ratios though so I am guessing they are just stoichiometric proportions.

I can't upload a photo of the list because my new device won't take a pic from it and put it into the upload bar, it's just comes up with no file chosen. I had to do the last photo on another device.

 

KClO3/lactose ....... 195°C

KClO3/Mg ....... 540°C

KNO3/lactose ....... 390°C

KNO3/Mg ....... 565°C

Black powder (75:15:10) ....... 340°C

KClO3/S/Al Chinese flash....... 150°C

KClO4/S/Al flash .......450°C

 

Two things I notice:

 

☆ Potassium chlorate has the lowest ignition temperatures because of its rare exothermic decomposition where heat is given off upon melting. It is also unsafely mixed with sulfur in the first flash comp.

 

☆ Mixtures with metal fuels have much higher ignition temperatures.

 

I think another main major contributor to varying ignition temperatures would be particle size of the chemicals used.

Edited June 29, 2018 by greenlight

[gunner1]

Wow! This has been a really interesting discussion. Thanks alot guys and keep it coming!

[Arthur]

While there are lots of theories, and some numbers, please consider what would happen if/when your device ignited with your hands in close proximity.

 

I continue with my opinion that hot glue is for cases not compounds.

[greenlight]

I totally agree, hot glue or anything hot probably shouldn't be in contact with any pyrotechnic mixtures. There are too many variables that come in to play.

Unusual things have happened before like staple guns setting off black match in one incident I read. I believe it was friction between the staple and a piece of metal but it's still wouldn't be expected.

Casings on the other hand are fine.

Edited June 29, 2018 by greenlight

[justvisiting]

At the risk of being overly cautious, I thought I would emphasise my point above. My concern has nothing to do with the hot glue or tip of the gun igniting anything. It's not about a static spark or compounds getting into the contacts. My concern is about the tendency of hot glue guns to occasionally short out internally. This can happen at any moment. If there are any pyrotechnic items with exposed fuses in the same room, they could be ignited. The sparks shoot several feet in some instances. It has not happened to me, but I have read about several cases of this happening.

 

I would suggest never having a 'live' hot glue gun in the same room with pyrotechnic materials at any time.

[NeighborJ]

Awe shucks, I'm gonna need to make a steam powered glue gun now.

I really dont use hot glue any more, the only reason I would is as a time saver but I'm not really in that much of a hurry.

[Boophoenix]

According to some papers I’ve read there seems to indications there is some correlation between cooking temps of charcoals and the ignition temps of the BP it is in. This is attributed to the volotilities remaining in the charcoal after cooking. I can’t substantiate those statements just yet so I’ll have to take the information at the face value it has from such folks as Whiting and Sasse.

 

Since many of these papers are publicly released from the us army ballistics laboratory they tend to be a little dated around the 70’s and 80’s with some being older. I was pointed in the direction of these papers from a kind gentleman who had spent the better part of his life testing and working with BP formulas to the best of my knowledge.