Composition safing agents?

[aerialpyro]

I am designing a safing mechanism for a system that may contain display fireworks composition and parts. I know for many compositions, such as potassium nitrate based ones, increased water or moisture content will decrease the burn rate, or in some cases prevent ignition. Is this true for most of the other composition types used in display fireworks? If not, what composition types would not be effected this way? Are there any other ways to safe/destroy compositions without ignition or energy release? For now I am just concerned about the composition, don't worry about assembled fireworks.

[displayfireworks1]

In your other post you state you are mechanical engineer. Does the above paragraph stand on its own to explain something or ask a specific question?

[PyroMike79]

I am designing a safing mechanism for a system that may contain display fireworks composition and parts. I know for many compositions, such as potassium nitrate based ones, increased water or moisture content will decrease the burn rate, or in some cases prevent ignition. Is this true for most of the other composition types used in display fireworks? If not, what composition types would not be effected this way? Are there any other ways to safe/destroy compositions without ignition or energy release? For now I am just concerned about the composition, don't worry about assembled fireworks.

I would love to help you but your post went over my head so fast that my hair is on fire! I will leave this one to smarter people than I.

[aerialpyro]

OK, looks like I failed at phrasing the question. I want to build a catastrophic abort system to render the composition unviable. There are multiple applications, I won't bore you with unless you are interested. The purpose is to allow a computer system to safely prevent combustion if it detects an ignition source or shock/friction event is likely. Right now I am only concerned about raw composition, stars, etc.

Question: Is water effective at retarding/preventing burn for the other compositions used in 1.3G display fireworks like it is for black powder or sugar compositions?

Is there a better method of accomplishing this? I am not concerned about destroying the product, as safety is more important.

If you guys don't know the answer, is there a list of composition types commonly used somewhere?

[Kenny East]

So your looking at making a fire arrest system for an automated fireworks assembly machine? Water is fine for most compositions in display and consumer, only ones that would pose an issue would be ones that contain high amounts of powder aluminum, titanium, and especially magnesium... They can react with water quite a bit... They typically use a class D fire extinguisher on those fires... Has a copper chloride powder that smothers the fire. But that wouldn't destroy the composition.. Just put out the fire... Same with a halon gas system... Only puts out a fire, and wont render the composition destroyed or inert. There are some foam additives that may work... Hope this helps

[aerialpyro]

Not an assembly machine yet, but would help with that also. I don't think class D fire extinguishers work with pyro mixtures as they contain their own oxidizer.

[Kenny East]

Yeah, thought about that later after i posted.. Water would be the best way to go, most formulas now days use magnalium... As opposed to straight magnesium. Same thing with titanium, usually alloyed with another metal to stabilize and enhance effect.
There are only a very few compositions i can think of that react with water, and need to be prepared with oil before mixing them... And usually their made in very small batches, in case you have a negative reaction. Some whistle mixes, and formulas that contain very strong oxidizers react with water. But their not typically used or found in consumer or display fireworks components... More commonly found in high power rocketry, or hobby fireworks making. The more reactive oxidizers are typically too expensive to make them a viable option for mass production, or are too dangerous for large scale mixing.
Never really given this idea much thought but it has given me some ideas i want to test... A-D fire extinguisher against pyrotechnic compositions... Got plenty of abc extinguishers around as well as a few water ones... But i only have one class D, and their not super cheap...
Cool idea for fireworks manufacturing though

[aerialpyro]

In my opinion, the best way to put out a composition fire is to physically disturb the mixture with a moderator/heat absorber to inhibit the transfer of activation energy from the combustion front throughout the composition. Separating the mixture from air is useless assuming a flammable solvent isn't in the mix, but diluting the mixture can help, however this best be done while the pyrotechnition and all other personnel are on the run...


I did read of some potentially problematic mixtures. Do you know if these are used much?

Chlorates and ammonium compounds - double decomposition to chlorine dioxide (explosive gas) in presence of water... really bad.

Chlorates with metals and nitrates - decomposition to ammonium in the presence of water - considered death mix by some. Can explode during drying... bad!


PH sensitive mixtures:

Aluminum and nitrates, decomposes to a base which reacts with aluminum to produce heat and must be acid moderated.

Chlorates and sulfur - sulfur and water can form sulfuric acid which can produce chlorine dioxide, an explosive gas. Can be moderated by a base.

These last two could work fine as long as the appropriate acid or base is incorporated in dry form in the composition.

[Kenny East]

Chlorates and sulphur comps are used pretty frequently. Most people and companies use perchlorate in place of less stable chlorates... But some colors and effects are best made with chlorate.
I can't recall a formula outside of rocket propellant that i use ammonium in, and in that formula i use fructose as a modifier to keep a good burn while avoiding sulphur.
There are a few iron oxide comps that can produce some heat when water is added, that may pose an issue.
I work with about 30 different formulas and i wouldn't hesitate to say most can be rendered safe or neutralized by water.

[aerialpyro]

Chlorates and sulphur comps are used pretty frequently.

As long as there is a base included in the mixture to buffer any sulfuric acid produced, I don't see any problem.

If you had to do a show only with water compatible compositions, what functions/effects would be missing or less spectacular?

[Kenny East]

Still could have a spectacular show without using any non water compatible comps. You can change out sulphur in some formulas with sugar used as a modifier... Not as good as sulphur, but there are many substitutions for chemicals available.. Some indoor or close prox fireworks have very stable non toxic comps. Or some fireworks that are used on water, like a water shell or cake... I don't have much experience with those though.