Merlin Posted October 10, 2015 Share Posted October 10, 2015 I am aware of critical mass of 70/30 so I only make it in 20 gm batches. What is a safe quantity of 5/3/2 nitrate flash? Link to comment Share on other sites More sharing options...
ivars21 Posted October 10, 2015 Share Posted October 10, 2015 There is no such thing as safe quantity in my eyes. I am handling my 20g batches the same way I do 200g batches. 1 Link to comment Share on other sites More sharing options...
Merlin Posted October 10, 2015 Author Share Posted October 10, 2015 please allow me to rephrase question. I am well aware there is no safe amount of flash. Truth be told there is no safe BP either. However I make my BP in 2 lb batches. So I suppose my question is what is the critical mass of nitrate based flash? Can it be made in 50 gram batches without self detonation spontaneously occurring. I know also that that 50 grams is 2.5 times more dangerous than 20 grams.I am considering replacing my 70/30 central flash bags in 3 to5 inch shells with the nitrate flash. Also is it advisable to add boric acid due to the presence of AL and S? Link to comment Share on other sites More sharing options...
schroedinger Posted October 10, 2015 Share Posted October 10, 2015 Merlin i saw 50 g Batches of kno3 flash not explode under compression and same construction bang like hell (about 40 K temperature difference) but still i wouldn't want these to go off in the open being near it. They burn really hot. Just use as much as you need. 20 g is enough to boost at least 5 shells, Link to comment Share on other sites More sharing options...
Mumbles Posted October 10, 2015 Share Posted October 10, 2015 I would assume you're thinking about this move from a safety point of view? You do need to take into account that you'll be using significantly more slow flash in flash bags as compared to 70/30. I'm not sure how much exactly, but I'd expect somewhere around double the amount. I do not have any idea where this particular slow flash will self-confine. I've used slow flash in flash bags a couple of time, but generally didn't like them. I would think that it's more forgiving as far as dialing it in. The biggest thing I didn't like was that it seemed like it had a more noticable and distracting flash at the center of the shell. Link to comment Share on other sites More sharing options...
Merlin Posted October 10, 2015 Author Share Posted October 10, 2015 Thanks. It seems quite powerful . I have not decided yet whether or not to try it. Last year I made 4 inch ball shells by Lloyd Spontenberg as posted on passfire. They worked pretty well. This year I will make some 5's. The fours had 5 grams of 70/30 in a central flash bag surrounded by 80 grams BP. This time I will be fill void with 7:1 meal coated rice hulls. I was thinking of using 10 grams nitrate flash in the central bag. If I stay with 70/30 I fell compelled to not use more than 5 grams like the fours. 10 just seemed like a lot of 70/30! Link to comment Share on other sites More sharing options...
Mumbles Posted October 10, 2015 Share Posted October 10, 2015 When I was writing my reply, I had cylinder shells on the mind where the flashbag provides basically all the breaking power. Ball shells as per Lloyd's directions might be different. Are you planning to use the coated rice hulls bulk filled in around the stars, or line the hemi and fill the center? If you're lining the hemi, you might want to try just dusting the BP coated rice hulls with the slow flash as opposed to using a flash bag. The BP in the method actually provides plenty of bursting power on it's own. Using slow flash instead of 70/30 might not make quite as big of a difference, as opposed to if it were the primary burst. Since you know the performance of your 4's, maybe you could dial it in with slow flash in this size. Link to comment Share on other sites More sharing options...
Merlin Posted October 11, 2015 Author Share Posted October 11, 2015 Thanks for your insight. I will be lining the hemispheres and attempting some basic pattern she'll. I take it with the hemispheres lined MCRH suffice alone and with peony she'll the flash bag would be appropriate. Link to comment Share on other sites More sharing options...
Mike Posted October 11, 2015 Share Posted October 11, 2015 If we are talking about baal shells, just tumble your hulls with 2% slow flash and use paper hemis. Link to comment Share on other sites More sharing options...
OblivionFall Posted October 11, 2015 Share Posted October 11, 2015 It depends on the KNO3 flash that you work with. How fast does it burn in a 1g batch? Stuff like that. I would assume that standard KNO3 flash that goes wooosh would take around 100g in a pile to go boom. And you would have to light it from the bottom first.But that's not to say that you should be very careful with 20g batches of it. KNO3 Flash is more sensitive than KCLO4 flash. 1 Link to comment Share on other sites More sharing options...
Merlin Posted October 11, 2015 Author Share Posted October 11, 2015 I think so as well -it just seems it would make a good ignition and Booster in 4 and five inch hemispheres, especially peony and chrysanthemum. When fused in an open container it just burns like a hot BP but is quite powerful under containment. Last year I made 4 inch plastic peony type shells with 5 grams 70/30 in a central flash bag. I will likely experiment with a couple 4 inchers. Yes I know any type flash is dangerous but I also think BP can be dangerous. It would seem that pattern shells might be best with just MCRH maybe dusted lightly with nitrate flash. Sent from my iPhone On Oct 11, 2015, at 2:41 PM, APC Forum <admin@amateurpyro.com> wrote: in Link to comment Share on other sites More sharing options...
FloridaCracker Posted October 13, 2015 Share Posted October 13, 2015 Actually power of explosives is supposed to be based on the square of the mass. So 50g may be 2.5x the mass as 20g but should be 6.25x as powerful or 625% greater power. However, I don't remember exact details of the formula and it may be for high explosives though it seems like I remembering it being applied to BP that deflagrates. Just something to think about. Link to comment Share on other sites More sharing options...
Merlin Posted October 13, 2015 Author Share Posted October 13, 2015 I read that you can use dark flash for break Booster. 70/30 perc/benzoate that doesn't have a bright flash. Have not tried it yet but it sounds like whistle mix. Link to comment Share on other sites More sharing options...
Ubehage Posted October 13, 2015 Share Posted October 13, 2015 (edited) Can it be made in 50 gram batches without self detonation spontaneously occurring.What do you mean by "critical mass" and "self detonation"?Is it a mass that will detonate upon ignition, or a mass that is able to ignite by itself because of the amount (like Uranium)? Edited October 13, 2015 by Ubehage Link to comment Share on other sites More sharing options...
Merlin Posted October 13, 2015 Author Share Posted October 13, 2015 Critical mass refers to the amount of 70/30 perc/al that can self detonate uncontained at atmospheric pressure all by itself. 1 Link to comment Share on other sites More sharing options...
Mumbles Posted October 13, 2015 Share Posted October 13, 2015 I prefer the term self-confine, but I assume he means the mass that will transition from simply burning in the open to exploding. It's sort of the low explosive version of a DDT (deflagration detonation transition). Flash powders don't really detonate under normal circumstances. [edit] Merlin beat me to it. 1 Link to comment Share on other sites More sharing options...
FloridaCracker Posted October 13, 2015 Share Posted October 13, 2015 That is whistle mix which is powerful though that is not the ratio for most power. I would be careful with most of the other dark report compositions. They use chlorate and antimony which is normally considered a big no-no as it's very sensitive and can likely go high order. Link to comment Share on other sites More sharing options...
MrB Posted October 14, 2015 Share Posted October 14, 2015 I prefer the term self-confine, but I assume he means the mass that will transition from simply burning in the open to exploding. If self-confinement is what he's going at, there is bad news for him... There is just no way to give him an accurate number. For perc-based flash i've seen sources quoting "less then 1gr", while pyro's struggle to get 5gr piles to do more then spit sparks, and if lucky, burn violently. Same goes for nitrate-based which is less powerful, but more sensitive, and the amounts supposedly are about the same. So, why the difference? Well, it goes without saying. particlesize, quality of chemicals, how well mixed it is, and so on.Regardless, 20gr batches are safe, only in the regard that it's a known fact they will take your hand of, if they go off on you. If he's thinking about autoignition / spontaneous combustion then i'm not sure there is an amount that would cause this... Anyway, if he's trying to switch to a safer compound,he should stick with 70/30.B! 1 Link to comment Share on other sites More sharing options...
Merlin Posted October 14, 2015 Author Share Posted October 14, 2015 I was under the false impression that 70/30 could simply explode if quantity was 50 grams or so without any spark or static. Apparently if you need 50 grams just make and use it. I make plastic ball shells by Lloyds method on passfire. It uses a central flash bag of 5 grams 70/30. Since I am going to 5 inch shells with MCRH I thought the 70/30 might be too powerful. I read that nitrate flash is commonly used in pyrotechnics. What are it's uses?I also read that perc/benzoate is a dark flash greatly reducing the blinding flash at break.Having said that do you guys think I should just stay with standard 70/30 in 5 inch shells? Link to comment Share on other sites More sharing options...
MrB Posted October 14, 2015 Share Posted October 14, 2015 Flash, no matter what composition, doesn't autoignition / spontaneous combustion, in any amount you can actually handle.As far as i'm aware, it wont autoignition / spontaneous combust, at all. Ever. It needs heat, shock, friction, or some of the other means of ignition we constantly worry about. People mix flash in kilo-batches, and are fine. And at least they know if it goes of, they wont be there to suffer the consequences... B! 1 Link to comment Share on other sites More sharing options...
Merlin Posted October 14, 2015 Author Share Posted October 14, 2015 Flash, no matter what composition, doesn't autoignition / spontaneous combustion, in any amount you can actually handle.As far as i'm aware, it wont autoignition / spontaneous combust, at all. Ever. It needs heat, shock, friction, or some of the other means of ignition we constantly worry about. People mix flash in kilo-batches, and are fine. And at least they know if it goes of, they wont be there to suffer the consequences... B!Flash, no matter what composition, doesn't autoignition / spontaneous combustion, in any amount you can actually handle.As far as i'm aware, it wont autoignition / spontaneous combust, at all. Ever. It needs heat, shock, friction, or some of the other means of ignition we constantly worry about. People mix flash in kilo-batches, and are fine. And at least they know if it goes of, they wont be there to suffer the consequences... B! Link to comment Share on other sites More sharing options...
Merlin Posted October 14, 2015 Author Share Posted October 14, 2015 Yes I am aware of that now. I guess where I hot hung up on 20 gm batches is if worse comes to worse you might live for a while afterwards. At any rate I take the standard precautions for safety as well as making the smallest amount to be used immediately.But I am honestly asking what is nitrate flash used for and what is dark flash used for or are they not used much at all? Link to comment Share on other sites More sharing options...
rogeryermaw Posted October 14, 2015 Share Posted October 14, 2015 In my limited experience, nitrate flash vs perc flash is a sound quality thing. Perc is sharper higher pitched bang while nitrate gives a deeper resounding boom. I have seen dark flash used in reports alternating with perc flash to give varying light output. The flash of light from dark comps is less noticeable and less distracting. Dark flash is also sometimes used to break crossettes. Again, my limited experience. 1 Link to comment Share on other sites More sharing options...
pyrojig Posted October 14, 2015 Share Posted October 14, 2015 LOts of commercial cakes use nitrate flash as the solo burst for smaller inserts. I have demoed several failed inserts on shows to see what technique they use to manufacture /. Lots of us amateurs use dark flash as a booster for smaller shells . I like a few grams for 3-4" shells . It helps cut back on the pasting ,and give nice wide breaks with out sacrificing the viewers pupils ( light output). Flash if handled/made with respect and caution , can and has been proven pretty safe in industry . Link to comment Share on other sites More sharing options...
MrB Posted October 14, 2015 Share Posted October 14, 2015 (edited) But I am honestly asking what is nitrate flash used for and what is dark flash used for or are they not used much at all? It's alot about the sound. But if i look to my self, it's something else. I have a finite amount of perchlorate, which is most definitely reserved for colors, and a tiny amount of whistles.I use KNO3/MgAl for my flash, exclusively. I use my flash for salutes. big and small. (not that small gets very tiny, i need / want good confinement for the right effect.)Im not sure my flash is cheaper, but it's a huge step up in availability. KNO3 can be had locally, where as (per)chlorates are going extinct in my part of the world. As it turns out, even if you get licensed to make pyro, your still not allowed to buy the stuff, the law is simply not allowing it. A small hobbyist has to start a company, get the permits, and the company can by the stuff. A bit out of most peoples scope, and clearly not a hobby anymore. And your right of course. 20gr is going to hurt you less then 50, when it goes of on you. If thats good or bad... There are people doing kilo batches, that, when asked, implies part of the reason is that if it should go of, they know it ends there, and then. No suffering past that point. And they have been in to pyro for years, work safely, and have no intentions of dying anytime soon.B! Edited October 14, 2015 by MrB Link to comment Share on other sites More sharing options...
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