50AE Posted November 4, 2008 Posted November 4, 2008 Hmm trying to think when the last time I seen a good thermite shell... ;{) I mean, just to use it for lighting compositions on the ground
TheSidewinder Posted November 4, 2008 Posted November 4, 2008 I can't see that that has anything whatsoever to do with "Flash Safety", the topic at hand here. Let's stay on-topic, please. Thank you.
bobby9101 Posted November 23, 2008 Posted November 23, 2008 (edited) I'm working on a little setup where I use two paper cups that are attached to a wooden dowel that I have rigged through a metal blast shield so that I can slowly turn the cups to mix the powder from a meter away behind a piece of sheet metal. Seems pretty safe to me, but I am still careful to spray anti-static guard all over the place and rotate the cups ever so slowly. Edited November 23, 2008 by bobby9101
Swede Posted November 24, 2008 Posted November 24, 2008 (edited) I like that idea... two cup halves that mate together, and can be rotated manually from a safe location. Something like that could also be rigged up using a gearmotor, and remotely activated with a switch. Selecting cups that do not retain static, and grounding the entire contraption using a copper wire, would be adviseable. How about PVC? Again, there would be static issues with PVC plastic, but a grounding strap should take care of that. You could even figure out a way to open the cups remotely, with a string or something, and now you'd have a ladle-like contraption containing the FP. Like a foundry worker. Carry the ladle to your shell or salute, carefully pour it in, and the entire time, until you seal the shell, you will be 5 to 6 feet away. With a face shield and gloves, you should be reasonably safe from smaller batches. Edited November 24, 2008 by Swede
bobby9101 Posted November 24, 2008 Posted November 24, 2008 I like that idea... two cup halves that mate together, and can be rotated manually from a safe location. Something like that could also be rigged up using a gearmotor, and remotely activated with a switch. Selecting cups that do not retain static, and grounding the entire contraption using a copper wire, would be adviseable. How about PVC? Again, there would be static issues with PVC plastic, but a grounding strap should take care of that. You could even figure out a way to open the cups remotely, with a string or something, and now you'd have a ladle-like contraption containing the FP. Like a foundry worker. Carry the ladle to your shell or salute, carefully pour it in, and the entire time, until you seal the shell, you will be 5 to 6 feet away. With a face shield and gloves, you should be reasonably safe from smaller batches. I'd be wary of using a gear motor just because it increases the risk of something going wrong, but if you aren't near the cups it probably isn't that bad of an idea.
mdawson Posted May 6, 2009 Posted May 6, 2009 Call me crazy, and I'm sure someone will. I usually almost never mix up less than 8oz. of flash. Anything less wouldn't meet my needs, except when I am testing new equipment I will mix up a super small batch. I take the usual precautions as most others do.
Mumbles Posted May 6, 2009 Posted May 6, 2009 There are absolutely two schools of thoughts. If I had the appropriate storage, I would probably mix up a couple of pounds on a day I was feeling lucky, and store it for when I needed it. Making flash is inherently the most dangerous part. As it stands I don't have convenient storage, so I only make as much as I will need in one manufacturing session.
Aimlesspayload Posted May 6, 2009 Posted May 6, 2009 I can't remember where I've heard it... I've heard of people putting a "v" of pvc on a turntable. the pvc is filled with the comp and capped off. then the turntable is angled with the rotating part perpendicular to the floor. the machine is then turned on/off from a distance. seems similar to your cup method.
Mumbles Posted May 6, 2009 Posted May 6, 2009 Using PVC seems like one of the dumber containers I can think of. It is static-y, and fragments. Cardboard is far safer is just about every regard I can think of. Cheaper too.
Ralph Posted May 6, 2009 Posted May 6, 2009 the whole mixing flash in a sealed container away from you seems pretty good to me but i mean your confining it in something that we avoid launching shells from as it is known to scatter into dangerous fragments. i mean for a larger batch confinement or not it will be dangerous if it goes off my for a smaller batch it would actually make things worse (i think) ralph
firetech Posted May 6, 2009 Posted May 6, 2009 In one of the more recent Skylighter articles a method of mixing flash powder is presented that is supposed to be fairly safe. The flash chems are simply poured in separately into the desired container, leaving about 1/3 of space left in the container. The container is then shaken to thoroughly mix the chems. Heres the link http://www.skylighter.com/fireworks/how-to...composition.asp
Aimlesspayload Posted May 6, 2009 Posted May 6, 2009 Using PVC seems like one of the dumber containers I can think of. It is static-y, and fragments. Cardboard is far safer is just about every regard I can think of. Cheaper too. well then use cardboard. you get the idea...
mdawson Posted May 6, 2009 Posted May 6, 2009 I just use a whole sheet of newspaper. I turn it from one side to the other.
Mumbles Posted May 7, 2009 Posted May 7, 2009 You don't shake the container in the binary method. The idea is that normal handling will be sufficient to mix it all. I'm still skeptical. I've heard from more than one very reliable source that partially full casings offer an additional level of danger and risk of prematurely going off. This is generally in regards to salute insert, siattines, and especially. bottom shots.
firetech Posted May 7, 2009 Posted May 7, 2009 I've had no experience with the binary method, nor any type of flash powder or flash powder device. I'm just simply passing on the information I've taken in. Thanks for that bit of information though, its crucial and could lead to some type of accident.
TYRONEEZEKIEL Posted May 7, 2009 Posted May 7, 2009 Broken ear drums, possible blindness from the flash or debris, possible concussion..or death by the aforementioned debris. Fingers gone to stumps depending on position, general fire/mayhem in the area, busted out windows in a small room. 10g is a powerful amount. Hell, 1g is. When I first started Pyro, I was completely unaware of flash powders mighty power. I made about 3g of KNO3/Mg flash.. I lit about a gram of it a knife and a flint rock. It tore the flesh off of my first finger. I would post the pictures, but they are kinda gross. It is sccary freakin stuff!!! I dont need it
Ralph Posted May 7, 2009 Posted May 7, 2009 just expanding on what mumbles said if you have a partially empty container the flash can slide around and we all know that there is no such thing as movement with out friction and so the flash (a friction sensitive explosive) is able to have frictional force applied to it. if you fill the container fully it isnt really able to move as there is no free space and so it will not be exposed to the same frictional forces. i personally always fill things completely ralph
FrankRizzo Posted May 7, 2009 Posted May 7, 2009 (edited) The decreased safety with partially empty containers containing flash is not due to the friction. What Mumbles is referring to specifically is the bottom shot of a cylinder shell. The bottom shot needs to be the toughest break of a shell because it's what supports the shell, and is exposed to the force of the lift charge. If the casing isn't completely full, the inside of the casing isn't fully supported, and you've created a weak point. As an example, have you ever tried to crush a full Coke can (the long way) with your bare hands, how about one that is missing a few ounces? Granted, most people have probably never tried to crush a partially-filled soda can as it would be a mess, but you understand what would happen if you tried. The can would crush to the point where there was still liquid inside, deforming the can and possibly piercing it where the metal crumples. If this happened to a bottom shot, the lift gases could get inside the bottom shot and ignite the flash. Most bottom shots are either filled to the brim with only flash, or the flash is mixed with a bulking agent like rice hulls so that it can be filled to the brim with less materials (cheaper). Edited May 7, 2009 by FrankRizzo
Ralph Posted May 7, 2009 Posted May 7, 2009 crushing a partially filled can of coke and a full can of coke that to has been opened would have little difference i would say it is just that a full can of coke is still sealed
FrankRizzo Posted May 7, 2009 Posted May 7, 2009 (edited) When I say "full", I mean unopened. Though even if the can were still sealed, but had 1/4 of it's contents replaced by air, it would still be "easier" to crush than an unopened can. The reason of course is that air (gas) is compressible, wheras liquid (or firmly packed flash) is not. That compressibility can allow the container to flex, which can introduce weaknesses. EDIT: And Ralph, I don't mean to minimize your assertion that flash is friction sensitive. It is. But, if flash could be ignited simply by shaking, bumping, or dropping a shell, it wouldn't be used commercially. Edited May 7, 2009 by FrankRizzo
Ralph Posted May 7, 2009 Posted May 7, 2009 yes we all no that 70 30 perc flash insnt that sensitive to friction but it is still sensitive to friction that can not be denied personally have tried (for about 2 min) and have never sucsessfuly got it to ignite with friction but adding ti sulfur or making flash with other oxidisers as we all know further increases sensitivity i would say that this can play a roll
TrueBluePyro Posted May 7, 2009 Posted May 7, 2009 (edited) I am fairly new to flash so dont knock me, but what I have been doing is; Weighing the chemicails in a plastic bowl and then because the plastic is a smooth surface and the chem's I have are VERY fine, I just kind of move the plate and shak it sofly and I have mixed flash in a few seconds. It looks safe and I think it is safe and much easeyer and quicker than doing it on a peice of paper. And I wouldnt think there would be a build up of static electricity. Edited May 7, 2009 by TrueBluePyro
Fluorescein Posted May 7, 2009 Posted May 7, 2009 My common type of mixing flash powder is to screen both compounds through a 100µm stainless steel sieve with a brush.Is there any hazard of frictional electricity?
TrueBluePyro Posted May 7, 2009 Posted May 7, 2009 My common type of mixing flash powder is to screen both compounds through a 100µm stainless steel sieve with a brush.Is there any hazard of frictional electricity? umm, I would stop befor you kill your self cause that is exactly how flash is going to be set off. someone correct me if I'm wrong but I have like read this every where that it should "NEVER BE SCREENED OR BALL MILLED".
Fluorescein Posted May 7, 2009 Posted May 7, 2009 I make is becauso of the minimalized stress by friction on the flash powder. Futher I think that there is a different danger between a metal oder a plastic sive. The only thing that might be dangerous is the brush, but I can`t imagine how a separation of carge could function if everywhere is metal powder.
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