Dave France and the blowup while pouring powder

[Ken Hansgen, 11094]

Dave, while replying on another thread, recently reported that an electrical engineer told him he had had an accident while pouring powder into a container. He or Dave theorized that was due to static electricity. I said I was concerned because I do that often--when I finish a loading session I pour the unused BP still in my measure though an aluminum funnel back into a 1# can that usually has more BP already in it. I asked Dave if he knew whether that was dangerous. Maybe he'll answer here.

[Timmeu]

HI

I am no engineer but I use plastic funnels from RCBS for the very reason you mention.

Timmeu

[Ken Hansgen, 11094]

And I've been told that plastic is more likely to build up static than aluminum Perhaps RCBS has added something that prevents this?

[DAVE FRANCE]

Ken,

He is an engineer, and I think he is an electrical engineer.

I will ask him for details and I will ask if I can put his name on this BB.

I am glad you wanted more information. Let me put some background information here.

1) There was a test done and showed on the internet, and reported in the skirmish Line. It showed electrical sparks hitting a small pile of black powder and the powder never caught fire. I think the reason given was that the powder never got hot enough to catch fire because BP is too good of a conducter to get hot. That makes sense to me.
2) BP will ignite without a spark, just from heat. And I think the ignition temperature is less that 500 degrees F. If you took a nail and heated it up to red hot, it will ignite BP without a flame. If you let the nail cool off, it will still ingite BP until the nail temperature gets below the ignition temperature (less than 500 degrees).
3) A spark will ignite BP if it is above the ignition temperature. Sparks from a flame, a cigarette, etc. will ignite BP. Two people I know were burned because of smoking near BP or shooting near an open container of BP. There was an accident in Michigan (not at an N-SSA event) that killed several people in the 1960s. I understand that it was caused by a spark or floating ember that fell into the powder storage container.
4) Several things can blow up while in a powder or dust form in air. They can explode from a spark (including a static spark) or from contacting something that is hot. I looked up informationa bout this some time ago, but I am no expert on this and may have something wrong. My recollection is that the dust must be at a high level concentration to explode from static electriciy. Many types of plants or storage facilities can have explosions. I think rice, wheat, and sugar are liable to explode under the right conditions. And these types of explosions occur fairily often.
5) I worked in an ammunition plant in part of 1966 and 1967. I was the production engineer for F - Line, which was actually one of several plants in the plant. Louisiana Army Ammuntition Plant where BP is made now. To access some parts of the plant it was necessary to wear conductive soul shoes to prevent a static buildup. One part of F-Line was a melt building where explosive was brought in and melted, and then poured into small (soft ball size) cluster bombs. One of the things I did while there was improve the ventilation system to keep the explosive dust level low. The plant seemed to think that static sparks could cause an explosion.
6) I was drafted In September 1967. I skipped part of Basic and was sent to an Army Ordnance facility. The next year, the melt building of F Line blew up. It left a big hole in the ground and killed everyone in the melt building. F-Line was closed permanently. One of my uncles worked in another part of the plant and he said it was a terrifying experience. I think the explosive used in the bombs was not something that is easily ignited. I think most explosives used by the militay then had to be exploded by a smaller charge, that caused the main explosive to explode.

7) By a strange coincidence, my mother worked in an ammunition plant in Nebraska in 1944 or maybe 1945. She worked in the melt building, but when my father came back from some training and found out he made her quit. The next week the building blew up and killed everyone there.
8) I am sure BP will blow up while in a powder form in the air. And it will probably do it from a static spark. when I saw the information about the sparks hitting the pile of black powder pile, I thought that could cause some confusion that might lead to someone being careless and result in an accident. But probably it would have to be a heavy concentration to explode while in powder form.
9) Last item. While I was in the first grade, a friend of mine who lived less than a block from where I did, lost both his hands. He picked up blank 22 rounds that the pirates dropped in the Gaspirilla Parade in Tampa. I don't know exactly what he did to cause the accident, but both his hands were burned very badly. He probably emptied the powder from the blanks and lit it. That was in Tampa, Florida in 1947 or 48.


All this is from my aging memory, and I am not an expert in BP or explosives.

Good luck!

David

[R. McAuley 3014V]

Ken,
1) There was a test done and showed on the internet, and reported in the skirmish Line. It showed electrical sparks hitting a small pile of black powder and the powder never caught fire. I think the reason given was that the powder never got hot enough to catch fire because BP is too good of a conducter to get hot. That makes sense to me.

http://www.ctmuzzleloaders.com/ctml_exp ... ricml.html

It’s rather interesting that the author of this article describes how in his earlier experiments in attempting to ignite black powder failed because he had not used sufficient current, so in this subsequent article describes how in performing other experiments:

http://www.ctmuzzleloaders.com/ctml_exp ... parks.html

“I had measured the resistance of a lightly packed pile of black powder and found it to be about 1000 Ohms. When you apply a voltage to something that conducts, current passes through it and some of the energy is dissipated as heat. The formula for this is:

Power (watts) = Voltage*Voltage/Resistance.

If I put 100 volts through that pile of powder, I get a power dissipation of 100*100/1000, or 10 watts. It's not much, but in a tiny pile of powder, the heat builds up and will ignite it almost instantly. After playing around with it a bit, I decided to use about 200-300 volts to ensure almost instant ignition.”

How then could 200-300 volts of electric current “ensure almost instant ignition” when according to his previous article, when he had applied 10,000 volts had failed to accomplish the same result. So what's that stuff they coat black powder with so as to reduce friction and static electricity? It's graphite, isn't it? I wonder whether being coated in graphite might have something to do with delaying black powder kernals from heating up until the reach their autoignition temperature?

[DAVE FRANCE]

It seems like for the pile of BP there was no complete electical circuit to allow current to flow. For his rifle, he had to contacts that contacted the cup with powder in it. And there was a path for the current through the powder in the cup. I did not read his paper carefully, and I may have missed something.


David

[Ken Hansgen, 11094]

That's all very nice, but just remember that we "commoners" are seeking practical advice. Seems like Goex is dustier that Swiss--does that mean it's more explosive? What can we do in our loading area to reduce the risk of static buildup? Is plastic riskier than aluminum? What does RCBS do to their plastic funnels (if anything) to recommend them for BP? Is there a practice I should avoid? Stuff like that.

[DAVE FRANCE]

Pour slowly. Don't pour near a flame or anything hot. Pour where there is good ventilation and where the powder that gets in the air does not build up. Read what is on the internet about explosions in flour silos, ect. if you want to know more.

David

[Jim Brady Knap's Battery]

It might be good to do as we always did in my aviation carreer when fueling aircraft. To avoid the chance of static sparks with aircraft we would ground the fuel truck to the earth and airframe and the fuel nozzle to the airframe. Perhaps keeping physical contact with the item pouring from, the funnel, and the item being poured into would help avoid any static charge developing that could cause sparking.


Jim Brady
2249V
Knap's Battery

[R. McAuley 3014V]

You gents seem to have missed the point. The granules or powder kernels of black powder, as well as smokeless powder, are often coated with graphite as a lubricant to prevent the build-up of static electricity as well as act as a burn moderator. Synthetic graphite is made from anthracite coal and is an excellent conductor of electricity, allowing the static charge to pass from particle to particle eventually discharging harmlessly to a grounding source. The fact that the graphite (carbon) coating also helps round irregular edges of the propellant increases its surface area and acts as a heat sink preventing the build-up of heat from entering the granule, which, if otherwise uninhibited, would allow it to reach its auto-ignition temperature and self-combust. So certainly the rougher you handle a propellant and injure its lubricant coating the greater the likelihood that some injured particles may more quickly self-combust and thus contribute to the explosive train with the remaining propellant. However, it should be emphasized that some manufacturers, such as Swiss, supposedly don’t use graphite as a lubricant so may be more unstable than other brands. According to Owens Compliance Services (representing Goex), graphite is not contained in all grades of black powder. So be careful when handling your powder.