Sensitivity of Black Powder to Static Discharge

[omgb]

The old #5 was most definitely made with BP in mind. All of the old catalogs say as much. I have a very good one but rarely use it these days as a Belding and Mull works well for me.

[super6]

indian joe, Do you run your ball mill in your house? There are a lot of ball mill story's out there of exploding mills Just seems like a no brainier, What caused that to happen? You use lead as the media? Don't make a difference.

[M-Tecs]

I started driving these things in 1963 which of course counts for little in the face of a edicated engineer (Ben whatisname) - by some strange coincidence I never burnt one - musta been lucky eh?

The flip side can be stated also. Since the mid 80's my cousin harvests 30,000 acres of grain on land that he owns or leases but once he's done he custom combines/trucks for others. I know one year his operation harvested about 55,000 acres total. Thats 85.9 square miles.

He owns 11 18-wheel tractor trailer rigs just to haul the grain. I don't know how many harvesters he owns since they are never at a single location like the trucks are. I do know he did not us any type of static dissipater until he started having issues with damaging the onboard computers/navigation systems. After he started using chains but he had a major fire in one so he switched to a disk type that penetrates the soil. I built some parts for the protype. They still had a couple of small fires since using the static dissipaters but they did reduce dust buildup so they do provide some benefits. He's had several small fire issues since he started using static dissipaters so he musta been unlucky eh?

His operation was part on a university study on this issue. Shortly after the study he built a fuel/oiling/servicing truck with a very large compressor for dust removal and hasn't had any fire issues of late.

He just sent me this link as to what he does and recommends. He sent some other links but you have to be a member to view them.

https://extension.oregonstate.edu/pub/em-9326
Avoid electrical shorts and static
Blowing several fuses might be a sign of an electrical short that is waiting to spark at the worst moment. It is worth checking hard-to-reach areas for stray or loose wires. Static electricity can also build on combines and create a small spark when discharged. Some earlier studies suggested that static electricity can start combine fires, and drag chains or other devices should be used. However, recent research shows that static electricity likely does not start fires, but is rather listed as a potential cause when poor combine sanitation is also a factor. A single spark is typically not enough to start a fire in a combine, but repeated sparking at the same location can. You can use conductive brushes fitted near rotary components, such as the radiator fan, to reduce static buildup if it becomes an issue. Case-IH sells whiskers for fans on its combines that the company suggests for producers harvesting under fire-prone conditions.


Back to the subject at hand. Can BP be set off with static? Tests show no but those tests weren't done on ultra-fine dust like encountered during ball milling.

[indian joe]

indian joe, Do you run your ball mill in your house? There are a lot of ball mill story's out there of exploding mills Just seems like a no brainier, What caused that to happen? You use lead as the media? Don't make a difference.

replied to this earlier and its vanished!!
NO NO NO its 200yards from the main house and a half mile to the next neighbor.
Mill runs in the end of an open ended tin shed attached to (part of) my workshop - its ten feet to the side walls and roof, daylight one way ahead and 30 feet to the back wall - if the thing did blow not much harm gonna come from it - some stuff I have stored there would get maimed - some shrapnel holes in some old tin . its switched remotely from about 50 feet with a wall between - only run it at night for couple reasons 1) cooler and more humidity lessens the odds a bit 2) night time if theres any static buildup you can see it !
drive is from a sealed motor on a four foot vee belt - internal sparks from an unsealed motor (blokes using salvaged motors from old appliances etc) is a danger point to my mind. Lead media - clean screened ingredients - nothing that is used around the mill gets used for anything else. Barring accidents (like the canister running off the rails) its a pretty safe setup.
My danger point is that large open container of meal when I am blending it before processing pucks, and later when I blend my graded powder, both these happen outside in the yard and in a stainless pot / wooden spoon kept for the purpose. If I get ignition when I'm doing the blending my goose is cooked proper - no question of that. I make sure I am wearing cotton clothes (do that most times anyway)
I have read a couple of factory blowup reports (Goex in the 1990's for one) carelessness with electricity and poor hygiene (dust buildup) figured large in what I read.

[shaune509]

Combines and static. IMHO, static only allows/aids collection of fine dust. Fires are caused by 2 main things, house keeping and maintenance. I.E. collection of flammable dust/chaf and over heating bearing failure. As a side note on static, I have not seen 1985 or newer fuel tank trucks with static strips. I've had sparks when fuel nozzle touches fill port and no fire/explosion, same with a buzbox welder hitting the cap on field repairs. Safety Nazi's always have the sky is falling and pants on fire nanny state ideals.
Shaune509

[M-Tecs]

"Urban legends die hard…The tankwagons with the chain dragging, someone FINALLY figured out THAT did NOTHING…Some fuel delivery companies still connect a ground strap between the truck body and the filler-pipe connection before they connect the hose…This is ALWAYS done when refueling aircraft…"