Black powder not affected by static?

[deadman]

So I have been just surfing the net and ran across this:
http://www.ctmuzzleloaders.com/mlexperiments/sparks/sparks.html

If this is correct and not doctored then it would seem that black powder isn't set off by electricity. This of course does NOT mean sparking media can be used because those are not electric sparks.

BTW I do not believe these pictures to be doctored, but you shouldn't always believe pictures from one source.

[Jacks Complete]

That's pretty neat. I would say that the results for Swiss 4F (or any other commercial BP) is probably different to a home-made BP, as commercial BP is coated with graphite and polished, which stops, er, static discharge issues, as well as increases ease of handling. The coated grains take up moisture more slowly, don't cake, and don't tend to clog.

Homemade BP generally doesn't have this coating, so static might still be an issue.

Also, the capacitance of those spark sources will be low, as the current carried in the arc is tiny. Don't forget that lightning, which blows trees apart, is static electricity, and that many, many powder mills have been blown to bits by static discharges in the past.

[nbk2000]

The reason is likely because of the non-porous nature of commercial BP, as well as the conductive graphite dust that the grains are coated with.

Compare that with home-made powder, which is both porous and non-conductive, allowing heat to be created by the resistance to the flow of the electricity.

[Zajcek]

I also experimented with sparks and black powder some time ago. In some cases it went off, in some it don't. I think it relay depends of frequency of the current and the current(I <A>) itself and other factors.

If I added a resistor with big resistance and lowered the frequency, to prevent arc forming (arc is very hot) then in most cases the black powder/gunpowder did not ignite. And it depends of the powder used. If I remember correctly, the gun powder was more stable than homemade BP. (If you wet the paper, then the gunpowder nor the black powder will ignite)

If you will experiment with this, be careful, use safety glasses at all time ( I learned that the hard way )

[Bert]

I have seen industry data on static ignition in processing. The ammount of energy needed for ignition is TINY. I will look for my source materials. In the meantime, do not feel emboldened by this guy's experiments, they have little bearing on home manufacture!

[Cobalt.45]

Just conducted a very non-scientific experiment, but one that was interesting.

Regardless of the outcome, I'm gonna assume that static and BP don't mix.

Using a BBQ lighter (the electrical sparking kind) a one gram pile of bone dry BP would not ignite when sparked repeatedly. Nor would flash.

Same BP, lighter. This time, the BP was placed in a 6" cardboard cube, lighter leads fed into the box through a 1/16" hole, and a 1/4" hole was made for the tip of an air hose connected to a regulated air supply set to 5 psi. With the BP suspended in the air, it went off with the first strike of the lighter.

Granted, these were contrived conditions that wouldn't ordinarily be encountered. Many dust explosions have been documented, from grain silos on down, so this comes as no surprise. But to someone who is careless, this phenomena could get them into trouble.

Upping the amperage of an electrical discharge will also light BP. Same one gram of dry BP, in a pile.
Set my arc welder to it's lowest setting (40A). I used a 22 gage copper wire as the electrode, grounded the plate that the BP was placed on, and struck an arc. Yep, it lit immediately.

So somewhere between the two (BBQ lighter and DC welder) is where BP ignites.

Someone with a regulated DC power supply could narrow this down considerably.

[inventorgp]

Well I'm pretty sure an arc welder would work.
As soon as you strike an arc it creates intense high-temperature plasma.
The temperature would ignite it.


EDIT: My big mouth

[Cobalt.45]

With six mistakes in grammar in two sentences, I'd go easy on the "duh's", 'twas thee me. And I'm having a hard time igniting H2O with the old Lincoln...

duh, of course an arc welder would work - on any thing.
As soon as you strick an arc it creates intense high-temperature plasma,
inturn lighting the powder.

For sparking, it depends on the current:)


Oh, and amperage IS current.
Is there a difference in the heat of a small electrical discharge compared to a larger one? Or is it a function of amperage over time?

"The temperatures of both types of spark are high and are potential sources of fire or explosion. The incendivity of a spark depends to a large extent upon its total energy content but also on time over which the energy is deposited. It is difficult to measure the incendivity of sparks, however it is typical and prudent to regard any which occur in a vulnerable region as a hazard." (On thermal and voltage sparking, quoted from the NLSI web page.)

Then, from ctmuzzleloaders.com, this: "For the second experiment, I used an Oudin coil, which is used for testing glass neon fixtures for leaks. It produces pulses in excess of 40,000 volts and will give you quite a burn (and shock) if you let it hit you.



This was impressive! The pile of powder was hit dozens of times, and again, it never ignited. You can see little flashes where the sparks strike; these are caused by vaporization of material from the surface. Although I couldn't get a picture of it, the paper had hundreds of tiny holes punched in it where the sparks burned through.

The next picture shows a similar test set-up, except this time the black powder was ground into dust-like consistency. Again, no ignition, even though the sparks striking the middle of the pile blew powder clear from the areas where they struck."

So, at what amperage will ignition occur?

[inventorgp]

If you were talking to me about grammar, the only word spelled wrong
was strike. I spelled it strick.

Oudin coil is a type of configuration for a Tesla Coil. The end of the secondary
is connected to the primary coil instead of ground. TC's doesn't produce a lot
of current.

I've built a triac circuit and hooked up a 7mF cap to a auto ignition coil.
It produced about 100000V (100kV) at 20mA. And the heat from the
arc was hot enough to light matches etc. not the spark.

I've also have built an 21VAC 60A transformer hooked up with a bridge rectifier. I started to
pull small arcs about 1cm. It started to melt MnO2!
Just think of arc furnaces.:)

EDIT: Spelling/Grammar

[deadman]

I am positive he was talking to you about grammar. I'm sorry I have to actually tell you this, but spelling has nothing to do with grammer. And "spelt" should be spelled. For better grammar work on using the right article or in some cases any article.

[inventorgp]

I must be the most illiterate and blind person in this would, especially after 12 years of schooling.

I'm Sorry for my rudeness:o

I'll go fix my mistakes.

[Cobalt.45]

Earlier, I had clicked on a web site that was featured in a post by deadman, "ctmuzzleloaders.com". Copied and pasted an excerpt from that site. It totally slipped my mind where I had gotten the site from.

The National Materials Advisory Board did a study involving the minimum ignition energy of various dusts. Closest to BP was coal dust, 200 mesh. It required .06 joules to ignite.

The power supply used was various values of capacitors discharging through the primary of a neon light fixture transformer. Measurements of current and voltage was done with a Fluke meter.

They tested all manner of dusts, but alas, no BP.

I suppose the bottom line for me is to be careful with potential static discharges, period.

[Jacks Complete]

I've got to say that if you hit a drop of water with a 40A arc, you will get an explosion of steam. D'uh!

Anyway, you are right about the total energy being what matters. A high voltage goes further as a spark than a low voltage, and the current is what does the damage.

It's the volts that jolt,
but the mills that kills.

(Mills refers to milliamps, as only a few milliamps across the heart will kill.)