Sciencemadness Discussion Board - SA (Ag2C2.AgNO3) - SENSITIVITY TO STATIC DISCHARGE

The key to a good pyrotechnician is in its primary.

A lot of good "pyrotechnicians" have less than 10 fingers and injuries. A kid named AnonymousUploads from YT had one with nitrotetrazole. Yet he still chirps about how primaries are important. Consequently, he sounds like a fool. I have 2 more examples like that, but meh...

There is no safe primary alternative and never was. Dextrinated lead azide is the best thing available, but safe manufacturing requires very meticulous control of the crystal size before and after recrystallization.

Rosco Bodine - 29-7-2011 at 07:30

@homes1880 How about you get off your little campaign of ignorance and stupidity regarding the danger of primary explosives since it has long ago worn very thin. You don't have clue one what you are talking about so please stop teaching until you do have a clue. Tens of millions of ammunition cartridges and other devices containing primary explosives as an essential component have
been handled correctly (not mishandled) without even one "just going off" unintentionally, but of course nothing is absolutely idiot proof since always can be found the special idiot who is the exception.

Rosco Bodine - 29-7-2011 at 07:46

You are making the generalizations which are not reconcilable with reality and history. Mishandling of primary explosives is exposing them to stimuli known to cause their initiation when that is not wanted. File that under operator error
and keep it filed there.

holmes1880 - 29-7-2011 at 07:54

@Bodine Are you summarizing all primary explosives in one group? I'll assume commercially accepted. Yes, sure, proper production and handling is always 99.9% safe, but new "pyrotechnics" often come in trying to replicate it, with rather sad results for them.

You can't possibly make an argument about primary's perfect safety after I showed with concrete facts that a strong static spark is enough to detonate lead azide, with a healthy margin of mJ surplus. I'll give you plenty time to rebuttal, but I don't think you have anything concrete.

You've been around since mercury fulminate was a primary of choice, so I can't blame for you for being biased towards primary initiation.

EDIT: I would choose LA based detonator over NONEL, because the latter is an umbilical cord of an initiation. Expensive, and limiting in every way.

holmes1880 - 29-7-2011 at 08:00

You are making the generalizations which are not reconcilable with reality and history. Mishandling of primary explosives is exposing them to stimuli known to cause their initiation when that is not wanted. File that under operator error
and keep it filed there.

You are a Six Sigma type of person and that is commendable. But no commercial handling is error free. A simple Google search of blasting cap accidents, will show a list of examples where some type of error resulted in lost fingers and injuries.

You would want to give some degree of safety to a detonator, not just go by "zero tolerance" approach.

Rosco Bodine - 29-7-2011 at 08:24

You have what you think is a "needed solution" to a mischaracterized problem,
but you fail to recognize that if what you regard is a problem is characterized accurately in the first place, then the dubious need for the problem solution
to a problem that really isn't a problem can be recognized in a practical way
as being a need for a problem solution which does not actually exist.

I am not trying to redefine reality. You are.

The WiZard is In - 29-7-2011 at 10:59

You are a Six Sigma type of person and that is commendable.

Six-sigma? Sorry you worship a false God.

Extracted from —

Science 29 September 2000:
Vol. 289 no. 5488 pp. 2260-2262
DOI: 10.1126/science.289.5488.2260
NEWS FOCUS
SCIENTIFIC PRIORITY

CERN's Gamble Shows Perils, Rewards of Playing the Odds
Charles Seife

Igo-Kimenes is certain that even an extra month of experiments—
about as much overtime as LEP can get without triggering harsh
penalty clauses in builders' contracts—will not boost the data
across the threshold particle physicists use to separate true
discoveries from the chaff of statistical fluctuations: five standard
deviations, or five sigma. The LEP data are languishing in the
three- to four-sigma range, far short of what is needed to declare
a stone-solid discovery.

To physicists and astronomers, the five-sigma rule is the acid test
for judging discoveries and assigning credit. So why do the
physicists at LEP persist when they know they can't possibly make
the grade? Because they also know that reality is a lot messier
than theory. In practice, the five-sigma rule is far from golden.
Discoveries that seem statistically unassailable can vanish
overnight, while flimsier looking findings have entered the award
rosters and the textbooks without cavil. Qualitative factors, such as
the reputation of a team of scientists, whether a finding conforms
to prevailing theory, and how and why the team announces a
discovery, can determine whether it wins the Nobel Prize or
languishes as an also-ran.

Vanishing probabilities

To a statistician, such vagaries may seem absurd. On the surface,
finding a new particle should be little different from figuring out
whether a medication is effective or when a coin is biased.
Numerically, a five-sigma result corresponds to less than one
chance in 3 million that a sighting is due to chance (see sidebar).
Even a much weaker three-sigma result in particle physics means
that the scientists are 99.9% sure that their signal didn't appear
by accident. By definition, then, a mere one three-sigma result in
1000 results is wrong. Right?

Not exactly. “Half of all three-sigma results are wrong,” says John
Bahcall, a particle physicist and astrophysicist at Princeton
University. “Look at the history.” He's right: Not only do a
surprising number of three-sigma results vanish on closer
inspection, but an astounding number of five- and six-sigma results
have done so, too.

In the mid-1980s, for example, physicists at the Organization for
Heavy Ion Research (GSI) in Darmstadt, Germany, looked well on
their way to the Nobel Prize. Two separate experiments had found
peaks in their data, hinting at a new particle in the 600- to 700-
KeV (thousand electron volts) range. It wasn't predicted by the
Standard Model, but the signal was strong—more than six sigma,
corresponding to a one-in-a-billion chance of error. Today, the
mysterious particle is gone forever. “We have given up the
experiments,” sighs GSI physicist Helmut Bokemeyer. “We have
not been able to see what we had seen before.”

What went wrong? Bokemeyer thinks that the GSI experiments
were highly “optimized” to find the peak. In other words, change
the experiment ever so slightly, and the peak disappears, which
explains why the result is so difficult to reproduce. “Otherwise, we
have no idea what it could be,” he says. There are other possible
explanations. For instance, the researchers might have begun an
experimental run and looked for a growing peak to make sure that
the equipment was set up properly. If there was no indication of a
bulge in the data, they would change aspects of the experiment
and try again.

Some physicists believe that this habitual restarting of the
experiment may have introduced an unintentional bias into the
results. Subtle statistical effects like this, or problems with
equipment, or a slight error in calculation, or an overlooked source
of conflicting data, can throw off statistical calculations in a
tremendous way. “It's the systematic errors that kill you,” Bahcall
says. Bahcall knows that the perils of failure against the odds
stretch far beyond particle physics: Seven years ago he saw it
strike on a cosmic scale.

Vanishing planets

“It was the thing that one fears more than anything else in one's
scientific life, and it was happening,” says Andrew Lyne, an
astrophysicist at Jodrell Bank Observatory in Manchester, U.K. “I
certainly at the time thought that it was the end of my career.”

In January 1992, Lyne was celebrating a monumental discovery.
He and his team had spotted what appeared to be the first planet
circling a foreign star. Their radio telescope had found a pulsar
whose clocklike pulses sped up and slowed down in a way that
suggested it was being tugged around by an invisible orbiting body.
“Indeed, based upon a straightforward statistical analysis, the
effect was very highly significant—hundreds of sigmas, a
certainty,” Lyne says. “We did all sorts of tests on the data and
tried to think of all the possible ways we might be making a
mistake.” After finding their procedures sound, the team published
their discovery: the first extrasolar planet. “It received a lot of
interest, as you can imagine, from the media and others,” he says
.
Bahcall, then president of the American Astronomical Society,
called a special session together to discuss the discovery at the
society's annual meeting. But then disaster struck. “Ten or 12 days
before I was due to give that talk, I discovered the error and the
true source for the periodicity,” Lyne says. “It was rather subtle.”

When timing signals that come from pulsars, astronomers have to
correct for Earth's motion around the sun, which introduces a tiny
periodic distortion in the signal. To save computer resources,
Lyne's group used an approximation of Earth's orbit for the
preliminary calculations. For a more detailed analysis, they
planned to switch to a more accurate model and redo their work
from scratch. Unfortunately, with one of the 200 or so pulsars that
they looked at, they forgot to perform the more accurate
calculation and based their conclusions on the rough
approximation. “The full high-precision analysis was not carried
out,” Lyne says. The slight inaccuracy in accounting for Earth's
orbit led to a periodic signal that mimicked a planet around the
pulsar. Hundreds of sigmas crumbled to dust just before Lyne was
to present his findings.

Lyne gave a presentation anyhow—a retraction. “It was an
extremely difficult time,” he says. “It was a large audience of
extremely eminent astronomers and scientists.” But at the end of
his presentation, the audience broke out into a long, loud round of
applause. “Here I was, with the biggest blunder of my life and …”
Lyne pauses, gathering himself. “But I think that many people have
nearly done such things themselves.”

Lyne's reputation didn't suffer; other planet hunters weren't quite
so lucky. Peter Van de Kamp of Swarthmore College in
Pennsylvania will always be known as the one who found the planet
around Barnard's Star. It was a planet that made it into the
textbooks, even though it didn't exist.

Vanishing chances

As in the heavens, so, more subtly, on Earth. Going by statistics, if
physicists discovered a new five-sigma particle every day,
mistaken sightings ought to turn up about once every 10,000
years. In fact, the history of high-energy physics is littered with
five-sigma mirages. One was the “split A2,” an unexpected double
peak that, in the 1960s, seemed to signal the existence of two
particles where only one was expected. “It was believed by
everybody,” Bahcall says. But as scientists made more
measurements, the two peaks filled in, and the mysterious second
particle vanished. The story replayed itself in the early 1980s,
when physicists at Stanford, at DESY in Hamburg, and elsewhere
found something that looked remarkably like a Higgs boson at an
energy of about 8 giga electron volts (GeV), well short of the 114
GeV where CERN's current Higgs candidate lurks (Science, 31
August 1984, p. 912). The discovery, dubbed the zeta particle, had
a five-sigma significance, but it didn't survive for long. “They kept
measuring, and it disappeared,” SLAC's Riordan recalls. Physicists
on the zeta particle team still suffer from the memory.

Decades of such reverses have taught experimental physicists that
five-sigma rules and one-in-a-million errors are not to be taken
literally. “[The statistical analysis] is based upon the assumption
that you know everything and that everything is behaving as it
should,” says Val Fitch, who won the 1980 Nobel Prize in physics
for discovering charge-parity violation in K mesons. “But after
everything you think of, there can be things you don't think of. A
five-sigma discovery is only five sigma if you properly account for
systematics.”

"Lies, damned lies and statistics."

djh
----
"It is essential that persons having explosive
substances under their charge should never
lose sight of the conviction that, preventive
measures should always be prescribed
on the hypothesis of an explosion."

Marcellin Berthelot - 1892
Explosives and their power - Page 47

Attachment: Six-sigma.pdf (164kB)
This file has been downloaded 628 times

holmes1880 - 29-7-2011 at 11:56

You have what you think is a "needed solution" to a mischaracterized problem,
but you fail to recognize that if what you regard is a problem is characterized accurately in the first place, then the dubious need for the problem solution
to a problem that really isn't a problem can be recognized in a practical way
as being a need for a problem solution which does not actually exist.

I am not trying to redefine reality. You are.

No, but you are redefining complex and compound sentence structure. Reality is that accidents happen because primary explosives can't tolerate too much error. Why do you think the Manhattan project engineers went with EBW? Oh oh.

Hey, WiZ, you don't happen to know about accidents related to static electricity? I remember you posted in the ETN accident thread about detonators going off when being tested with volt meter.

Rosco Bodine - 29-7-2011 at 12:45

It is possible that an automobile driver can fall asleep while driving, so according
to your logic every automobile should therefore be equipped with optional countermeasures to address that foreseeable danger. It is also conceivable that an automobile driven by someone who falls asleep at the wheel could go off a cliff and freefall for a thousand feet before striking the ground, therefore should all automobiles additionally be equipped with automatic ejection seats and parachutes to address the foreseeable need? Of course the logic for safety is flawless in its indifference to costs and complexity and practical need which is precisely the kind of "counterfeit intelligence" which motivates so many social and political agendas. But do not pretend that such "engineering" is science, when it is only salesmanship and politics and deception.

The WiZard is In - 29-7-2011 at 12:54

It is possible that an automobile driver can fall asleep while driving, so according
to your logic every automobile should therefore be equipped with optional countermeasures to address that foreseeable danger. It is also conceivable that an automobile driven by someone who falls asleep at the wheel could go off a cliff and freefall for a thousand feet before striking the ground, therefore should all automobiles additionally be equipped with automatic ejection seats and parachutes to address the foreseeable need? Of course the logic for safety is flawless in its indifference to costs and complexity and practical need which is precisely the kind of "counterfeit intelligence" which motivates so many social and political agendas. But do not pretend that such "engineering" is science, when it is only salesmanship and politics and deception.

Well... the Eco Nuts are against transport of nuclear power
reactor waste in well tested containers on account off ....
a truck may fall off a bridge onto a train carrying the
cannisters rupturing them.

djh
----
The Religion of
Global Warming
is not happy.

New NASA Data Blow Gaping Hole
In Global Warming Alarmism

http://news.yahoo.com/nasa-data-blow-gaping-hold-global-warm...

holmes1880 - 29-7-2011 at 13:57

Poor, poor analogy. A more appropriate analogy would be why cars are designed to crush as a way to reduce the impact on the driver and why every automobile now has airbags. Airbags quite significantly upped the costs. You'd think the seat belt is enough!

So far, you've ducked my question of why EBW was used for Manhattan Project and whether lead azide is susceptible to static inside a blasting cap. You gave no response to that because you know you can't debate it.

Rosco Bodine - 29-7-2011 at 14:07

I know but like some other things I know it is not something I care to discuss.

Your problem is you know just enough to mistake what you think for what you know for sure but not care there is a difference and you will argue forever anything you "think" but don't really know, as if there is a debate where there really isn't and you are simply the last one to know.

EBW and "safety detonators" are absolutely nothing new, but after you made your first one and it worked now you are the forums self-appointed expert on safety who like most self-appointed experts don't really know as much as they pretend to know or even may have convinced themselves they know.

Go back to the ETN accident thread and see what you did after the forum owner asked you not to keep posting there ....you just don't know when to shut up.

KemiRockarFett - 29-7-2011 at 15:49

The most primaries will be possible to set of with a static electricity spark. SA will not ignite so easily by a fire steel:

http://en.wikipedia.org/wiki/Swedish_firesteel

So how is the risk than the Ag2C2 . NO3 is pressed and in place in the detonator inside a Faraday cage on top of a secondary.

As I see it the risk is almost zero to get it go from static when charged in the detonator ( not if fuse are going to be inserted afterwards), otherwise tell me why its still a danger. Compare to electronics that is much more sensitive in this ESD bags...

[Edited on 29-7-2011 by KemiRockarFett]

holmes1880 - 29-7-2011 at 16:04

Have you tested it with that firesteel or that's just your assumption?

[Edited on 30-7-2011 by holmes1880]

holmes1880 - 29-7-2011 at 16:46

@Bodine

Not this sh*t again. No sources, references, and subliminal condescension. Try harder, David.

I have made 1 practical, non-primary detonator that works on par with any commercial ones in terms of performance, dimensions, and strength. I don't think you can brag that. In fact, for someone who chooses the keyboard route to experimentation, you are not the person to truly discuss safety. Keyboard doesn't blow up, unless you spill coffee on it.

Just to review your input on static sensitivity of silver acetylide and primaries, here is what you provided us with:

Quote:

Your problem is you know just enough to mistake what you think for what you know for sure but not care there is a difference and you will argue forever anything you "think" but don't really know, as if there is a debate where there really isn't and you are simply the last one to know.

and this,

Quote:

and this revealing piece of information,

Quote:

How about you get off your little campaign of ignorance and stupidity regarding the danger of primary explosives since it has long ago worn very thin. You don't have clue one what you are talking about so please stop teaching until you do have a clue.

.

Spoken like a chemistry keyboard safety expert.

KemiRockarFett - 30-7-2011 at 02:17

Have you tested it with that firesteel or that's just your assumption?

[Edited on 30-7-2011 by holmes1880]

Tried that very many times in the past. If same procedure was done with acetone peroxide it ignited directly , even with guncotton, but the silver acetylide silver nitrate was hard to get going with a fire steel. But it was extremley sensitive to flame.

What do you think about the risk when the detonator is done and the primary is compressed on top of a compressed secondary inside a al-tube.

I think primarys are fun in small amount just as coriusity but dont recommend anybody to use them in playing with explosives. Bye a low inductance capacitor and bulid bridge wire detonators to set of PETN or EN instead.

EAPyrotox - 30-7-2011 at 03:41

I think the spark generated by static electricity (piezo lighter) has nothing to do with the sparks of fire steel.

Sparks of fire steel are only a emission of hot particles in very short time (T° < SA Tmin Ignition) like when you put your finger over a flame, below 2 seconds you do not feel any heat (the matter and its surface has a greater resistance until time Tmin).

When the spark comes from the static energy, there is a stimulating effect on the matter (one can perceive a mini shock wave that scatters the SA crystals in the test piezo lighter), so the igntion come over the shock of the spark (regime DET primary).

I think we can define several types of sparks, especially |Shock vs. heat| and indeed the primary appear to be more sensitive in a short time to a shock stimulus.

KemiRockarFett - 30-7-2011 at 05:29

I think the spark generated by static electricity (piezo lighter) has nothing to do with the sparks of fire steel.

Sparks of fire steel are only a emission of hot particles in very short time (T° < SA Tmin Ignition) like when you put your finger over a flame, below 2 seconds you do not feel any heat (the matter and its surface has a greater resistance until time Tmin).

When the spark comes from the static energy, there is a stimulating effect on the matter (one can perceive a mini shock wave that scatters the SA crystals in the test piezo lighter), so the igntion come over the shock of the spark (regime DET primary).

I think we can define several types of sparks, especially |Shock vs. heat| and indeed the primary appear to be more sensitive in a short time to a shock stimulus.

What you trie to say is namned "power" in physics and is measured in W = J/s = Nm/s = kg m^2/s^3

EAPyrotox - 30-7-2011 at 06:15

Yes I know, I dont have accurate measurements of my spark ignition test so I illustrate the explanations with some examples physically correct.
And accurate measurements are not very helpful, they are seen to vary from one batch to another and other variables.

If it stays on SA, its resistance to "POWER" as you say is very thin.

KemiRockarFett - 30-7-2011 at 06:23

Yes I know, I dont have accurate measurements of my spark ignition test so I illustrate the explanations with some examples physically correct.
And accurate measurements are not very helpful, they are seen to vary from one batch to another and other variables.

If it stays on SA, its resistance to "POWER" as you say is very thin.

So how to increas its resistance to static electricity? Is it possible to deflegmatice it in some way not reducing initating properties to much ?
And is it necesarry to do so if the SA is in place and compressed in an detonator?

quicksilver - 30-7-2011 at 06:47

Gentlemen, we DO have some discussion on static testing.

Unfortunately one cannot "increase resistance" to static discharge initiation. The work that proceeded the joule-threshold initiation figures were completed with a clean, well-synthesized sample; so some had thought that if the particulate were "coated" or in some manner kept from direct discharge contact. They [had thought this] would raise the level of production cost (beyond reason), lower the effectiveness, & generally be impracticable. This obviously will not succeed due to the need for complete shielding, the cost, & ruination of the material, etc. The concerns proved realistic.

-> When a certain level of electrical energy has been reached; there is very little on can do to protect free accessed material! However the "self-grounded detonator" and it's associated patents (there are several) appeared to make a marginal difference. A difference, such that, even today certain production techniques of capsule-wall grounding have continued in certain production fields. A few of the patents with capsule-wall grounding do promote a concept of returning the static to it's origin. However in studying these patents there have been comments from some electronic engineering students that only certain conditions would it succeed in providing a margin of safety.

User - 30-7-2011 at 07:18

I have quite some experience with this substance.
What I believe is of great importance that it seems nearly impossible to produce this material twice and actually obtain the same material.
I know this there is no magic involved but it appears that there are a lot of factors that have influence on the final product.
Not only color but also physical appearance seems to vary every single time, even tough I paid a lot of attention to duplicate the synthesis.
I also found that temperature conditions have great impact on the final product.

When it comes to static discharge, either I have always been lucky or I actually never experienced any problems in this field.
Indeed a good subject to touch.
Ironically I did have a little accident caused by friction.
A tiny sample (range of 5 mg) was mixed with MHN(mannitolhexanitrate) upon mixing the sample detonated probably by pressing too hard.
I was very well protected, no harm done.
Scared me though.

quicksilver - 30-7-2011 at 07:29

One complexity is the depth of the solution during exposure to acetylene gas. The deeper the solution within the container, naturally, the more exposure to the gas. The vessel (it appears) ideally should be elongated for greater contact & consistent in it's (solution height) depth. When examining the synthesis there are many variables; even the pressure of the delivered gaseous element plays a role as the higher pressure, the shorter the exposure (faster "bubble rise"). Once upon the surface of the solution the actual contact is diminished, thus a very gentle introduction of gas become a variable.

holmes1880 - 30-7-2011 at 08:59

Has it been proposed to completely insulate the primary in a polyethylene or other static insulating materials?
http://www.waterfront-woods.com/Articles/Electricity/static....

Coating/wrapping the capsule in polyethylene would be highly problematic in amateur conditions, but sealing few mg of primary shouldn't be too hard to manage. To help melt through the cover, an ignition mix of your choice can be used- black powder substitutes, DBSP, etc...

gregxy - 30-7-2011 at 12:27

Actually it is possible to greatly decrease the sensitivity to static. In smokeless powder they do it by forming the grains into small balls and coating them with graphite. The current then flows over the surface of the grains without igniting them. Discharges of several joules fail to ignite it.

I suspect the physical properties have a lot to do with static sensitivity. Materials with sharp pointed crystals, high melting points and low ignition energy would be most
sensitive.

If the melting point is above the ignition temperature sensitivity is greater. Consider picric acid and picarate salts. The acid is not flamable while the salts are, yet I would expect the salts to be more stable from a chemical standpoint.

holmes1880 - 30-7-2011 at 15:22

Yes, but somehow they didn't bother to use that for primary initiators, so there might be some kink in this concept. I'd recommend testing primaries in polyethylene for the simplicity/time sake, and then play around with coating small SA pellets with ground up pencil lead. I did not do much research into coating methodologies, but I would assume a small spray on adhesive+ lead powder. That's just the first thing that comes to mind, but research DBSP production process.

AndersHoveland - 30-7-2011 at 16:36

Perhaps treating the substance with graphite spray would help reduce sensitivity to static:
http://www.tedpella.com/technote_html/16051TN.pdf
http://www.aircraftspruce.com/catalog/cspages/drygraphite520...

Rosco Bodine - 30-7-2011 at 17:19

There are a lot of variables which apply to "static sensitivity", most notable would be the state of subdivison of the particles, their mesh size and crystalline form
and the density of the particles in the "reaction zone" through which the static discharge occurs. A compressed pellet is expected to be less sensitive to static discharge due to increasing compaction having the direction of dead pressing .
Dielectric stress then becomes operable as the concern. It is somewhat analogous to the situation where a cloud of coal dust or even ordinary flour can be ignited by a small spark, which would have no ignition effect upon a lump of coal or a hardtack biscuit. Ignition requirement then becomes a different order magnitude several times over due to the distribution and different relative concentration being lowered for the stimuli as an average insult to each individual particle in the sample ....understanding of course that the chain reaction has to first begin with one particle with the local reaction then progressing. Free moisture and high humidity are good for preventing buildups of static charges
because the moisture conducts and provides a bleed path for large potential differences to equalize. Where handling loose powders is a necessity, high humidity, even misting the area with free water from a trigger sprayer can be
a wise precaution. Misting of the technician ankle and shoes and hair on the head
is not a bad idea either, as a bad hair day is better than a final day on the job.

holmes1880 - 30-7-2011 at 20:55

Thanks for the find, Anders. I did not know there was a graphite spray. I guess the only variable is how to apply the spray- is it by coating an primary, high density SA pellet all the way around it(assuming it can still ignite with a standard pyro mix) or spray the loose small pile and then gently mix it around. I would go with the former approach because it seems more likely to get a seamless seal that way.

Some of the primary users need to definitely test this method for spark initiation. Spray can be bought cheap online. Since you'll be dealing with a larger pellet size(100-200mg), take apart your piezoelectric igniter and use additional wiring as in this video:

http://www.youtube.com/watch?v=spT2vvOZlvc&feature=chann...

a_bab - 30-7-2011 at 23:43

@holmes
EBW was used for the nuke as any other approach would have been too far in terms of reliable TIMINGS (rather then risk) that were needed to properly detonate the HE shell. Simply put, with any primary approach one cannot reliably initiate simultaneously some 20+ charges with a ns resolution.

It has been discussed before, but I'm too lazy to lookup.

"Conventional blasting caps use electricity to heat a bridge wire rather than vaporize it, and that heating then causes the primary explosive to detonate. Imprecise contact between the bridgewire and the primary explosive changes how quickly the explosive is heated up, and minor electrical variations in the wire or leads will change how quickly it heats up as well. The heating process typically takes milliseconds to tens of milliseconds to complete and initiate detonation in the primary explosive. This is roughly one to ten thousand times longer and less precise than the EBW electrical vaporization." - Yes, I know. Wiki.

As about SA, here you have it: more then 20 years ago I had about 0.5 grams go off accidentaly in a small plastic box. I tried to peel off a label of that box when it went off. The resulted in some minor bruises and an eager need for a find another primary, less sensitive to static discharge. Eventually LA was chosen.

BTW, still typing with 10 fingers.

[Edited on 31-7-2011 by a_bab]

holmes1880 - 31-7-2011 at 01:54

Quote: Originally posted by a_bab

As about SA, here you have it: more then 20 years ago I had about 0.5 grams go off accidentaly in a small plastic box. I tried to peel off a label of that box when it went off. The resulted in some minor bruises and an eager need for a find another primary, less sensitive to static discharge. Eventually LA was chosen.
BTW, still typing with 10 fingers.

Definitely appreciate the info. It really validates TS's concern. I know it was 20 years ago, but you wouldn't happen to remember if you had a carpet in your quarters, whether it was a dry time of the year, or other things that may have caused a build up of a strong spark? And yes, it was a clever thing to have been keeping only 500mg. Many people mindlessly keep batches of 5-10g, and not even under isopropyl.

About atomic bomb, makes sense that timing could have been a big factor in choosing the initiation system. It was a win/win for them, because they weren't risking cratering the whole project cite plus thousands people living there, and they got a initiation system that met the requirements. Although, the EBW system was first pioneered by a Soviet Russian guy who was skeptical of primaries. MF was probably still used at the time, so I don't blame him.

a_bab - 31-7-2011 at 02:26

holmes, there was no carpet as I was outdoors. I can't remember the clothing but it must have been cotton, so no static issues either. The plastic was probably some PS as it broke in sharp shards. There was no serious damage besides the minor bruising. The hand did feel like being struck with a hammer though.

PS plastic + rubbing = small sparks. The truth is, SA is so sensitive to static discharges that I bet ANY kind of spark should be able to set it. Another fact was that the interior of the box was "dusted" with SA. Also, the SA was rather old (a week), thus grey in color. It was also very dry.

At any rate, I would not reccomend anyone SA for a primary.

quicksilver - 31-7-2011 at 05:22

Frankly - crushed carpet, low to no humidity (in certain altitudes as well) can yield up some serious static. Perhaps the worst I have personally seen was a summer, zero humidity at above 4000-4500 ft elevation and heavy "older" compressed carpeting. One could SEE the spark from body to ground. In conditions similar to those, there really isn't a method to "safe" the situation. Shoe soles could be either rubber or smooth leather: it doesn't seem to alter it. I have no idea what the energy rate was (due to discharge variations) but I believe it would be possible to ignite high-end fuse grain BP; it was strong enough to to make contact painful. Humidity could have an inhibiting effect but air-conditioning would ruin it.

Rosco Bodine - 31-7-2011 at 06:47

It was a win/win for them, because they weren't risking cratering the whole project cite plus thousands people living there, and they got a initiation system that met the requirements. Although, the EBW system was first pioneered by a Soviet Russian guy who was skeptical of primaries. MF was probably still used at the time, so I don't blame him.

You just keep harping on a matter where your ignorance is showing. Do you not know that electrical detonation of nitroglycerin predates the use of the fulminate blasting cap for detonating NG and the use of primary explosives is the more modern method? Your continual harping on your obsessive and disproportional estimation of the danger of primary explosives is a neurosis comparable to that pseudo debate which was Edison's tirade against the use of alternating curent for commercial electric power distribution grids, simply because of Edison's vested interest or illogical preference and misbelief that somehow DC was superior to AC.

Ultimately where your tirade against the evils of primary explosives is leading is to the abolition of all firearms using
ammunition cartridges which could just "go off" unexpectedly, therefore only battery powered rayguns
will be allowable for citizens, while doubtlessly all the cops and soldiers and other government agents will be staying
with the old fashioned weapons which work very reliably and safely just as they always have.

Really I do not want to hear any more shit from you holmes1880 .....go spread your ignorance elsewhere
with your sweeping general condemnation of primary explosives as being some unacceptable danger which must be eliminated ......because the snake oil you are selling here in this forum is a damn lie.

http://www.youtube.com/watch?v=0R_XMQTOcg8 Pipeline

Knowledge has been put in the pipeline .....open the valve and get wet ......or get lost

[Edited on 31-7-2011 by Rosco Bodine]

KemiRockarFett - 31-7-2011 at 07:44

The primary in firearms are well protected. Therefore how big is the risk of static to initiate Ag2C2.AgNO3 compressed in a sealed al-capsule above compressed PETN?

As I see it the risk for static to set it off is zero here. Wrong?

The risks are as I can se it under the manufacturing of the cap.

Rosco Bodine - 31-7-2011 at 08:06

People can be careless and stupid at doing anything, ignoring the known risks and taking their chances with consequences, but that doesn't make the argument that their ignorance somehow translates to an unpredictability about about
the currents in the water where they are drowned, or the gasoline that burns them to death. People do encounter "anomalies" that are one in a million .....
but that doesn't mean that all wells or streams drown people or that every fuel pump is a land mine. There needs to be a sense of proportion applied by holmes1880 to inject some realism and reality into his perspective so that he may join the rest of us on earth instead of whatever planet it is on which he resides where all primary explosives are somehow dangerously unpredictable. I have many boxes of strike anywhere matches. None of them just independently strike themselves.

http://www.youtube.com/watch?v=PvTnu5-V_YI Games People Play

holmes1880 - 31-7-2011 at 10:16

Well, a dry day provides good medium for a spark to travel through. I don't know if scratching off a label on a rigid plastic box is the same as rubbing a plastic bag, but if they are similar, the voltage worked up can be up to 20,000. Considering that only 3,000V equates to .25mJ of energy, there was probably spark 3-5 times that, which would be enough to initiate lead stypnate or SA.

@Bodine. Are you taking all the necessary precautions with your keyboard today? I hope you sprayed your hair and feet to prevent static discharge before sitting down to type at your trolling station. You've been a useless troll in most threads EXCEPT for your beloved primary synth threads, so you should go back there where you can put your time to better use. Pal, we are not running a perfect factory here, so people will get a bit relaxed from time to time doing their amateur testing. Here is a clear example of a primary that is dangerous, both on paper and we now know in practice. This was just one report from Energetics section member. There are many more unaccounted reports we'll never hear about. I didn't say every primary was terryfing-lead/silver azide and maybe DDNP are acceptable for amateur use. LA is the most time-friendly to make and has a static threshold 7-10X that of SA. Someone ought to do piezoelectric spark test on LA, I'm about 99% sure it won't initiate.

Unlike you at your keyboard, I tested 7 pyro-based blasting caps yesterday, 1 was with a 20g kinepak charge underwater. The 6 caps were tested in an empty plastic gallon can filled with sand because I do testing in a fire exit stairwell. All were successful in either shredding apart a 357 Mag brass cartridge tied to the cap or initiating the kinepak. DDT concept of dense plug formation is very much real.

Rosco Bodine - 31-7-2011 at 10:48

The safety troll certainly isn't me but displacement is a common symptom of a neurosis. And with regards to the perfect factory example, you simply underscore the point that a relaxed song in the head approach instead of a practical situational awareness is what kills people, whether they are crossing at a crosswalk or doing anything else where a misadventure may occur. Amateur is just that ....amateur...in knowledge and in practices....but not all amateurs are equal in their recklessness or ignorance. It is ultimately Darwinian, you place your bets based on what you think is smart, and roll the dice hoping you were right.
Having ten fingers, eyesight, and a life in this world when you pick up the dice, doesn't mean the same math will be your blessing when the tumbling dice stop rolling. All your tests don't amount to shit if you can't objectively interpret your
own data within the experiment as well as in perspective of the larger knowledge of the art. You have tunnel vision which you mistake for panoramic. You can pull loose a sparkplug wire and set aflame a piece of paper with it by putting the paper in the arc path. That doesn mean that every book on every library shelf is at risk of ignition when you do your little experiment. The locality of the specific reaction zone and the condition operable there is highly specific and qualified,
and so is the susceptiblity of various things to ignition by electric discharge.
Even stadardizing of a test to fit a particular model would be somewhat an abstraction. Aircraft are regularly struck by lightning, even aircraft that are armed warplanes, but it a rarity that a lightning strike would cause an aircraft to explode in midflight. How would you reconcile that with your theory of susceptibility
to unitended detonation? There has been no argument from me that there are different mechanisms and pathways to detonation and this has been discussed for years without missing any substantive "discovery" on which you seem to have assigned yourself a mission to enlighten us. You are simply biased and you let that bias cause conclusions which are without validity. Maybe you are seeking to make amateur experimentation with energetic materials "idiot proof" .....well good luck on that.....but bad information is not helpful. There is also a lot of gray area which is a matter of interpretation for tests and models being translated to guidelines for actual handling procedures. Truly the idea that chemistry, particularly chemistry involving energetic materials, is something so simple that any idiot can safely do it, is an illusion that will continue delivering painful lessons
with missing fingers, eyes, and lives which are witness to a different reality.
Not everyone is fit to be an aircraft pilot either, or a hunter, or a soldier or
many other specialized pursuits and the truth is that some people are not temperamentally or intellectually suited to such pursuits. Not everyone is even fit to be behind the wheel of a car, but ask a lot of them and they would be the first to say it is so simple any idiot can do it, even if they could not pass a driving test.

holmes1880 - 31-7-2011 at 11:36

I agree 110% that very few people have the right demeanor and situational IQ to work with HE. Anyone under 20 should postpone testing of energetics. Age isn't a qualifying safety requirement, but teenagers tend to underestimate the severity of consequences of dangerous acts and overestimate their own judgement and abilities.

Quote:

Do you not know that electrical detonation of nitroglycerin predates the use of the fulminate blasting cap for detonating NG and the use of primary explosives is the more modern method?

.

Liquid blasting cap sounds like a one shitty idea. It probably made MF seem like a safe alternative. Bhahaha. Hey, BP blasting cap used to detonate NG also predates that. They were messing with a lot of impractical things back then, what else is new...

Rosco Bodine - 31-7-2011 at 11:57

There was no liquid blasting cap used, just two wires to a spark gap and I think it was a Wimhurst machine with Leyden jars ....they zapped the crap out of the NG and bingo! That'll do it ....and still does actually, if anyone cares to try it...but I'm not going to lay out a step by step and haven't tried it to confirm. I have misplaced my Wimhurst machine and Leyden jars. Now where are they.

holmes1880 - 31-7-2011 at 12:13

Ahhhh..no cap, just wires and an aluminum bottle of NG. Humm. How about PGDN instead, that could be interesting. It would be a booster and a blasting cap all in one. I may suggest it to a young experimenter with electrical savvy.

[Edited on 31-7-2011 by holmes1880]

Rosco Bodine - 31-7-2011 at 12:22

Wizard should have weighed in on this one since it was posted years ago at ye olde alt.eng.explosives newsgroup IIRC. The story went a ball of cotton
compressed in an empty .22 shell and wet with NG could have a piece of coax used as an HV lead and spark gap across its cut end pressed against the NG wetted cotton, with the other operator end of the coax attached to a stun gun
or an auto ignition coil pumped by a CD discharge as a one shot and this
little gadget reportedly would high order on throwing the switch.

holmes1880 - 31-7-2011 at 18:10

This is what I meant when I said people keep 5-10g batches of SA.....in a darn plastic baggie. If that catches a spark, you won't be counting to 10 using fingers on your hands. The picture is a courtesy of "unclefesterscrew1", a pyro on YT. He later switched to LA/mannitral blasting caps.

[Edited on 1-8-2011 by holmes1880]

User - 1-8-2011 at 00:42

I would be heavily concerned about static discharges in the picture above.
I really wouldnt mind if the person that made this bag blew his hands off.

Also I am wondering, this SA seems awfully grey, so that must mean that there are more products here than only SA.
It would be really awesome if someone has the time and equipment to actually do a full spectrum analysis of such a batch.
Ill just stick to hammering the fact that I dont really believe in any decent solution as long as there is no actual data of the material that is used.
I bet most people just use calciumcarbide to produce their SA, asking for contaminations, asking for instability and probably for higher risk of static electric accidental detonations, espically in these quantaties.
My own batches never exceeded 1000 mg, which imo exceeds even the risk I would want to take.

Btw Does anyone actually discharge himself before touching explosives, people can carry quite a charge themselves?

[Edited on 1-8-2011 by User]

KemiRockarFett - 1-8-2011 at 01:57

This is what I meant when I said people keep 5-10g batches of SA.....in a darn plastic baggie. If that catches a spark, you won't be counting to 10 using fingers on your hands. The picture is a courtesy of "unclefesterscrew1", a pyro on YT. He later switched to LA/mannitral blasting caps.

[Edited on 1-8-2011 by holmes1880]

This looks like a binary explosive based on Al and not any Ag2C2. AgNO3. As the DS have a whiteish coulor.

To store primary explosive in this way, if its a primary in the zip bag , is for idiots.

Store it under water and DONT believe that its safe because of the water. Water reduces some risks but not all.

The best is to solve the primary, if possible , therefore for example if expermenting with acetone peroxide it should be stored in acetone solution.

On topic,, what about the risks with static AFTER the cap is finnished and the primary is compressed on top of the seconary in an al-capsule.

holmes1880 - 1-8-2011 at 02:32

I know it was SA, because it is a still from a video where the kid was testing out caps with it- he showed it packed in a pen tubing and set off on a piece of wood. Maybe he did add aluminum to it or maybe it was exposed to light or just contaminated.

Water storage would prevent static accidents, but mechanical accidents could still happen. And as far as pressing it inside Al cap, well, I am really not sure if that would make a difference, but I'd expect a static spark to make its way through thin aluminum. Maybe al may help disperse the spark's energy, but that is my speculation.

quicksilver - 1-8-2011 at 06:57

Often, silver salts like that exposed to UV could discolor that badly. Considering the "manufacturing background" I'd think it was even not that unique. What becomes of it chemically from strong UV exposure is interesting however.

I believe that at certain levels of static there may be few ways of maintaining safety aside from semi-permanent grounding, etc. Frankly I believe that the USBoM had some recommendations but that was from a time when most all was experimental & surety was unconfirmed (refrigeration, etc).

[Edited on 1-8-2011 by quicksilver]

KemiRockarFett - 1-8-2011 at 07:34

I know it was SA, because it is a still from a video where the kid was testing out caps with it- he showed it packed in a pen tubing and set off on a piece of wood. Maybe he did add aluminum to it or maybe it was exposed to light or just contaminated.

Water storage would prevent static accidents, but mechanical accidents could still happen. And as far as pressing it inside Al cap, well, I am really not sure if that would make a difference, but I'd expect a static spark to make its way through thin aluminum. Maybe al may help disperse the spark's energy, but that is my speculation.

1) If its real Ag2C2. AgNO3 in this zip bag this person is insane.
2) The compound Ag2C2. AgNO3 is not that sensitive to light, offcourse direct sun light will be bad. This guy must have done some serius error under synthesis.
3) The primary explosive compressed in an al-tube should be in some kind of Faraday cage and therefore the risk of static to set it off should be very small.
4) How the double salt is compatible with other chemicals, for example mixed with aluminium and a drop of water, is for you to explore and report.

[Edited on 1-8-2011 by KemiRockarFett]

Bot0nist - 1-8-2011 at 08:57

*snip
3) The primary explosive compressed in an al-tube should be in some kind of Faraday cage and therefore the risk of static to set it off should be very small.
*snip

[Edited on 1-8-2011 by KemiRockarFett]

I thought this as well, but The Wizard is IN recently pointed out to me that it has no bearing on static. Only em fields.

"Such an enclosure blocks out external non-static electric fields." - wiki

Do you have source of the Faraday's cage phenomenon being used to help reduce the risk of static discharge?

EAPyrotox - 1-8-2011 at 09:02

It is rare to have a totally white precipitate with calcium carbide method, I have the same result SA like him even following a perfect synthesis, look like gray as many other people.

http://en.wikipedia.org/wiki/File:Silver_acetylide3.jpg

KemiRockarFett - 1-8-2011 at 09:08

It is rare to have a totally white precipitate with calcium carbide method, I have the same result SA like him even following a perfect synthesis, look like gray as many other people.

http://en.wikipedia.org/wiki/File:Silver_acetylide3.jpg

Temperature and ammonut of nitric acid in the maxium 10 % solution of AgNO3 ?

EAPyrotox - 1-8-2011 at 09:30

I realize the synthesis at 70 ° C, I use 45ml H2O + 35 ml NO3 (60%). 80ml.
=> the equivalent of 3/4 (60ml) H2O and 1/4 (20ml) NO3 (conc. 100%). 80ml.
with 1gr of pure silver of course.

But the gray precipitate are due to a non-pure acetylene gas.

KemiRockarFett - 1-8-2011 at 12:49

I realize the synthesis at 70 ° C, I use 45ml H2O + 35 ml NO3 (60%). 80ml.
=> the equivalent of 3/4 (60ml) H2O and 1/4 (20ml) NO3 (conc. 100%). 80ml.
with 1gr of pure silver of course.

But the gray precipitate are due to a non-pure acetylene gas.

This should be almost okey but first test to increase the temperature to 80-90 degrees C to increase pE. Secondly, if necesarry, increase the nitric konc, but stay well below 10 % weight % ragarding silver nitate or you will , as you know , get the 1:6 compound.
The sulfide and phoshine compounds will not survive when you rise pE , and probably you will end upp with a more whitish product.
Actually you can run with copper containing Ag alloy , common, as the copperacetylide will not form at this conditions.

KemiRockarFett - 1-8-2011 at 13:00

Quote: Originally posted by Bot0nist

My reference is that zip bag for electronic components gives ESD protection for the components inside the zip-bag, and therefore i assumed that a blasting cap of metal will work in the same way as charges prefer to be on the outer surface on the so called faradays cage. BUT if I am wrong some heavy physisits on the forum may tell us more.

watson.fawkes - 2-8-2011 at 06:59

Faraday cages work because mobile charges on the outside surface move, thereby changing their induced field to cancel out any on the inside. When those charges can't move fast enough, you get a failure to shield outside fields. In the case of ESD protection bags, they're not great conductors, but they do bleed off charge difference over a time to prevent electrostatic buildup. A metal can is even better at that. One of the reasons that ammunition primers are pretty insensitive to ESD is exactly because they're inside metal cans.

This isn't the whole story, though. Faraday cages protect against outside electric fields, but not so much ones generated inside the cage. Consider an electric dipole (a pair of separated opposite charges) inside such a can. You will get charge motion on the surface that will cancel that dipole, but only as it appears to the outside. On the inside of the can, there's still an induced electric field.

Why does this matter? Triboelectric and piezoelectric dipoles is why; that's friction and strain. If you've got mechanical motion going on inside a can, you can get internal ESD purely from the fields induce by motion. So you've got to manufacture the primer and formulate its contents with an eye to eliminating such motion: pressing and binders, for example.

Bot0nist - 2-8-2011 at 07:20

Thank you for clearing that up watson.fawkes!

The WiZard is In - 2-8-2011 at 08:20

Quote: Originally posted by watson.

A metal can is even better at that. One of the reasons that ammunition primers are pretty insensitive to ESD is exactly because they're inside metal cans.

Forsooth! Inside metal cans. Where did you get this
gem from?! The closest they get to being in metal cans
is the presence or lighting rods.

Re la Faraday Cage - comparing static electricity and EMF
is like comparing Mamey apples and Mamoncillo fruit, i.e.,
there is none.

The only hazard of EMF is when blasting with long leg wires
for more that you probable want to know 'bout it....
I commend the Institute of Explosives [IME] Safety
Library Publication Nol. 20.

Safety Guide for the Prevention of Radio Frequency Radiation
Hazards in the Use of Commercial Electric Detonators. (Blasting
Caps) [Sigh. I had to pay for a copy years ago ... now you
can DL their entire Safety Library Pubs for free!]

http://www.ime.org/ecommerce/downloads.php

Byda reminds upon my mind. Years ago when Jack Drewes
CEO of American Fireworks News and I visited the Goex black
powder plant, then at Mossic PA. I took notice their fine
collection of telephone poles with lightning rods atop. They also
had a hide on the hillside for employees to take shelter in the
event of a thunderous lightning storm. One of their wheel mills
had gone Kaboom a bit before our visit. I don't remember it
being the result of lighting.

I suffer from the believe the use of sferics meters is not
uncommon at explosives plants.

djh
----
When struck by lightning it almost invariably explodes violently.

On the night of June 30, 1898, a violent storm raged in Belgium accompanied
by many electrical discharges, one of which struck the black powder factory in
Clermont-sur-Meuse An explosion followed immediately. Three buildings with
their contents of about 865 kilograms of black powder in various stages of
preparation were destroyed by the lightning discharge and the accompanying
detonation. There was no loss of lives. In view of the location of the factory in a
deep valley surrounded by high trees, where a stroke of lightning had never
been observed, it was not provided with lightning rods. On examination it was
found that the lightning had first struck a very tall acacia tree and stripped it
entirely of its bark. It then sprang to the belt gearing only a few meters distant
and traversed its entire length, sending secondary discharges into the various
factory buildings. This is the only explanation of the fact that three separate
buildings blew up at the same instant, for only one detonation was heard. After,
this accident the supposition of the protection offered by the high trees was
abandoned and lightning rods were put on all dangerous buildings.**

**Mem. poudr. salp., X, 59; 1899-1900.

Dr. H Brunswig (1909)
Explosives: A Synoptic And Critical Treatment Of The Literature Of The
Subject As Gathered Form Various Sources
Translated and Annotated by
Charles E Munroe and Alton L Kibler
John Willey &B Sons
1912

----------
100 YEARS AGO

Major Jameson was found lying on his face in a field quite dead.

Around him, in a radius of several yards, were his clothes and
boots, which had been torn and scattered about in an
extraordinary manner. The lightning appears to have struck him
on the right side of the head tearing his cap to pieces and
burning his hair off. It then passed inside his collar down the
front of his body and both legs into his boots, which were torn
to pieces, and then passed into the ground, making a hole about
eighteen inches in circumference and three inches deep. His
collar was torn to pieces, the front of his shirt was rent into
ribbons, the jacket and under vest were literally torn to shreds,
and the knickerbockers he was wearing were literally stripped
from him and scattered on the ground. His stockings and
gaiters were similarly torn to pieces, and on the boots the
lightning had a remarkable effect. They were burst open, some
of the brass eyelet holes were torn out, the nails were forced
out, and the soles torn off. The skin had been torn off the
chest, and the right leg was torn and blackened; blood was
issuing from the mouth and right ear. It is difficult to account
for these appalling effects, or to explain why the electric
discharge should produce widely different results upon different
[time permitting I'll hunt down the missing text.]

Nature 9 September 1897

watson.fawkes - 2-8-2011 at 10:50

Forsooth! Inside metal cans.

Wee little metal cans. Surely you, of all folk on this board, can appreciate a bit of language-stretching.

EAPyrotox - 4-8-2011 at 07:24

HI,
Anyone have a perfect synthesis for SA with ag, HNO3 method.
I find mine incorrect, What do you think of that?

http://woelen.homescience.net/science/chem/exps/silveracetylide/index.html

The WiZard is In - 4-8-2011 at 08:23

Quote: Originally posted by watson.fawkes

Forsooth! Inside metal cans.

Wee little metal cans. Surely you, of all folk on this board, can appreciate a bit of language-stretching.

Working on my post-doc in serendipitous discovery ...
have (re)stumbled upon this.

Explosion; Circumstances attending an , in the Press House and
Incorporating Mills, which occurred at the factory of the
Sedgwick Gunpowder Co., Ltd., at Sedgwick, near Kendal,
Westmorland, on June 23, 1906. By Major A. Cooper-Key,
H.M. Inspector of Explosives.
Journal of the Society of Chemical Industry 25 [20] 1067.
November 15 1906

DURING a severe thunderstorm, which passed over the
factory in question, the cake press house and four
incorporating mills exploded. The explosions were
undoubtedly due to lightning, and they all took place at the
same instant, and there would appear to have been at least
three separate strokes from the same flash. Of these three
strokes, viz., those which struck a poplar tree in front of one
of the mills and the copings of another mill respectively,
could not have been due to surging, sideflash, or other
inductive effect, as the material struck was in each case
non-conducting, but it is not impossible that the presshouse
was blown up by an induced spark or flash in the interior of
the building. There is, therefore, evidence of the somewhat
rare phenomenon of a divided flash striking simultaneously
two unprotected' objects nearly 100 yards apart, whilst at
the same moment, a third object, the press house, 40 yards
from the nearer of the other two, and protected by
conductors, was separately exploded either directly or
indirectly by a portion of the same flash. A description is
given of the " cage " system of lightning conductors
recommended by Major Cardew for explosives factories in
South Africa, where thunderstorms are so frequent and
severe. The following modification of that system is
recommended as securing a reasonable degree of safety, in
the case of explosives factories in Great Britain. Two or
more well-earthed conductors should be raised as high as
practicable on poles standing a yard or two away from the
actual building. These should be connected near their upper
terminals by means of barbed-wire cables. The " finials "
should consist of as many points as possible, and all joints
should be made thoroughly good mechanically, and soldered
in addition. If the conductors are actually in contact with the
building, there is an increased risk of a portion of the flash
seeking an alternative path through some metal inside the
building, with disastrous results, many, if not most, building
materials being better conductors than dry air, and,
moreover, sharp bends are not so easily avoided as when
separate poles are used. Internal masses of metal should be
thoroughly well connected to each other and to earth, and
should be situated at as great a distance as practicable from
the conductors. All external metal, such as rain gutters, lead
flashing, iron door plates, &c., should be connected to the
conductors or otherwise thoroughly earthed. The press
house under consideration in the report, was protected by
two conductors of copper tape of the usual weight, one at
each end of the building, connected along the ridge and well
earthed in wet soil. Neither the metal inside the building nor
the pressure feed pipe leading into it from the pump were
connected to earth, and the conductors had not been tested
for nearly three years. Moreover, the copper tapes were
attached to the building instead of being raised on poles
some little distance away. The building was, therefore,
exposed to danger from all the sources mentioned above.

—G. W. McD

quicksilver - 4-8-2011 at 09:34

The above article (Journal of the Society of Chemical Industry 25 [20] 1067.) sounds similar to the "FARADAY CAGE" used to protect various things (& people) from high level discharge (see Tesla Coils, etc).

~~~~~~~~~

I did a little reading about what level of static electricity it would take to initiate various primaries & this is NOT a simple question to answer. To cut to the chase it could take as little as 1/10 of a joule at 6Kv but the actual number means very little as you all pretty much realize by now.
"Static" electricity means just that. Static means "not moving", at a charged state, capacitance in some thinking. According to US OSHA testing:
As little as 0.2 millijoules may present an ignition hazard; such low spark energy is often below the threshold of human visual and auditory perception.

Typical ignition energies at minimum are:

0.017 mJ for hydrogen
0.2-2 mJ for hydrocarbon vapors
1–50 mJ for fine flammable dust
40–1000 mJ for coarse flammable dust
An interesting feature is that there MAY be little difference between primaries and little differences between primaries and flammable dust for ignition causation (Wiley InterScience & OSHA). So what level may present an ignition potential? It seems that .100 joule & 6kv will do it but what about any lower? Are we still bound to voltage carrier current to arrive as a set number? It appears that we can't say what specifics WILL ignite specifically but we can say that there is a fairly wide field that may encompass this. It appears that the TYPE of primary has less influence than the physical composition (dust). That's perhaps a reason why lead azide (which is often small enough to air float and flash w/ 2um Al are so suitable for this danger).

I believe this may be too dependent on size of particulate, area of particulate (is it floating is air, etc) and area of exposure. It DOES appear that the old idea that "if you can feel it: it will ignite" is false. This, then is a serious cautionary note. You no longer may be dependent on the "feel" of static charge to use as a warning sign.

"Wiki" has some REFERENCES that may be valuable. Yet it seems it might be physical features & not so much the chemical that make up the "seriously sensitive to predictably dangerous" issues.
http://en.wikipedia.org/wiki/Static_electricity

The WiZard is In - 4-8-2011 at 10:24

Quote: Originally posted by quicksilver

The above article (Journal of the Society of Chemical Industry 25 [20] 1067.) sounds similar to the "FARADAY CAGE" used to protect various things (& people) from high level discharge (see Tesla Coils, etc).

Well... the most common use of Faraday's cage is to keep
RF energy out/in, therefore they are completely (very)
sealed to RF. Remember we? Yes! The relationship of frequency
and wavelength.

Granted the frequency/wavelength of DC is zero, however,
in this context this count for naught.

Some have posited the reason static discharge ignites explosives
is mechanical not electrical.

A Heuristic Approach to Spark Ignition of Reactive Solids

http://www.sciencemadness.org/talk/viewthread.php?tid=13719

Page down.

At 19 pages I am not willing to scan this.

Here dobe a FC for sale on eBay.

http://tinyurl.com/3s8ojr8

I am not impressed with it.

The only one I have ever seen/stood next to was ca. 1960
it was v/ well made. All copper/brass.

holmes1880 - 4-8-2011 at 17:27

Particle size is surely critical, no doubt. But that characteristic is mostly linked to the compound itself, no? Lead styphnate:

"Lead styphnate is particularly sensitive to fire and the discharge of static electricity. When dry, it can be readily detonated by static discharges from the human body. The longer and narrower the crystals, the more susceptible lead styphnate is to static electricity." (http://design.caltech.edu/micropropulsion/styphnate.html)

SA is in that same ballpark-easy to ignite, and rather detonate, from flame and is static sensitive. If anyone looked at it under microscope, probably found the crystals in little long needles.

watson.fawkes - 5-8-2011 at 06:35

This is just plain wrong. The lower the frequency the electric field, the better a Faraday cage shields it. (I should point out that the Wikipedia page on the subject is also wrong.) For any given cage, the best it performs is at DC, that is, in the electrostatic case. The operation of a Faraday cage is based on Gauss's law. Rather than rewrite everything here, I looked up some online references:

Understanding the Faraday Cage
What Is the Physics of Shields for Electromagnetic Fields and Waves?
http://www.suite101.com/content/understanding-the-faraday-cage-a53389

Replicating Faraday's original experiment, which used electrostatic fields and an electroscope:
http://www.juliantrubin.com/bigten/faradaycageexperiments.html

The WiZard is In - 5-8-2011 at 06:53

Quote: Originally posted by watson.fawkes

You created an answer/criticism for something I did not say/imply.

Actually you are agreeing with me! What I said was
(remembering basic physics - the relationship between
frequency and wavelength) the higher the frequency the
shorter the wavelength, making shielding more difficult. And as
I noted — the frequency/wavelength of DC being zero has no meaning here.

[Edited on 5-8-2011 by The WiZard is In]

watson.fawkes - 5-8-2011 at 08:32

You created an answer/criticism for something I did not say/imply.

Fair enough. But this was not clear to me, not at all.

The WiZard is In - 5-8-2011 at 09:17

Quote: Originally posted by watson.fawkes