Newsgroups: rec.pyrotechnics
From: arno@utu.fi (Arno Hahma)
Subject: Re: Na/KClO3 w/ Vaseline??
Organization: University of Turku
Date: Wed, 5 Jul 1995 10:16:03 GMT

In article <3tavr6$rh1@geraldo.cc.utexas.edu>,
Gerald L. Hurst <glhurst@onr.com> wrote:

>not both.  My question relates to whether the 
>material truly supports a classic detonation head
>or if, instead, it reacts only at the deflagrating
>surface like a propellant, only much faster than

Yes and no. The (per)chlorate/vaseline mixture detonates at about 3000 m/s
at a density of 1.3 g/ccm and about 4000 m/s at a density of 1.5. [J.
Wuorinen, "Räjähdysaineoppi", Otava (1928), Helsinki, Finland, pp.
162-165, in Finnish; T. Urbanski, "Chemistry and Technology of
Explosives", Pergamon Press (1986 reprint), Exeter, Great Britain,
Vol.  3, pp. 277-279].

If you calculate the theoretical detonation velocity assuming 100 %
reactivity, you'll get something like 5000..6000 m/s.  With the mere
3000 m/s there is still a detonation, but only about 30 % of the
material is reacting based on calculations. Thus, the detonation is
highly unideal (i.e. not a classic one) and sensitive to the particle
size of the chlorate (more surface, more contact to the fuel, more fuel
reacting, higher detonation velocity) and to the way the material is
packed and initiated. Also, the nature of the fuel is going to make a
big change - use something like nitrobenzene or dinitrobenzene and
you'll get a considerably higher velocity because shocking the fuel is
not eating so much energy as shocking vaseline.

Potassium chlorate is pretty "neutral" towards shock, it releases some
energy when decomposed, but not enough to sustain detonation. As a
result, you only need to add a little energy to get the detonation
going. But, you need a continous phase of some kind to transmit the
shockwave through the mass without too much attenuation. This
is one of the reasons, why powdered mixtures (like perchlorate/Al or
chlorate/sugar) are so hard to detonate.

KClO4/Al at least does not detonate at all (not even deflagrates
reliably, unless the Al is extremely fine powder), which doesn't mean
it wouldn't be hazardous or wouldn't explode. I have an article
in print about this in Propellants, Explosives, Pyrotechnics and I'm
also going to present information about it in the next ADPA conference
in September.

>Many people might say "who cares," but it is of
>very great interest to me and probably others
>in this forum.

Yep! The same applies to ANFO as well. ANFO also detonates
very unideally with only about 50 % of the material contributing
to the shock energy unless extremely well confined. Again, the amount
of material reacting at the reaction zone (as far as classical
detonation is concerned) is highly dependent on variables like charge
diameter, confinement, particle size, degree of mixing, fuel
composition etc. Good references are C. Mader, "Numerical Modeling of
Detonations", UCLA Press, Berkeley and LA (1984), p. 99 and A. C. van
der Steen et al., "Detonation Velocities of the Non-Ideal Explosive
Ammonium Nitrate" in Propellants, Explosives, Pyrotechnics 15 pp. 58-61
(1990).

Phew, I still owe a couple of followups to you... ;).


ArNO
    2

From: glhurst@onr.com (Gerald L. Hurst)
Newsgroups: rec.pyrotechnics
Subject: Re: Na/KClO3 w/ Vaseline??
Date: 6 Jul 1995 15:54:30 GMT
Organization: Consulting Chemist
Lines: 133

In article <DB8n6r.Fwq@utu.fi>, arno@utu.fi (Arno Hahma) says:

>In article <3tavr6$rh1@geraldo.cc.utexas.edu>,
>Gerald L. Hurst <glhurst@onr.com> wrote:
>
>>not both.  My question relates to whether the 
>>material truly supports a classic detonation head
>>or if, instead, it reacts only at the deflagrating
>>surface like a propellant, only much faster than
>
>Yes and no. The (per)chlorate/vaseline mixture detonates at about 3000 m/s
>at a density of 1.3 g/ccm and about 4000 m/s at a density of 1.5. [J.
>Wuorinen, "Räjähdysaineoppi", Otava (1928), Helsinki, Finland, pp.
>162-165, in Finnish; T. Urbanski, "Chemistry and Technology of
>Explosives", Pergamon Press (1986 reprint), Exeter, Great Britain,
>Vol.  3, pp. 277-279].
>
>If you calculate the theoretical detonation velocity assuming 100 %
>reactivity, you'll get something like 5000..6000 m/s.  With the mere
>3000 m/s there is still a detonation, but only about 30 % of the
>material is reacting based on calculations. Thus, the detonation is
>highly unideal (i.e. not a classic one) and sensitive to the particle
>size of the chlorate (more surface, more contact to the fuel, more fuel
>reacting, higher detonation velocity) and to the way the material is
>packed and initiated. Also, the nature of the fuel is going to make a
>big change - use something like nitrobenzene or dinitrobenzene and
>you'll get a considerably higher velocity because shocking the fuel is
>not eating so much energy as shocking vaseline.
>
>Potassium chlorate is pretty "neutral" towards shock, it releases some
>energy when decomposed, but not enough to sustain detonation. As a
>result, you only need to add a little energy to get the detonation
>going. But, you need a continous phase of some kind to transmit the
>shockwave through the mass without too much attenuation. This
>is one of the reasons, why powdered mixtures (like perchlorate/Al or
>chlorate/sugar) are so hard to detonate.
>
>KClO4/Al at least does not detonate at all (not even deflagrates
>reliably, unless the Al is extremely fine powder), which doesn't mean
>it wouldn't be hazardous or wouldn't explode. I have an article
>in print about this in Propellants, Explosives, Pyrotechnics and I'm
>also going to present information about it in the next ADPA conference
>in September.
>
>>Many people might say "who cares," but it is of
>>very great interest to me and probably others
>>in this forum.
>
>Yep! The same applies to ANFO as well. ANFO also detonates
>very unideally with only about 50 % of the material contributing
>to the shock energy unless extremely well confined. Again, the amount
>of material reacting at the reaction zone (as far as classical
>detonation is concerned) is highly dependent on variables like charge
>diameter, confinement, particle size, degree of mixing, fuel
>composition etc. Good references are C. Mader, "Numerical Modeling of
>Detonations", UCLA Press, Berkeley and LA (1984), p. 99 and A. C. van
>der Steen et al., "Detonation Velocities of the Non-Ideal Explosive
>Ammonium Nitrate" in Propellants, Explosives, Pyrotechnics 15 pp. 58-61
>(1990).
>
>Phew, I still owe a couple of followups to you... ;).
>
>
>ArNO
>    2

Arno, I want to thank you for the most excellent posting. Everything
you said tracks perfectly with the mental model I have had of these
non-ideal phenomena for many years.  I was aware of Urbansky's
report of the 3,000 and 4,000 m/sec det velocities, but took them
as overlapping approximations given the one-significant-figure
form.

A related low velocity phenomenon. as you know, is the LVD. I knew
Bob VanDolah and was familiar with his cavitation theory many wears
ago, but there were aspects of some explosives that I found
troublesome.  Basically I was never satisfied with my own attempts
to understand why certain liquids, like nitromethane are so very
resistant to LVD, but detonate ideally in reasonably modest
diameters. There are other energetic liquids which require
considerably greater initiation energy than (sensitized) NM to
shoot at high velocity, but they may go off at the drop of a hat
in a tube of high sonic impedance.  Indeed, it is not too
difficult to find liquids which are almost impossible to drive into
HVD mode when unconfined, but are dangerously sensitive in a hard,
but open-ended cylinder.

Heavily aluminized Astrolite was actually less sensitive to
initiation than the straight material.  Although the Al contributed
significantly to the power, it made it necessary to use a #8 cap
or better to get it into high gear. With a #6 cap, it would let
out an undiminished roar, but not dent a steel plate which it
would otherwise blow a hole through. The low explosions took
place perfectly well in unconfined polyethylene bottles, so
cavitation was not involved.  This same material in steel tubing
would behave in the classic LVD manner. In fact, it killed or
injured several workers one day when an explosion apparently began
in a small diameter SS pipe thread while a wrench was being used on
it (we believe).

Card gap tests with the unconfined Astrolite yielded values of the
order of a cm, but in metal tubes one could use meter-long plastic
rods for the stand-off and still get initiation.

The phenomena described above were also observed in non-metallized
versions of the straight liquid under appropriate conditions. For
instance, I once (and only once) managed to explode an unconfined
charge of the clear liquid with a 30-06 bullet. Not an LVD, but
certainly a low, but complete explosion.

When we discuss mixtures like vaseline/NaClO3 I take it pretty
much for granted that they will shoot faster as the density
increases up to a point, but then will rapidly lose sensitivity/
velocity as the void volume is further decreased. Near absolute
density, I expect the mixture to be practically inert as far as
detonation goes, unless one can cause it to cavitate.  However,
in the case of liquids, I know that an energetic mixture or pure
compound is not only quite likely to explode under confinement,
but may or may not also do so at modest velocity even if it is
unconfined. Furthermore I cannot predict the behaviour under
confinement from a knowledge of the unconfined sensitivity.

There is not so much a single question lost in these ramblings
as there is an invitation for some light-shedding on the general
subject of non-ideal detonations in liquids and solid as well as
liquid heterogeneous fuel-oxidizer mixtures.

BTW have you ever seen a clear case of LVD in heterogeneous
liquids? I've tested some aqueous emulsions at up to 6" in heavy
steel pipes without getting a stable LVD or HVD.

Jerry

From: glhurst@onr.com (Gerald L. Hurst)
Newsgroups: rec.pyrotechnics
Subject: Re: Na/KClO3 w/ Vaseline??
Date: 8 Jul 1995 03:29:45 GMT
Organization: Consulting Chemist

In article <3tiev0$9eu@odo.PEAK.ORG>, billn@PEAK.ORG (Bill Nelson) says:

>Gerald L. Hurst (glhurst@onr.com) wrote:
>
>: BTW have you ever seen a clear case of LVD in heterogeneous
>: liquids? I've tested some aqueous emulsions at up to 6" in heavy
>: steel pipes without getting a stable LVD or HVD.
>
>Hm, I don't know if you consider them heterogeneous, but both NG and
>a 50:50 mixture of NG and NGc undergo LVD if lightly initiated. Have
>you checked either of those?

I would consider NG and its EGDN (NGc) mixtures as homogeneous.  They
do indeed show great sensitivity to LVD.

>I believe Taylor did some studies on this, in the 50s.
>
>It is interesting that NG can go LVD/HVD/LVD, depending on the diameter of
>the charge. 
>
>It may be that the porocity of the explosive is critical, in some cases. If
>no pores, then no LVD may be possible. This might explain the "dead pressing"
>problem of some explosives, such as mercury fulminate. 

Actually, liquids which undergo LVD will do so at remarkably high
pressures.  I have shot some of them at 12,000 psi.  Materials
which tend to shoot only HVD are subject to dead-pressing.  
Sensitized nitromethane, for instance loses its cap sensitivity
under high pressure in a steel bomb.  NM is very resistant to
LVD except (perhaps) in large quantities.

Intstitial spaces in solids and bubbles in liquids have a very
potent effect in sensitizing materials to HVD, but they do little
or nothing to enhance LVD.


Jerry

From: glhurst@onr.com (Gerald L. Hurst)
Newsgroups: alt.engr.explosives
Subject: Re: Detonation or Explosion ?
Date: 28 Jan 1996 00:29:03 GMT

In article <4e89i9$o1p@rs18.hrz.th-darmstadt.de>,
meixner@rbg.informatik.th-darmstadt.de (Matthias Meixner) says:

>I was discussing with a friend of mine, if a mixture of 1 part phosphor
>and 5 parts KMnO4 would detonate or just explode.
>
>I thought, that it would burn too slow to detonate, because the "fuel"
>and the oxidizer are two separate components, whereas in "real"
>explosives like e.g. nitroglycerine both are within one molecule.
>
>Any comments ?

The fuel and the oxidizer do not have to be in the same molecule,
but it sure does help. There are borderline cases like the 
cheddites where detonation occurs weakly although the ingredients
are arguably not detonable per se. (Ok, KClO3 is exothermic with
respect to O2 and KCl). It is generally agreed that many 
fuel/oxidizer physical mixes would be detonable in suitably
large amounts.

In your particular case of KMnO4 and phosphorus, there is no
reasonable set of conditions under which it would detonate, 
but it should still be dangerous as heck as a "mere" explosive.

Jerry (Ico)