BASF
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Registered: 5-11-2002
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formula for approximation of Trauzl-test
I wondered wether there is a good formula......
Older patents often refer only to Trauzl-test-values, which are quite difficult to bring in a relationship with their true brisancy, because the test
is based on a 10g-sample, and not on on a specific volume at a specific density... (telling nothing new, i know)
For example, PETN (520ccm) has a far bigger expansion in the test than HMX, and RDX has exactly the same expansion as HMX(480ccm), thats because of
the different molecular weight.
Naturally, it would be very comfortable if such a formula used values like density, Vod, molecular-weight.
I would be glad about any input.
HLR
[Edited on 6-6-2003 by BASF]
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a_bab
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I suppose that the Trauzl-test reveals only a property of the explosive (the gas expansion volume) and not the VOD or brissance. You cannot determine
the VOD out of the Trauzl results .
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PHILOU Zrealone
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Trauzl test display too much explosive properties to give simple relation to VOD!
Expansion is familly dependant!
Ester nitrates are different than primaries, than nitroaromatics, than nitramines, ... each familly display a certain kind of heat of explosion that
softens the lead (function of OB), a certain volume of gas (depending on its OB too or heat of explosion), a certain speed of detonation.
Thus heat of explosion, VOD, Volume of detonation gases are important cofactors.
"thats because of the different molecular weight."
Nope, that's because of density difference, familly difference or volume of the charge of explosive difference.
Here are listed properties of different explosive of various families.You clearly see there is no relation between expansion and molecular weight!
Volume (Lead block test / molecular weight /VOD m per s)
10g of RDX = 5,49 ccm (480 ccm / 222,1/ 9000)
10g of HMX = 5,23 ccm (480 ccm / 296,2/ 9200)
10g of MN = 8,217 ccm (610 ccm / 77/ 6300)
10g of EGDN = 6,75 ccm (620 ccm / 152,1/ 7300)
10g of MHN = 5,78 ccm (510 ccm / 452,2/ 8260)
10g of PETN = 5,68 ccm (523 ccm / 316,2/ 8800)
10g of Pb(N3)2 = 2,083 ccm (110 ccm / 291,3/ 5600)
10g of AgN3 = 1,96 ccm (115 ccm / 149,9/ 6800)
10g NM = 8,78 ccm (400 ccm / 61/ 6290)
10g TNT = 6,09 ccm (300 ccm/ 227,1/ 7100)
10g TNB = 5,68 ccm (325 ccm/ 213,1/ 7700)
10g HNBP = 6,25 ccm (344 ccm/ 424,2/ ???)
10g TNA = 5,67 ccm (310 ccm/ 228,1/ 7500)
10g HNDPA = 6,09 ccm (325 ccm/ 439,2/ 7400)
10g HNDPO = 5,88 ccm (373 ccm/ 440,2/ 7400)
So by dividing LBT by the volume of the charge we get LBTccm/1ccm of explosive...I have listed them aside their VOD!
RDX = 87,43 / 9000
HMX = 91,77 / 9200
MN = 74,23 / 6300
EGDN = 91,85 / 7300 (*)
MHN = 88,23 / 8260
PETN = 92,077 / 8800
Pb(N3)2 = 52,8 / 5600
AgN3 = 58,67 / 6800
NM = 45,5 / 6290
TNT = 49,26 / 7100
TNB = 57,21 / 7700
HNBP = 55,04 / ??? (**)
TNA = 54,67 / 7500
HNDPA = 53,36 / 7400
HNDPO = 63,43 / 7400 (***)
This give you a totally other look on the subject!You also see that primaries usually perform bad in LBT but the calculated number shows they are not
far from nitroaromatics when we compare volumic power and not massic power!(****)
We have simply divided LBT volumes by the volume of explosive (10g/maximum density).To get numbers and those numbers fit quite well with VOD max at
max density under confinement!
But it is only true when you compare identical familly compounds!
So compare apples with apples and pineapples with pineapples!
(*)There is an anomality with EGDN, but I have seen text where the VOD is listed to be 8500 especially when frozen (so maybe the anomality comes from
that).
(**)By the number I have calculated I can estimate VOD to be 7500-7600 without much error.
(***)Here also there is something unusual; following the number I have found VOD should be higher; maybe the expansion is better owing to a better OB?
(****)My idea exposed a few years ago on alt.engr.explosives was to make several LBT with different constant volume (like the number I have
calculated), constant mass (like normal) and constant molar ratio...to get numbers to play with and a more real view of the problem.And also to make
those test with
0,1 - 0,5 - 1 - 2 - 5 - 10 - 20 to see power as function of the mass (when grams) and critical mass; or to see power as function of the volume (when
ccm) and critical volume.
Finally to see power as a function of the number of mole (deciMolar) and critical number of mole.
... (2g-2ccm-2dM)...
This would make 21 test for each explosives (or family) to see behaviour.An give complet curve dependance!
Same thing should be done with sand crush test (maybe in lead block to diminish risks!)
Brisance is characterised by the sand crushing test where a 0,4g sample of the explosive is pressed to 1,2g/ccm into a detonating cap containing
sufficent lead Azide (or Mercury fulminate) and tetryl to initiate detonation of the sample depending on its sensitivity).
In the sand bomb there is 200g of sand 30 mesh.The cap is detonated in the bomb and the sand is sieved to determine what has become finer than 30
mesh. The same has been done for the detonator alone without the tested explosive.So you get two weight of sand to substract...and the value is called
brisance (determined by sand crushing test).The value is then compared to TNT (if I remember wel TNT crushes 42-48 g of sand with 0,2 g Mercury
fulminate).
Sand test allows also to know sensitivity to initiation by increasing slowly the amount of priming explosive and determining the sand crushed vs
blasting cap alone...once the brisance is constant (it increases during initiation regio).
I personnally would play with bigger amounts than 0,4g (many explosives have critical mass far over this).But it would be dangerous and a lot of work
to perform test on 10g...except maybe an hybrid lead block test/sand test?
At home I have gathered a lot of lead and I will perform LBT on my own!
So I will have personnal datas!
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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