Sciencemadness Discussion Board


IndependentBoffin - 27-4-2011 at 07:40

Hello folks,

What do you all think about this mixture?

As a propellant, it should be easy to make given that zeolite-based oxygen concentrators can be bought off-the-shelf and so can activated carbon. Then all you need is your own compressor to turn your oxygen-enriched air mixture into a compressed gas form in pressure vessels. Probably some aluminium or steel tube with threaded ends to receive end caps.

You then inject your high purity oxygen into a combustion chamber filled with porous graphite. As a propellant you could probably do with either a liquid or gas phase injection of oxygen. For explosive purposes obviously liquid phase is preferable to gas phase, due to higher reactant concentrations and less reactant diffusion needed. But given that coal dust can detonate even in a standard atmosphere, getting carbon with enriched gaseous oxygen to detonate is just an engineering issue.

Making your own liquid oxygen DIY is trickier. Furthermore, without thermal insulation LOX would need to be allowed to boil off periodically (hence your rocket motors have a very finite shelf life), while compressed oxygen obviously incurs a weight penalty from the strong pressure vessels needed but has no shelf life issues.

I think no explosives licenses at all are needed for this because liquid or compressed oxygen on its own is not explosive, and neither is activated carbon. However if stored pre-mixed then apart from it being a hazard you will probably need a license if held in any quantity.

What do you all think about the feasibility of this as an explosive or propellant? If you go for compressed oxygen gas, the raw material and running costs are next to nothing, and the only main expenditure is the capital for the oxygen concentrator, compressor and pressure vessels. After that you can make as much propellant as you wish. If you want the oxyliquit explosive using LOX, the capital expenditure would be much higher but the same principles of next-to-nothing running costs apply. This of course is assuming you can't buy the LOX off the shelf.

[Edited on 27-4-2011 by IndependentBoffin]

Déjà vu allover again

The WiZard is In - 27-4-2011 at 09:52

Quote: Originally posted by IndependentBoffin  
Hello folks,

What do you all think about this mixture?

I have a SL more info, however, this should do.

Arthur Marshall
"Explosives" 1917


For the same reason liquid oxygen explosives have received renewed attention in
Germany. In 1895 Professor F. C. Linde discovered that a mixture of liquid oxygen and
various organic or carbonaceous materials could be detonated, and he gave the
explosive thus made the name of Oxyliquit. It possesses several advantages : it is
cheap, for liquid oxygen can be produced at a cost of a few pence per kg. ; it can be
fired with safety fuse without a detonator, and in the case of a missfire the charge
becomes quite safe in half an hour in consequence of the evaporation of the oxyen. It
was tried on a large scale in 1899 in the construction of the Simplon tunnel. The car-
tridge consists of kieselguhr mixed with petroleum, or of absorbent cork charcoal, in a
suitable envelope. Liquefied air rich in oxygen is obtained from a liquefying plant near at
hand, and the cartridge is dipped into this just before use. The charging, tamping and
firing of the charge must be carried out rapidly before too much of the oxygen has
evaporated. This is the principal objection to the method, and until recently has
prevented its adoption, but the necessities of war have led to its revival, and possibly
the extended experience thus gained may lead to its retention in times of peace. L.
Sieder recommends the use of a cartridge case so constructed that the oxygen gas
given off has to travel backwards and forwards the whole length of the cartridge several
times, thus hindering the absorption of heat by the very cold explosive. A cartridge of
this sort, 38 mm. (1 -1 inch) in diameter, retains sufficient oxygen for 8 or 10 minutes to
permit of full detonation. It is charged with a mixture of 40 per cent. petroleum and 60
per cent. guhr; a cartridge 200 mm. long weighs 91 grammes before steeping in liquid
oxygen, and 295 grammes immediately afterwards.

In the process of Kowatsch and Baldus the liquid oxygen is not introduced into the
cartridge until the charging of the bore-hole is otherwise complete. The cartridge is
provided with two small tubes, one for the introduction of the liquid oxygen and the
other for the escape of gas. The can in which the liquid oxygen is kept is closed except
for a spout. This is connected with one of the tubes of the cartridge, and then the can is
tipped up, whereby the liquid is forced out by the vapour pressure. The filling is
continued until liquid oxygen comes out of the other tube. It is objected to this process
that in the case of very deep bore-holes the charging with oxygen will not be reliable. [1]

[1] See Spielmann, Zschft. Steinbruch -Berufs -Gen. through S.S,, 1915, p. 104.
Sieder, S.S., 1915, pp. 165 and 179. Also S.S., 1915, p. 186.

Velocity of Detonation m./sec

Carben [sic] of density 0.24 in iron tube 6 435
0.24 in cardboard tube 4 890
Soot 0.19 in cardboard tube 4 360
Cork Meal 0.22 in iron tube 3 315
Wood-meal ? in iron tube 3 345

H Kast and A Haid Z. angew. Chem, 1924, p. 979
in Arthur Marshall "Explosives" Volume III 1932

Arthur Marshall "Explosives" Volume III 1932

Liquid oxygen explosives

These were used during the war on a large scale in Germany, but since then
there has been considerable controversy as to their advantages and disadvantages as
compared with solid explosives. Liquid oxygen is cheap, and in the case of a misfire the
explosive becomes absolutely safe after a short time, because the oxygen evaporates
off. On the other hand, they are decidedly sensitive both to friction and to sparks, and
cases have been reported of spontaneous ignition. The power is high when calculated
by weight of the cartridge, but as the density of the explosive is not more than about
1-1, the brisance is comparatively low, especially if the liquid contains not more than
85 per cent. oxygen, as is often the case, because with purer oxygen the sensitiveness
increases. Although the explosive can be fired by safety fuse alone, the ignition is not
certain under these conditions, and it does not develop its full effect. It is therefore
better to use a detonator, but sometimes these also give misfires, due apparently to the
low temperature, or the penetration of moisture or liquid oxygen. [2] If safety fuse be
used, it should have a special incombustible covering, but it is better to fire the
detonator electrically. To get good results with liquid oxygen explosives requires greater
skill and experience on the part of the shot-firer, as the time for firing and charging a
hole is limited. [3] The results also are not so certain. [4] Attempts to make
liquid oxygen explosives safe for use in coal mines have not been successful. [5]
They are now used on the Continent on a considerable scale, especially in potash salt
mines and quarries, but in some cases its use has been discontinued. [6] It has not
made much progress in England, [7] but 309,000 lb. of liquid oxygen were used in
British quarries in 1929, and 201,466 lb. in 1930. In Germany the consumption of liquid
oxygen as an explosive was 1,447 cubic metres (over 3,000,000 lb.) in 1930, and the
accident rate was considerably lower than with solid explosives. [8]

The liquid oxygen is transported in large Dewar flasks made of sheet brass or copper,
in which it can be kept for twenty-four hours without serious loss. In the evacuated
space between the double walls and in contact with the inner flask is a pocket
containing activated charcoal which absorbs any gas which may pass through minute
pores in the metal.

The cartridges are generally made of lamp black or wood-meal capable of absorbing
five or six times its weight of liquid oxygen. The wrappers are of paper. The cartridges
are soaked in the liquefied oxygen in cylindrical Dewar vessels. The charge should be
fired within five minutes of soaking, but win generally explode even after fifteen
minutes, although with diminished strength and with the production of much carbon
monoxide, which is very poisonous. [1a] The Dewar vessels themselves have been
known to explode. This was traced to the presence of a considerable percentage of iron
oxide in the charcoal in the vacuum chamber. When the vessel began to leak, the
oxygen coming into contact with this charcoal caused it to ignite spontaneously, and
this led to an explosion. [2a]

1 S. P. Howell and J. E. Crawshaw, U.S. Bureau of Mines, Serial No. 2,436, 1923.
2 A. Stettbacher, S.S., 1917, p. 187.
3 See J. Herling, S.S., 1927, p. 214.
4 C. Burge, S.S., 1918, p. 193; Mathias, S.S., 1928, p. 297.
5 S.S., 1924, p. 97.
6 See A. Milde, S.S., 1924, pp. 19, 97.
7 J. Weir, S.S., 1929, p. 219.
8 S.S., 1931, p. 240.

1a See U.S. Bureau of Mines, 1923, Technical Paper, 294; also F. W. O'Neill and H. V.
Fleet, Mining and Metallurgy, February, 1920.
2a L. Wöhler, S.S., 1918, pp. 365, 386, 445.

TL Davis
"The Chemistry of Powder & Explosives"

Liquid Oxygen Explosives

Liquid oxygen explosives were invented in 1895 by Linde who had developed a
successful machine for the liquefaction of gases. The Oxyliquits, as he called them,
prepared by impregnating cartridges of porous combustible material with liquid oxygen
or liquid air are members of the general class of Sprengel explosives, and have the
unusual advantage from the point of view of safety that they rapidly lose their
explosiveness as they lose their liquid oxygen by evaporation. If they have failed to fire
in a bore hole, the workmen need have no fear of going into the place with a pick or a
drill after an hour or so has elapsed.

Liquid oxygen explosives often explode from flame or from the spurt of sparks from a
miner's detonator, or, putting the matter fuse, and frequently need no otherwise, some
of them are themselves satisfactory detonators. Like other detonating explosives, they
may explode from shock. Liquid oxygen explosives made from carbonized cork and
from kieselguhr mixed with petroleum were used in the blasting of the Simplon tunnel in
1899. The explosive which results when a cartridge of spongy metallic aluminum
absorbs liquid oxygen is of theoretical interest because its explosion yields no gas; it
yields only solid aluminum oxide and heat, much heat, which causes the extremely
rapid gasification of the excess of liquid oxygen and it is this which produces the
explosive effect. Lampblack is the absorbent most commonly used in this country.

Liquid oxygen explosives were at first made tip from liquid air more or less self-
enriched by standing, the nitrogen (b.p. - 195o) evaporating faster than the oxygen (b.p.
-183o), but it was later shown that much better results followed from the use of
pure liquid oxygen. Rice reports [33] that explosives made from liquid oxygen and an
absorbent of crude oil on kieselguhr mixed with lampblack or wood pulp and enclosed
in a cheesecloth bag within a corrugated pasteboard insulator were 4 to 12% stronger
than 40% straight nitroglycerin dynamite in the standard Bureau of Mines test with the
ballistic pendulum. They had a velocity of detonation of about 3000 meters per second.
They caused the ignition of fire damp and produced a flame which lasted for 7.125
milliseconds as compared with 0.342 for an average permissible . explosive (no
permissible producing a flame of more than 1 millisecond duration). The length of the
flame was 21/2 times that of the flame of the average permissible. In the Trauzl lead
block an explosive made up from a liquid air (i.e., a mixture of liquid oxygen and liquid
nitrogen) containing 33% of oxygen gave no explosion; with 40% oxygen an
enlargement of 9 cc.; with 50% 80 cc., with 55% 147 cc.; and with 98% oxygen an
enlargement of 384 cc., about 20% greater than the enlargement produced by 60%
straight dynamite. The higher temperatures of explosion of the liquid oxygen explosives
cause them to give higher results in the TrauzI test than correspond to their actual
explosive power.

Liquid oxygen explosives are used in this country for open-cut mining or strip mining,
not underground, and are generally prepared near the place where they are to be used.
The cartridges are commonly left in the "soaking box" for 30 minutes, and on occasions
have been transported in this box for several miles.

One of the most serious faults of liquid oxygen explosives is the ease with which they
inflame and the rapidity with which they burn, amounting practically and in the majority
of cases to their exploding from fire. Denues [34] has found that treatment of the
granular carbonaceous absorbent with an aqueous solution of phosphoric acid results
in an explosive which is non-inflammable by cigarettes, matches, and other igniting
agents. Monoand diammonium phosphate, ammonium chloride, and phosphoric acid
were found to be suitable for fireproofing the canvas wrappers. Liquid oxygen
explosives made up from the fireproofed absorbent are still capable of being detonated
by a blasting cap. Their strength, velocity of detonation, and length of life after
impregnation are slightly but not significantly shorter than those of explosives made up
from ordinary non-fireproofed absorbents containing the same amount of moisture.

[33] George S. Rice, "Development of Liquid Oxygen Explosives during the War," U. S.
Bur. Mines Tech. Paper 243, Washington, 1920, pp. 14-16. Also, S. P. Howell, J. W.
Paul, and J. L. Sherrick, "Progress of Investigations on Liquid Oxygen Explosive 6," U.
S. Bur Mines Tech P 294 Washington, 1923, pp. 33, 35, 51.

[34] A.R.T. Denuses, "Fire Retardant Treatments of Liquid Oxygen Explosives," U.S.
Bureau of Mines Bull. 429, Washington, 1940.

PATR 2700 1975
L 19 &ff


Liquid Air and Liquid Oxygen Explosives originally consisted of porous combustible
materials impregnated with liquid air. Soon after liq oxygen became commercially avail-
able it began to replace liq air in these explosives, Consequently this article is devoted
almost entirely to Liquid Oxygen Explosives commonly called LOX. It should be noted
that LOX are not to be confused with FuelAir Explosives (See FAE in Vol 6, p F3). For
LOX the oxidizer is liq and the fuels are either solids or liquids, while in FAE the oxidizer
is atmospheric oxygen and the fuels are usually gaseous or liquid droplets at the time of
explosion. General references on liq air and liq oxygen expls are Refs 2, 3, 5, 7, 8, 14,
16, 19 & 52

In what follows we will examine:
1) The history of LOX
2) Typical LOX compositions
3) Uses
4) Detonation and sensitivity characteristics
5) Recent Patents

1) History. LOX, or more precisely Liquid Air Explosives, were invented by Linde in
1895 . who called these expls Oxyliquits (Ref 1). They were made by impregnating
porous combustible solids with liquid air shortly before firing the charge. Usually the
combustibles, in some type of combustible cartridge, were soaked in liq air just before
loading into the bore hole. Liq air expls were used extensively in 1899 in the driving of
the Simplon tunnel between Italy and Switzerland Liq nitrogen has a much lower heat of
vaporization than liq oxygen, and thus evaporates more readily. Because of this, liq air
(a mixt of nitrogen and oxygen) becomes progressively richer in oxygen as it is warmed
or even in storage. This makes it almost impossible to control the oxygen content of a
liq air expl charge, even if it is fired promptly after preparation. Variable oxygen content
can result in poor performance, or even non-performance, and in uncontrolled explosive
fumes. Thus, the natural tendency to replace liq air with liq oxygen in these expls began
as soon as liq oxygen became commercially available. This occurred some years prior
to WWI

During WWI the Germans used LOX (and also liq air explosives) extensively in coal,
iron and potassium mines, in tunneling and in demolition work. In 1922 LOX were used
in Mexican silver mining and a few years later they were introduced into the copper
mines of Peru and Chile

In the USA, LOX have been used primarily in the strip mining of coal. For example, in
1950, 99.5% of all the LOX used was in coal mining (Ref 18). Most of this must have
been for moving overburden, since LOX are nonpermissible (not allowed by law in
gassy mines), and their fume characteristics make them unsuitable in many
underground mines even if they are non-gassy. The following tabulation (from Ref 18)
shows that LOX consumption in the 1950's amounted to some two to three percent of
the total expls used

Table I

Since then the use of LOX has declined greatly, as ANFO and Slurry Explosives
began to replace them. An indication of the decline in the use of LOX is given in the
patent literature. For example, a 1936 review (Ref 8) lists 64 German patents on LOX.
Undoubtedly by 1936 there were also many patents issued in the USA, UK and France.
In the period of 1936-1960 a considerable number of patents on LOX is listed in CA.
Some of these are abstracted in Section 5 below. Since 1960, however, the number of
LOX patents has declined drastically. Almost none is listed in the most recent
Quintennial Index of CA

2) Typical LOX Compositions
Both Liq Air and Liq Oxygen expls contain porous combustible material as fuel. These
fuels are generally contained in paper or cloth cartridges. Occasionally liq fuels such as
petroleum are mixed with the porous solids; eg, some of Linde's early compositions
(Ref 1) contained kieselguhr mixed with petroleum. Carbonized cork was also used in
early Liq Air Expls, although charcoal was the original absorbent. More recently, as liq
air was replaced by liq oxygen, lampblack became the absorbent most commonly used
in LOX (Ref 12). The fuel content of LOX compositions should be capable of absorbing
5 to 6 times their weight of liq oxygen

LOX Compositions and Properties

Initial Composition (a) ........................... Sp Gr g/cc ..Rel ..Strength ... Det Rate m/sec

38/225 LampBlack/LO............................. 0.23(c) ......... 0.95 ......... 4200
57/230 LampBlack/LO..............................0.33(c) ..........1.14 ......... 5000
65/225 Gas Black/LO................................0.33(c) ..........1.16 ......... 5000
49/12/215 Gas Black/FeSi/LO
36/28/193Woodpulp/Kieselguhr/LO .........1.07 ..............0.92 .......... 4180
49/12/216 Woodpulp/Lampblack/LO .........0.76 ..............0.80 ......... 3350
58/7.3/167 Woodpulp/Kerosene/LO ..........0.93 ............. 0.95 ........ 4660
64/26/182 Woodpulp/Kerosene/LO ...........1.09 ............. 0.80 ......... 4080
33/49/218 Fuel Oil/MgCO3/LO ................... -- ............. 0.99 ........ 4000
47/210 Carbene /LO (d) ............................ 0.24 ............. 1.13 ......... 5200
........................................................................................................... 6430

(a) Before any appreciable evaporation of liq oxygen (LO)
(b) Relative to 40% Dynamite on a volume basis
(c) "Unsoaked" fuel; "soaked" sp gr not given
(d) Carbene is polymerized acetylene
(e) In an iron tube; presumably all other detonation rates are for unconfined cartridges

Many other fuels such as soot, turf, corkmeal, powdered anthracite, woodmeal,
carbene (polymerized acetylene), calcium hydride, and spongy aluminum have been
tried. Physical and chemical properties of many LOX fuels are given by Howell et al
(Ref 3) and ONeil & Van Fleet (Ref 5a)

Several of the potentially useful LOX compositions with some of their physical and
detonation characteristics are listed in Table 2 (taken from Ref 6). Some recent LOX
compositions are given in Section 5

3) Uses. In section 1, we showed that most of the LOX in the USA are used in the strip
mining of coal. In Europe LOX were also extensively used in open pit mining, tunneling
and construction. Indeed, in the first half of this century, LOX were used in most expls
applications, although not extensively, where fumes were not a problem. O'Neil & Van
Fleet (Ref 5a) consider LOX economical and safe (See Sect 4 on LOX safety). La
Magna (Ref 9) prefers LOX to Dynamites. In the last decade LOX have been almost
entirely replaced by ANFO or Slurry Explosives

In actual practice LOX were always prepared near the explosion site. Usually a paper
cartridge containing the absorbent fuel was "soaked" in liq oxygen. The soaked
cartridges were quickly placed in the borehole and fired promptly. Extensive tests (Ref
3) showed that firing had to occur within 5 to 15 minutes after soaking, otherwise
enough liq oxygen evapd to affect LOX performance or even cause misfires. The LOX
charges were generally fired with blasting caps. Under favorable conditions, LOX
charges can be initiated by flame, but this type of initiation is uncertain, and the
performance of LOX thus initiated tends to decrease. As discussed in Section 4, the
sensitivity of LOX to flame can be a safety hazard

In some operations, a cartridge packed with absorbent fuel was inserted in the
borehole and filled with liq oxygen thru a tube reaching to the bottom of the cartridge. A
vent for evapg oxygen had to be provided

Yet another method was to make cartridges with two compartments, one for absorbent
and the other for liq oxygen. After insertion in the borehole, the partition was ruptured
(either by pressure from the oxygen or by mechanical means from outside) to mix the
liq oxygen with absorbent. To increase the allowable time between liq oxygen
impregnation and firing (from 10 minutes to 16-22 minutes), Wakabayshi (Ref 21)
suggests precooling the borehole by pouring small amounts of liq oxygen into it

4) Detonation and Sensitivity Characteristics
a) Detonation Characteristics. LOX are commercial explosives and as such are
used primarily in breaking and moving rock and over burden. From a practical point of
view, it is important to have a measure of the effectiveness of LOX blast in fracturing
and moving the "burden". No single universally accepted measure of blast effectiveness
exists today, and certainly none existed in the 1920-1940 period when most of the exptl
studies of LOX were carried out. Practical experience suggests that the effectiveness of
an explosive for fracturing "burden" is related to its brisance. Brisance is a measure of
the shattering power of an explosive and is closely related to the detonation
pressure (commonly called PCj or Chapman Jouguet pressure) of the explosive (See
Brisance in Vol 2, p B265-300). The effectiveness of an explosive for moving "burden"
is related to its strength or power (See Vol 4, p D730-L). It is customary to rate
explosive strength on a relative basis, ie, as a percentage of the strength of some
standard explosive - usually TNT or some standard Dynamite. This rating is based on
comparison tests, the most common of which is the Ballistic Mortar Test (See Vol 2, p

Unlike the relation between brisance and PCP expl. strength is not readily related to
some detonation characteristic of the explosive. Attempts to relate strength to
detonation energy are not wholly successful. Relative strength, based on ballistic mortar
tests, correlates rather well with computed nRT, where n & T are the computed moles
of gas and detonation temp, of the explosive, and R is the gas constant. Although n & T
can differ appreciably with the equation of state used in the computation, it appears that
ratios of nRT (at least for similar explosives) do not suffer from this drawback

In the early expls literature (and much of the LOX work is in the "early" literature)
there is a great deal of confusion between brisance and strength

Now, with the above caveat, we can examine what is known of LOX detonation

Perrott (Ref 4) examined the effect of packing density on the relative strength of six
liq oxygen lamp black compns, and measured their detonation rates, D. Relative
strengths on a weight basis increased as packing density increased except that the
relative strength at the highest packing density tested (0.46g/cc "unsoaked") was low.
On a volume basis the compn at the lowest packing density (0.19g/cc "unsoaked") had
the highest relative strength. Detonation rate increased from 4500 to 6000m/sec,
although it is not clear whether this increase, as expected, occurred as packing density
was increased. Periott also found that substituting Al for some of the absorbent did not
increase D but made the compn easier to detonate

In a subsequent study (Ref 5) Perrott found that 1 1/4 inch diameter cartridges of
LOX, containing lamp black, gave optimum blast results at an "unsoaked" packing
density of 0.30g/cc. This takes into account not only the strength of the LOX but also
their effective "life", ie, the maximum allowable time between "soaking" and firing. For
example, 5 minutes after soaking, LOX cartridges were found to have a relative
strength (on a volume basis) 115% that of a standard Dynamite, but after 25 minutes
their strength was only 65% of the Dynamite. Perrott suggests using as large a
cartridge diameter as practicable to reduce oxygen evapn. He also made further
measurements of detonation rate and found that it is controlled by the finest particle
size component of the absorbent. Clark & La Motta (Ref 7) also found that D increases
as absorbent particle size decreases. For gas-black LOX, D varied from 4000 to
6200m/sec, while for lamp black LOX D varied from 4200 to 5000 m/sec. Perrott states
that LOX will burn without detonation when unconfined but will detonate erratically
when ignited under confinement

Okada (Ref 15) states that the oxygen to carbon ratio for LOX of maximum brisance is
2.6. This is essentially the theoretical ratio to convert all the carbon to C02. This writer
believes that Okada really meant maximum strength rather than maximum brisance, as
the latter depends not only on compn but also on packing density

Okada's conclusions are supported by Streng & Kirshenbaurn (Ref 20) who found
that a stoichiometric mixture (33 mole% CH4) of liq methane and liq oxygen had a
higher brisance (in this case they really measured brisance) and a higher detonation
rate than other mixts containing from 6 to 80 mole % CH4. They also determined the
expl limits and detonation rates of these mixts and examined the sensitivity of the
stoichiometric mixt to impact, shock waves, and flame & sparks. Their results are
summarized below:

Although the above are not practical LOX compositions, these results are of
considerable interest. They show that the detonation limits of LOX compns are quite
wide, and that D (at least for liquid methane-liquid oxygen mixtures)is not strongly
affected by considerable changes in compns or even density

Cook (Ref 22) studied a chemically similar mixt consisting of 78/22 LOX/kerosene
(stoichiometric to C02 & H20), but the kerosene, ie, the fuel, in his case was frozen,
so that he dealt with a slurry rather than a solution. His results are as follows:

Density D PCJ
1.04g/cc 2246m/sec 10.4kbar

Note that D for the slurry is much lower than for the liq CH4-liq oxygen solns even
though the apparent slurry density is higher than those in Table 3. Possibly this is due
to incomplete reaction, even though Cook emphasizes that he used mechanical stirring.
Cook's D is also very low compared to the D's in Table 2, for practical LOX comps
containing solid absorbent fuels

Cook (Ref 18a) presents theoretical calculations of the detonation parameters of
several carbon black-liq oxygen comps. He gives no comparisons with experimental
results. In this writer's opinion, Cook's values (Table 12.20 of Ref 18a) of TCj are too
high and his PCj are too low; the products probably contain more free carbon than
shown. However, there is little doubt that most LOX detonations are "hot", ie, they will
readily ignite firedamp (Refs 2, 3, 12 & 14). Also the computed detonation velocities
(estimated from Cook's Pcj) show a much greater variation with compn and density than
the experimental data of Table 3

b) Sensitivity characteristics. Early investigators (Refs 5a & 9) tended to over-
estimate the safety of LOX because they were non-explosive before mixing, and
because they became non-explosive, even after a misfire, as the oxygen evapd. An
interesting comment, by Wakabayashi (Ref 21), significant in these days of terrorist
bombings, is that LOX are burglar-proof. Nevertheless, modern consensus is that LOX
are more dangerous to handle than conventional Dynamites (Refs 7, 12, 14, 17 & 21)

One of the most serious faults of liq oxygen explosives is the ease with which they
inflame and the rapidity with which they bum, amounting practically, in the majority of
cases, to their exploding from fire. Denues (Refs 10 & 11) has found that treatment of
the granular carbonaceous absorbent with an aqueous solution of phosphoric acid
results in an explosive which is nonflammable by cigarettes, matches, and other igniting
agents. Mono- and diammonium phosphate, ammonium chloride, and phosphoric acid
were found to be suitable for fireproofing the canvas wrappers. Liq oxygen expls made
up from the fireproofed absorbent are still capable of being detonated by a blasting cap.
Their strength, velocity of detonation, and length of life after impregnation are slightly,
but not significantly, less than those of expls made from ordinary non-fireproofed
absorbents containing the same amount of moisture

Streng & Kirshenbaurn (Ref 20) found that a stoichiometric mixture of liq methane
and liq oxygen will explode from the flame of a safety fuse

Some LOX compns are liable to self ignite (Ref 12). Cook (Ref 18a) makes the
interesting suggestion that many LOX compns do not self-ignite only because they are
so cold

Clark & La Motta (Ref 7) showed that LOX made with gas black or lamp black are
more sensitive to impact than the standard Bureau of Mines 4017o straight Dynamite.
Impact sensitivity increased when small amounts of iron oxides, aluminum dust or
ferro-silicon were added to the LOX. Impact sensitivity also increased as absorbent
particle size was reduced. As the oxygen evapd, impact sensitivity, as expected,

In tests of materials saturated with liq oxygen and subjected to 71-75 lb drop weight
tests, the following were found acceptable (one detonation/40 impacts or none/20):
fluorocarbon oils & greases, graphite, halogenated biphenyl & molybdenum disulfide
lubricants, polyethylene & pure poly fluorocarbons. The following explode: synthetic
elastomers & Thiokols, cellulose-based papers, silicone-based oils & greases,
thermoplastics (except pure Teflon), thermosetting plastics, petroleum-based oils and
greases (Ref 17)

LOX are sensitive to sympathetic detonation, ie, detonation initiated by a nearby
charge separated from the LOX by an air gap (Refs 7 & 20)

The pseudo-LOX of liq methane-liq oxygen are exploded by bullet impact (Ref 20)

LOX compositions are sensitive to friction (Refs 12 & 14) and to static discharge.
Assonov (Ref 13) attributes the premature explosions of liq oxygen on adsorbents
(fuels) to small dust particles. As the charge is dropped into the borehole, the small
particles become detached from the adsorbent. These particles are carried upward by
the oxygen vapors and become electrostatically charged by friction.

Potentials of the order of 15000-20000 volts were measured on these particles. A dis-
charge of such potentials suffices to initiate the LOX. Dust can be minimized by
moistening the adsorbent with 20-25% of water or by providing special capsules for the
expl. Good results were obtained by using briquetted fibrous vegetable matter, peat,
straw, wood pulp and the like as adsorbents. Such briquets did not produce dust when
dropped from a height of 25m. The brisance of the LOX made of such briquets was only
`10-4% less than that of ordinary LOX

Streng & Kirshenbaum (Ref 20) exploded stoichiometric liq methane-liq oxygen by
the discharge of a 0.1 microfarad condenser, charged to 1500V, across 1-3mm air gaps

5) List of Recent Patents on LOX

Attachment: Explosives LOX.doc (93kB)
This file has been downloaded 552 times

IndependentBoffin - 27-4-2011 at 09:56

Oooh...thank you! New bedtime reading material :D

The WiZard is In - 27-4-2011 at 10:52

Quote: Originally posted by IndependentBoffin  
Oooh...thank you! New bedtime reading material :D

For an interesting report on actual use of LOX in mining I commend

MH Kurlya and GH Clevenge
Liquid-oxygen Explosives a Pachuca
Transactions American Institute of Mining, Metallurgical and
Petroleum Engineers
Presented at the New York meeting, February 1923. p. 271-340.

The on site LO2 plant produced 25 l. (27.5 kg, 60.6 lb per hour.)

The life of their cartilages max out at 11.5 minutes. LOX explosives
cartridges are the ultimate safety explosive — after a few minutes
they are no longer explosive.

A quick check of Google find that this can be DL'd for $$$.
At 69 pages I am not planning on scanning/OCR'ing it.

You can also from Google Books DL —

Progress of investigation of liquid-oxygen explosives
Spencer Pritchard Howell, James Washington Paul, Jacob Leighty Sherrick
Dept of the Interior Technical Paper 294
1923. 91 pages.

It will take a little searching to out it. If I can find it... anyone can.

IndependentBoffin - 27-4-2011 at 11:02

Suppose you start off with a fixed mass of carbon powder of specified specific surface area, in a steel pressure tank of fixed volume.

You pour in a fixed quantity of liquid oxygen of fixed oxygen concentration, and then seal the vessel's cap. The oxygen and carbon are at stoichiometric quantities.

If you have two test circumstances:
1) Liquid oxygen + carbon powder
2) Gaseous oxygen allowed to boil off from the liquid at room temperature + carbon powder

and detonate both.

The concentration of oxygen in both instances are the same. In case #2 though, you are starting at a higher initial pressure and the heat of vapourisation of liquid oxygen has already been absorbed from the environment.

The questions are:
1) Which will be more powerful, and by how much? VOD, brisance, peak pressure, etc.
2) Do you get unreacted carbon at stoichiometric quantities with oxygen, and which one will have more complete combustion?

I reckon case #2 will be more powerful, because some of the evolved heat in case #1 must go towards boiling the liquid oxygen, whereas all the heat in case #2 goes towards raising the pressure.

You'd get more unreacted carbon in case #2, because the higher pressure rise of case #2 means that the reactants are not kept in intimate contact for as long before they are blown apart.

[Edited on 27-4-2011 by IndependentBoffin]

Neil - 27-4-2011 at 12:08

LOX/Kerosene Monopropellant Rocket Engine

94-1 11.01 8755

LOX/Kerosene Monopropellant Rocket Engine


An innovative propulsion system is proposed that uses a
monopropellant consisting of liquid oxygen and solid kerosene
particles uniformly suspended in the liquid oxygen. This original
and imaginative approach combines the best features of solid and
liquid propulsion. Like a solid propulsion system, the fuel and
oxidizer are premixed into a uniform mixture with reliable
ignition and combustion properties. Yet, the propellant is a
liquid so it can be burned in a small combustion chamber, loaded
into a rocket at the launch pad and be injected at variable rates
to throttle the engine during a mission.
This propulsion system will benefit NASA by supporting the need for
lower cost boosters, upper stages and orbital transfer vehicles by
using a low cost propellant and a reduced number of components when
compared to conventional propulsion systems.
The Phase I objective is to determine the LOX/kerosene rocket
engine's feasibility by evaluating key components with subscale
engine tests. Critical monopropellant properties will also be
measured to determine its feasibility for use in launch vehicles.
Phase I results are expected to be positive and lay the foundation
for Phase II which will be the development of a test weight rocket
engine system.

The first commercial application will be the incorporation of
this engine system into a new low cost sounding rocket. This new
rocket will have capabilities similar to the Black Brant V. Other
commercial applications include strap-on boosters (Castor Class)
and small launch vehicles (Scout Class). Future commercial sales
may include a pump-fed version targeted as a replacement for the
main engines of the Atlas and Delta rockets. At NASA's
discretion, these engines may also be considered for man-rated
applications such as replacements for the Shuttle SRBs and OMS

IndependentBoffin - 27-4-2011 at 12:44

Thanks for the info. The thing about LOX/kerosene is that you need two tanks now and piping to your combustion chamber. That's fine for NASA but for the amateur rocketeer it is too much hassle, complexity and cost.

With LOX or compressed oxygen you just need one tank + piping to your combustion chamber. You can have activated carbon slugs in your combustion chamber, over which oxygen flows to support combustion.

Neil - 27-4-2011 at 14:54

I think the idea with the mono propellant engines are that the kerosene is actually kerosene snow which is suspended in the liquid oxygen so that they only have one tank but it's able to be throttled. now how you keep the flame from popping back up into the fuel tank.. that's another story. :cool:

Now if you managed to make some FLOX and suspend a silicon or boron powder it in it...

IndependentBoffin - 27-4-2011 at 15:08

Having an intimate mix of oxidiser and fuel in the same tank has accident written all over it ;)

In fact some "monopropellant" accidents have been due to things like bubbles in pipes being trapped and compressed when you shut off the flow. The first ever nitromethane industrial accident was posited to be caused by this.

And once you mix the two together, explosives licensing laws may apply.

Neil - 27-4-2011 at 16:14

But imagine how much fun it would be! and you'd even get a thread about how you lost your life in pursuit of... something... I'm really looking forward to the day when the fuel feed on those things becomes public domain and we get to see how they kept it from exploding. Who knows maybe that tech will one day be in the hands of model rocketry fans.

"And once you mix the two together, explosives licensing laws may apply." To be honest I really do not think they'd get a chance to apply, Darwin:D would take you first.