Preparation and performance Evaluation of a Hexachloroethane ...

13 th International Conference on
AEROSPACE SCIENCES & AVIATION TECHNOLOGY,
ASAT- 13, May 26 – 28, 2009, E-Mail: asat@mtc.edu.eg
Military Technical College, Kobry Elkobbah, Cairo, Egypt
Tel : +(202) 24025292 – 24036138, Fax: +(202) 22621908
*
Syrian Armed Forces, Syria, fadlmaryam@yahoo.com
**
Egyptian Armed Forces
1/9
Paper: ASAT-13-CA-02
Preparation and performance Evaluation of a Hexachloroethane-
Based IR Chemical Smoke Mixture
F. A. Maryam * , M. A. Kassem ** , M. Sh. Fayed**, A. M. Sultan**
Abstract: Chemical smoke systems are based on the production of obscuring cloud due to
burning of certain pyrotechnic mixtures, named chemical smoke mixtures (CSM). The
smoke-producing pyrotechnic compositions used in producing a smoke screen against
infrared radiation transmission may include the following components: a fuel (most often
magnesium powder), an oxidizer (such as hexachloroethane), a carbon generator such as
(naphthalene) and a chlorinated binder such as (poly vinyl chloride PVC). In view of
performance, thermal attenuation, availability, cost and stability as well as processing, the
obtained results reveal that: chemical smoke mixture based on hexachloroethane
approximately consisting of: [(20% magnesium powder (Mg), 60% hexachloroethane
(C2Cl6), 15% naphthalene (C10H8), and 5% poly vinyl chloride (PVC)] could provide
relatively high level of thermal attenuation. Consequently, acceptable maximum camouflage
in visual and IR (8-12µm) range is obtained.
Keywords: Hexachloroethane, Naphthalene, Magnesium, Attenuation, Chemical Smoke.
1. Introduction
Great efforts have been devoted to develop systems for generation of smoke. Smoke
generation systems could be classified into two main categories, mechanical systems
(physical transformation.) or chemical systems (pyrotechnical mixtures). The obscuring
smoke cloud may be produced by the combination of physical transformation and chemical
reaction, one process after the other. Chemical smoke mixture may include (metal chloride
[1], hexachloroethane [2], aromatic hydrocarbons [3, 4], halogenated polymeric binders [4, 5],
white phosphorus [6], or red phosphorus [7]). Percentage attenuation in target temperature can
be calculated using the following formula:
Percentage attenuation
A%
(T
Target measured
� (1)
T
�T
Target
�T
in targettemperature
Ambient
) * 100
where: Ttarget is the temperature of the hot body (target). Tmeasured is the temperature of hot
body (target) as measured by the IR camera during the production of smoke. Tambient is the
temperature of the room in which the experiments had done.

Paper: ASAT-13-CA-02
The aim of this work is to select the most suitable IR smoke mixture composition from the IR
obscuring point of view. This was done by preparing different samples of IR chemical smoke
mixtures, based on hexachloroethane as an oxidizer, source of carbon by itself , mixing with
metal powder as a fuel (magnesium), a carbon producing agent (naphthalene), and a binder
such as polyvinyl chloride for enhancing the mechanical properties of the pyrotechnical
mixture [8]. The prepared pyrotechnic samples could be readily ignited.
2. Experimental
2.1 Chemicals
All the chemicals used in this experimental work were of the commercial grade shown in
table (1) and used directly without any purification or treatment.
Table (1) Chemicals used in this experimental work
No Chemical Name Chemical Formula Supplier
1 Hexachloroethane C2Cl6
Aldrich Chemical Co.
Ind.
2 Magnesium powder Mg GPR
3 Sulphur S
VEB Laborchemie
APOLDA
4 Carbon C
Arabic Laboratory
Equipment Co. GPR
Laboratory MTS
5 Potassium nitrate KNO3
Chemical Misr
Trading Company
6 Naphthalene C10H8 ABWIC GPR
7 PVC (poly vinyl chloride) (CH2CHCl)n
Arabic Laboratory
Equipment Co. GPR
2.2 Instruments
The used instruments during different steps of the experimental work are illustrated in figures
(1 : 7). Complete specification, effective working ranges, and available diagrams of the used
instruments are illustrated during the description of each step of the experimental work. The
thermal characteristics of the produced cloud of smoke were measured by thermal imager
model 760 LW Infra-metrics of spectral range (8-12) µm. It is equipped with computer,
depending on a soft-ware program and video-recorder to record the thermal image of the
infrared radiating from hot plate model (laboratory HP). Thermal characteristics and data
were processed and analyzed with IBM computer model OPTIPLEX GX520 Pentium(R) 4
CPU 3.00 GHz 504MB of RAM, high performance processor. The relative humidity values
were measured by digital thermo-hygrometer model TFA 4001.
2.3. Experimental Setup
An Experimental setup was specially designed including smoke tunnel, thermal imager, and
data acquisition system and laboratory hot plate, as a source of IR radiation. The smoke
tunnel used for testing the smoke mixtures was constructed for the purpose of smoke testing;
equipped with suction and recycling fans as well as measuring apparatuses to record
temperature. The infrared radiator was used to represent a field target. The thermal imager
2/9

3/9
Paper: ASAT-13-CA-02
and the accompanied devices for recording and processing were placed at the other end of the
smoke tunnel. An air curtain is applied in front of them to prevent the smoke from diffusion in
the space of laboratory. Effect of smoke in reducing target temperature and radiation level of
the infrared region was recorded as a function with time. Data was graphed and analyzed for
each smoke sample. The setup used for measurements is illustrated in figure (8).
2.4 Evaluation of Obscuring Efficiency of the Prepared Smoke Mixtures
The mixtures shown in Table (1) were investigated as infrared smoke producing chemical
agents. The igniters of this smoke mixture were made from a locally prepared black powder.
The smoke was generated by ignition of the mixture in a stainless-steel container inside the
test chamber and then withdrawn to the smoke tunnel in front of the infrared object. Thermal
characteristics of the smoke cloud was investigated by measuring the attenuation of the
infrared radiation through the smoke cloud of each chemical smoke mixture, and recording
the data by the computer connected with the IR Camera. The recorded information were
analyzed by the computer using the excel office program.
2.5. Preparation of Smoke Igniter:
Black powder was used in this work for ignition to supply the required temperature for
initiating the burning of the chemical smoke mixture. This powder is a granular mixture of a
potassium nitrate (KNO3) or potassium chlorate (KClO3) as oxidizers, carbon and sulfur (S)
as fuel. The current standard composition for black powder manufactured by pyrotechnics is
(75% potassium nitrate, 15% softwood charcoal, and 10% sulfur) [9]. Preparation of igniter
proceeds as following:
1. (75) g of (KNO3), (15) g of (C), and (10) g of (S).
2. Potassium nitrate was crushed, and then, charcoal and sulfur were added for the
crushed powder by using Pestle and Mortar. The mixing continues for five minutes to
homogenize the black powder mixture.
2.6. Preparation and testing the smoke sample mixtures:
The pyrotechnic smoke mixtures were prepared as follows:
1. The components of every sample were weighed by Digital Balance.
2. After weighing, the samples are crushed and mixed by (Pestle and Mortar).
3. The smoke mixture is placed in stainless-steel cylindrical vessel and placed in the test
chamber.
4. The ventilation system is operated, and the target is let to come to the required
temperature (40 o C-220 o C). These temperatures are measured by the infrared camera.
5. Preparation and testing the smoke sample mixture weighed (10, 20, 30, 40, 50, 60, 70,
80, 90, 100, and 120g) of that percentage: [[(20% magnesium powder (Mg), 60%
hexachloroethane (C2Cl6), 15% naphthalene (C10H8), and 5% poly vinyl chloride
(PVC)]. Each component is crushed alone and the mixture is mixed together.
6. Approximately (1g) of the prepared black powder is placed on the top surface of the
chemical smoke mixture.
7. The reaction starts by the ignition of the black powder.
8. The produced smoke is withdrawn to the tunnel in front of the IR object.
9. On the other side of the tunnel, the IR Camera is placed and connected with the PC to
record the data.
10. The IR Camera measures the change in the target temperature as a function of time.

4/9
Paper: ASAT-13-CA-02
11. The change in the observed temperature of the infrared object during the propagation
of smoke cloud in the tunnel and the disappearance of the target thermal image is
recorded on computer video recording program.
12. When the observed temperature of the infrared camera reaches its initial value before
producing the smoke (i.e. the observed temperature returned as initial target
temperature). The smoke tunnel circulation system is operated for (10) min without
producing any smoke in the tunnel to remove any residual particle from the previous
experiments.
13. The minimum attenuating temperatures for each smoke sample are illustrated by
Computer Excel Program in the tables and figures.
14. A series of preliminary experiments were done on (10g.) bases of smoke mixture to
choose the best composition from the IR point of view.
15. Another series of experiments were done on the best composition to get the suitable
sample weight. The tested weights are (30, 40, 50, 60, 70, 80, 90, 100, and 120g.) and
the target temperature is changed from: (100, 150,200 and 220 C ).
3. Results and Discussion
For target temperature 100 o C as recorded by the IR camera varies from (74 o C) to (32 o C) by
increasing of mixture weight from (10, 20, and 30g). As shown in table (2), and figures (9 and
10, the first mixture, which contains (10g), has the lowest thermal attenuation properties. It
decreases the IR object temperature from (100 o C) to (74 o C) with (38%) attenuation
percentage in target temperature. It is also important to note that, this mixture has the lowest
time to maximum attenuation. (20g) has attenuation (85%) after (16 sec), but (30, and 40g)
have attenuation (100%) after (23, and 24 sec) respectively. It is clear that, (30g) from this
mixture is enough to attenuate (100 o C) of the target temperature. For target temperature
(150 o C), the first mixture, which contains (30g), has the lowest thermal attenuation properties.
It decreases the IR object temperature from (150 o C) to (53 o C) with (80%) attenuation
percentage in target temperature after (28 sec). (40g) has attenuation (94%) at (28 sec), and
(50g) has attenuation (95%) after (35 sec). For target temperature (200 o C), the tested weights
are (30-120g). The first mixture, which contains (30g), has the lowest thermal attenuation
properties. It decreases the IR object temperature from (200 o C) to (90 o C) with (65%)
attenuation percentage in target temperature after (29 sec). (40g) has attenuation (75%), (50g)
has attenuation (84%), (60g) has attenuation (95%), (70g) has attenuation (97%), (80g) has
attenuation (98%), and (90g) has attenuation (100%). This relation is shown in figure (10). As
shown in the figure, in the range (30g, 40g, 50g, and 60g) every (10 g) attenuates 17 o C. In
other words every 10g attenuates about 10%.
However, in the range from (70g to 90g) every (10 g) attenuates (30C). In other words every
10g attenuates about (1.7 %).
The proposed reaction mechanism for the combustion of this pyrotechnic mixture
can be explained as follows:
3 Mg + C2Cl6 ��� 3 MgCl2 + 2 C + heat
C10H8
heat
���� 10 C + 4 H2
MgCl2 + H2 ��� 2HCl + Mg
=================================
2 Mg + C2Cl6 + C10H8 ��� 2MgCl2 + 2HCl + 3H2 + 12 C

5/9
Paper: ASAT-13-CA-02
The formed carbon black when dispersed as black smoke may absorb the IR radiation and
consequently attenuate the target temperature for certain period of time. The binder
degradation may take place as follows:
(CH2CHCl)n
���� heat
2n C +n H2 +n H Cl
The formed (MgCl2) may react with the moisture of the air producing Mg (OH)2, forming a
cloud of the white smoke, enhancing the camouflaging in the visible range.
MgCl2+2 H2O ��� Mg(OH)2 + 2HCl
heat
Mg(OH)2 ���� MgO + H2O
4. Conclusions
Modern chemical smoke mixtures may include a fuel (most often magnesium powder), an
oxidizer (hexachloroethane), a carbon generator (Naphthalene), and a chlorinated polymer
binder such as Poly Vinyl Chloride PVC). Characteristics of these prepared compositions
were determined. Performance, effecting of different factors on the thermal attenuation
properties were investigated.
Conclusions are as follows:
� The smoke mixture which contains (20% Mg, 20% C2Cl6, 15% naphthalene, and 5%
PVC), is the most efficient.
� 120g of the proposed smoke mixture can attenuate any Target temperature (in range 50 o C
-220 o C) to ambient temperature (20 o C-40 o C), in RH (35% - 75%)
� (30) g of the proposed smoke mixture is the minimum weight which can attenuate
temperature from (100 o C) to ambient temperature (20 o C-40 o C), in RH (35% - 75%).
� The recorded reduction in the target temperature can be related to the weight of employed
smoke mixture.
5. References
[1] D. Gerard, Sauvestre, Espagnacq, Bourges, FR.. United States Patent 4724018.
http://www.freepatentsonline.com/4724018.html. Copyright 2004-2007
[2] P .K. Mishra Defence Science Journal, Vol 44, No 2, April 1994, pp 173-179 @ 1994,
DESlDOC REVIEW PAPER. Role of Smokes in Warfare. Institute of Armament
Technology, Pune-411 025
[3] S.Amarjit, S.G Avachat, S.A Joshi, and S. Haridwar " Evaluation of Pyrotechnic Smoke
for Anti Infrared and Anti Laser Roles” Propellent, Explosive and Pyrotechnics V.20, P.
16-20, 1995.
[4] D. Gerard, Sauvestre, Espagnacq, Bourges, FR United States Patent 4724018
http://www.freepatentsonline.com/4724018.html. Copyright 2004-2008.
[5] J. Vega and P. Morand,”Castable Smoke Generating Compounds Effective Against
Infrared”, http://www.freepatentsonline.com/4698108.html. US Patent 4698108,
Copyright 2004-2008.
[6] P. Polansky, "Theoretical Principles of Chemical Weapons, Incendiary and Smoke”, A-
569, MTC. Cairo, 1973.

6/9
Paper: ASAT-13-CA-02
[7] Ernst-Christian Koch .Special Materials in Pyrotechnics: V. Military Applications of
Phosphorus and its Compounds. Review paper00212 2007. Propellants, Explosives,
Pyrotechnics 33, No. 3 (2008)
[8] A. A. Mansour, “Military Application Of Polymeric Materials: The Use Of Polymeric
Material
[9] Y.Ahmad Hassan., "Gunpowder Composition for Rockets and Cannon in Arabic
Military Treatises In Thirteenth and Fourteenth Centuries", History of Science
and Technology in Islam, 2002
(a)
Fig. (1) (a) Infra-metrics 760 thermal scanner (IR Camera).
(b) Infra-metrics thermal image-processing systems.
Fig. (2) Hot plate
(b)
Fig (3) IBM Computer

Fig. (4) Digital thermo hygrometer
Fig. (6) Digital balance
Testing Chamber
Burning
vessel
Hot Plate
From
tunnel to
outside
Tunnel
7/9
Paper: ASAT-13-CA-02
Fig. (5) Vessel for sample burning
Fig. (7) Pestle and mortar
IBM
Computer
Air Screen
IR
Radiometric
IR Camera
Fig. (8) Schematic diagram of the setup used for smoke generation and testing

8/9
Paper: ASAT-13-CA-02
Table (2) Effect of the weight of chemical smoke mixture on thermal
attenuation percentage, with accorded target temperature.
Wt
g
10
20
30
40
30
40
50
30
40
50
60
70
80
90
100
120
A%
100
90
80
70
60
50
40
30
20
10
0
Tambient
o C
32
32
32
32
30
30
30
30
30
30
30
30
30
30
32
32
Ttarget
o C
100
100
100
100
150
150
150
200
200
200
200
200
200
200
220
220
Time
sec
10
16
23
24
28
28
35
29
29
36
59
55
53
53
59
55
Anti IR Chemical smoke mixture
Ttarget100 o C
Ttarget150 o C
Tmeasured
o C
74
42
32
32
53
37
36
90
73
58
39
35
33
30
37
32
Ttarget 200 o C
0 10 20 30 40 50 60 70 80 90 100
Wt (g)
A
%
38
85
100
100
80
94
95
65
75
84
95
97
98
100
97
100
Fig. (9) Relation between the weights of chemical smoke mixture and
thermal attenuation percentage, at (100 o C, 150 o C, and 200 o C)
of target temperature.

Minimum measured temperature(
O C)
100
90
80
70
60
50
40
30
20
10
0
Tmeasured o C
Wt (g)
1 2 3 4 5 6 7
9/9
Samples
Paper: ASAT-13-CA-02
Fig. (10) Relation between weight of CSM and minimum measured
temperature by IR camera (Tmeasured ), where Tambient = (30 o C),
relative humidity (RH75%), and Ttarget = (200 o C).