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RECEIVED OPPTNCIC 2003APR30 PM * 5 2
FLUORINATED SURFACTANTS IN FIRE FIGHTING FOAMS:
ANY INPUT FOR WATER MIST TECHNOLOGY
Martial PABON, PhD DuPont de Nemours (France)
Chantereine, Mantes le Ville F-78202 Mantes la Jolie Cedex
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Martial PABON. Mobile (AL), 26/02/2003
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Structure of a fluorinated surfactant
Hydrophilic head
Ex. : CnF2n+1Hydrophobic and oleophobic chain
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Particularity of the periluorinated chain
Higher rigidity than a perhydrogenated chain : (radius of covalently bonded fluorine, only 0,72 A ->no steric stress)
More hydrophobic than a perhydrogenated chain : 1 CF2 4* 1.7 CH2
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Martial PABON, Mobile (AL), 26/02/2003
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Element with the Highest electronegativity
=> the valence electron is strongly attracted by the fluorine atome
=> Great thermal and chemical stability
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Martial PABON. Mobile (AL), 26/02/2003
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Low CMC
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(g/1)
carboxybetain ( g of active matter / 1)
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Martial PABON, Mobile (AL), 26/02/2003
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Products Charge
THERMAL STABILITY
Loss o f Mass
(w t% )
100C
(212F)
FORAFAC Anioni
1033
c
0
FORAFAC Anioni
1176
c
0
FORAFAC Ampho
1157
teric
0
FORAFAC Ampho
1183
teric
0
200C
(392F)
56
0
0
65
300C
(572F)
94
0
87
92
400C
(752F)
96
50
95
100
500C
(932F)
98
85
100
100
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Martial PABON, Mobile (AL), 26/02/2003
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PARTICULARITY OF THE PERFLUOR1NATED CHAIN/ consequences on the surfactant properties
Property
Effectiveness (mN/m) Efficiency (weight percent) Stability : Strong acid/alkaline Oxidising media Thermal Activity in organic media Relative price index
Type of surfactant
Hydrocarbon
Silicone Fluorochemical
30 and up
20-35
16-20
0.5-5
0.1-0.5
0.01-0.05
Poor Poor Medium Poor to none
1
Medium Poor
Medium
Medium-Good About 10
Excellent Excellent Excellent Very good About 100
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Martial PABON, Mobile (AL), 26/02/2003
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US E O F AQ UIH0 US FO A iW FO R - 1R E FiG H"PF!G
FOAM used to :
- Stop the vapor emission - Prevent flames from heating the solvent
O / KED PROPERTIES: - Thermal stability as high as possible - Positive spreading coefficient on the solvent
FOAM CREATION:
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Martial PABON, Mobile (AL), 26/02/2003
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Composition of a foam concentrate
I Hydrocarbon surfactant or protein
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Butylcarbytol
1,2 propane diol Polysaccharide Mw " 2,5.10s
- Foam formation
; Foam fo rm a tio n ... * : Spreading c o e ffic ie n t
: Thermal stability
Foam stabilizer cosolvent for surfactants
I i Protection against freezing
Formation of a precipitate at the solvent surface
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Martial PABON, Mobile (AL), 26/02/2003
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Conditions for a water film formation at the hydrocarbon surface
Spreading coefficient (SC; > 0
Hydrocarbon surface tension
'x.
Diluted foam concentrate surface tension
Interfacial tension between diluted foam
concentrate and hydrocarbon
[s o = *
- ( -Y&8 + Y i )
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Use o f rlnor incited surfactants in order to lower the surface tension o f the diluted foam concentrate
Use o f hydrocarbon surfactants in order to lower interfacial tension between diluted foam concentrate and hydrocarbon
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Martial PABON. Mobile (AL), 26/02/2003
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1 g/l of fluorinated carboxybetain Cyclohexane alone
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Effect of a film of water onto heptane's rate of evaporation: role of the surfactants
: Measurement of the heptane vapours going through : water Aqueous solution of fluorinated carboxybetain Aqueous solution of hydrocarbon surfactants
| Experimental set up Valve
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Martial PABON, Mobile (AL). 26/02/2003
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Effect of a film of water onto heptane's
rate of evaporation: role of the surfactants
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Martial PABON, Mobile (AL), 26/02/2003
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Effect of a film of water onto heptane's rate of evaporation: role of the surfactants
LXAPON
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Martial PABON, Mobile (AL), 26/0212003
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Effect of a film of water onto heptane's rate of evaporation: role of the surfactants
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J Carboxybtane fluore Ig/I
Carboxybtane t Carboxybtane 0 PLi
fluore 2,5g/l
fluore 10g/l
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4500
5000
Martial PABON. Mobile (AL), 26/02/2003
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Effect of a film of water onto heptane's rate of evaporation: role of the surfactants
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Martial PABON, Mobile (AL), 26/02/2003
The miracles f science'
Effect of a film of water onto heptane's rate of evaporation: role of the surfactants
CONCLUSION!
-The amount of heptane going through a water droplet is not detectable
- The hydrocarbon surfactant has to be carefully chosen.
-Fluorinated surfactants do not participate to the heptane transfer through the water droplet
Martial PABON, Mobile (AL), 26/02/2003
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GENERAL CONCLUSION
#Fluorinated surfactants have a high thermal and chemical stability
^They give some very low surface tension values in water: Lower droplet diameter; Improved spreading of droplet also on solid surfaces.
An appropriate formulation prevents the burn back
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Martial PABON, Mobile (AL), 26102/2003
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