AU658341B2

AU658341B2 - Liquid foam concentrate for portable fire extinguishers

Info

Publication number: AU658341B2
Application number: AU60595/94A
Authority: AU
Inventors: Ivan Devaux; Gilbert Garcia; Casimir Kalinka; Elisabeth Morillon; Christian Varescon
Original assignee: Elf Atochem SA
Current assignee: Arkema France SA
Priority date: 1993-04-23
Filing date: 1994-04-20
Publication date: 1995-04-06
Anticipated expiration: 2014-04-20
Also published as: JPH06312030A; CA2121654A1; EP0621057A1; EP0621057B1; DK0621057T3; AU6059594A; DE69400885T2; JP2575289B2; DE69400885D1; ES2094028T3

Description

658 6Z 4- S F Ref: 269834

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

as~~ Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: Elf Atochem S.A.

4 8 Cours Michelet La Defense 92800 Puteaux

FRANCE

Gilbert Garcia, Elisabeth Morillon, Christian Varescon, Ivan Devaux and Casimir Kalinka Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Liquid Foam Concentrate for Portable Fire Extinguishers t* The following statement is a full description of this invention, including the best method of performing it known to me/us:- 5845/3 2 The present invention relates to the field of extinguishing fires and more particularly to liquid foam concentrates for water-spray portable extinguishers.

One of the well-known means for extinguishing hydrocarbon liquid fires consists in spraying a foam obtained by mixing water and a liquid foam concentrate based on surface-active agents at high pressure onto the site of the fire. Most of the liquid foam concentrates available on the market may be arranged in two large categories according to 10 the nature of the foaming base. In a first family of liquid Sfoam concentrates, the foaming base generally consists of a hydrolysate of animal proteins (hair, horns, hooves and haemoglobin). Fluorinated surface-active agents may be added *oci to this protein base in order to obtain a fluoroprotein liquid foam concentrate; such liquid foam concentrates are described, for example, in Patents GB 1,280,508, GB 1,368,463, US 4,424,133, EP 49,958, US 4,460,480, FR 2,230,384, GB 2,011,784 and WO 88 03,425.

*e In the other large family of liquid foam concentrates, the foaming base is composed of a mixture of hydrocarbon surface-active agents. Film-forming fluorinated surface-active agents may also be incorporated. In this latter type of liquid foam concentrates, known in the business as AFFF liquid foam concentrates, the presence of the fluorinated surfactant makes it possible to produce a foam which forms an aqueous film floating on the surface of the hydrocarbon by settling. The purpose of this aqueous film -3 is not only to extinguish the fire but also to prevent a possible re-ignition of the surface of the hydrocarbon.

Liquid foam concentrates of this type have been described in numerous patents, in particular the following: GB 1,258,299, US 5,085,786, FR 2,347,426, US 3,957,657, FR 2,040,316, US 4,350,206, FR 3,562,156, FR 2,148,442, FR 2,407,724, FR 2,385,413, US 3,772,195, FR 2,397,847, US 3,661,776, *i US 3,839,425, FR 2,103,669, US 3,957,657, US 3,963,776 and FR 2,296,625.

In or4er to obtain good resistance to re-ignition, the liquid foam concentrate must, after dilution with water and addition of air, produce a foam which forms, on settling, an aqueous film which spreads over the whole surface of the S:hydrocarbon and for which the thermal stability is the highest possible. The thermodynamic equilibrium condition necessary for forming the aqueous film is linked to the too* coefficient of spreading (CS) which must be positive.

S CSY THC- s+ where CS coefficient of spreading in mN/m YHC surface tension of the hydrocarbon y, surface tension of the extinguishing composition after dilution of the liquid foam concentrate 7i interfacial tension between the hydrocarbon and the extinguishing composition after dilution of the liquid foam concentrate Although the coefficient of spreading must be 4 positive, care must be taken to ensure that the interfacial tension (7y) is not too low in order to avoid emulsification of the hydrocarbon by the extinguishing composition or too great a thinning down of the aqueous film. In fact, emulsification of the hydrocarbon by the extinguishing composition runs the risk of resulting in the entrainment of part of the hydrocarbon into the interior of the extinguishing foam, of contaminating the latter and of "Ii igniting it.

10 Another important factor with regard to the phenomenon of re-ignition is the heat resistance of the aqueous film. In this regard, an excessive spreading rate leads to the formation of a film which is very thin and of low heat resistance; inversely, the films which are the most heat resistant are those for which the rate of formation is th, slowest. It is therefore important to find a compromnise between the spreading rate and the heat resistance of the aqueous film, this property being essential for obtaining *e.

good resistance to re-ignition. In fact, the aqueous film which suppresses the hydrocarbon vapours may at any moment, for example on agitation, be separated from the foam from which it has arisen and find itself in direct contact with a part in flames. If its heat resistance is too low, the film may be destroyed and liberate hydrocarbon vapours which immediately ignite and continue to destroy the rest of the film.

The AFFF liquid foam concentrates which are I 5 generally used with firefighting jet pipes are not suitable in a portable extinguisher, which is designed to be carried and used in the hand and which, in working order, has a mass less than or equal to 20 kg. In a portable extinguisher, the quantity of water available for diluting the liquid foam concentrate to the operating concentration (0.5 to most regularly 1 to is limited and generally fixed at 6 or 9 litres, whereas in the system of application by means of a Sjet pipe the quantity of water available is unlimited. As a 10 result, in order to satisfy the homologation standards relating to liquid foam concentrate liquids for hydrocarbon fires, a liquid foam concentrate for a portable extinguisher must be of much greater performance than a standard liquid foam concentrate for firefighting jet pipes. By way of example, In order to obtain the certification for a 6-litre extinguisher for fires of 144 B type, the portable extinguisher will have to carry out the extinction with only 6 litres of extinguishing composition obtained by diluting the liquid foam concentrate to a concentration of 3% (French standard S61-900), whereas in the case of extinction with a firefighting jet pipe the maximum available quantity of extinguishing composition obtained by diluting the liquid foam concentrate to a concentration of 3% will be able to range up to 28.5 litres (French standard S60-220) or 22.3 litres (standard UL 162).

According to the present invention there is provided a liquid foam concentrate for portable i 6 extinguishers, which concentrate comprises an aqueous solution containing by weight: from 1 to 15% (preferably 2 to 12%) of at least one fluorinated betaine of general formula:

R

I

RfCH2)m-X-N-(CH2)n-(CH 2 )p-Y (1) R R 2 5 from 1 to 20% (preferably 3 to 15%) of at least one ,i fluorinated amine oxide of general formula:

I

RF(CH2)m-X(CH2)n'-N 0 from 2 to 8% (preferably 3 to of at least one e alkyl glycoside of general formula: H(CHioO5)qOR 3 (II1 from 2 to 10% (preferably 3 to of at least one anionic, nonionic or amphoteric non-fluorinated surfaceactive agent other than those of formula III; from 20 to 50% (preferably 30 to 45%) of at least one monoalkyl ether of mono- or diethylene (or propylene) glycol; the total content of fluorinated compounds a and b being between 5 and 25% (preferably between 7 and 18%) and the weight ratio (a d) being between 1 and 2 7 S .i 0 10 *00 0 0*0 .i 0* r.

0 0 *000 0 (preferably between 1.3 and 1.7).

In formulae I, II and III above, the various symbols have the following meanings: Rf and Rp, which may be identical or different, each represent a linear or branched perfluoroalkyl radical containing at least 6 carbon atoms, preferably from 6 to 16 carbon atoms; m and which may be identical or different, are each an integer ranging from 0 to 6, preferably equal to 0 or 2, X and which may be identical or different, each denote a group CO or S02, preferably a group S0 2 R and which may be identical or different, each represent a hydrogen atom or a methyl or ethyl radical; n and which may be identical or different, are each an integer ranging from 1 to 5, prefe, ably equal to 3; R, R and which may be identical or different, each represent a methyl or ethyl radical; p is an integer ranging from 1 to 5, preferably equal to 1 or 2; YO denotes a group SO, 0 osoO or COO 0 q is an integer ranging from 1 to 6, preferably equal to 1 or 2;

R

3 represents a linear or branched alkyl radical 0000 0 000 8containing from 6 to 18 carbon atoms, preferably 8 to 14 carbon atoms.

The non-fluorinated surface-active agent may be chosen, without any limitation being implied, 'rom the compounds of the following formulae:

R

4 -030 3 M

(OVA).

*.2

~R

4

C

2 H4)C-OSO3M I/)

R

4 (002H4)rOH (IV-3) 060 0 R4N-CH*CO 2 4_ N 9 R4-CONH-C 3 H6-N(CH3)C2CH2COO R4-N(CH3)2 -40 (IV-11) in which R 4 represents a linear or branched alkyl radical containing from 8 to 18 carbon atoms, r is an integer ranging from 1 to 16, M denotes an alkali metal ion or a quaternary I ammonium ion and M' an alkali metal ion.

S* 5 Examples of monoalkyl ethers which may be 4 mentioned, without any limitation being implied, are ethylene glycol monoethyl or monobutyl ether and diethylene glycol monobutyl ether, the latter being preferred.

Particularly preferred liquid foam concentrates are 10 those which contain: a constituents a mixture of fluorinated betaines of formula: o CxF2x+ -CH 2

CH

2

-SO

2

NH-CH

2 CH2CH 2

-N(CH

3 2

CH

2

COO

S*4* in which x is an even integer ranging from 6 to 16, the C 6 F1 radical betaine content of the mixture being at least 50% by weight; as constituent the fluorinated amine oxide of formula:

C

6 Fl3CH 2

GH

2

-SO

2

NH-CH

2

CH

2 CH2-N(CH 3 )2 0 as constituent an amido ether propionate of formula an alkyl 0-iminodipropionate of formula (IV- 10 8) or an alkylamidopropylbetaine of formula The liquid foam concentrates according to the invention may be prepared by simple mixing of the various constituents until homogenization is achieved, In order to accelerate the homogenization, heating may be carried out at a temperature between room temperature and the boiling temperture of the mixture, preferably at a temperature between 30 and 600C.

a 4 The pH of the liquid foam concentrate is t: 10 advantageously stabilized at a value at least equal to 7 (preferably between 8 and 10) by means o? a weak base, for example ammonia solution or an organic base such as diethanolamine, triethanolamine or urea, If so desired, various additives may optionally be incorporated into the liquid foam concentrates according to the invention, such as: 4**6 an antifreeze such as ethylene glycol or propylene glycol, 4 a co-solvent, for example a (C 1 to C 4 lower alcohol, an anti-corrosion agent such as tolyltriazole or sodium nitrite, a preservative such as sodium benzoate, formaldehyde, o-phenylphenol or dichlorophene.

The liquid foam concentrates according to the invention may be used An a portable extinguisher in a proportion of 0.5 to 6 parts by weight (preferably 1 to 3 parts) of liquid foam concentrate per 100 parts by weight of 11 water.

The performance of the liquid foam concentrates according to the invention may be evaluated by the .following tests.

Spreading test This test, which indicates the rate of formation of the aqueous film on the surface of the hydrocarbon, is carried out by pouring 50 ml of hydrocarbon (heptane) into a Potri dish (diameter: 11.5 cm) whose external face is painted 10 black in order to be able to see the film. When the surface **6 is immobile, 0.1 ml of an aqueous solution of the liquid foam concentrate at a concentration of 3% is deposited with the aid of a micropipette. The solution must be deposited dropwise starting from the centre and so as to effect an eccentric motion. The stopwatch is started at the time of deposition of the first drop and stopped when the film has covered all of the hydrocarbon surface. The time is noted. If complete covering is not obtained in less than one minute, the percentage of surface covered after one minute is noted.

The spreading is satisfactory if total covering is obtained in less than 30 seconds, preferably between 5 and seconds.

Heat resistance te t Evaluation of the heat resistance of the aqueous film is obtained by measuring the Film Stability Limit Temperature (FSLT). This test, which can only be carried out in the case where all of the hydrocarbon surface is covered 12 by the tilm, is carried out in a brass measuring vessel with a diameter of 6.5 cm and a total volume of 100 ml, placed on a thermostated heating plate. 80 ml of hydrocarbon .(heptane) are poured into this vessel and, when the surface is immobile, 0.1 m2 of an aqueous solution of the liquid foam concentrate at a concentration of 3% is deposited thereon as indicated fer the spreading test After 60 seconds, the tip of a thermometer is placed in contact with the aqueous film and a flame is positioned approximately 1 cm above the film.

S 10 The thermostat is regulated for a temperature increase of The temperature (FSLT) at which ignition of the hydrocarbon is produced is noted.

A good liquid foam concentrate should lead to an FSLT greater than 35 0 C, preferably greater than approximately 40 0

C.

ea. t lume R4ell The volume swell (or degree of expansion) is the ratio of the volume of foam produced from an aqueous solution 0 of the liquid foam concentrate at a concentration of 3% to the initial volume. In order to determine volume swell, 100 ml of aqueous solution of the liquid foam concentrate at a concentration of 3% is introduced into a 1-litre measuring cylinder and the solution is then beaten for one minute at a rate of one beating action per second using a perforated circular piston (30 holes of 5 mm diameter representing of the surface) and secured at its centre to a metal rod.

A satisfactory liquid foam concentrate should lead 13 to a volume swell at least equal to 8.

Surface and interfacialI tensions The surface tension with tap water and the interfacial tension (7y) with heptane are measured by means of a LAUDA tension meter in accordance with standards ISO 304 and ISO 6889, but carrying out the procedure at 25 0

C.

In the following examples, which illustrate the invention without any limitation being implied thereto, the percentages indicated are expressed in weight and the main 10 constituents used are denoted, for simplicity, by the following abbreviations: mixture of fluorinated betaines of formula: CxF2x+CH 2

CH

2 -S02NH-CH 2

CCH

2 -N (CH)2CH2CO0 having the following weight composition: oor0 x 0 15 6 8 23 12 14 0.4 16 0.1 used in the form of an aqueous solution at a concentration of R Fluorinated amine oxide of formula:

CGFI

3

-CH

2

CH

2

-SO

2

NH-CH

2

CH

2

CH

2

-N(CH

3 2 -4 0 14 marketed by Elf Atochem S.A. in the form of an aqueousalcoholic solution at a concentration of C= Alkyl(Cg and CIO) glucoside marketed in the form of an aqueous solution at a. concentration of 70% by the Company UNION CARBIDE under the name Triton BG -P1 Alkyl(Cs and C 1 )amido ether pro~ionate of formula: Osee: AlkyU-CONH-CH1 2

CH

2

-NH-CH

2

CH

2

-OCH

2

CH

2 COONa marketed in the form of an aqueous solution at a concentration of 50% by the Company REWO under the name Rewoteric ANVSF *D2 N-Lauryl-f3-iminodipropionate of formula: CH2H2SS fee

CH

2

CH

2 COOHa Al- -CNHCHCH 2

CH

2 00NaH)C2O marketed as an aqueous solution at a conrcentration of 309% byde the Come AhNE nsd 15 B4 by the Company ZSCHIMMER and SCHWARTZ.

*D4 Decyl ether sulphate of formula:

C

10

H

2 1

(OC

2

H

4 2 OSO3Na used as an aqueous solution at a concentration of E Diethylene glycol mono-n-butyl ether:

C

4 Hg0-C 2

H

4 -0-C 2H4 0 H EXAMPLE 1 a) A liquid foam concentrate according to the invention is prepared by mixing, at 4000 under moderate stirring, suitable quantities of the abovementioned commercial products, for 10 which liquid foam concentrate the content of active materials is the following: Constituents Content A 10.8 B 6.2 S 15 C 3.3 D1 7.9 E 40.0 ethanol 5.4 water (qs 100%) 26.4 This composition, brought to pH 9.3 by addition of diethanolamine, has the following characteristics: freezing temperature -22±2oC 16 density 1.065 viscosity 18 mPa.s refractive index 1,414 y, tap water) 16.4 mN/m 'y tap water/heptane) 2.5 mN/m flashpoint (in a closed cup): 5 0

°C

When subjected to the tests described above, this liquid foam concentrate leads to the following performances: ,j S S i spreading 20 seconds 10 FSLT 470C 0#0* volume swell 10.2 ml of this liquid foam concentrate are placed in the cartridge of a 6-litre portable extinguisher, and its efficiency is then tested on a 144 B heptane fire (French standard NF S61-900). Extinction was obtained with an excellent behaviour regarding the phenomenon of re-ignition.

In fact, if after extinction the floating aqueous film is broken and the hydrocarbon vapours placed in contact with air are ignited, the film immediately reforms and totally recovers the hydrocarbon surface, thus extinguishing the developing fire.

b) By way of comparison, two liquid foam concentrates (bl) and which are not in accordance with the present invention, were prepared and their pH was brought to 8.5 by means of diethanolamine. Their composition and their performance are summarized in the following table: r 17 LIQUID FOAM CONCENTRATE bl b2 Constituents A 4.2 17.0 B 2.4 C 6.5 3.3 D1 15.1 7.9 E 40.0 40.0 ethanol 6.0 10 water 25.8 28.8 Performance: spreading 15 FSLT (OC) 27 volume swell 10 9.3 15 In the heat resistance test (FSLT), the liquid foam concentrates (bl) and (b2) turn out to perform less well than the liquid foam concentrate of Example 1-a.

Example 2 Example 1-a is repeated, but the proportions of the various constituents are modified and/or the surface-active agent Dl is replaced by the compound D2.

The table which follows indicates the composition and the performance of three liquid foam concentrates thus obtained.

1 18 LIQUID FOAM CONCENTRATE 2a 2b 2c Constituents A 2.5 2.5 10.8 B 14.4 14-4 6.15 C 5.6 5.6 3.25 91 D2 5.5 7.9 E 40 40 10 ethanol 12.6 12.6 5.4 water 19.4 19.4 26.5 Performance spreading 7 6 FSLT 50 43 volume swell 9.4 10.6 11 o EXAMPLE 3 The procedure is carried out as in Example 1-a, but part of the ether E is replaced by monoethylene glycol (MEG below) and the proportions of the various surface-active agents are varied.

Four liquid foam concentrates are thus prepared which are brought to pH 8.5 by addition of diethanolamine, Their composition and their performance are summarized in the following table.

19 LIQUID FOAM CONCENTRATE 3a 3b 3c 3d Constituents A 1.2 1.5 2.7 4.1 B 7 8.8 5.4 4.1 C 3.4 3.4 3.4 3.4 D2 3.4 3.4 3.4 3.4 E 30 30 30 d.

MEG 15 15 15

S

10 ethanol 6.85 8.6 6.3 6 water 33.15 29.3 33.8 34 Performance spreading 5 7 8 16 FSLT (OC) 41 43 42 volume swell 10 9.2 9 9.2 EXAMPLE 4 The procedure is carried out as in Example 1-a, but part of the ether E is replaced by monoethylene glycol and at least one of the surface-active agents D2, D3 and D4 is used in place of 01 and/or in place of the alkyl glucoside C.

Ten different liquid foam concentrates are thus prepared: 5 liquid foam concentrates according to the invention (4a, 4b, 4c, 4d and 4e) 5 liquid foam concentrates not in accordance with the invention (4f, 4g, 4h, 4i and 4j) which are brought to pH 8.5 by means of diethanolamine before carrying out the tests.

The composition and the performance of thesp various liquid foam concentrates are combined in the following table:

A

a. C a *a a a. C. S. a *b as

I

LIQUID FOA14

CONCENTIRATE

Constituents f%)

A

B

C

02 D3 D4 7M M EG ethanol water Perfornance: spreading (s) FSLT volume swell 4a 4b 4c 4d 4e 4f 4g 4h 4i 4j 6.7 3.8 2-7 4.1 6.7 6.7 3-8 3.8 2.7 3.4 1.7 6.7 3.8 2.05 4.75 6.7 3,tL 3-.4 3,.4 6.7 6.7- 3.8 3.8 6-8 3.4 6.7 6.7 3.8 3.8 6.8 6.7 3-8 2.7 1.4 30 30 10 10 7.3 7.3 35.4 35.4 1.7 30 10 7.3 35.4 3 1 3 3.4 3.4 3.4 0 30 30 30 30 P- 10 10 10 10 7.3 7.3 7.3 7.3 7.3 5-4 35.4 35.4 35.4 35.4 6.8 30 10 -7.3 35.4 7.3 35.4 15 37 9.6 14 37 11.3 15 44 7.3 29 10.2 9. 5 10 8.8 Less than 10% of the surface covered after 1 minute of surface covered after 1 minute

V

I

Examination of the resuits shows that in the absence of alky. glucoside (liquid foam concentrates 4g, 4h, 4i and, 4j) a satisfactory -,reading and/or a high FSLT is, (are) not obtained, wher~eas this hydr'ocarbon co-surf actant alone (liquid foam concentrate 4f) leads to an insufficient volume swell.

a o.

@tooS

Claims

3. A liquid foam concentrate according to Claim 1 or 2, in which the total content of fluorinated compounds is between 7 and 18%.
4. A liquid foam concentrate according to any one of Claims 1 to 3, in which the weight ratio (a d) is between 1.3 and 1.7.
5. A liquid foam concentrate according to any one of Claims 1 to 4, in which the radicals Rr and/or RF contain from 6 to 16 carbon atoms, m and/or m' is equal to 0 or 2, n and/or n' is equal to 3, p is equal to 1 or 2, q is equal to 1 or 2, and che radical R 3 contains from 8 to 14 carbon atoms.
6. A liquid foam concentrate according to claim containing a mixture of fluorinated betaines of formula: i CxF2X+ICH2CH2 -S2NH-CH2CH2CH2-N©(CH3)2CH2COO in which x is an even integer ranging from 6 to 16, the C 6 F13 radical betaine content of the mixture being at least 50% by weight.
7. A liquid foam concentrate according to Claim 5 or 6, in which the amine oxide is the compound: C 6 F 1 3-CH 2 CH 2 -SO 2 NH-Ot 2 CH 2 CH 2 N(CH 3 2 0. 26
8. A liquid foam concentrate according to any one of claims 1 to 7, in which the non-fluorinated surface-active agent is chosen from the compounds of f ormulae! R 4 -oOO 3 (IV-1) R 4 C2H4)rOso-M (P1-2) R 4 (OC 2 H4)-OH (13 ses 4 W A see goos R4N(HoC 2 H 4 rOOH W7 R{OC HI N r R 02H4C I R 4 CONH-3H-NH-0 2 CH 4 0C 2 N00 (IV- R 4 -N(0H 3 2 0 (IV-11) 27 in which R 4 represents a linear or branched alkyl radical containing from 8 to 18 carbon atoms, r is an integer ranging from 1 to 16, M denotes an alkali metal ion or a quaternary ammonium ion and M' an alkali metal ion.
9. A liquid foam concentrate according to any one of Claims 1 to 8, in which the ether is diethylene glycol monobutyl ether. S
10. A liquid foam concentrate according to any one of Claims 1 to 9, stabilized at a pH at least equal to 7.
11. A liquid foam concentrate according to any one of claims 1 to 9, stabilised at a pH between 8 and
12. A liquid foam concentrate according to any one of Claims 1 to 11, additionally comprising an alcoholic co- S* S solvent, an antifreeze, a preservative and/or an anti- S 15 corrosion agent. 0I e 13. A liquid foam concentrate according to claim 1 substantially as described in any one of the Examples. S" 14. Use of a liquid foam concentrate according to any one of Claims 1 to 13 in a portable extinguisher, in a proportion of 0.5 to 6 parts by weight of liquid foam concentrate per 100 parts by weight of water. Use according to claim 14 in which 1 to 3 parts of liquid foam concentrate are used per 100 parts by weight of water.
16. A portable fire extinguisher containing a liquid foam concentrate according to any of claims 1 to 13 in a -I 28 proportion of 0.5 to 6 parts by weight per 100 parts by weight of water.
17. A fire extinguisher according to claim,16 which contains 1 to 3 parts of liquid foam concentrate per 100 parts by weight of water. DATED this NINETEENTH day of APRIL 1994 Elf Atochem S.A. Patent Attorneys &for the Applicant .000 so