ISO 7203-3:2011

INTERNATIONAL ISO
STANDARD 7203-3
Second edition
2011-08-01

Fire extinguishing media — Foam
concentrates —
Part 3:
Specification for low-expansion foam
concentrates for top application to water-
miscible liquids
Agents extincteurs — Émulseurs —
Partie 3: Spécifications pour les émulseurs bas foisonnement destinés à
une application par le haut sur les liquides miscibles à l'eau




Reference number
ISO 7203-3:2011(E)
©
ISO 2011

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ISO 7203-3:2011(E)

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©  ISO 2011
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ISO 7203-3:2011(E)
Contents Page
Foreword . v
Introduction . vi
1  Scope . 1
2  Normative references . 1
3  Terms and definitions . 2
4  Grades and uses of foam concentrates . 3
4.1  Grades . 3
4.2  Use with sea water . 4
5  Tolerance of the foam concentrate to freezing and thawing . 4
6  Sediment in the foam concentrate . 4
6.1  Sediment before ageing . 4
6.2  Sediment after ageing . 4
7  Viscosity of the foam concentrate . 4
7.1  Newtonian foam concentrates . 4
7.2  Pseudo-plastic foam concentrates . 4
8  pH of the foam concentrate . 4
8.1  pH limits . 4
8.2  Sensitivity to temperature . 5
9  Surface tension of the foam solution . 5
9.1  Before temperature conditioning . 5
9.2  Temperature sensitivity . 5
10  Interfacial tension between the foam solution and cyclohexane . 5
10.1  Before temperature conditioning . 5
10.2  Temperature sensitivity . 5
11  Spreading coefficient of the foam solution on cyclohexane . 5
12  Expansion and drainage of foam . 6
12.1  Expansion . 6
12.2  Drainage . 6
13  Test fire performance . 6
14  Marking, packaging and specification sheet . 7
14.1  Marking . 7
14.2  Packaging . 7
14.3  Specification sheet . 7
Annex A (normative) Preliminary sampling and conditioning of the foam concentrate . 8
Annex B (normative) Determination of tolerance to freezing and thawing . 9
Annex C (normative) Determination of percentage of sediment . 11
Annex D (normative) Determination of viscosity for pseudo-plastic foam concentrates . 12
Annex E (normative) Determination of surface tension, interfacial tension
and spreading coefficient . 14
Annex F (normative) Determination of expansion and drainage time . 15
Annex G (normative) Determination of test fire performance . 20
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ISO 7203-3:2011(E)
Annex H (informative) Small-scale fire test .24
Annex I (informative) Description of a radiation measurement method .34
Annex J (informative) Compatibility .38
Bibliography .39

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ISO 7203-3:2011(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 7203-3 was prepared by Technical Committee ISO/TC 21, Equipment for fire protection and fire fighting,
Subcommittee SC 6, Foam and powder media and fixed firefighting system using foam and powder.
This second edition cancels and replaces the first edition (ISO 7203-3:1999), which has been technically
revised.
ISO 7203 consists of the following parts, under the general title Fire extinguishing media — Foam
concentrates:
 Part 1: Specifications for low-expansion foam concentrates for top application to water-immiscible liquids
 Part 2: Specification for medium- and high-expansion foam concentrates for top application to water-
immiscible liquids
 Part 3: Specification for low-expansion foam concentrates for top application to water-miscible liquids

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ISO 7203-3:2011(E)
Introduction
Firefighting foams are widely used to control and extinguish fires of flammable liquids and for inhibiting
reignition. They can also be used to prevent the ignition of flammable liquids and, in certain conditions,
extinguish fires of solid combustibles.
Foams can be used in combination with other extinguishing media, particularly halons, carbon dioxide and
powders, which are the subject of other International Standards including ISO 5923, ISO 6183, ISO 7201-1,
1)
ISO 7201-2 and ISO 7202. A specification for foam systems [ISO 7076 (all parts) ] designed in accordance
with this part of ISO 7203 is being prepared and will be published as ISO 7076 (all parts).
Attention is drawn to Annex J, which deals with the compatibility of foam concentrates, and the compatibility of
foams and powders.

1) To be published.
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INTERNATIONAL STANDARD ISO 7203-3:2011(E)

Fire extinguishing media — Foam concentrates —
Part 3:
Specification for low-expansion foam concentrates for top
application to water-miscible liquids
1 Scope
This part of ISO 7203 specifies the essential properties and performance of liquid foam concentrates used to
make low-expansion foams for the control, extinction and inhibition of reignition of fires of water-miscible
liquids. Minimum performance on certain test fires is specified.
These foams are suitable for top application to fires of water-miscible liquids. Those foams that also comply
with ISO 7203-1 are also suitable for top application to fires of water-immiscible liquids.
The foam concentrates can be suitable for use in non-aspirating sprayers or for subsurface application to
liquid fires, but requirements specific to those applications are not included in this part of ISO 7203.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 304, Surface active agents — Determination of surface tension by drawing up liquid films
ISO 3104, Petroleum products — Transparent and opaque liquids — Determination of kinematic viscosity and
calculation of dynamic viscosity
ISO 3219, Plastics — Polymers/resins in the liquid state or as emulsions or dispersions — Determination of
viscosity using a rotational viscometer with defined shear rate
ISO 3310-1, Test sieves — Technical requirements and testing — Part 1: Test sieves of metal wire cloth
ISO 3696:1987, Water for analytical laboratory use — Specification and test methods
ISO 3734, Petroleum products — Determination of water and sediment in residual fuel oils — Centrifuge
method
ISO 7203-2, Fire extinguishing media — Foam concentrates — Part 2: Specification for medium- and high-
expansion foam concentrates for top application to water-immiscible liquids
BS 5117-1.3, Testing corrosion inhibiting, engine coolant concentrate ('antifreeze'). Methods of test for
determination of physical and chemical properties. Determination of freezing point
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ISO 7203-3:2011(E)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
characteristic value
value declared by the foam concentrate supplier for the chemical and physical properties and the
performances of the foam, foam solution, and foam concentrate
3.2
25 % drainage time
time for 25 % of the liquid content of a foam to drain out
3.3
expansion
ratio of the volume of foam to the volume of the foam solution from which it was made
3.4
low-expansion
with expansion in the range 1 to 20, as applied to foam and to associated equipment, systems and
concentrates
3.5
medium-expansion
with expansion in the range 21 to 200, as applied to foam and to associated equipment, systems and
concentrates
3.6
high-expansion
with expansion greater than 200, as applied to foam and to associated equipment, systems and concentrates
3.7
foam
aggregate of air-filled bubbles formed from an aqueous solution of a suitable foam concentrate
3.8
concentrate
liquid that, when mixed with water in the appropriate concentration, gives a foam solution
3.9
protein foam concentration
P
foam concentrate derived from hydrolized protein materials
3.10
fluoroprotein foam concentrate
FP
protein foam concentrate with added fluorinated surface active agents
3.11
synthetic foam concentrate
S
foam concentrate based on a mixture of hydrocarbon surface-active agents and which can contain
fluorocarbons with additional stabilizers
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ISO 7203-3:2011(E)
3.12
alcohol-resistant foam concentrate
AR
foam concentrate resistant to breakdown when applied to the surface of alcohol or other water-miscible
solvents
3.13
aqueous film-forming foam concentrate
AFFF
foam concentrate based on a mixture of hydrocarbon and fluorinated surface-active agents with the ability to
form an aqueous film on the surface of some hydrocarbons
3.14
film-forming fluoroprotein foam concentrate
FFFP
fluoroprotein foam concentrate that has the ability to form an aqueous film on the surface of some
hydrocarbons
3.15
foam solution
solution of foam concentrate and water
3.16
forceful application
application of foam such that it falls directly onto the surface of a liquid fuel
3.17
gentle application
application of foam indirectly to the surface of a liquid fuel via a backboard, tank wall or other surface
3.18
sediment
insoluble particles in the foam concentrate
3.19
spreading coefficient
value calculated from the measured surface and interfacial tensions to indicate the ability of one liquid to
spontaneously spread across the surface of another
3.20
lowest temperature for use
temperature claimed by the manufacturer or supplier to be the lowest temperature at which the foam
concentrate can be proportioned correctly using equipment normally available
4 Grades and uses of foam concentrates
4.1 Grades
Based on the test fire performance of the foam concentrate (see Clause 13), it shall be graded
 as class I or II for extinguishing performance;
 as level A, B or C for burn-back resistance.
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ISO 7203-3:2011(E)
4.2 Use with sea water
If a foam concentrate is marked as suitable for use with sea water, the recommended concentrations for use
with fresh water and sea water shall be identical.
5 Tolerance of the foam concentrate to freezing and thawing
Before and after temperature conditioning in accordance with A.2, the foam concentrate, if claimed by the
supplier not to be adversely affected by freezing and thawing, shall show no visual sign of stratification and
non-homogeneity when tested in accordance with Annex B.
Foam concentrates complying with Annex B shall be tested for compliance with the appropriate requirements
given in other clauses and subclauses of this part of ISO 7203 after freezing and thawing in accordance with
A.2.1.
6 Sediment in the foam concentrate
6.1 Sediment before ageing
Any sediment in the concentrate prepared in accordance with A.1 shall be dispersible through a 180 µm sieve,
and the percentage volume of the sediment shall be not more than 0,25 % when tested in accordance with
Annex C.
6.2 Sediment after ageing
Any sediment in the concentrate aged in accordance with C.1 shall be dispersible through a 180 µm sieve,
and the percentage volume of sediment shall be not more than 1,0 % when tested in accordance with
Annex C.
7 Viscosity of the foam concentrate
7.1 Newtonian foam concentrates
The viscosity of the foam concentrate at the lowest temperature for use claimed by the manufacturer shall be
2 1
determined in accordance with ISO 3104. If the viscosity is  200 mm s , the container shall be marked:
“This concentrate can require special proportioning equipment”.
7.2 Pseudo-plastic foam concentrates
The viscosity of the foam concentrate shall be determined in accordance with Annex D. If the viscosity at the
1
lowest temperature for use is greater than or equal to 120 mPa·s at 375 s , the container shall be marked:
“Pseudo-plastic foam concentrate. This concentrate can require special proportioning equipment”.
8 pH of the foam concentrate
8.1 pH limits
The pH of the foam concentrate, before and after temperature conditioning in accordance with A.2, shall be
not less than 6,0 and not more than 8,5 at (20  2) °C.
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ISO 7203-3:2011(E)
8.2 Sensitivity to temperature
The difference in pH between before and after temperature conditioning shall not be greater than 1,0 pH units.
9 Surface tension of the foam solution
9.1 Before temperature conditioning
The surface tension of the foam solution prepared from the concentrate, before temperature conditioning in
accordance with A.2 at the supplier's recommended concentration, shall be within  10 % of the characteristic
value when determined in accordance with E.2.
9.2 Temperature sensitivity
The surface tension of the foam solution prepared from the concentrate, after temperature conditioning in
accordance with A.2 at the supplier's recommended concentration, shall be determined in accordance with
E.2.
The value obtained after temperature conditioning shall not be less than 0,95 times, or more than 1,05 times
the value obtained before temperature conditioning.
10 Interfacial tension between the foam solution and cyclohexane
10.1 Before temperature conditioning
The difference between the interfacial tension between the foam solution prepared from the foam concentrate,
before temperature conditioning in accordance with A.2, and cyclohexane (when determined in accordance
with E.3) and the characteristic value, shall not exceed 1,0 mN/m or 10 % of the characteristic value,
whichever is the greater.
10.2 Temperature sensitivity
The interfacial tension between the foam solution prepared from the foam concentrate, after temperature
conditioning in accordance with A.2, and cyclohexane shall be determined in accordance with E.3.
The two values obtained before and after temperature conditioning shall not differ by more than 0,5 mN/m.
11 Spreading coefficient of the foam solution on cyclohexane
The spreading coefficient of the foam solution prepared from a concentrate claimed by the supplier to be “film-
forming” before and after temperature conditioning in accordance with A.2, calculated in accordance with E.4,
shall be positive.
NOTE Foam concentrates complying with Clause 11 are more likely to be of types AFFF or FFFP than of types FP, P
or S.
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ISO 7203-3:2011(E)
12 Expansion and drainage of foam
12.1 Expansion
12.1.1 Limits
The difference between the expansion of the foam produced from the foam concentrate, before and after
temperature conditioning in accordance with A.2, with potable water and, if appropriate, with the synthetic sea
water of G.2.4, and the characteristic value shall be within either  20 % of the characteristic value or  1,0 of
the characteristic value, whichever is the greater, when tested in accordance with Annex F.
12.2 Drainage
12.2.1 Limits
The difference between the drainage time of the foam produced from the foam concentrate, before and after
temperature conditioning in accordance with A.2, with potable water and, if appropriate, with the synthetic sea
water of G.2.4, and the characteristic value shall be within  20 % of the characteristic value when tested in
accordance with Annex F.
13 Test fire performance
The foam produced from the solution prepared using the foam concentrate sampled in accordance with
Annex B at the supplier's recommended concentration with potable water, and if appropriate at the same
concentration with the synthetic sea water in accordance with F.4, shall have an extinguishing performance
class and burn-back resistance level as specified in Table 1, when tested in accordance with G.1 and G.2.
Table 1 — Extinguishing performance classes and burn-back resistance levels
Times in minutes
Extinguishing Burn-back Extinction time not 25 % burn-back time not
performance class resistance level more than less than
A 3 15
I B 3 10
C 3 5
A 5 15
II B 5 10
C 5 5
NOTE 1 The values obtained with sea water can differ from those obtained with potable water.
NOTE 2 Annex H describes a small-scale fire test which can be suitable for quality control purposes.
NOTE 3 Extinction time is the period from the start of foam application until the time when all flames are extinguished.
NOTE 4 25 % burn-back time is the period from the ignition of the burn-back pot until 25 % of the tray is covered by sustained flames.

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ISO 7203-3:2011(E)
14 Marking, packaging and specification sheet
14.1 Marking
14.1.1 The following information shall be marked on the shipping container:
a) designation (identifying name) of the concentrate and the words “low-expansion foam concentrate”;
b) class (I or II) and level (A, B, or C) of the foam concentrate and, if the concentrate complies with
Clause 11, the words “aqueous film-forming”;
c) recommended usage concentration for use (most commonly 1 %, 3 % or 6 %);
d) any tendency of the foam concentrate to cause harmful physical effects, the methods required to avoid
them and the first aid treatment if they occur;
e) recommended storage temperature and temperature of use;
f) if the concentrate complies with Clause 5, the words “Not affected by freezing and thawing” or, if the foam
concentrate does not comply with Clause 5, the words “Do not freeze”;
g) nominal quantity in the container;
h) supplier's name and address;
i) batch number;
j) words “Not suitable for use with sea water” or “Suitable for use with sea water”, as appropriate.
WARNING — It is extremely important that the foam concentrate, after dilution with water to the
recommended concentration and in normal usage, not present a significant toxic hazard to life in
relation to the environment.
The packaging of the foam concentrate shall ensure that the essential characteristics of the concentrate are
preserved when stored and handled in accordance with the supplier's recommendations.
14.1.2 Markings on shipping containers shall be permanent and legible.
14.1.3 It is recommended that non-Newtonian concentrates be appropriately identified.
14.1.4 Foam concentrates in accordance with ISO 7203-2 shall also be marked “medium-expansion” or
“high-expansion” or both.
14.1.5 Foam concentrates in accordance with ISO 7203-3 shall also be marked “alcohol resistant”.
14.2 Packaging
14.2.1 If requested by the user, the supplier shall provide a list of the characteristic values.
14.3 Specification sheet
14.3.1 If the foam concentrate is Newtonian and the viscosity at the lowest temperature for use is more than
2
200 mm /s when measured in accordance with ISO 3104, the words “This concentrate can require special
proportioning equipment” shall be marked.
14.3.2 If the foam concentrate is pseudo-plastic and the viscosity at the lowest temperature for use is greater
than or equal to 120 mPas at 375/s, the words “Pseudo-plastic foam concentrate. This concentrate can
require special proportioning equipment” shall be marked.
14.3.3 It is recommended that non-Newtonian concentrates be appropriately identified.
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ISO 7203-3:2011(E)
Annex A
(normative)

Preliminary sampling and conditioning of the foam concentrate
A.1 Preliminary sampling
The sampling method shall ensure representative samples, whether taken from a bulk container or a number
of individual packages.
Store samples in tightly closed containers.
NOTE Containers of capacity 20 l are suitable.
A.2 Conditioning of foam concentrate
A.2.1 If the supplier claims that the concentrate is not adversely affected by freezing and thawing, condition
the concentrate sample through four cycles of freezing and thawing, generally as described in B.2, before
conditioning in accordance with A.2.2.
If the foam concentrate is adversely effected by freezing and thawing, it is conditioned in accordance with
A.2.2 without prior freezing and thawing.
A.2.2 Condition the concentrate in the sealed container for 7 d at (60  2) °C, followed by 1 d at (20  5) °C.
A.3 Subsequent testing
Test samples shall be prepared in accordance with A.1, or A.2.1 and A.2.2 as appropriate. Agitate the sample
container before sampling for further tests.
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ISO 7203-3:2011(E)
Annex B
(normative)

Determination of tolerance to freezing and thawing
B.1 Apparatus
The usual laboratory apparatus and, in particular, the following.
B.1.1 Freezing chamber, capable of achieving the temperatures required in B.2.
B.1.2 Tube, polyethylene, approximately 10 mm in diameter, approximately 400 mm long and sealed
and weighted at one end, with suitable spacers attached; see Figure B.1 for a typical form.
B.1.3 Measuring cylinder, glass, of capacity 500 ml, approximately 400 mm high and approximately
65 mm in diameter, with a stopper.
B.2 Procedure
Set the temperature of the freezing chamber (B.1.1) to at least 10 °C below the freezing point of the sample
measured in accordance with BS 5117, Section 1.3 (excluding 5.2).
To prevent the glass measuring cylinder (B.1.3) from breaking due to expansion of the foam concentrate on
freezing, insert the tube (B.1.2) into the measuring cylinder with the sealed end downward, weighted if
necessary to avoid flotation, with the spacers to ensure that it remains approximately on the central axis of the
cylinder. Fill the cylinder and fit the stopper.
Place the cylinder in the freezing chamber, cool it and maintain at the required temperature for 24 h. At the
end of this period, thaw the sample for not less than 24 h and not more than 96 h in an ambient temperature
of (20  5) °C.
Repeat three times to give four cycles of freezing and thawing before testing.
Examine the sample for stratification and non-homogeneity.
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ISO 7203-3:2011(E)
Nominal dimensions in millimeters
ø10
1
1
1
1
1
1
2

Key
1 spacers (e.g. plastics cable strap)
2 weight at sealed end
Figure B.1 — Typical form of polyethylene tube
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ISO 7203-3:2011(E)
Annex C
(normative)

Determination of percentage of sediment
C.1 Sampling
Use a sample prepared in accordance with A.1. Ensure that any sediment is dispersed by agitating the
sample container. Take two samples, testing one immediately and the other after ageing for (24  2) h at
(60  2) °C in a filled container without access to air.
C.2 Apparatus
The usual laboratory apparatus and, in particular, the following.
C.2.1 Centrifuge tubes, graduated.
2
C.2.2 Centrifuge, operating at (6 000  600) m/s .
NOTE A centrifuge and tubes in accordance with ISO 3734 are suitable.
C.2.3 Sieve, of nominal aperture siz
...