ISO 7204:2023

INTERNATIONAL ISO
STANDARD 7204
First edition
2023-11
Specification for wetting agents for
application on Class A fires
Reference number
© ISO 2023
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Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Type and use of wetting agent concentrates .2
4.1 General . 2
4.2 Use with sea water . 2
5 Tolerance of the wetting agent concentrate to freezing and thawing .2
6 Sediment in the wetting agent concentrate . 3
6.1 Sediment before conditioning . 3
6.2 Sediment after conditioning . 3
7 Determination of viscosity .3
7.1 Newtonian wetting agent concentrates . 3
7.2 Pseudo-plastic wetting agent concentrates . 3
8 pH of the wetting agent concentrate . 3
8.1 pH limits . 3
8.2 After conditioning . 3
9 Surface tension of the wetting agent solution . 3
9.1 Before conditioning . 3
9.2 After conditioning . 4
10 Test fire performance . .4
11 Corrosion .4
12 Toxicology and environmental Information .4
13 Marking, packaging and specification sheet .4
13.1 Marking . 4
13.2 Packaging . 5
13.3 Specification sheet . 5
Annex A (normative) Preliminary sampling and conditioning of the wetting agent
concentrate .6
Annex B (normative) Determination of tolerance to freezing and thawing .7
Annex C (normative) Determination of percentage of sediment .9
Annex D (normative) Determination of viscosity for pseudo-plastic wetting agent
concentrates .10
Annex E (normative) Determination of surface tension .12
Annex F (normative) Determination of fire test performance .13
Annex G (normative) Toxicology and environmental information .15
Annex H (informative) Compatibility between wetting agent concentrates .16
Bibliography .17
iii
Foreword
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This document was prepared by Technical Committee ISO/TC 21, Equipment for fire protection and fire
fighting, Subcommittee SC 6, Foam and powder media and firefighting systems using foam and powder.
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iv
Introduction
Firefighting wetting agents are widely used to control and extinguish Class A fires and for inhibiting
reignition.
Wetting agents can be used in combination with other extinguishing media, particularly halocarbons,
carbon dioxide and powders, which are the subject of other International Standards including ISO 6183,
ISO 7201-1, ISO 7201-2 and ISO 7202. A specification for foam systems can be found in the ISO 7076
series.
A specification for portable extinguishers can be found in ISO 7165.
v
INTERNATIONAL STANDARD ISO 7204:2023(E)
Specification for wetting agents for application on Class A
fires
1 Scope
This document specifies the essential properties and performance of liquid wetting agent concentrates
used to make wetting agents for the extinction and inhibition of reignition of fires of Class A fuels.
This document specifies the minimum performance on certain test fires.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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.
EN 1568-3:2018, Fire extinguishing media — Foam concentrates — Part 3: Specification for low expansion
foam concentrates for surface application to water-immiscible liquids
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, Rheology
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 7165, Fire fighting — Portable fire extinguishers — Performance and construction
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
characteristic value
value declared by the wetting agent (3.6) concentrate (3.2) manufacturer for the chemical and physical
properties and the performances of the wetting agent solution (3.9), and wetting agent concentrate
3.2
concentrate
wetting agent (3.6) liquid that, when mixed with water in the appropriate concentration, gives a wetting
agent solution (3.9)
3.3
sediment
insoluble particles in the wetting agent (3.6) concentrate (3.2)
3.4
temperature for use
maximum and minimum temperature claimed by the manufacturer between which the wetting agent
(3.6) concentrate (3.2) is ready for use
3.5
Class A fire
fire involving solid materials, usually of an organic nature, in which combustion normally takes place
with the formation of glowing embers
Note 1 to entry: See ISO 3941:2007, Clause 2 for the classification of fires.
3.6
wetting agent
liquid added to water to produce a solution with a surface tension less than that of water alone, which is
capable of readily spreading across and penetrating into Class A fuels (3.7)
Note 1 to entry: Wetting agents are not required to produce foam.
3.7
Class A fuel
solid material, usually of an organic nature (such as vegetation, wood, cloth, paper, rubber, and some
plastics), in which combustion can occur at or below the surface of the material with or without the
formation of glowing embers
3.8
freezing point
temperature at which the first ingredient of a mixture starts to solidify or freeze out
3.9
wetting agent solution
solution of wetting agent (3.6) concentrate (3.2) and water
4 Type and use of wetting agent concentrates
4.1 General
Wetting agent concentrates shall be capable of providing positive fire testing results if tested in
accordance with Annex F. See also Annex H.
4.2 Use with sea water
If a wetting agent concentrate is marked as suitable for use with sea water, the recommended
concentrations for use with fresh water and sea water shall be identical.
NOTE Increased corrosiveness can occur on equipment used if a wetting agent solution is prepared using
sea water.
5 Tolerance of the wetting agent concentrate to freezing and thawing
The wetting agent concentrate shall be preliminarily sampled and conditioned in accordance with
Annex A.
Before and after temperature conditioning in accordance with Clause A.2, the wetting agent 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.
Wetting agent concentrates in conformance with Annex B shall be tested for conformance with the
appropriate requirements given in other clauses and subclauses of this document (indicated by the
term “conditioning” in their respective headlines) after freezing and thawing in accordance with A.2.1.
6 Sediment in the wetting agent concentrate
6.1 Sediment before conditioning
Any sediment in the concentrate sampled in accordance with Clause 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 conditioning
Any sediment in the concentrate aged in accordance with Clause A.2 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 Determination of viscosity
7.1 Newtonian wetting agent concentrates
The viscosity of the wetting agent concentrate at the lowest temperature for use claimed by the
2 −1
manufacturer shall be 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 wetting agent concentrates
The viscosity of the wetting agent concentrate shall be determined in accordance with Annex D. If the
−1
viscosity at the lowest temperature for use is greater than or equal to 120 mPa⋅s at 375 s , the container
shall be marked: “This concentrate can require special proportioning equipment.”.
NOTE Pseudo-plastic wetting agent concentrates are a particular class of non-Newtonian wetting agent
concentrates and have a viscosity that decreases with increasing shear rate at constant temperature.
8 pH of the wetting agent concentrate
8.1 pH limits
The pH of the wetting agent concentrate, before and after conditioning in accordance with Clause A.2,
shall be not less than 6,0 and not more than 8,5 at (20 ± 2) °C.
8.2 After conditioning
The difference in pH between before and after conditioning according to Clause A.2 shall not be greater
than 1,0 pH units.
9 Surface tension of the wetting agent solution
9.1 Before conditioning
The surface tension of the wetting agent solution prepared from the concentrate, before conditioning in
accordance with Clause A.2 at the supplier's recommended concentration, shall be within ±10 % of the
characteristic value when determined in accordance with Annex E.
9.2 After conditioning
The surface tension of the wetting agent solution prepared from the concentrate, after conditioning
in accordance with Clause A.2 at the supplier's recommended con
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