ISO/TS 20885:2003

TECHNICAL ISO/TS
SPECIFICATION 20885
First edition
2003-06-15

Gaseous media fire-extinguishing
systems — Area coverage fire test
procedure — Engineered and pre-
engineered extinguishing units
Systèmes d'extinction d'incendie utilisant des agents gazeux — Mode
opératoire de couverture de la zone enflammée — Unités extinctrices
centralisées et modulaires




Reference number
ISO/TS 20885:2003(E)
©
ISO 2003

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ISO/TS 20885:2003(E)
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ISO/TS 20885:2003(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope. 1
2 Application. 1
3 Extinguishing system. 2
4 Extinguishing concentration. 3
5 Nozzle distribution verification tests . 3
5.1 Nozzles minimum height/maximum area coverage test . 3
5.1.1 Test facility. 3
5.1.2 Fuel specification. 7
5.1.3 Test procedure. 7
5.1.4 Determination of distribution performance of the nozzle. 8
5.2 Nozzles maximum height test. 8
5.2.1 Test facility. 8
5.2.2 Fuel specification. 8
5.2.3 Test procedure. 9
5.2.4 Determination of distribution performance of the nozzle. 9
6 Extinguishing concentration tests. 9
6.1 Wood crib test . 9
6.1.1 Test facility. 9
6.1.2 Fuel specification. 11
6.1.3 Test procedure. 11
6.1.4 Determination of design extinguishant concentration . 13
6.2 Heptane pan test . 13
6.2.1 Test facility. 13
6.2.2 Fuel specification. 13
6.2.3 Test procedure. 14
6.2.4 Determination of design extinguishant concentration . 14
6.3 Polymeric sheet fire test. 14
6.3.1 Test facility. 14
6.3.2 Fuel specification. 14
6.3.3 Test procedure. 16
6.3.4 Determination of design extinguishant concentration . 18
6.4 PVC cable tray fire test. 18
6.4.1 Test facility. 18
6.4.2 Fuel specification. 19
6.4.3 Test procedure. 20
6.4.4 Determination of design extinguishant concentration . 21

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ISO/TS 20885:2003(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.
In other circumstances, particularly when there is an urgent market requirement for such documents, a
technical committee may decide to publish other types of normative document:
 an ISO Publicly Available Specification (ISO/PAS) represents an agreement between technical experts in
an ISO working group and is accepted for publication if it is approved by more than 50 % of the members
of the parent committee casting a vote;
 an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical
committee and is accepted for publication if it is approved by 2/3 of the members of the committee casting
a vote.
An ISO/PAS or ISO/TS is reviewed after three years in order to decide whether it will be confirmed for a
further three years, revised to become an International Standard, or withdrawn. If the ISO/PAS or ISO/TS is
confirmed, it is reviewed again after a further three years, at which time it must either be transformed into an
International Standard or be withdrawn.
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/TS 20885 was prepared by Technical Committee ISO/TC 21, Equipment for fire protection and fire
fighting, Subcommittee SC 8, Gaseous media fire extinguishing systems.
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ISO/TS 20885:2003(E)
Introduction
The need for the tests specified in this Technical Specification arises from the fact that the Class A fire test
3
currently used, which employs wood crib, heptane pan and heptane can test fires in an enclosure of 100 m ,
may not indicate extinguishing concentrations suitable for the protection of plastics fuel hazards such as may
be encountered in electronic data processing, telecommunications and process control facilities.
The test protocol which forms the subject of this Technical Specification was developed by a special working
group of ISO/TC 21/SC 8. It comprises tests for determination of the extinguishing concentrations and system
performance, and is designed to allow individual installers to use their system and to carry out all of the
extinguishing tests themselves. Different extinguishing concentrations are proposed that may result from tests
involving the same fuel/agent combination; in addition different nozzles and nozzle heights are used in order
to reflect various room heights and fire behaviour. Owing to the fact that the given extinguishing
concentrations for each agent are only dependent on fuel and not on the type of system, the working group
proposes to separate the agent tests (determination of extinguishing concentrations) from the system tests.
In the future, ISO/TC 21/SC 8 intends to restructure the current Annex C of ISO 14520-1:2000, Gaseous fire-
extinguishing systems — Physical properties and system design — Part 1: General requirements to include
polymeric sheet fuel arrays [polymethyl methacrylate (PMMA), polypropylene (PP) and acrylonitrile-butadiene-
styrene (ABS)] and polyvinyl chloride (PVC) cable arrays (heptane pan ignited).
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TECHNICAL SPECIFICATION ISO/TS 20885:2003(E)

Gaseous media fire-extinguishing systems — Area coverage
fire test procedure — Engineered and pre-engineered
extinguishing units
1 Scope
This Technical Specification specifies a test method for determination of the extinguishing concentrations and
system performance of engineered or pre-engineered extinguishing system units designed to mix and
distribute the extinguishant, and to totally flood the enclosure.
It is designed to allow individual installers to use their system and to carry out all of the extinguishing tests
themselves.
2 Application
2.1 When tested in accordance with the requirements contained in 5.1, 5.2 and 6.2, an extinguishing
system unit shall extinguish all visible flaming within 30 s after the end of extinguishant discharge. When
tested in accordance with the requirements contained in 6.1 an extinguishing system unit shall extinguish all
visible flaming and prevent re-ignition of the fires after a 10 min soak period (also measured from the end of
extinguishant discharge). When tested in accordance with the requirements contained in 6.3 and 6.4 an
extinguishing system unit shall extinguish all visible flaming within 60 s after the end of extinguishant
discharge. The system unit shall also prevent re-ignition of the fires after a 10 min soak period (also measured
from the end of extinguishant discharge).
NOTE The 60 s time limit for “no flaming” is provisional. At the time of preparation of this Technical Specification
there was no published information providing details of the manner of extinguishment of plastics fires test articles. One
laboratory reports that upon discharge of an HFC agent at the same concentration which satisfactorily extinguishes the
wood crib test article, the following behaviour of the plastic was observed.
a) The flame size was reduced within 1 min to a very small edge-effect flame measuring approximately 20 mm to
30 mm in size.
b) The time at which the edge-effect flame became extinguished varies but may be longer than 60 s.
c) The edge-effect flame on the plastic test articles is analogous to the persistent smouldering observed to be in effect
during the post-flame-out period of the wood crib test (see 6.1.2 to 6.1.4).
d) The 10 min hold period allows the hot test article, wood or plastic, to cool to the point where the low-level combustion
reactions cease.
2.2 The tests described in this Technical Specification take into consideration the intended use and
limitations of the extinguishing system unit with specific reference to
a) the area coverage for each type of nozzle,
b) the operating temperature range of the system,
c) the location of nozzles in the protected area,
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ISO/TS 20885:2003(E)
d) either the maximum length and size of piping and number of fittings to each nozzle, or the minimum
nozzle pressure,
e) the maximum discharge time,
f) the maximum fill density, and
g) the extinguishing concentrations for specific fuels.
Details of the tests are given in Table 1.
Table 1 — Test objectives and details
Test objective Enclosure size Test fires Subclause
Nozzle distribution verification
Nozzles minimum to suit nozzle heptane test cans 5.1
height/maximum area
coverage

3
Nozzles maximum height W100 m heptane test cans 5.2
no side less than 4 m in height, to
suit nozzle

3 a) wood crib 6.1
Extinguishing concentration W100 m
b) heptane 6.2

c) polymeric sheet 6.3
height, h: 3,5 m u h u 4 m
i) PMMA
ii) PP
iii) ABS
d) PVC cable tray 6.4
3 Extinguishing system
3.1 For the extinguishing tests described in 5.1 and 5.2, the agent containers shall be conditioned to the
minimum operating temperature specified in the manufacturer's installation instructions.
The extinguishing system shall be assembled as follows:
a) pre-engineered-type extinguishing system unit  using the maximum piping limitations with respect to the
number of fittings and length of pipe to the discharge nozzles and nozzle configuration(s) as specified in
the manufacturer's design and installation instructions;
b) engineered-type extinguishing system unit  using a piping arrangement that results in the minimum
+2
nozzle design pressure at 20 °C °C.
0
3.2 For the extinguishing tests described in 6.1, 6.2, 6.3 and 6.4, the agent containers shall be conditioned
at 20 °C ± 2 °C for a minimum period of 16 h prior to conducting the test. In these tests the jet energy from the
nozzles shall not influence the development of the fire. Therefore the nozzle(s) shall direct agent parallel to
the test enclosure ceiling.
3.3 For all tests, the extinguishing system shall be arranged and dimensioned with regard to the following.
For liquefied extinguishants, the time for the discharge of the pre-liquid gas phase plus the two-phase flow
shall be 8 s to 10 s.
For non-liquefied extinguishants, the discharge time shall be 50 s to 60 s, limited by cutting off the discharge
with an appropriate means positioned close to the nozzle.
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ISO/TS 20885:2003(E)
4 Extinguishing concentration
4.1 The extinguishing concentration for each test shall be 76,9 % (i.e. 100 divided by the safety factor,
where the safety factor is 1,3) of the intended end use design concentration specified in the manufacturer's
design and installation instructions at an ambient temperature of approximately 20 °C within the enclosure. In
the tests described in 5.1 and 5.2, the same extinguishing concentration shall be used as in the test described
in 6.2.
The quantity to reach the concentration within the enclosure can be established using Equation (1).
4.2 A cold discharge test using the same quantity of extinguishant shall be conducted to verify the actual
concentration of extinguishant.
For liquefied extinguishants, the agent concentration shall be measured in the cold discharge test.
For non-liquefied extinguishants, the agent concentration or alternatively the oxygen concentration shall be
measured. The extinguishant concentration is then calculated from the oxygen concentration using the
following formula:
ϕ
O
2
ϕ=−100 1 (1)

E

20,9

where
ϕ is the extinguishant concentration, expressed as a volume fraction in percent;
E
ϕ is the oxygen concentration measured in the test enclosure, expressed as a volume fraction in
O
2
percent.
5 Nozzle distribution verification tests
5.1 Nozzles minimum height/maximum area coverage test
5.1.1 Test facility
5.1.1.1 Construction
The test enclosure shall meet the following requirements.
a) The area (ab) and height (h) of the enclosure (see Figure 1) shall correspond to the maximum nozzle area
coverage and minimum nozzle height respectively specified by the manufacturer.
b) A means of pressure relief shall be provided.
c) Closable openings shall be provided directly above the test cans to allow for venting prior to system
actuation.
d) One baffle shall be installed between the floor and the ceiling (at height h), halfway between the nozzle
location and one of the corners of the enclosure (Figure 1 illustrates a 360° nozzle and Figure 2 illustrates
a 180° nozzle). The baffle shall be perpendicular to the line connecting the nozzle location and the
enclosure corner (see Figures 1 and 2), and shall have a length equal to 20 % of the length of the short
wall of the enclosure.
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ISO/TS 20885:2003(E)
5.1.1.2 Instrumentation
5.1.1.2.1 Oxygen concentration
The sampling and storage of data from the sensors described in this subclause shall occur at a rate of at least
4 Hz.
The oxygen concentration shall be measured using a calibrated oxygen analyser capable of measuring the
percentage oxygen to within at least one decimal place (0,1 %). The sensing equipment shall be capable of
continuously monitoring and recording the oxygen concentration inside the enclosure throughout the duration
of the test. The accuracy of the measuring devices shall not be influenced by any of the fire products.
Three sensors shall be located within the enclosure (see Figure 3). They shall be located at a distance of
850 mm to 1 250 mm from the centre of the room and at the following heights above the floor: 0,1h, 0,5h and
0,9h (where h is the height of the enclosure).

Key
h minimum nozzle height specified by manufacturer
ab maximum nozzle area coverage for a single nozzle
1 test cans
2 nozzle
3 baffle
4 vents
Figure 1 — Example configuration for nozzles minimum height/maximum area coverage test
for 360° nozzles
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ISO/TS 20885:2003(E)

Key
h minimum nozzle height specified by manufacturer
ab maximum nozzle area coverage for a single nozzle
1 test cans
2 nozzle
3 baffle
4 vents
Figure 2 — Example configuration for nozzles minimum height/maximum area coverage test
for 180° nozzles

5.1.1.2.2 Carbon dioxide (CO ) and carbon monoxide (CO) concentration

2
The CO concentration should be monitored.
2
Fire products such as CO and CO shall not influence the evaluation of the extinguishing capacity of the
2
investigated extinguishing gas.
5.1.1.2.3 Nozzle pressure
The nozzle pressure during system discharge shall be recorded by a pressure transducer in the pipe work at a
distance not greater than 1 m from the nozzle.
5.1.1.2.4 Enclosure temperature
The temperature shall be measure at a position located 850 mm to 1 250 mm horizontally from the centre of
the room and at a height 0,5h above the floor (see Figure 3).
It is recommended to use K-type thermocouples (Ni-CrNi) of 1 mm diameter.
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ISO/TS 20885:2003(E)
Dimensions in millimetres

Measuring points:
M1 record O concentration
2
M2 record O concentration and temperature
2
M3 record O concentration
2
Figure 3 — Instrumentation placement for nozzles minimum height/maximum area coverage test
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ISO/TS 20885:2003(E)
5.1.1.2.5 Nozzle temperature
For liquefied extinguishants, the temperature of the liquid jet just outside the nozzle shall be recorded.
Cameras, e.g. infrared-cameras, or an alternative means of directly viewing the fire can be useful as an aid to
determining flame-out times. A thermocouple may be located centrally 30 mm above each test can to provide
additional information.
5.1.2 Fuel specification
5.1.2.1 Test cans
The test cans shall be cylindrical, 80 mm ± 5 mm in diameter, at least 100 mm high and made of mild or
stainless steel with a thickness of 5 mm to 6 mm.
5.1.2.2 Heptane
The heptane shall be commercial grade with the following characteristics:
a) distillation:
1) initial boiling point: 90 °C
2) 50 %: 93 °C
3) dry point: 96,5 °C
3 3
b) density (15,6 °C): 700 kg/m ± 50 kg/m
5.1.2.3 Fire configuration and placement
The test cans shall contain either heptane or heptane and water. For test cans containing heptane and water,
the heptane shall be at least 50 mm deep. The level of heptane in the cans shall be at least 50 mm below the
top of the can.
As a minimum, one test can shall be placed in either the four top or the four bottom corners of the test
enclosure at a maximum perpendicular distance of 50 mm to the two adjacent sides and an additional test can
shall be positioned directly behind the baffle (see Figures 1 and 2). The cans shall be located vertically within
300 mm of the top or the bottom of the enclosure. If the enclosure permits such placement, two test cans may
be placed in each of the corners as specified above; in this case one test can shall be located vertically within
300 mm of the top of the enclosure and the other test can within 300 mm of the bottom.
5.1.3 Test procedure
5.1.3.1 Operation
Prior to commencing the test, analyse the composition of the extinguishing gas.
Ignite the heptane-filled test cans and allow them to burn for 30 s with the closable openings facing upwards in
the open position.
After 30 s close all openings and actuate manually the extinguishing system. At the time of actuation of the
system, the volume fraction of oxygen within the enclosure shall be not more than 0,5 % lower than the
normal atmospheric oxygen concentration. During the test, the oxygen concentration shall not change more
than 1,5 % owing to fire products. This change shall be determined by comparing the oxygen concentration
measured in the cold discharge test with the oxygen concentration measured in this test (averaged over the
three sensors).
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ISO/TS 20885:2003(E)
5.1.3.2 Results recording
After the required pre-burn period, record the following data for each test:
a) the calculated discharge time of extinguishant, i.e. the time needed to reach 95 % of the laboratory
extinguishant concentration, in seconds;
b) the effective discharge time ― for liquefied extinguishants, the time of the pre-liquid gas phase plus the
time of the two-phase flow (the discharge time for liquefied extinguishants has to be determined by nozzle
pressure, nozzle temperature or a combination of both); for non-liquefied extinguishants, the time from
opening the container valve(s) to cutting off the discharge;
c) the time required to achieve extinguishment, in seconds, determined by visual observation or other
suitable means;
d) the total mass of extinguishant discharged into the test enclosure.
5.1.4 Determination of distribution performance of the nozzle
Using the extinguishing concentration for heptane, determined in accordance with 6.2.4, all test cans shall be
extinguished within 30 s after the end of agent discharge.
As an alternative to the use of the heptane steel cans, the concentration of the extinguishing agent (or for non-
liquefied gases, the oxygen concentration) can be measured at the locations specified for steel test cans. The
concentration shall be measured at each location and shall be at least the extinguishing concentration, to be
reached within 30 s after the end of discharge time.
5.2 Nozzles maximum height test
5.2.1 Test facility
5.2.1.1 Construction
The test enclosure shall meet the following requirements.
3
a) The test enclosure shall have a minimum volume of 100 m . The height shall be at least 3,5 m. The floor
dimensions shall be at least 4 m wide by 4 m long. The test enclosure shall have a maximum ceiling
height as specified in the manufacturer's installation instructions.
b) A means of pressure relief shall be provided.
c) Closable openings shall be provided directly above the test cans to allow for venting prior to system
actuation.
d) One baffle shall be installed between the floor and the ceiling (at height h), halfway between the nozzle
location and one of the corners of the enclosure (Figure 1 illustrates a 360° nozzle and Figure 2 illustrates
a 180° nozzle). The baffle shall be perpendicular to the line connecting the nozzle location and the
enclosure corner (see Figures 1 and 2), and shall have a length equal to 20 % of the length of the short
wall of the enclosure.
5.2.1.2 Instrumentation
The instrumentation of the enclosure shall be as described in 5.1.1.2.
5.2.2 Fuel specification
5.2.2.1 Test cans
The test cans shall be as described in 5.1.2.1.
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ISO/TS 20885:2003(E)
5.2.2.2 Heptane
The heptane shall be commercial grade as specified in 5.1.2.2.
5.2.2.3 Fire configuration and placement
The test can filling requirements and placement within the enclosure shall be as described in 5.1.2.3.
5.2.3 Test procedure
5.2.3.1 Operation
The operation shall be as specified in 5.1.3.1.
5.2.3.2 Results recording
Record the results as specified in 5.1.3.2.
5.2.4 Determination of distribution performance of the nozzle
Determine the distribution performance of the nozzle as specified in 5.1.4.
6 Extinguishing concentration tests
6.1 Wood crib test
6.1.1 Test facility
6.1.1.1 Construction
The test enclosure shall meet the following requirements.
3
a) The test enclosure shall have a minimum volume of 100 m . The height shall be at least 3,5 m, and 4 m
maximum. The floor dimensions shall be at least 4 m wide by 4 m long.
b) A means of pressure relief shall be provided.
6.1.1.2 Instrumentation
6.1.1.2.1 Oxygen concentrations
The sampling and storage of data from the sensors described in this subclause shall occur at a rate of at least
4 Hz.
The oxygen concentration shall be measured using a calibrated oxygen analyser capable of measuring the
percentage oxygen to within at least one decimal place (0,1 %). The sensing equipment shall be capable of
continuously monitoring and recording the oxygen concentration inside the enclosure throughout the duration
of the test. The accuracy of the measuring devices shall not be influenced by any of the fire products.
Three sensors shall be located within the enclosure (see Figure 4). One sensor shall be located at the
equivalent height of the top of the test object from the floor, at a horizontal distance 600 m to 1 000 m from the
test object. The other two sensors shall be located at 0,1h and 0,9h (where h is the height of the encl
...