ISO 16405:2015

INTERNATIONAL ISO
STANDARD 16405
First edition
2015-03-01
Room corner and open calorimeter —
Guidance on sampling and
measurement of effluent gas
production using FTIR technique
Mesurage de la production de gaz toxique à l’aide de la technique
IRTF pour l’essai en coin de salle et calorimétrie ouverte
Reference number
ISO 16405:2015(E)
©
ISO 2015

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ISO 16405:2015(E)

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ISO 16405:2015(E)

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Gas sampling system . 2
5.1 General . 2
5.2 Gas sampling probe . 2
5.2.1 Sampling position . 2
5.2.2 Exhaust duct sampling application . 3
5.2.3 Alternative sampling applications . 4
5.3 Filter . 5
5.4 Tubing . 5
5.5 Pump . 5
6 FTIR instrument . 6
6.1 General . 6
6.2 Gas cell. 6
6.3 Spectrometer parameters . . 7
6.4 Detector . 7
7 Measurement . 7
7.1 Requirements . 7
7.2 Calibration . 7
7.3 Test procedure . 7
8 Analysis of spectra . 8
9 Expression of results . 8
Annex A (normative) Calculation .10
Bibliography .13
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ISO 16405:2015(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.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
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. Details of any
patent rights identified during the development of the document will be in the Introduction and/or on
the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity
assessment, as well as information about ISO’s adherence to the WTO principles in the Technical Barriers
to Trade (TBT), see the following URL: Foreword — Supplementary information.
The committee responsible for this document is ISO/TC 92, Fire safety, Subcommittee SC 1, Fire initiation
and growth.
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ISO 16405:2015(E)

Introduction
This International Standard is intended to obtain concentrations of effluent gases produced in large-
scale or simulated real-scale fire tests, such as the room corner test and open calorimeters. These tests
describe the fire behaviour of a product under controlled laboratory conditions.
The test standard can be used as part of a fire hazard assessment which takes into account all of the
factors which are pertinent to an assessment of the fire hazard of a particular end use.
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INTERNATIONAL STANDARD ISO 16405:2015(E)
Room corner and open calorimeter — Guidance on
sampling and measurement of effluent gas production
using FTIR technique
1 Scope
This International Standard gives guidance concerning suitable apparatus and procedures to be used
when applying the FTIR method to measure concentrations of effluent gases produced in large-scale
or simulated real-scale fire tests. Such tests include the room corner test (see ISO 9705) and open
calorimeter tests as described in ISO 24473.
This guidance and measuring method only describes the way in which the sampling of the gases and
collection of FTIR spectra are performed. Analysis of spectra and calibration is part of ISO 19702.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
ISO 9705, Fire tests — Full-scale room test for surface products
ISO 13943, Fire safety — Vocabulary
1)
ISO 19702:— , Guidance for sampling and analysis of toxic gases and vapours in fire effluents using Fourier
Transform Infrared spectroscopy (FTIR)
ISO 24473, Fire tests — Open calorimetry — Measurement of the rate of production of heat and combustion
products for fires of up to 40 MW
ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM: 1995)
3 Terms and definitions
For the purposes of this document, the definitions given in ISO 13943 apply.
4 Principle
By using the on-line FTIR technique, it is possible to simultaneously measure the time resolved
concentration of several gases during a fire test.
The practical measurement procedure is to continuously extract a fraction of the effluents from the
exhaust duct (the most common application) from the opening of the test room or, alternatively, from
a position in the vicinity of a test object through a heated sampling system and into a heated optical
cell. There, the specific absorption patterns of infrared-active species are recorded by a detector.
This information is subsequently presented as an absorption spectrum that is used to determine
the concentrations of effluent components. The frequency of collection of absorption spectra, the
1) To be published. (Revision of ISO 19702:2006)
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ISO 16405:2015(E)

characteristics of the flow in the exhaust duct (if applicable), and the residence time and flow pattern in
the optical cell determine the time resolution of the measurements.
NOTE FTIR is based on infrared absorption. Polyatomic and heteronuclear diatomic compounds have
absorption in the infrared region. Specific to FTIR is conversion of regular irradiance from a broad band infrared
source into interfered irradiance by an interferometer and conversion of the recorded interferogram into
a conventional wavelength spectrum. The main advantage of the FTIR technique is that information from all
spectral elements is measured simultaneously and another advantage is that the measurement is made with a
high optical throughput giving a high signal to noise ratio. See ISO 19702 for a more detailed background on FTIR
theory.
5 Gas sampling system
5.1 General
The gas sampling system consists of a probe for sampling fire effluent gases, a filter system for removing
particulates from the sampled gas, sampling tubing for transporting the gas to the FTIR gas cell, and
a pump for drawing the gas. The parts of the sampling system placed before the FTIR gas cell shall be
heated to avoid condensation and losses of certain water soluble compounds (e.g. HCl).
A temperature of the sampling system between 150 °C to 190 °C shall be used (see ISO 19702).
The temperature throughout the heated part of the sampling system shall be homogeneous or slightly
increasing along the sampling system from the probe to the gas cell to avoid any cold points that could
act as a condensation point for water and soluble gases.
NOTE 1 It is important that the gas in the sampling system is heated to a temperature as close as possible to the
set-temperature of the sampling system. Procedures for checking the gas temperature are given in ISO 19702.
Information on delay and response time of the overall system is necessary and shall be reported.
NOTE 2 Method for determination of the response and transport time of the measurement system is given in
ISO 19702. Besides the transport time from the gas sampling probe to the gas cell, there is also a transport time
from the room to the gas sampling probe.
NOTE 3 The response and delay time can be obtained at the same time as burner calibrations are performed
(see ISO 9705). It also allows an overall check of the system.
5.2 Gas sampling probe
5.2.1 Sampling position
In enclosure tests, the normal sampling position is in the duct of the smoke collection system. This
sampling position represents cooled and diluted fire effluents.
NOTE 1 This sampling position is preferred in many cases as matrix effects from the fire effluents are
minimized by the dilution. A further advantage is that when fire effluents are quantitatively collected with the
hood system, the production of toxic gases can be quantitatively measured.
NOTE 2 In the early stages of an enclosure fire or when sampling from a small fire in an enclosure, the dilution
of the fire effluents can result in concentrations below practical detection limits.
An alternative sampling position in an enclosure test, which can be preferred in certain cases, is in the
top of the doorway (i.e. sampling from the undiluted out-flowing fire effluents).
NOTE 3 For sampling from the doorway, it is important to ascertain that a representative sample is taken over
the out-flowing area. It is further important to consider that hot fire gases sampled from the opening might not be
sufficiently oxidized and will continue to react outside of the opening.
NOTE 4 For quantitative measurement of toxic gas production, the flow rate out from the room has to be
quantified.
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ISO 16405:2015(E)

Another alternative sampling position in an enclosure test is at various local positions within the
enclosure.
NOTE 5 The results from measurements at specific positions within an enclosure are, however, only relevant
for the specific test scenario.
In open tests where the fire effluents are collected by a hood/smoke gas collection system, the normal
sampling position is in the duct of the smoke collection system.
Alternative sampling positions in open tests are at various local positions in the vicinity of the fire.
NOTE 6 The results from point measurements in the vicinity of the fire are, however, only relevant for the
specific test scenario.
5.2.2 Exhaust duct sampling application
The gas sampling probe shall extract a representative sample of gases from the exhaust duct.
The probe shall be mounted at a position in the smoke gas duct where the diluted fire effluents are
uniformly mixed.
NOTE 1 This is normally the case at a distance of 5 diameters to 10 diameters from the bend of the duct after
the collection hood.
NOTE 2 A suitable probe construction and arrangement for the ISO 9705 test is shown in Figure 1 (information
on probe positioning is available in ISO 9705, Annex E).
NOTE 3 General information on sampling probes for FTIR-measurement is available in ISO 19702.
Dimensions in mm
Key
1 exhaust duct
2 16 Ø 2 mm holes on downstream side of flow
3 15 Ø 3 mm holes on downstream side of flow
4 connection to the sampling line
Figure 1 — Gas sampling probe for the ISO 9705 room exhaust duct
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ISO 16405:2015(E)

5.2.3 Alternative sampling applications
When sampling directly from poorly mixed and inhomogeneous fire gases (for example, in the door
opening of a test enclosure), one shall ascertain representative sampling.
NOTE 1 The flow patterns through the opening of a test enclosure are complicated and it varies during the
course of a fire test. Typically, the upper part of the exit flow is well-mixed but this is surrounded by a relatively
slow-moving boundary layer between effluent and air that can be partly diluted by the incoming air. Ideally, it is
useful to observe the flow shape and characteristics for the particular test before selecting a probe type and its
position in the effluent stream. It is likely that a multi-hole probe will be necessary.
One method to accomplish representative sampling is to use a multi-hole probe with gradation of hole
sizes along the length of the probe and to place the probe such that it crosses the fire gases monitored.
NOTE 2 An example of a suitable multi-hole probe is given in Table 1. This probe has been successfully applied
to measurements taken in the door of the ISO 9705 room, where the top of the probe (closest to the pump) was
placed at the top of the ISO 9705 door and the probe traversed the door diagonally, finishing 30 cm below the top
[3]
of the doorway.
A simpler but less precise method is to place a single-port probe in a well-mixed location; in a door
opening, the probe shall be placed in the relatively well-mixed upper layers of the out-flowing effluents.
Measurement of the volumetric exit flow rate from a door opening is necessary whatever probe type is
used in order to convert measured concentrations to total flow of gas species out from the test enclosure.
NOTE 3 The exit flow in enclosure fire tests varies during a test. The rate of the exit flow grows with increasing
fire intensity and the position of the neutral plane stabilises first at “steady-state” where the fire growth is
relatively stable (e.g. due to ventilation control of burning rate rather than fuel involvement control of burning
rate).
NOTE 4 The exit flow can be measured using traditional velocity probes such as pitot tubes, McCaffrey probes,
or more advanced optical methods such as particle image velocimetry. It is, however, not always possible to
directly measure the exit flow using velocity probes as the pressure difference over the opening is relatively small
and the often turbulent outflows in the opening have velocity components in directions other than the normal
direction to the exit plane.
NOTE 5 An alternative method is to calculate the exit flow based on the pressure difference between the room
and outside and the height of the neutral plane (i.e. a virtual horizontal plane separating the outgoing effluent
from the incoming air) in the stratified case. An example of this method is given in Reference [4] and more details
can be found in Reference [5].
Table 1 — Example of a probe suitabl
...