ISO 16840-10:2021/Amd 1:2024

International
Standard
ISO 16840-10
Second edition
Wheelchair seating —
2021-06
Part 10:
AMENDMENT 1
Resistance to ignition of postural
2024-04
support devices — Requirements
and test method
AMENDMENT 1: Amended with
additional Annexes and test method
Sièges de fauteuils roulants —
Partie 10: Résistance à l'inflammation des dispositifs de soutien
postural — Exigences et méthode d'essai
AMENDEMENT 1: Annexes et méthode d'essai supplémentaires
Reference number
ISO 16840-10:2021/Amd.1:2024(en) © ISO 2024

ISO 16840-10:2021/Amd.1:2024(en)
© ISO 2024
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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Published in Switzerland
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ISO 16840-10:2021/Amd.1:2024(en)
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
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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 document should be noted. This document was drafted in accordance with the editorial rules of the
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related to conformity assessment, as well as information about ISO's adherence to the World Trade
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This document was prepared by Technical Committee ISO/TC 173, Assistive products Sub-committee SC1,
Wheelchairs.
A list of all parts in the ISO 16840 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iii
ISO 16840-10:2021/Amd.1:2024(en)
Wheelchair seating —
Part 10:
Resistance to ignition of postural support devices —
Requirements and test method
AMENDMENT 1: Amended with additional Annexes and test method

Clause 4
Replace the first paragraph with the following:
Test materials used in integrated and non-integrated seat and back supports, and other postural support
devices as used in wheelchairs are assembled in either horizontal or vertical samples and subjected to a heat
source that is equivalent to a smouldering cigarette. The resulting effects on the test materials are observed
and measured.
6.4
Change NOTE 4 to read:
NOTE 4 Other means, such as a NiCr coil, that achieve the same heat transfer to the test sample, can be used as an
alternative heat source (see Annexes D and E).

6.5
Replace the first paragraph with the following:
Prior to conditioning described in this subclause, any removable covering materials which have been
subjected to water-soluble flame retardants shall be subjected to the washing and drying procedures
described in Annex B.
Clause 9
Add the following NOTE after list item j):
NOTE A report template which can be used to meet this Clause is provided in Annex F.
Annex D, E, and F
Add the new annexes after Annex C.

ISO 16840-10:2021/Amd.1:2024(en)
Annex D
(informative)
Test method using a NiCr wire coil as a heat source
D.1 Principle
A NiCr wire coil heat source as described in this Annex has been designed and validated to approximate the
heat output and thermal mass of a burning cigarette as determined by observing the ignition behaviour
and resulting burn patterns from a variety of cigarettes. The repeatability of the ignition behaviour and
[10]
resulting burn pattern from the device has been validated through interlaboratory testing .
D.2 Test environment
The test environment shall have a temperature between 10 °C and 30 °C and a relative humidity between
15 % and 80 %.
D.3 Test enclosure
For the protection of the lab technician the test enclosure shall consist of either a room or a smaller
enclosure designed to extract smoke and fumes. In absence of such conditions, the technician shall take
other precautions against smoke inhalation. The enclosure shall be capable of controlled air flow between
0,0 m/s and 0,2 m/s when measured at 25 mm ± 5 mm from the heat source.
D.4 Test apparatus
D.4.1 General
The test apparatus shall be a heat source that shall consist of a wire coil of NiCr alloy resistance wire, heated
by a DC power supply that has a constant current output mode.
NOTE 1 The means to create the test apparatus is contained in Annex E.
NOTE 2 By adjusting the current, this apparatus can be utilized to simulate a ‘match’ or other heat sources.
D.4.2 Wire coil
The wire shall be made from an alloy of 60 % nickel, 16 % chromium, and 24 % iron (known as “Nichrome 60”
or “Chromel C”). The diameter of the wire shall be 0,39 mm to 0,41 mm (commonly sold as 26 AWG).
NOTE 1 Nichrome 70 or 80 wire can be substituted since the paper strip calibration will account for small
differences in resistance.
The wire shall be wound to produce a wire coil with the specifications shown in Figure D.1.
NOTE 2 A method for winding the wire coil to these specifications is provided in Annex E.

ISO 16840-10:2021/Amd.1:2024(en)
Dimensions in millimetres
Figure D.1 — Dimensions of wire coil
D.4.3 Power supply and connection to the wire coil
The power supply shall be capable of producing a constant current between 1 A and 5 A with adjustments in
0,10 A increments. The wire coil shall be connected to the power supply by a means to ensure good electrical
conductivity.
NOTE 1 Crocodile (alligator) clips on high-temperature silicone insulated wire leads are an effective means of
connection.
NOTE 2 Setting the centre of the wire coil 25 mm from the crocodile clips results in a predictable length of wire
through which current flows actively. This provides calibration by paper strip ignition at approximately 2,2 A to 2,3 A.
D.4.4 Conditioning the wire coil
Before the wire coil can be used for testing, it shall be conditioned for use to relax stress from the winding
process and burn off any residual oil. To condition the wire, set the power supply to run at a constant current
set to 12 V (to ensure adequate power) and adjust the current to 4 A for 10 s ± 1 s.
NOTE The wire coil will glow red hot, and, after cooling, will relax, increasing the width of the wire coil from
10 mm to (12–14) mm, with no significant change in the diameter.
D.4.5 Paper calibration strip
A paper calibration strip shall be made from 80 g/m white bond copier paper cut to
5 mm ± 1 mm x 40 mm ± 5 mm and folded, as shown in Figure D.2.
NOTE This paper is equivalent to 20 lb paper.

ISO 16840-10:2021/Amd.1:2024(en)
Figure D.2 — A paper calibration strip, folded in half
D.5 Heat source calibration
Calibration is required after conditioning a new wire coil, or if any other changes have been made to the
connections or power supply. Calibration shall be done with the wire coil placed in the position which will
be used for subsequent testing to ensure effects of air flow passing over the heat source are consistent.
Calibration shall be conducted without a test sample in place, as the presence of a test sample can affect the
local airflow around the wire coil.
The following process shall be followed.
a) Place a folded paper calibration strip between middle coils (Figure D.3), with the power turned off (cold).
NOTE 1 The middle coils will be hottest.
Figure D.3 — Paper calibration strip placed between middle coils
b) Ensure the current setting results in the paper exhibiting a visible red glowing ignition within 10 s to
14 s after turning on power.
c) If ignition occurs after 14 s, or does not occur at all, raise the current and repeat.

ISO 16840-10:2021/Amd.1:2024(en)
d) If ignition occurs before 10 s, decrease the current and repeat.
NOTE 2 To aid in seeing ignition, you can dim the lights.
NOTE 3 Based on interlaboratory experiments, 2,2 A to 2,3 A is likely to achieve this result.
NOTE 4 Variations in positioning and wire connections can contribute to variations in the current needed to
achieve the paper ignition specification.
D.6 Wire coil cleaning between tests
Ensure that there is no carbon build up on the wire coil. If present, turn the power supply up to 4 A to burn
off any deposits.
WARNING — Do not exceed 5 amps. A current of 5 A will heat the coil wire to a temperature of over
1 000 °C. Until the power is removed and the coil cools, this is a burn and fire hazard.
D.7 Test methods
D.7.1  Sample size
Because this test is intended to test for ignition of composite PSD samples, and not the component level
materials, there is no minimal sample size requirement. Samples are tested in the orientation and
configuration in which they are used. Burn area is not a pass/fail requirement, hence a minimal sample size
specification is not necessary.
D.7.2 Preparation
a) Identify the PSD.
b) Select the surface(s) that the manufacturer assesses to be at risk from a fire source (see Annex C). These
shall be identified as the test surfaces.
c) If testing items that are intended to be used only in the range of the horizontal plane ± 30°, use the
horizontal test, and for all other items, use the vertical test. If the item is intended for use in either plane,
then only the vertical test is necessary.
d) Place the test sample in the test environment for a minimum of 12 h to condition it for testing.
D.7.3  Horizontal test
a) Set up the test sample in the same location used for calibration of the wire coil. The test sample shall be
positioned such that the surface to be tested is horizontal ± 3°. A suitable test rig may be used to hold
the test sample in position.
ISO 16840-10:2021/Amd.1:2024(en)
Figure D.4 — Placement position of wire coil heat source on a horizontal surface
b) Apply the side of the wire coil to the test surface, pressing lightly, with some visible deflection of the
surface. (see Figure D.4).
c) Photograph the sample, with the hot wire coil in position, prior to testing.
d)
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