ISO/TR 24496:2012

TECHNICAL ISO/TR
REPORT 24496
First edition
2012-11-15
Office furniture — Office work
chairs — Methods for the
determination of dimensions
Mobilier de bureau — Sièges de travail pour bureau — Méthodes
pour déterminer les dimensions
Reference number
ISO/TR 24496:2012(E)
©
ISO 2012

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ISO/TR 24496:2012(E)

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© ISO 2012
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any
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Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General measurement conditions .28
4.1 Preliminary preparation .28
4.2 Tolerances .28
4.3 Measurement uncertainty and compliance evaluations .29
5 Test equipment.29
5.1 Floor surface .29
5.2 CMD placement fixture .29
5.3 Chair measuring device (CMD) .29
5.4 High friction material .29
6 Measurement methods and procedures .31
6.1 General .31
6.2 Chair set-up and placement of CMD .31
6.3 Measurement procedures.35
7 Test report .51
Annex A (informative) Drawings and specifications, PDF files .52
Annex B (informative) Anthropometric equivalents of terms and definitions .56
Annex C (informative) Development history and rationale .65
Bibliography .69
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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 exceptional circumstances, when a technical committee has collected data of a different kind from
that which is normally published as an International Standard (“state of the art”, for example), it may
decide by a simple majority vote of its participating members to publish a Technical Report. A Technical
Report is entirely informative in nature and does not have to be reviewed until the data it provides are
considered to be no longer valid or useful.
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/TR 24496 was prepared by Technical Committee ISO/TC 136, Furniture.
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Introduction
The test methods in this Technical Report are based on the manner in which anthropometric
measurements are measured.
Therefore, in order to be able to relate the dimensions of office seating to the anthropometric dimensions,
a theoretical reference seating posture has been adopted. This posture does, however, not automatically
correspond to the ideal or optimum seating posture.
The reference seating posture is as follows:
— the sole of the foot placed on the floor;
— the foot forms an angle of approximately 90° with the lower leg;
— the lower leg is approximately vertical;
— the lower leg forms an angle of approximately 90° with the thigh;
— the thigh is almost horizontal;
— the thigh forms an angle of approximately 90° with the trunk;
— the trunk is erect.
Further information on the anthropometric dimensions can be found in ISO 7250 (all parts) and ISO 14738.
This Technical Report is meant to be used in conjunction with requirements documents. Such documents
will specify which of the dimensions must be measured. It is possible that not all of the measurements
that can be taken by this Technical Report will be specified by the individual requirements document.
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TECHNICAL REPORT ISO/TR 24496:2012(E)
Office furniture — Office work chairs — Methods for the
determination of dimensions
1 Scope
This Technical Report specifies methods for the determination of the dimensions of office chairs.
It does not contain dimensional specifications or requirements.
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.
Not applicable.
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
NOTE They do not describe measurement procedures. Measurement procedures can be found in Clause 6.
3.1
angle between backrest and seat
angle γ between the loaded backrest and the loaded seat
Note 1 to entry: See Figure 1.
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Key
a backrest
b seat
c Chair Measuring Device (CMD) buttocks pad
d CMD thoracic pad
e CMD pelvic pad
f backrest line
γ angle between backrest and seat
Figure 1 — Angle between backrest and seat
3.2
angle – origin and sign convention
angle sign convention viewed from the right side of the chair is: clockwise angle rotation is positive (+);
counter-clockwise is negative (–)
Note 1 to entry: See Figure 2.
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Figure 2 — Angle – origin and sign convention
3.3
armrest height
distance from the top surface of the armrest to the bottom of the loaded CMD buttocks pad parallel to
the backrest line at a distance of 180 mm from the backrest line
Note 1 to entry: See Figure 3.
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Dimensions in millimetres
Key
a CMD vertical member
b armrest
c CMD buttocks pad
d intersection of projection of vertical member front face and armrest
e backrest line
f armrest height
Figure 3 — Armrest height
3.4
armrest length
distance along the armrest within an envelope down from the top of the armrest that is 20 mm deep
Note 1 to entry: See Figure 4.
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Dimensions in millimetres
Key
a armrest
b armrest length
Figure 4 — Armrest length
3.5
armrest – clear distance between
smallest horizontal distance between armrest from the rear of the seat surface width zone (3.28) forward
to the front edge of the seat (see Figure 5) within the measurement zone 5 mm down from the top of the
armrest (see Figure 7)
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Key
a armrest
b armrest pad measurement zone
c clear distance between armrest
d rear of seat width zone
Figure 5 — Armrest – clear distance between
3.6
armrest position – front of
perpendicular distance from the backrest line to the front of the armrest that is in the measurement
zone 120 mm and greater above the top surface of the loaded CMD buttocks pad
Note 1 to entry: See Figure 6.
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Dimensions in millimetres
Key
a armrest
b backrest line
c CMD buttocks pad
d measurement zone
e front of armrest position
Figure 6 — Armrest position – front of
3.7
armrest width
horizontal distance across the armrest within the measurement zone 5 mm down from the top of the armrest
Note 1 to entry: See Figure 7.
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Dimensions in millimetres
Key
a armrest
b armrest width
Figure 7 — Armrest width
3.8
back to seat movement ratio
ratio of change of the backrest angle relative to the change of angle of the seat that occurs when a seat
and backrest move concurrently
Note 1 to entry: Not applicable to chairs with seat and/or back angles that only move independently.
3.9
backrest angle to vertical
angle β between vertical and the loaded backrest
Note 1 to entry: See Figure 8.
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Key
a CMD thoracic pad
b CMD pelvic pad
c backrest line
d vertical
β backrest angle to vertical
Figure 8 — Backrest angle to vertical
3.10
backrest width
smallest horizontal dimension of the backrest within the lumbar zone (3.18)
Note 1 to entry: See Figure 9.
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Key
a backrest
b lumbar zone
c backrest width
Figure 9 — Backrest width
3.11
backrest height
distance from the loaded seat to the top of the backrest, measured parallel to the backrest line
Note 1 to entry: See Figure 10.
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Key
a backrest
b CMD buttocks pad
c backrest line
d backrest height
Figure 10 — Backrest height
3.12
backrest inclination – range
tilt range of the backrest from its foremost inclination to its most rearward inclination
Note 1 to entry: See Figure 11.
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Key
a backrest
b CMD thoracic pad
c CMD pelvic pad
d forward most tilt backrest line
e rearward most tilt backrest line
Δ range of backrest inclination
Figure 11 — Backrest inclination – range
3.13
backrest radius – horizontal
horizontal radius of the backrest measured within the lumbar zone (3.18)
Note 1 to entry: See Figure 12.
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Key
a seat
b backrest
c lumbar zone
r horizontal radius of backrest
Figure 12 — Backrest radius – horizontal
3.14
chair measuring device
CMD
instrument for measuring dimensions of chairs
Note 1 to entry: Specified in Annex A.
3.15
hip breadth clearance
smallest horizontal distance between armrest assembly from the rear of the seat width zone (3.28) forward
to the front edge of the armrest or armrest assembly as measured above the top of the seat surface
Note 1 to entry: See Figure 13.
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Key
a armrest assembly
b rear of seat surface width zone to front of armrest
c hip breadth clearance
Figure 13 — Hip breadth clearance
3.16
lumbar support – height
distance from the loaded seat to the most prominent segment (or segments) of the lumbar support as
determined by the measuring indicators on the CMD (see Figure 35), measured parallel to the backrest
line (see Figure 14)
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Key
a backrest line
b height of lumbar support
L the most prominent segment (or segments) of the lumbar support
Figure 14 — Lumbar support – height
3.17
lumbar support – protrusion
distance from the backrest line to the most prominent segment (or segments) of the lumbar support as
determined by the measuring indicators on the CMD (see Figure 35), measured perpendicular to the
backrest line (see Figure 15)
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Key
a backrest line
b protrusion of lumbar support
L most prominent segment (or segments) of the lumbar support
Figure 15 — Lumbar support – protrusion
3.18
lumbar zone
area parallel to the backrest line, 160 mm to 270 mm above the bottom of the loaded CMD buttocks pad
Note 1 to entry: See Figure 16.
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Dimensions in millimetres
Key
a lumbar zone
Figure 16 — Lumbar zone
3.19
median plane
vertical plane dividing the chair into two generally symmetrical parts (right and left)
Note 1 to entry: See Figure 17.
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Key
a median plane
Figure 17 — Median plane
3.20
neck/head rest protrusion
perpendicular distance from the backrest line to the foremost protrusion on the neck/head rest
Note 1 to entry: See Figure 18.
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Key
a neck/head rest
b backrest line
c neck/head rest protrusion
Figure 18 — Neck/head rest protrusion
3.21
neck/head rest height
distance from the loaded seat to the most prominent segment of the neck/head rest, measured parallel
to the backrest line when the neck/hear rest is in its most vertical position
Note 1 to entry: See Figure 19.
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Key
a neck/head rest
b backrest line
c neck/head rest height
Figure 19 — Neck/head rest height
3.22
seat depth
distance from the backrest line measured parallel to the CMD buttocks pad to the front of the seat
Note 1 to entry: See Figure 20.
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Key
a seat
b CMD buttocks pad
c backrest line
d seat depth
Figure 20 — Seat depth
3.23
seat height
vertical distance, measured at the front of the seat, from the loaded seat to the floor
Note 1 to entry: See Figure 21.
Note 2 to entry: Adjustment of the seat inclination does not constitute a change in seat height.
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Key
a seat
b CMD buttocks pad
c front of seat
d seat height
Figure 21 — Seat height
3.24
sitting height
vertical distance, measured 85 mm ahead of the CMD backrest line, from bottom of the loaded CMD
buttocks pad to the floor
Note 1 to entry: See Figure 22.
Note 2 to entry: Adjustment of the seat inclination does not constitute a change in sitting height.
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Dimensions in millimetres
Key
a chair seat
b CMD buttocks pad
c backrest line
d sitting height
e sitting height line marked on the CMD
Figure 22 — Sitting height
3.25
seat inclination
angle between the loaded CMD buttocks and the horizontal
Note 1 to entry: See Figure 23.
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Key
a CMD buttocks pad
b horizontal
α seat inclination
Figure 23 — Seat inclination
3.26
seat surface depth
dimension of the least seat depth within the zone 115 mm either side of the median plane
Note 1 to entry: See Figure 24.
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Dimensions in millimetres
Key
a seat
b median plane
c seat surface depth
Figure 24 — Seat surface depth
3.27
seat surface width
smallest dimension of the seat surface within the seat surface width zone (3.28) marked on the CMD
Note 1 to entry: See Figure 25.
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Key
a seat
b seat surface width zone
c seat surface width
Figure 25 — Seat surface width
3.28
seat surface width zone
area along the seat surface, from 65 mm forward of the backrest line to 120 mm forward of the 65 mm
line, that supports the user’s buttocks as marked on the CMD
Note 1 to entry: See Figure 26.
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Dimensions in millimetres
Key
a seat surface
b backrest line
c seat surface width zone (120 mm)
Figure 26 — Seat surface width zone
3.29
under-frame – maximum off-set
maximum off-set of the under-frame is the maximum distance between the outermost point of the
under-frame including castors or glides and the axis of rotation
Note 1 to entry: See Figure 27.
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Under-frame without castors Under-frame with castors
Key
s maximum off-set of under-frame
Figure 27 — Under-frame – maximum off-set
4 General measurement conditions
Caution must be used to assure that any chair movement, adjustments and/or applied forces do not
dislodge the CMD causing injury to the user or damage to the CMD.
4.1 Preliminary preparation
The chair should be assembled and/or configured according to the instructions supplied with it.
If mounting or assembly instructions are not supplied, the mounting or assembly method should be
recorded in the report.
All adjustments should be operated through their range of adjustments at least one time before
measurements are taken.
If a measurement cannot be taken as specified in the procedures due to the design of the product, it
should be carried out as far as possible as described, and deviations from the measurement procedure
should be recorded in the test report.
The test should be carried out in indoor ambient conditions. If during a test, the temperature is outside of the
range of 15° C to 25° C the maximum and/or minimum temperature should be recorded in the test report.
4.2 Tolerances
The following equipment tolerances should be applicable unless otherwise specified:
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— Forces: specified in the relevant clauses;
— Masses: ± 1 % of the nominal mass;
— Dimensions: ± 1 mm of the nominal dimension;
— Angles: ± 1° of the nominal angle.
Test weights, forces, dimensions and angles should be targeted at the nominal values specified.
4.3 Measurement uncertainty and compliance evaluations
Compliance evaluations should consider the measurement uncertainties in determining compliance to
the recommendations or requirements of this Technical Report.
The following measurement uncertainties should be applicable unless otherwise specified:
— Backrest angles: ± 10 %, but not more than ± 2°;
— Backrest-to-seat angles: ± 15 %, but not more than ± 2°;
— Seat angles: ± 1,5°;
— All other dimensions: ± 5 %.
NOTE The uncertainty for this device and method will be evaluated and determined when round-robin
evaluations are complete. The above uncertainties are based on BIFMA, International CMD-1-2002 Universal
measurement procedure for the use of BIFMA chair measuring device (CMD).
5 Test equipment
5.1 Floor surface
A rigid, horizontal and flat surface.
5.2 CMD placement fixture
A fixture which holds the chair in position while applying the horizontal force and lowering the CMD
into the chair. This device should not prevent adjustment of the chair. An example of the device (or
devices) is shown in Figures 28 and 29.
5.3 Chair measuring device (CMD)
Device as specified in detail in Annex A.
NOTE A common calibration procedure of the lumbar support measuring device is subject to current research.
5.4 High friction material
Friction cloth: for placing between the seat and the CMD in order to prevent the CMD from sliding on the
seat during measurements. It can be e.g. anti-slip material used underneath carpets. The thickness of
the material, when compressed by the CMD, should not exceed 1 mm.
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Key
a CMD lowering crane
b horizontal force loading device [see 6.2.2 e)]
c chair base restraint mechanism
Figure 28 — Example of CMD placement fixture without chair
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Key
a CMD lowering crane
b horizontal force loading device [see 6.2.2 e)]
c chair base restraint mechanism
d CMD
Figure 29 — Example of CMD placement fixture with chair and CMD
6 Measurement methods and procedures
6.1 General
The measurements should be taken to determine the dimensions and angles of the chair.
After the chair set-up and the CMD placement (6.2) the measurements should be taken as specified in
the measurement procedures (6.3).
6.2 Chair set-up and placement of CMD
6.2.1 Chair set-up
a) Position the chair on the floor surface (5.1) with the seat in the highest position.
b) Adjust all of the following to the mid position of their range: seat depth, back rest tilt tension, back
rest height, and lumbar devices. If there are independently adjustable lumbar device(s), adjust
the height to the approximate midpoint of the lumbar zone, then adjust the protrusion to its mid-
position, if that can be done without altering the height setting.
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c) Adjust the seat so that it is approximately horizontal, without forcing the functions of the chair.
d) If independently adjustable, position the backrest so that the support surface is approximately
vertical. If the adjustment of the backrest to a vertical position will change the seat inclination, the
horizontal seat position should take precedence.
6.2.2 Initial placement of CMD on chair
a) Place a layer of high friction material (5.4) between the CMD and the seat in order to ensure that the
CMD does not slide on the seat.
b) The vertical member of the CMD should be locked at 90° until step g), 6.2.2 (see Figure 30).
Key
a CMD vertical member to buttocks lock
Figure 30 — CMD vertical member locked
c) Place and attach the chair in the CMD placement fixture (5.2), so that CMD vertical member is close
to, but not touching, the chair’s backrest.
d) Ensure the CMD, chair and chair fixture are in alignment with the median plane. Ensure the CMD
buttocks pad is approximately horizontal. Place the CMD seat depth indicator at a position that will
be near, but not in contact with, the front edge of the seat as the CMD is lowered into the chair. Lower
the CMD until it is just above seat (no part of the CMD should touch the seat) and just in front of the
back rest (see Figure 31).
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Figure 31 — CMD hovering above chair
e) Push the CMD towards the backrest with a force F of (40 ± 2) N (see Figure 32).
f) With this force acting, lower the CMD into the seat while maintaining CMD alignment with the chair.
Ensure the seat depth indicator does not touch the chair during loading/placement.
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Key
F force of (40 ± 2) N
Figure 32 — Installation fixture force application
g) Release the vertical member lock;
h) Remove the force F;
i) Position the CMD seat depth indicator so that it is just touching the front edge of the seat (see Figure 33).
Key
a seat depth indicator
Figure 33 — Location of the seat depth indicator
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6.2.3 Final placement of CMD on chair
With the CMD fully resting on the seat, re-adjust the chair (typically by adjusting the seat inclination), if
needed, so that the CMD buttocks pad is as horizontal as possible.
NOTE This may require removal and re-placing of the CMD.
If any adjustments to the chair were made, reclamp the vertical member at 90°, remove the CMD and
follow the procedure in 6.2.2 to reposition the CMD in the chair.
Mark the chair with the seat surface width zone identified on the CMD (3.28).
Mark the lumbar zone (3.18) as defined.
6.3 Measurement procedures
6.3.1 Initial chair measurements
6.3.1.1 Lumbar support protrusion and height (Probe method)
Lock the CMD vertical member to the CMD buttocks pad at the angle that it has taken after its
release from 90°.
Apply a force perpendicular to the vertical member of the CMD simultaneously to 18 vertically stacked
segments. The bottom of the lowest segment should start at 150 mm from the base of the buttocks pad.
Each segment should apply a force of (3,5 ± 0,5) N against the backrest through a 10 mm high by 60 mm
wide surface area. The scale on the CMD should be used to indicate the height and depth of the most
prominent segment of the lumbar protrusion (see Figures 34 and 35).
Make the various lumbar support protrusion depth adjustments available to cause the lumbar protrusion
to be its greatest dimension. If adjustments are made, remove the force and reapply it. Record this
dimension as the maximum lumbar protrusion. Record the lumbar support height at this setting. If the
greatest lumbar protrusion is the same over more than one height indication, record all those heights
with the same protrusion.
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