SIST EN 14179-1:2005

Glass in building - Heat soaked thermally toughened soda lime silicate safety glass - Part 1: Definition and description

This European Standard specifies the heat soak process system together with tolerances flatness, edgework, fragmentation and physical and mechanical characteristics of monolithic flat heat soaked thermally toughened soda lime silicate safety glass for use in buildings.
Information on curved heat soak thermally toughened soda lime silicate safety glass is given in Annex B, but this product does not form part of this European Standard.
Other requirements, not specified in this European Standard, can apply to heat soaked thermally toughened soda lime silicate safety glass which is incorporated into assemblies, e.g. laminated glass or insulating units, or undergo an additional treatment, e.g. coating. The additional requirements are specified in the appropriate product standard. Heat soak thermally toughened soda lime silicate safety glass, in this case, does not lose its mechanical or thermal characteristics.

Glas im Bauwesen - Heißgelagertes thermisch vorgespanntes Kalknatron-Einscheibensicherheitsglas - Teil 1: Definition und Beschreibung

Diese Europäische Norm legt das Heißlagerungsprozess-System sowie die Toleranzen, Geradheit, Kantenbearbei-tung,
das Bruchverhalten und physikalische und mechanische Eigenschaften von einscheibigem, flachem heißge-lagertem
thermisch vorgespanntem Kalknatron-Einscheibensicherheitsglas für die Verwendung im Bauwesen fest.
Anhang B enthält Angaben zu gebogenem heißgelagertem thermisch vorgespanntem Kalknatron-Einscheiben-sicherheitsglas,
dieses Produkt ist aber nicht Bestandteil dieser Europäischen Norm.
An heißgelagerte thermisch vorgespannte Kalknatron-Einscheibensicherheitsgläser können andere Anforderun-gen,
die in dieser Europäischen Norm nicht beschrieben sind, gestellt werden, wenn sie Bestandteil von Kombina-tionen
sind, wie z. B. Verbundglas oder Isolierglas, sind oder wenn sie weiterverarbeitet, z. B. beschichtet werden.
Die zusätzlichen Anforderungen sind in den für die Fertigprodukte zutreffenden Normen festgelegt. In diesem Fall
wird heißgelagertes thermisch vorgespanntes Kalknatron-Einscheibensicherheitsglas seine mechanischen
und/oder thermischen Eigenschaften nicht verlieren.

Verre dans la construction - Verre de silicate sodo-calcique de sécurité trempé et traité Heat Soak - Partie 1: Définition et description

Le présent document spécifie le systeme fonctionnel de stabilisation thermique ainsi que les tolérances, la planéité, la finition des chants, la fragmentation et les caractéristiques physiques et mécaniques du verre plat monolithique de silicate sodo-calcique de sécurité trempé thermiquement et traité Heat Soak dans la construction.
L'Annexe B fournit des informations relatives au verre bombé de silicate sodo-calcique de sécurité trempé thermiquement et traité Heat Soak, mais ce produit ne fait pas partie du présent document.
D'autres exigences, non spécifiées dans le présent document, peuvent s'appliquer au verre de silicate sodo calcique de sécurité trempé thermiquement et traité Heat Soak intégré dans des ensembles, par exemple du verre feuilleté ou des ensembles isolants préfabriqués scellés ou qui subit un traitement supplémentaire, par exemple une couche. Les exigences additionnelles sont spécifiées dans la norme de produit correspondante. Dans ce cas, le verre de silicate sodo-calcique de sécurité trempé thermiquement et traité Heat Soak ne perd pas ses caractéristiques mécaniques ou thermiques.

Steklo v gradbeništvu – HS-preskus kaljenega natrijevega-kalcijevega-silikatnega varnostnega stekla – 1. del: Definicije in opis

General Information

• Status: Withdrawn
• Publication Date: 31-Aug-2005
• Withdrawal Date: 13-Sep-2016
• ICS: 81.040.20 - Glass in building
• Technical Committee: STV - Steklo, svetloba in razsvetljava v gradbeništvu
• Current Stage: 9900 - Withdrawal (Adopted Project)
• Start Date: 13-Sep-2016
• Due Date: 06-Oct-2016
• Completion Date: 14-Sep-2016
• Directive: 89/106/EEC - Construction products
• Mandate: M/135 - Mandate to CEN/CENELEC concerning the execution of standardization work for harmonized standards on flat glass, profiled glass and glass block products
• Ref Project: EN 14179-1:2005 - Glass in building - Heat soaked thermally toughened soda lime silicate safety glass - Part 1: Definition and description

Relations

• Replaced By: SIST EN 14179-1:2016 - Glass in building - Heat soaked thermally toughened soda lime silicate safety glass - Part 1: Definition and description
• Effective Date: 01-Oct-2016

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 14179-1:2005
01-september-2005
Steklo v gradbeništvu – HS-preskus kaljenega natrijevega-kalcijevega-silikatnega
varnostnega stekla – 1. del: Definicije in opis
Glass in building - Heat soaked thermally toughened soda lime silicate safety glass - Part
1: Definition and description
Glas im Bauwesen - Heißgelagertes thermisch vorgespanntes Kalknatron-
Einscheibensicherheitsglas - Teil 1: Definition und Beschreibung
Verre dans la construction - Verre de silicate sodo-calcique de sécurité trempé et traité
Heat Soak - Partie 1: Définition et description
Ta slovenski standard je istoveten z: EN 14179-1:2005
ICS:
81.040.20 Steklo v gradbeništvu Glass in building
SIST EN 14179-1:2005 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 14179-1:2005

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SIST EN 14179-1:2005
EUROPEAN STANDARD
EN 14179-1
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2005
ICS 81.040.20
English version
Glass in building - Heat soaked thermally toughened soda lime
silicate safety glass - Part 1: Definition and description
Verre dans la construction - Verre de silicate sodo-calcique Glas im Bauwesen - Heißgelagertes thermisch
de sécurité trempé et traité Heat Soak - Partie 1: Définition vorgespanntes Kalknatron-Einscheibensicherheitsglas -
et description Teil 1: Definition und Beschreibung
This European Standard was approved by CEN on 19 May 2005.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Central Secretariat or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 14179-1:2005: E
worldwide for CEN national Members.

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SIST EN 14179-1:2005
EN 14179-1:2005 (E)
Contents Page
Foreword .4
Introduction.5
1 Scope .6
2 Normative references .6
3 Terms and definitions.6
4 Glass products.7
5 Manufacturing processes.7
5.1 General .7
5.2 Toughening process.7
5.3 Heat soak process cycle .8
6 Heat soak process system .9
6.1 General .9
6.2 Oven.9
6.3 Glass support.9
6.4 Glass separation .9
6.5 Calibration .11
7 Fracture characteristics .11
8 Dimensions and tolerances.11
8.1 Nominal thickness and thickness tolerances.11
8.2 Width and length (sizes).12
8.3 Flatness .14
9 Edge work, holes, notches and cut-outs.17
9.1 Warning .17
9.2 Edge working of glass for toughening .17
9.3 Profiled edges .18
9.4 Round holes .18
9.5 Notches and cut-outs .21
9.6 Shaped panes.21

10 Fragmentation test.22
10.1 General .22
10.2 Dimensions and number of test specimens .22
10.3 Test procedure .22
10.4 Assessment of fragmentation.23
10.5 Minimum values from the particle count.24
10.6 Selection of the longest particle .24
10.7 Maximum length of longest particle .24
11 Other physical characteristics .24
11.1 Optical distortion .24
11.2 Anisotropy (iridescence) .24
11.3 Thermal durability.25
11.4 Mechanical strength .25
11.5 Classification of performance under accidental human impact.25
12 Marking .25
Annex A (normative) Heat soak process system calibration test .26
A.1 Calibration criteria .26
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SIST EN 14179-1:2005
EN 14179-1:2005 (E)

A.2 Loading of oven and position for glass surface temperature measurement .26
A.3 Procedure .27
A.4 Records .27
A.5 Interpretation of the calibration test.28
Annex B (informative) Curved heat soaked thermally toughened soda lime silicate safety glass .37
Annex C (informative) Examples of particle count .38

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SIST EN 14179-1:2005
EN 14179-1:2005 (E)
Foreword
This European Standard (EN 14179-1:2005) has been prepared by Technical Committee CEN/TC 129 “Glass
in building”, the secretariat of which is held by IBN/BIN.
This European Standard shall be given the status of a national standard, either by publication of an identical
text or by endorsement, at the latest by December 2005, and conflicting national standards shall be withdrawn
at the latest by December 2005.
This European Standard has been prepared under a mandate given to CEN by the European Commission
and the European Free Trade Association.
This Part of the European Standard does not stand-alone, it is a part of one standard:
 EN 14179-1: Glass in building – Heat soaked thermally toughened soda lime silicate safety glass –
Part 1: Definition and description;
 EN 14179-2: Glass in building – Heat soaked thermally toughened soda lime silicate safety glass –
Part 2: Evaluation of conformity/Product standard.
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following
countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic,
Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland
and United Kingdom.

4

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SIST EN 14179-1:2005
EN 14179-1:2005 (E)
Introduction
Heat soaked thermally toughened soda lime silicate safety glass has a safer breakage behaviour when
compared with annealed glass. It also has a known level of residual risk of spontaneous breakage arising from
the possible presence of critical nickel sulphide (NiS) inclusions in the thermally toughened soda lime silicate
glass.
NOTE 1 This case deals with extremely large quantities of glass. These quantities are dealt with on a statistical basis.
Therefore it is impossible to select a quantity of heat soaked thermally toughened soda lime silicate safety glass, for a
building, and claim that ‘no break’ by NiS inclusion can occur. The breakage of heat soaked thermally toughened soda
lime silicate safety glass caused by other influences is excluded.[sl1]
When used to offer protection under accidental human impact, heat soaked thermally toughened soda lime
silicate safety glass also should be classified according to EN 12600 (all parts).
NOTE 2 CEN/TC 129/WG 8 is producing standards for the determination of the design strength of glass and is
preparing a design method.
The European Committee for Standardization (CEN) draws attention to the fact that it is claimed that
compliance with this document may involve the use of a patent concerning Heat Soak Tests. CEN takes no
position concerning the evidence, validity and scope of this patent right. The holder of this patent right has
assured CEN that he/she is willing to negotiate licences under reasonable and non-discriminatory terms and
conditions with applicants throughout the world. In this respect, the statement of the holder of this patent right
is registered with CEN. Information may be obtained from:
SAINT-GOBAIN GLASS FRANCE
Les Miroirs – 92096 La Défense Cedex
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights other than those identified above. CEN shall not be held responsible for identifying any or all such
patent rights.
5

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SIST EN 14179-1:2005
EN 14179-1:2005 (E)

1 Scope
This European Standard specifies the heat soak process system together with tolerances flatness, edgework,
fragmentation and physical and mechanical characteristics of monolithic flat heat soaked thermally toughened
soda lime silicate safety glass for use in buildings.
Information on curved heat soak thermally toughened soda lime silicate safety glass is given in Annex B, but
this product does not form part of this European Standard.
Other requirements, not specified in this European Standard, can apply to heat soaked thermally toughened
soda lime silicate safety glass which is incorporated into assemblies, e.g. laminated glass or insulating units,
or undergo an additional treatment, e.g. coating. The additional requirements are specified in the appropriate
product standard. Heat soak thermally toughened soda lime silicate safety glass, in this case, does not lose its
mechanical or thermal characteristics.
2 Normative references
The following referenced documents are indispensable for the application of this European Standard. For
dated references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
EN 572-1, Glass in building — Basic soda lime silicate glass products — Part 1: Definitions and general
physical and mechanical properties
EN 572-2, Glass in building — Basic soda lime silicate glass products — Pall 2: Float glass
EN 572-4, Glass in building — Basic soda lime silicate glass products — Part 4: Drawn sheet glass
EN 572-5, Glass in building — Basic soda lime silicate glass products — Part 5: Patterned glass
EN 1096-1, Glass in building — Coated glass — Part 1: Definitions and classification
3 Terms and definitions
For the purposes of this European Standard, the following terms and definitions apply.
3.1
heat soaked thermally toughened soda lime silicate safety glass
glass within which a permanent surface compressive stress has been induced in order to give it greatly
increased resistance to mechanical and thermal stress and prescribed fragmentation characteristics and
which has a known level of residual risk of spontaneous breakage due to the presence of critical nickel
sulphide (NiS) inclusions
3.2
level of residual risk
risk of spontaneous breakage of heat soaked thermally toughened soda lime silicate safety glass, on a
statistical basis, due to the presence of critical nickel sulphide inclusions, is no more than one breakage per
400 tonnes of heat soaked thermally toughened soda lime silicate safety glass
3.3
flat heat soaked thermally toughened soda lime silicate safety glass
heat soaked thermally toughened soda lime silicate safety glass that has not been deliberately given a specific
profile during manufacture
6

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SIST EN 14179-1:2005
EN 14179-1:2005 (E)
3.4
heat soaked enamelled thermally toughened soda lime silicate safety glass
heat soaked thermally toughened soda lime silicate safety glass which has a ceramic frit fired into the surface
during the toughening process. After toughening the ceramic frit becomes an integral part of the glass
NOTE In the UK, this glass is also known as heat soaked opaque thermally toughened soda lime silicate safety glass.
3.5
horizontal toughening
process in which the glass is supported on horizontal rollers
3.6
vertical toughening
process in which the glass is suspended by tongs
4 Glass products
Heat soaked thermally toughened soda lime silicate safety glass shall be made from a monolithic soda lime
silicate glass product generally corresponding to one of the following standards:
 soda lime silicate glass according to EN 572-1;
 float glass according to EN 572-2;
 drawn sheet glass according to EN 572-4;
 patterned glass according to EN 572-5;
 coated glass according to EN 1096-1.
5 Manufacturing processes
5.1 General
Heat soaked thermally toughened soda time silicate safety glass is manufactured as follows:
Basic soda lime silicate glass products (see Clause 4) are cut to size, shaped and edgeworked (see Clause 9).
The prepared glass panes are then thermally toughened (see 5.2).
The thermally toughened panes are then subjected to the heat soak process cycle.
After manufacture the heat soaked thermally toughened soda lime silicate glass shall comply with the
fragmentation test (see Clause 10) and mechanical strength requirement (see 11.4).
5.2 Toughening process
The cut, shaped and edgeworked glasses are toughened. The horizontal or vertical toughened glass shall
comply with the flatness criteria (see 8.3).
The thermally toughened soda lime silicate glass shall have a level of fragmentation that will ensure that after
the glass has been through the heat soak process, and subsequently tested to the fragmentation test (see
Clause 10), it shall comply with 10.5.

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SIST EN 14179-1:2005
EN 14179-1:2005 (E)
5.3 Heat soak process cycle
5.3.1 General
The heat soak process cycle consists of a heating phase, a holding phase and a cooling phase (see Figure 1).

Key
T glass temperature at any point, °C d ambient temperature
t time, h
a heating phase
1 first glass to reach 280 °C b holding phase
2 last glass to reach 280 °C c cooling phase
Figure 1 — Heat soak process cycle
5.3.2 Heating phase
The heating phase commences with all the glasses at ambient temperature and concludes when the surface
temperature of the last glass reaches 280 °C. The time to reach this temperature is defined in the calibration
process. This time will be dependent on the size of the oven, the amount of glass to be treated, the separation
between glasses and the heating system capacity.
NOTE 1 The glass separation and rate of heating should be controlled to minimise the risk of glass breakage as a
result of thermal stress.
To facilitate economic heating, the air temperature within the oven may exceed 320 °C. However, the glass
surface temperature shall not be allowed to exceed 320 °C. The period of glass surface temperature in excess
of 300 °C shall be minimised.
NOTE 2 When the temperature of the glass exceeds 300 °C, care should be taken to ensure that the properties of the
heat soaked thermally toughened soda lime silicate safety glass are not significantly altered i.e. they continue to meet
Clause 10.
5.3.3 Holding phase
The holding phase commences when the surface temperature of all the glasses has reached a temperature of
280 °C. The duration of the holding phase is 2 h.
Precise oven control is necessary in order to ensure that the glass surface temperature shall be maintained in
the range of 290 °C ± 10 °C during the holding phase.
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EN 14179-1:2005 (E)
5.3.4 Cooling phase
The cooling phase commences when the last glass to reach 280 °C has completed its holding phase, i.e.
been held for two hours at 290 °C ± 10 °C. During this phase the glass temperature shall be brought down to
ambient temperature.
The cooling phase can be concluded when the air temperature in the oven reaches 70 °C.
NOTE The rate of cooling should be controlled to minimise the risk of glass breakage as a result of thermal stress.
6 Heat soak process system
6.1 General
The heat soak process system consists of:
 oven (see 6.2);
 glass support (see 6.3);
 separation system (see 6.4).
The oven shall be calibrated, see 6.5 and Annex A, and this determines the method of operation of the heat
soak process system during manufacture of heat soaked thermally toughened soda lime silicate safety glass.
6.2 Oven
The oven shall be heated by convection and shall allow an unhindered air circulation around each glass pane.
In the event of glass breakage the airflow shall not be hindered. The airflow in the oven shall be led parallel to
the glass surfaces.
NOTE The openings for the air ingress/egress should be designed to ensure that fragments of broken glass do not
cause blockages.
6.3 Glass support
Glasses may be supported vertically or horizontally. The glasses shall not be fixed or clamped, they have to
be supported to allow free movement.
NOTE Vertically means true vertical or up to 15° either side of true vertical.
The distance between glasses affects the airflow, heat exchange and the heating time. Glass to glass contact
shall not be allowed.
6.4 Glass separation
The glasses shall be separated in a manner that does not hinder the airflow. The separators shall also not
hinder the airflow e.g. see Figure 2.
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EN 14179-1:2005 (E)
Dimensions in millimetres

Figure 2 — Example of a vertical glass support
The minimum separation of the glasses shall be determined during the calibration of the oven, see 6.5 and
Annex A.
NOTE 1 Generally, a minimum separation of 20 mm is recommended (see Figure 3).
NOTE 2 If glasses of very different size are put on the same stillage, they will require greater separation in order to
prevent glass breakage when the furnace is opened alter the heat soak process. The same applies to glasses with holes,
notches and cut-outs.
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EN 14179-1:2005 (E)


Figure 3 — Recommend separation between glass
The positioning of the separators, material of the manufacture and their shape shall be specified during the
calibration test of the oven and shall be reproduced during the manufacturing process.
6.5 Calibration
The heat soak system, e.g. oven, glass separation, separators, etc., shall be calibrated, see Annex A.
The calibration shall determine the heating phase of the process, glass separation distance, the positioning,
material and shape of separators, the type and positioning of stillage(s) and define the operating conditions for
use during manufacture.
7 Fracture characteristics
In the event of breakage, heat soaked thermally toughened soda lime silicate safety glass fractures into
numerous small pieces, the edges of which are generally blunt.
NOTE Fragmentation in service does not always correspond to that described in Clause 10, due to restraint from
fixing or reprocessing (e.g. laminating), or due to the cause of fracture.
8 Dimensions and tolerances
8.1 Nominal thickness and thickness tolerances
The nominal thicknesses and thickness tolerances are those given in the relevant product standard (see
Clause 4), some of which are reproduced in Table 1.
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SIST EN 14179-1:2005
EN 14179-1:2005 (E)

Table 1 — Nominal thicknesses and thickness tolerances
Dimensions in millimetres
Thickness tolerances for glass type
Nominal thickness
d
Drawn sheet Patterned Float
±0,2
±0,2
±0,5
3
±0,2
±0,2
±0,5
4
±0,2
5 ±0,3 ±0,5
6 ±0,2
±0,3 ±0,5
8 ±0,3
±0,4 ±0,8
10
±0,3
±0,5 ±1,0
12
±0,3
±0,6 not manufactured
15
not manufactured ±0,5
not manufactured
19
not manufactured not manufactured
±1,0
25
not manufactured
not manufactured
±1,0

The thickness of a pane shall be determined as for the basic product. The measurement shall be taken at the
centres of the 4 sides, and away from the area of any tong marks (see Figure 6), which may be present.
8.2 Width and length (sizes)
8.2.1 General
When heat soaked thermally toughened soda lime silicate safety glass dimensions are quoted for rectangular
panes, the first dimension shall be the width, B, and the second dimension the length, H, as shown in
Figure 4. It shall be made clear which dimension is the width, B, and which is the length, H, when related to its
installed position.

Figure 4 — Examples of width, B, and length, H, relative to the pane shape
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SIST EN 14179-1:2005
EN 14179-1:2005 (E)
NOTE For heat soaked thermally toughened soda lime silicate safety glass manufactured from patterned glass, the
direction of the pattern should be specified relative to one of the dimensions.
8.2.2 Maximum and minimum sizes
For maximum and minimum sizes, the manufacturer shall be consulted.
8.2.3 Tolerances and squareness
The nominal dimensions for width and length being given, the finished pane shall not be larger than a
prescribed rectangle resulting from the nominal dimensions increased by the tolerance, t, or smaller than a
prescribed rectangle reduced by the tolerance, t. The sides of the prescribed rectangles are parallel to one
another and these rectangles shall have a common centre (see Figure 5). The limits of squareness shall be
determined by the prescribed rectangles. Tolerances are given in Table 2.

Figure 5 — Tolerance limits for dimensions of rectangular panes
Table 2 — Tolerances on width, B, and length, H
Dimensions in millimetres
Tolerance, t
Nominal dimension of side,
nominal glass thickness, nominal glass thickness,
B or H
d ≤≤≤≤ 12 d > 12
≤2 000 ±2,5 (horizontal toughening) ±3,0
±3,0 (vertical toughening)
2 000 < B or H ≤ 3 000 ±3,0 ±4,0
>3 000
±4,0 ±5,0

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EN 14179-1:2005 (E)
8.2.4 Edge deformation produced by vertical toughening
The tongs used to suspend the glass during toughening can result in surface depressions, known as tong
marks (see Figure 6). The centres of the tong marks may be situated up to a maximum of 20 mm in from the
edge. A deformation of the edge less than 2 mm can be produced in the region of the tong mark and there can
also be an area of optical distortion. These deformations shall be included in the tolerances in Table 2.

Key
1 deformation
2 up to 20 mm
3 tong mark
4 100 mm radius maximum area of optical distortion
Figure 6 — Tong mark deformation
8.3 Flatness
8.3.1 General
By the very nature of the toughening process, it is not possible to obtain a product as flat as annealed glass.
The difference depends on the nominal thickness, the dimensions and the ratio between the dimensions.
Therefore a distortion known as overall bow may occur. There are two kinds of bow (see Figure 7):
 overall or general bow;
 local bow.
NOTE 1 Overall bow can, in general, be accommodated by the framing system.
NOTE 2 Local bow needs to be allowed for in the glazing materials and the weather seals. For special requirements
the manufacturers should be consulted.
8.3.2 Measurement of overall bow
The pane of glass shall be placed in a vertical position and supported on its longer side by two load bearing
blocks at the quarter points (see Figure 8).
The deformation shall be measured along the edges of the glass and along the diagonals, as the maximum
distance between a straight metal ruler, or a stretched wire, and the concave surface of the glass (see
Figure 7).
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EN 14179-1:2005 (E)
The value for the bow is then expressed as the deformation, in millimetres, divided by the measured length of
the edge of the glass, or diagonal, in millimetres, as appropriate.
The measurement shall be carried out at room temperature.


Key
1 deformation for calculating overall bow
2 B, or H, or diagonal length
3 local bow
4 300 mm length
Figure 7 — Representation of overall and local bow
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EN 14179-1:2005 (E)

Key
1 B or H
2 (B or H)/2
3 (B or H)/4
4 maximum 100 mm
Figure 8 — Support conditions for the measurement of overall bow
8.3.3 Mea
...