EN ISO 2431:2019

SLOVENSKI STANDARD
01-september-2019
Nadomešča:
SIST EN ISO 2431:2012
Barve in laki - Ugotavljanje iztočnega časa z uporabo iztočnih čaš (ISO 2431:2019)
Paints and varnishes - Determination of flow time by use of flow cups (ISO 2431:2019)
Beschichtungsstoffe - Bestimmung der Auslaufzeit mit Auslaufbechern (ISO 2431:2019)
Peintures et vernis - Détermination du temps d'écoulement au moyen de coupes
d'écoulement (ISO 2431:2019)
Ta slovenski standard je istoveten z: EN ISO 2431:2019
ICS:
87.040 Barve in laki Paints and varnishes
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 2431
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2019
EUROPÄISCHE NORM
ICS 87.040 Supersedes EN ISO 2431:2011
English Version
Paints and varnishes - Determination of flow time by use
of flow cups (ISO 2431:2019)
Peintures et vernis - Détermination du temps Beschichtungsstoffe - Bestimmung der Auslaufzeit mit
d'écoulement au moyen de coupes d'écoulement (ISO Auslaufbechern (ISO 2431:2019)
2431:2019)
This European Standard was approved by CEN on 11 June 2019.

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 CEN-CENELEC Management Centre 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 CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 2431:2019 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 2431:2019) has been prepared by Technical Committee ISO/TC 35 "Paints and
varnishes" in collaboration with Technical Committee CEN/TC 139 “Paints and varnishes” the
secretariat of which is held by DIN.
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 January 2020, and conflicting national standards shall
be withdrawn at the latest by January 2020.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 2431:2011.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 2431:2019 has been approved by CEN as EN ISO 2431:2019 without any modification.

INTERNATIONAL ISO
STANDARD 2431
Sixth edition
2019-06
Paints and varnishes — Determination
of flow time by use of flow cups
Peintures et vernis — Détermination du temps d'écoulement au
moyen de coupes d'écoulement
Reference number
ISO 2431:2019(E)
©
ISO 2019
ISO 2431:2019(E)
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address
below or ISO’s member body in the country of the requester.
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Published in Switzerland
ii © ISO 2019 – All rights reserved

ISO 2431:2019(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Temperature considerations . 2
5 Apparatus . 2
5.1 Flow cups . 2
5.1.1 Dimensions . 2
5.1.2 Material . 2
5.1.3 Construction . 2
5.1.4 Finish. 3
5.1.5 Measurement range . 4
5.1.6 Marking . 5
5.1.7 Care and checking of flow cups . 5
5.2 Supplementary apparatus . 6
6 Sampling . 6
7 Procedure. 6
7.1 Preliminary check for Newtonian flow . 6
7.2 Determination of flow time . 6
7.2.1 Choice of flow cup . 6
7.2.2 Temperature adjustment . 6
7.2.3 Preparation of the flow cup . 7
7.2.4 Filling the flow cup . . 7
7.2.5 Measurement of flow time . . 7
7.2.6 Repeat determinations . 7
8 Marking of products tested. 7
9 Precision . 8
9.1 General . 8
9.2 Repeatability limit, r . 8
9.3 Reproducibility limit, R . 8
10 Test report . 9
Annex A (normative) Checking flow cups for wear and tear .10
Annex B (informative) Conversion of flow times from one temperature to another .12
Bibliography .14
ISO 2431:2019(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 of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see
www .iso .org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 35, Paints and varnishes, Subcommittee
SC 9, General test methods for paints and varnishes.
This sixth edition cancels and replaces the fifth edition (ISO 2431:2011), which has been technically
revised. The main changes compared to the previous edition are as follows:
— a general reference to ISO 4618 has been added in Clause 3;
— the information in Clause 4 on measuring at other temperatures and humidities specified in this
document has been amended;
— Figure 1 has been corrected;
— information on conduction of measurements in a fume cupboard has been added to Clause 4.
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.
iv © ISO 2019 – All rights reserved

ISO 2431:2019(E)
Introduction
The first edition of this document, ISO 2431, published in 1972, specified only one flow cup with an
orifice diameter of 4 mm. The second edition specified three flow cups with an orifice diameter of
3 mm, 4 mm and 6 mm. The third edition corrected errors in Figures 2 and 4 and the formulae for those
figures. The fourth edition specified four flow cups with an orifice diameter of 3 mm, 4 mm, 5 mm and
6 mm. In the fifth edition the curves in Figures 2 to 5 have been placed in a single figure (Figure 2)
and the formulae for the conversion of flow time to kinematic viscosity and vice versa represented by
the curves in these figures have been moved from the figures to a table (Table 1). The procedure for
checking the flow cups for wear and tear has been revised to include two alternative methods (one
using a certified reference material or secondary working standard, the other using a certified flow
cup) and has been moved to an informative annex. The main changes made in this sixth edition are
given in the foreword.
As is well known, many countries over the years have developed their own standard flow cups and
the difficulty in correlation between them has led to considerable confusion in comparing values. The
standardization of an improved design of flow cup has been recommended after careful consideration
of the role of flow cups for the measurement of the flow time of paints, varnishes and related products.
Flow times are a measure for sample viscosity only for products with Newtonian or near-Newtonian
flow properties. This effectively limits the practical use of flow cups. Nevertheless, for checking
purposes, these flow cups do serve a useful purpose. Furthermore, the measurement of flow time is
often used to confirm the application consistency.
Paints often contain thickening agents to ensure increased viscosity. Such paints exhibit non-Newtonian
flow properties. Their viscosity during application can only be properly assessed using viscometers
such as that described in ISO 3219.
Resins and varnishes can exhibit Newtonian or near-Newtonian flow at much higher viscosities than
most paints and, where this applies, flow cups can provide a useful means of controlling the consistency.
As a result, this document provides flow cups suitable for viscosities up to about 700 mm /s.
With thixotropic materials, stirring or other such mechanical stress immediately before testing will
reduce the flow time compared with that for an unstirred sample. With such materials, uncertain and
variable flow time values are obtained with all the flow cups. The repeatability and reproducibility
limits given in Clause 9 cannot be achieved in the determination of the flow time of such materials.
INTERNATIONAL STANDARD ISO 2431:2019(E)
Paints and varnishes — Determination of flow time by use
of flow cups
1 Scope
This document specifies a method for determining the flow time of paints, varnishes and related
products that can be used to control consistency.
Four flow cups of similar dimensions, but having orifice diameters of 3 mm, 4 mm, 5 mm and 6 mm, are
specified. Two methods for checking the flow cups for wear and tear are given (see Annex A).
Flow cups with a replaceable jet are not covered by this document as the close tolerances on the supply
of the material under test to the jet are not met.
Commonly used dipping flow cups are also not covered by this document.
NOTE Since the fabrication tolerances for such flow cups are greater than those of the flow cups specified
in this document, flow time determinations with dipping flow cups give a precision which is lower than that
obtained with the flow cups specified in this document (see Clause 9).
The method described in this document is limited to testing materials for which the breakpoint of
the flow from the orifice of the flow cup can be determined with certainty. This point is difficult to
determine and reproduce for materials with flow times near the upper limit of the measurement range
(100 s) due to slowing-down effects.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements 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.
ISO 1513, Paints and varnishes — Examination and preparation of test samples
ISO 4618, Paints and varnishes — Terms and definitions
ISO 15528, Paints, varnishes and raw materials for paints and varnishes — Sampling
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 4618 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
flow time
t
time that elapses from the moment when the material under test starts to flow from the orifice of the
filled flow cup to the moment when the flow stream of material first breaks off close to the orifice
ISO 2431:2019(E)
3.2
Newtonian flow
behaviour where the shear viscosity is independent of shear rate, shear stress and time
3.3
non-Newtonian flow
beha
...