prEN ISO 4937

SLOVENSKI STANDARD
01-maj-2024
Jeklo in železo - Določevanje kroma - Potenciometrična ali vizualna titracijska
metoda (ISO/DIS 4937:2024)
Steel and iron - Determination of chromium content - Potentiometric or visual titration
method (ISO/DIS 4937:2024)
Stahl und Eisen - Bestimmung des Chromgehalts - Potentiometrische oder visuelle
Titrationsmethode (ISO/DIS 4937:2024)
Aciers et fontes - Détermination du chrome - Méthode par titrage potentiométrique ou
visuel (ISO/DIS 4937:2024)
Ta slovenski standard je istoveten z: prEN ISO 4937
ICS:
77.040.30 Kemijska analiza kovin Chemical analysis of metals
77.080.01 Železne kovine na splošno Ferrous metals in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 4937
ISO/TC 17/SC 1
Steel and iron — Determination
Secretariat: JISC
of chromium content —
Voting begins on:
Potentiometric or visual titration
2024-03-04
method
Voting terminates on:
2024-05-27
Aciers et fontes — Dosage du chrome — Méthode par titrage
potentiométrique ou visuel
ICS: 77.080.01
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
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Reference number
ISO/DIS 4937:2024(en)
DRAFT
ISO/DIS 4937:2024(en)
International
Standard
ISO/DIS 4937
ISO/TC 17/SC 1
Steel and iron — Determination
Secretariat: JISC
of chromium content —
Voting begins on:
Potentiometric or visual titration
method
Voting terminates on:
Aciers et fontes — Dosage du chrome — Méthode par titrage
potentiométrique ou visuel
ICS: 77.080.01
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2024
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
BE CONSIDERED IN THE LIGHT OF THEIR
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Website: www.iso.org
Published in Switzerland Reference number
ISO/DIS 4937:2024(en)
ii
ISO/DIS 4937:2024(en)
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Reagents . 2
6 Apparatus . 5
7 Sampling and sample preparation . 5
8 Procedure . 5
8.1 Test portion .5
8.2 Blank test .5
8.3 Determination .5
8.3.1 Preparation of the test solution .5
8.3.2 Oxidation of chromium and preparation for titration .6
8.3.3 Titration .7
9 Expression of results . 8
9.1 Method of calculation .8
9.1.1 Potentiometric titration.8
9.1.2 Visual titration .8
9.2 Precision . . .9
10 Test report . 10
Annex A (informative) Additional information on the international interlaboratory precision
tests .11
Annex B (Informative) Graphical representation of precision data .13
Bibliography .15

iii
ISO/DIS 4937:2024(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
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 17, Steel, Subcommittee SC 1, Methods of
determination of chemical composition, in collaboration with the European Committee for Standardization
(CEN) Technical Committee CEN/TC 459/SC 2, Methods of chemical analysis for iron and steel, in accordance
with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 4937:1986), which has been revised. The main
changes are as follows:
— re-assessment of the precision data.
— re-confirmation of upper limit of vanadium content in test portions by visual titration .
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
DRAFT International Standard ISO/DIS 4937:2024(en)
Steel and iron — Determination of chromium content —
Potentiometric or visual titration method
1 Scope
This document specifies a method for the determination of chromium in steel and iron by potentiometric or
visual titration.
The method is applicable to chromium contents between 0,25 % (mass fraction) and 35 % (mass fraction).
If vanadium is present, the visual titration is applicable only to test portions containing less than 3 mg of
vanadium.
NOTE The visual titration can be applicable to test portion containing between 3 mg and 6 mg of vanadium.
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 385, Laboratory glassware — Burettes
ISO 648, Laboratory glassware — One-mark pipettes.
IS0 1042, Laboratory glassware —One-mark volumetric flasks.
ISO 3696, Water for analytical laboratory use — Specification and test methods
ISO 14284, Steel and iron — Sampling and preparation of samples for the determination of chemical composition
3 Terms and definitions
No terms and definitions are listed in this document.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
4 Principle
Dissolution of a test portion with appropriate acids.
Oxidation of chromium in an acid medium to chromium(Vl) by ammonium peroxydisulfate in the presence
of silver sulfate. Reduction of manganese(VII) by hydrochloric acid.
Reduction of chromium(Vl) by an ammonium iron(II) sulfate standard solution.
In the case of potentiometric detection, determination of the equivalence point by measurement of the
potential variation when the ammonium iron(ll) sulfate standard solution is being added.

ISO/DIS 4937:2024(en)
In the case of visual detection, titration the excess of ammonium iron(II) sulfate by a potassium
permanganate standard solution which also acts as the indicator.
5 Reagents
During the analysis, unless otherwise stated, use only reagents of reco
...