EN ISO 21181:2025

Light conveyor belts - Determination of the relaxed elastic modulus (ISO 21181:2025)

This document specifies a test method for the determination of the relaxed elastic modulus of light conveyor belts according to ISO 21183-1 or other conveyor belts where ISO 9856 does not apply.

Leichte Fördergurte - Bestimmung des relaxierten Elastizitätsmoduls (ISO 21181:2025)

Dieses Dokument legt ein Prüfverfahren fest für die Bestimmung des relaxierten Elastizitätsmoduls von leichten Fördergurten nach ISO 21183 1 oder von anderen Fördergurten, für die ISO 9856 nicht anwendbar ist.

Courroies transporteuses légères - Détermination du module d'élasticité relaxé (ISO 21181:2025)

Le présent document spécifie une méthode d'essai permettant de déterminer le module d'élasticité relaxé des courroies transporteuses légères selon l'ISO 21183-1, ou d'autres courroies transporteuses lorsque l'ISO 9856 ne s'applique pas.

Naprave za kontinuirni transport - Lahki trakovi tračnih transporterjev - Ugotavljanje trajnega (relaksiranega) elastičnega modula traka (ISO 21181:2025)

General Information

• Status: Published
• Publication Date: 11-Nov-2025
• ICS: 53.040.20 - Components for conveyors
• Technical Committee: CEN/TC 188 - Conveyor belts
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 12-Nov-2025
• Completion Date: 12-Nov-2025
• Ref Project: SIST EN ISO 21181:2026 - Light conveyor belts - Determination of the relaxed elastic modulus (ISO 21181:2025)

Relations

• Replaces: EN ISO 21181:2013 - Light conveyor belts - Determination of the relaxed elastic modulus (ISO 21181:2013)
• Effective Date: 22-Nov-2023

Overview

EN ISO 21181:2025 is an international standard developed by CEN, specifying a test method for determining the relaxed elastic modulus of light conveyor belts. This standard is particularly applicable to belts manufactured according to ISO 21183-1 or other belts for which ISO 9856 does not apply. The relaxed elastic modulus is a critical characteristic that reflects the long-term behavior of conveyor belts under cyclic tension, accounting for permanent stretch and relaxation effects that arise during service.

This standard provides a repeatable and reliable method to measure how conveyor belts behave under repeated elongation, ensuring that industries using light conveyor belts can predict tensioning forces accurately throughout the belt’s lifespan.

Key Topics

• Scope and Purpose: Defines the methodology for testing light conveyor belts, important for applications where belts are initially tensioned without readjustment.
• Test Methodology: Involves cyclic elongation of test pieces between defined limits and recording tensile forces over 500 cycles.
• Relaxed Elastic Modulus: Represents the elastic modulus after cyclic loading, showing practical tension force changes, including permanent stretch.
• Apparatus Requirements: Requires a tensile testing machine compliant with ISO 7500-1, capable of displacement-controlled cyclic loading at ±5 mm and 0.5 Hz frequency.
• Test Pieces: Rectangular samples (50 mm wide, 500 mm free length) chosen from the conveyor belt’s full thickness along the longitudinal direction.
• Conditioning: Samples must be preconditioned as per ISO 18573 to ensure consistent test environments, particularly for materials with high moisture absorption.
• Test Conditions: Controlled temperature (23 °C ± 2 °C) and humidity (50% ± 5%) are specified to standardize testing accuracy.
• Calculation and Reporting: Elastic modulus is calculated by dividing tensile forces by belt width and analyzed using logarithmic regression based on tensile force variation over cycles.

Applications

The EN ISO 21181:2025 standard is highly valuable for industries relying on continuous light conveyor belt transport systems, including:

• Manufacturing and Packaging: Where precise conveyor belt tensioning affects production line efficiency and product quality.
• Material Handling and Logistics: To ensure durable and predictable belt performance in sorting, conveying, and distribution systems.
• Mining and Agriculture: For belts exposed to cyclic loads where relaxed modulus influences maintenance cycles and operational safety.
• Quality Control and Product Development: Material and belt manufacturers use this standard to verify belt properties, ensuring compliance with performance criteria and optimizing material formulations.

By understanding the relaxed elastic modulus, maintenance teams can better predict when belt tension adjustments will be necessary, minimizing downtime and avoiding premature belt failures.

Related Standards

EN ISO 21181:2025 references and complements several key standards in the conveyor belt and materials testing domain:

• ISO 21183-1: Defines principal characteristics and applications of light conveyor belts, serving as the baseline for belt specifications.
• ISO 9856: Describes the determination of elastic and permanent elongation for other conveyor belt types, applicable when EN ISO 21181:2025 does not apply.
• ISO 7500-1: Details the calibration and verification requirements for tensile testing machines assessing force measurements during cyclic tests.
• ISO 18573: Specifies standard conditioning atmospheres and periods ensuring material properties are tested under consistent environmental conditions.

Adhering to the EN ISO 21181:2025 standard helps synchronize quality assurance processes with international benchmarks, facilitating global trade and regulatory compliance in conveyor belt manufacturing and use.

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Keywords: light conveyor belts, relaxed elastic modulus, conveyor belt tension, cyclic elongation test, ISO 21181, conveyor belt testing, tensile force measurement, industrial conveyor standards, belt conditioning, conveyor belt maintenance.

Standards Content (Sample)

SLOVENSKI STANDARD
oSIST prEN ISO 21181:2025
01-februar-2025
Naprave za kontinuirni transport - Lahki trakovi tračnih transporterjev -
Ugotavljanje trajnega (relaksiranega) elastičnega modula traka (ISO/DIS
21181:2024)
Light conveyor belts - Determination of the relaxed elastic modulus (ISO/DIS
21181:2024)
Leichte Fördergurte - Bestimmung des relaxierten Elastizitätsmoduls (ISO/DIS
21181:2024)
Courroies transporteuses légères - Détermination du module d'élasticité relaxé (ISO/DIS
21181:2024)
Ta slovenski standard je istoveten z: prEN ISO 21181
ICS:
53.040.10 Transporterji Conveyors
53.040.20 Deli za transporterje Components for conveyors
oSIST prEN ISO 21181:2025 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN ISO 21181:2025
oSIST prEN ISO 21181:2025
DRAFT
International
Standard
ISO/DIS 21181
ISO/TC 41/SC 3
Light conveyor belts —
Secretariat: SAC
Determination of the relaxed elastic
Voting begins on:
modulus
2024-12-18
Courroies transporteuses légères — Détermination du module
Voting terminates on:
d'élasticité relaxé
2025-03-12
ICS: 53.040.20
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,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS.
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Reference number
ISO/DIS 21181:2024(en)
oSIST prEN ISO 21181:2025
DRAFT
ISO/DIS 21181:2024(en)
International
Standard
ISO/DIS 21181
ISO/TC 41/SC 3
Light conveyor belts —
Secretariat: SAC
Determination of the relaxed
Voting begins on:
elastic modulus
Courroies transporteuses légères — Détermination du module
Voting terminates on:
d'élasticité relaxé
ICS: 53.040.20
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
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
or ISO’s member body in the country of the requester.
NATIONAL REGULATIONS.
ISO copyright office
RECIPIENTS OF THIS DRAFT ARE INVITED
CP 401 • Ch. de Blandonnet 8
TO SUBMIT, WITH THEIR COMMENTS,
CH-1214 Vernier, Geneva
NOTIFICATION OF ANY RELEVANT PATENT
Phone: [phone]
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ISO/DIS 21181:2024(en)
ii
oSIST prEN ISO 21181:2025
ISO/DIS 21181:2024(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols . 2
5 Principle . 2
6 Apparatus . 2
7 Test pieces . 2
7.1 Shape, dimensions, number and selection .2
7.2 Conditioning.3
8 Test method . 3
8.1 Test room condition .3
8.2 Procedure .3
9 Calculation and expression of results . 4
10 Test report . 6
Bibliography . 7

iii
oSIST prEN ISO 21181:2025
ISO/DIS 21181:2024(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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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 41, Pulleys and belts (including veebelts),
Subcommittee SC 3, Conveyor belts.
This third edition cancels and replaces the second edition(ISO 21181:2013), which has been technically
revised.
The main changes are as follows:
— The title is changed from Procedure to Test method in Clause 8
— Test room condition is added in 8.1
— Clause No. of Procedure is changed from 8 to 8.2
A list of all parts in the ISO 21181 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 w w w.iso.org/members.html.

iv
oSIST prEN ISO 21181:2025
ISO/DIS 21181:2024(en)
Introduction
Many applications for light conveyor belts require that the belt is initially tensioned and there is no
subsequent change in belt length by adjustment of any rollers. In such cases, the tensioning force in the
belt changes throughout the life of the belt because of two effects: permanent stretch and relaxation of the
belt, both of which change it
...