prEN IEC 60216-4:2026

• Status: Not Published
• Publication Date: 09-Jan-2028
• ICS: 17.220.99 - Other standards related to electricity and magnetism
• ICS: 29.035.01 - Insulating materials in general
• Technical Committee: CLC/SR 112 - Evaluation and qualification of electrical insulating materials and systems (to be defined)
• Current Stage: 4020 - Enquiry circulated - Enquiry
• Start Date: 31-Jul-2026
• Due Date: 27-Nov-2026
• Completion Date: 31-Jul-2026
• Ref Project: oSIST prEN IEC 60216-4:2026 - Electrical insulating materials - Thermal endurance properties - Part 4: Ageing ovens

• Revises: EN 60216-4-3:2000 - Electrical insulating materials - Thermal endurance properties - Part 4-3: Ageing ovens - Multi-chamber ovens
• Effective Date: 10-Feb-2026
• Revises: EN 60216-4-2:2000 - Electrical insulating materials - Thermal endurance properties - Part 4-2: Ageing ovens - Precision ovens for use up to 300 °C
• Effective Date: 10-Feb-2026
• Revises: EN 60216-4-1:2006 - Electrical insulating materials - Thermal endurance properties - Part 4-1: Ageing ovens - Single-chamber ovens
• Effective Date: 10-Feb-2026

prEN IEC 60216-4:2026 is a draft IEC/CENELEC standard for ageing ovens used to evaluate the thermal endurance of electrical insulating materials. It specifies minimum construction, performance, test, reporting and in-service monitoring requirements for ventilated, electrically heated ovens, including single-chamber and multi-chamber designs.

What does prEN IEC 60216-4:2026 specify?

prEN IEC 60216-4:2026 covers minimum requirements for ventilated and electrically heated ovens with or without forced air circulation, for thermal endurance evaluation of electrical insulation. It applies to ovens designed to operate from 20 °C above ambient to 500 °C and includes acceptance tests and in-service monitoring tests.

The document is organized into clauses 1 to 8, followed by four informative annexes and a bibliography. Clause 4 covers construction, Clause 5 performance, Clause 6 test methods and procedure, Clause 7 the report, and Clause 8 conditions of use and in-service monitoring.

Annex	What it covers
Annex A	Test method to determine the rate of ventilation for single-chamber ovens
Annex B	Examples for calculating temperature deviation for single-chamber ovens
Annex C	Test methods and procedure for multi-chamber ovens
Annex D	Examples of multi-chamber ovens

What are the key requirements of prEN IEC 60216-4:2026?

Construction and materials

prEN IEC 60216-4:2026 requires the oven to be soundly built from suitable materials for continuous operation over the claimed temperature range. Internal materials and fittings must not influence specimen properties, and the interior must be corrosion-resistant, non-absorbent, leak-proof and easy to clean.

In practice, this means the oven materials, seals and internal parts have to be chosen so they do not contaminate or alter the ageing specimens. The standard also points to IEC 60335 (all parts) for additional safety information.

Single-chamber and multi-chamber designs

prEN IEC 60216-4:2026 sets specific construction rules for multi-chamber ovens: they must have at least two open-topped, approximately cylindrical chambers with lids, and lid leakage must be limited. The chambers and their internal parts must not contain copper, copper alloy or other materials that may release interfering volatiles.

An optional iso-box may be placed in the oven chamber to reduce temperature deviation. When used, it must allow the temperature requirements to be met over more than half of its internal space, and all ventilating air must pass through it in a turbulent way.

Ventilation and air movement

prEN IEC 60216-4:2026 requires pre-heated ventilating air to pass through the chamber, with air directed to promote mixing. The available rate of ventilation shall be in the range of 3 to 20 changes per hour, and the air speed must be controlled so the samples are not disturbed.

This matters because the ageing result depends on airflow as well as temperature. The standard gives typical air-speed ranges for laminar and turbulent flow and requires attention to the purity of incoming air and to cross-contamination between chambers or ovens.

Specimen loading and exposure volume

prEN IEC 60216-4:2026 requires specimens to be supported or suspended so they do not touch each other or the chamber walls. Specimens and supports must not occupy more than 25 % of the chamber cross-sectional area in any plane or more than 10 % of the effective working volume.

The standard also defines an exposure volume as a virtual zone that meets the temperature requirements, and that zone must be at least 50 % of the oven chamber volume. Its position relative to the chamber walls must be recorded and made easy to find, which matters when the same oven is re-used for qualifying different specimen loads.

Temperature control and performance limits

prEN IEC 60216-4:2026 requires the temperature in the exposure volume to be controllable within the limits given in Clause 5. The oven must have at least two temperature sensors, with one indicating chamber temperature and the other placed close to the specimen location.

The performance limits cover temperature fluctuation, temperature difference and temperature variation, with values given in Table 1. The temperature deviation within the exposure volume must not exceed 1.25 times the maximum allowable temperature variation. An independent excess-temperature control device is also required.

Test methods and reporting

prEN IEC 60216-4:2026 gives test methods for exposure volume, temperature-related parameters, ventilation rate, air speed and time constant. The procedures use multiple sensors, repeated measurements over about 3 hours, and, where needed, repositioning of sensors farther from the walls.

The report must comply with ISO/IEC 17025 wherever possible and include the test item identification, the manufacturer and laboratory details, supply-voltage range, ambient-temperature range, dimensions, mass, exposure volume definition, ventilation and air-speed ranges, test results, and any required time constant. This is the information a buyer or user needs to compare ovens and document their suitability.

In-service monitoring

prEN IEC 60216-4:2026 requires a loaded oven check immediately before each ageing test. The procedure uses eight temperature sensors around the mounted specimens, then determines the global average temperature and the temperature variation over at least 3 hours.

If the loaded oven does not meet the requirements, the ageing programme must be stopped and the mounting arrangement or equipment adjusted before retesting. In practice, this is the control step that confirms the oven is ready for the actual ageing run.

What terms does prEN IEC 60216-4:2026 define?

• rate of ventilation (N) - the number of air replacements per hour, based on fresh air entering the oven chamber.
• exposure volume - the central part of the oven chamber that meets the required temperature limits.
• exposure temperature (T) - the nominal temperature selected for ageing test specimens.
• temperature fluctuation (δT) - the maximum change in temperature at one point in the exposure volume over 3 hours.
• temperature difference (δT) - the maximum difference between any two points in the exposure volume at one time.
• temperature variation (δT) - the difference between the highest and lowest temperatures measured in the exposure volume over 3 hours.
• time constant - the time for a standard specimen to warm toward the exposure volume temperature.
• iso box - a metal box with a close-fitting door used in the oven chamber to reduce temperature deviation.

Who uses prEN IEC 60216-4:2026?

prEN IEC 60216-4:2026 is used by manufacturers of ageing ovens, testing and calibration laboratories, and organizations that evaluate or qualify electrical insulating materials and systems. It is also relevant to buyers, suppliers and quality managers who need to specify oven performance, compare test reports, or verify loaded-oven conditions before a thermal ageing test.

The standard is particularly relevant where thermal endurance testing is part of product qualification for electrical insulation, including work linked to electricity transmission and distribution. Users need it to set up ovens, perform acceptance checks, control specimen loading, and document the test environment.

What changed in prEN IEC 60216-4:2026 from the previous edition?

The foreword states that this edition replaces the third edition published in 1990 and is a technical revision. It also states these main changes:

• it combines the technical content of IEC 60216-4-1, IEC 60216-4-2 and IEC 60216-4-3
• it keeps the focus on single-chamber ovens
• it integrates descriptions of multi-chamber ovens
• it no longer considers precision ovens from the former IEC 60216-4-2
• it has been technically and editorially reworked and aligned across the former parts

Which standards are used with prEN IEC 60216-4:2026?

Standard	What it contributes
ISO/IEC 17025	General requirements for laboratory competence and the basis for the report format
IEC 60335 (all parts)	Additional safety information for household and similar electrical appliances
IEC 60216-4-1	Former single-chamber ageing-oven content now combined into this part
IEC 60216-4-2	Former precision-oven content referred to in the revision history
IEC 60216-4-3	Former multi-chamber ageing-oven content now integrated into this part
ISO 188:1998/Cor 1:2003	Cited in a note for an air-speed measurement method

What does the prEN IEC 60216-4:2026 document contain?

prEN IEC 60216-4:2026 contains construction rules, performance limits, and test procedures for ageing ovens, plus reporting and in-service monitoring requirements. It includes Table 1 for temperature limits, Figures 1 to 4 for the exposure volume within the oven chamber, and Figures D.1 and D.2 showing example multi-chamber oven cells.

The annexes add worked or procedural material that supports practical use: Annex A gives a ventilation-rate test method and its calculation, Annex B gives examples for temperature-deviation calculation, and Annex C gives the detailed test method for multi-chamber ovens. This makes the standard useful both for equipment design and for acceptance testing before thermal ageing work starts.

SLOVENSKI STANDARD
01-september-2026
Električni izolacijski materiali - Lastnosti v zvezi s toplotno vzdržljivostjo - 4. del:
Peči za staranje
Electrical insulating materials - Thermal endurance properties - Part 4: Ageing ovens
Ta slovenski standard je istoveten z: prEN IEC 60216-4:2026
ICS:
17.220.99 Drugi standardi v zvezi z Other standards related to
elektriko in magnetizmom electricity and magnetism
29.035.01 Izolacijski materiali na Insulating materials in
splošno general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

112/732/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 60216-4 ED3
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2026-07-31 2026-10-23
SUPERSEDES DOCUMENTS:
112/718/CD, 112/730/CC
IEC TC 112 : EVALUATION AND QUALIFICATION OF ELECTRICAL INSULATING MATERIALS AND SYSTEMS
SECRETARIAT: SECRETARY:
Germany Mr Bernd Komanschek
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):

TC 15
ASPECTS CONCERNED:
Electricity transmission and distribution
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft for
Vote (CDV) is submitted for parallel voting.
The CENELEC members are invited to vote through the
CENELEC online voting system.
This document is still under study and subject to change. It should not be used for reference purposes.
Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of which they
are aware and to provide supporting documentation.
Recipients of this document are invited to submit, with their comments, notification of any relevant “In Some Countries” clauses
to be included should this proposal proceed. Recipients are reminded that the CDV stage is the final stage for submitting ISC
clauses (SEE AC/22/2007 OR NEW GUIDANCE DOC).

TITLE:
Electrical insulating materials – Thermal endurance properties – Part 4: Ageing ovens

PROPOSED STABILITY DATE: 2029
NOTE FROM TC/SC OFFICERS:
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IEC CDV 60216-4 © IEC 2026
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ii
IEC CDV 60216-4 © IEC 2026
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Constructional requirements . 8
4.1 General . 8
4.2 Mechanical requirements . 8
4.3 Specimen chambers for multi-chamber ovens . 8
4.3.1 Iso-box . 9
4.4 Ventilation . 9
4.5 Specimen mounting arrangements . 10
4.6 Temperature control and indicator systems . 10
5 Performance requirements . 11
5.1 Temperature . 11
5.2 Temperature fluctuation, temperature difference, and temperature variation . 11
5.3 Maximum temperature deviation . 11
5.4 Rate of ventilation . 11
5.5 Air speed . 11
5.6 Exposure volume . 12
5.7 Time constant . 13
6 Test methods and procedure . 13
6.1 General . 13
6.2 Exposure volume . 14
6.3 Temperature and related parameters . 14
6.3.1 Practical aspects . 14
6.3.2 Calculations . 14
6.3.3 Results . 15
6.4 Rate of ventilation . 15
6.5 Air speed . 15
6.6 Time constant . 16
7 Report . 16
8 Conditions of use and instructions for in-service monitoring by the user . 17
8.1 Conditions of use . 17
8.2 Procedure . 17
8.3 In-service monitoring . 17
Annex A (informative) Test method to determine the rate of ventilation for single-
chamber ovens . 19
A.1 General requirement . 19
A.2 Sealed oven . 19
A.3 Ventilated oven . 19
A.4 Calculation . 19
Annex B (informative) Examples for calculation of temperature deviation for single-
chamber ovens . 21
Annex C (informative) Test methods and procedure for multi-chamber ovens . 22
IEC CDV 60216-4 © IEC 2026
C.1 Temperature and related parameters . 22
C.2 Time Constant . 22
Annex D (informative) Examples of Multi-Chamber Ovens . 24
Bibliography . 26

Figure 1 – Exposure volume within the oven chamber . 12
Figure 2 – Distance between left wall of the oven chamber (yellow) and the virtual zone
(green) needs to be noted . 12
Figure 3 – Distance between top wall of the oven chamber (yellow) and the virtual
zone (green) needs to be noted . 13
Figure 4 – Distance between front wall of the oven chamber (yellow) and the virtual
zone (green) needs to be noted . 13
Figure D.1 – Cell of a multi-chamber oven using a liquid heating medium . 24
Figure D.2 – Cell of a multi-chamber oven using a solid heating medium . 25

Table 1 – Maximum allowable Temperature fluctuation, temperature difference, and
temperature variation . 11

IEC CDV 60216-4 © IEC 2026
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Electrical insulating materials - Thermal endurance properties -
Part 4: Ageing ovens
FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for
standardization comprising all national electrotechnical committees (IEC National Committees).
The object of IEC is to promote international co-operation on all questions concerning
standardization in the electrical and electronic fields. To this end and in addition to other
activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National
Committee interested in the subject dealt with may participate in this preparatory work.
International, governmental and non-governmental organizations liaising with the IEC also
participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two
organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as
possible, an international consensus of opinion on the relevant subjects since each technical
committee has representation from all interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted
by IEC National Committees in that sense. While all reasonable efforts are made to ensure that
the technical content of IEC Publications is accurate, IEC cannot be held responsible for the
way in which they are used or for any misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC
Publications transparently to the maximum extent possible in their national and regional
publications. Any divergence between any IEC Publication and the corres ponding national or
regional publication shall be clearly indicated in the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies
provide conformity assessment services and, in some areas, access to IEC marks of conformity.
IEC is not responsible for any services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including
individual experts and members of its technical committees and IEC National Committees for
any personal injury, property damage or other damage of any nature whatsoever, whether direct
or indirect, or for costs (including legal fees) and expenses arising out of the publication, use
of, or reliance upon, this IEC Publication or any other IEC Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced
publications is indispensable for the correct application of this publication.
9) IEC draws attention to the possibility that the implementation of this document may involve
the use of (a) patent(s). IEC 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,
IEC [had/had not] received notice of (a) patent(s), which may be required to implement this
IEC CDV 60216-4 © IEC 2026
document. However, implementers are cautioned that this may not represent the latest
information, which may be obtained from the patent database available at https://patents.iec.ch
and www.iso.org/patents. IEC shall not be held responsible for identifying any or all such patent
rights.
IEC 60216-4 was prepared by subcommittee 15E: Methods of test, of IEC technical committee
15: Insulating materials, which has now been merged with IEC technical committee 98:
Electrical insulation systems into IEC technical committee 112: Evaluation and qu alification of
electrical insulating materials and systems (provisional title).
This fourth edition of IEC 60216-4-1 cancels and replaces the third edition, published in 1990,
and constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) This edition combines the exiting technical content from IEC 60216-4-1 [1], IEC 60216-4-2
[2] and IEC IEC 60216-4-3 [3].
b) While the focus on this edition is on single-chamber ovens (former IEC 60216-4-1 [1]),
descriptions on multi-chamber ovens (former IEC 60216-4-3 [3]) are integrated into this
standard.
c) Precision ovens as per former IEC 60216-4-2 [2] are not longer considered by this standard.
d) Generally, the document has been reworked technically as well as editorial changes, and
alignments between the above two standards have been made.
The text of this International Standard is based on the following documents:
Draft Report on voting
112/XXXX/XXX 112/XXXX/XXX
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this International Standard is English.
This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at https://www.iec.ch/members_experts/refdocs. The main document types developed by IEC
are described in greater detail at https://www.iec.ch/publications.
A list of all parts in the IEC 60216 series, published under the general title Electrical insulating
materials - Thermal endurance properties, can be found on the IEC website.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under https://webstore.iec.ch in the data related to
the specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
IEC CDV 60216-4 © IEC 2026
INTRODUCTION
IEC CDV 60216-4 © IEC 2026
1 Scope
This part of IEC 60216 covers minimum requirements for ventilated and electrically heated
ovens with or without forced air circulation, for thermal endurance evaluation of electrical
insulation. From design prospective this document covers either single-chamber or multi-
chamber ovens.
It covers ovens designed to operate over all or part of the temperature range from 20 °C above
ambient to 500 °C.
It gives acceptance tests and in-service monitoring tests for these ageing ovens.
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/IEC 17025, General requirements for the competence of testing and calibration laboratories
IEC 60335 (all parts), Household and similar electrical appliances – Safety
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
– IEC Electropedia: available at https://www.electropedia.org
– ISO Online browsing platform: available at https://www.iso.org/obp
3.1
rate of ventilation
N
air replacements per hour, determined from the flow of fresh air entering the oven and referred
to the relevant internal reference volume at room temperature
Note 1 to entry: Recirculated air within the oven system is not included in the rate of ventilation
Note 2 to entry: The rate of ventilation is expressed in reciprocal hours (1/h)
3.2
exposure volume
that central part of the oven chamber that meets the requirements for temperature fluctuation,
temperature difference and temperature variation
3.3
exposure temperature
T
nominal temperature selected for ageing test specimens to obtain data for the determination of
effects of temperature
Note 1 to entry: See also “global exposure temperature”
IEC CDV 60216-4 © IEC 2026
3.4
temperature fluctuation
δT
maximum change in temperature at one point in the exposure volume over a period of 3 h
3.5
temperature difference
δT
maximum difference of temperature between any two points in the exposure volume at any one
time
3.6
temperature variation
δT
v
difference between the highest temperature and the lowest temperature measured in the
exposure volume over a period of 3 h
3.7
global average temperature
average temperature, calculated from the results of determinations made over a period of at
least 3 h using nine sensors spaced throughout the exposure volume
3.8
global exposure temperature
considered to be equal to the global average temperature if the sensors are mounted in the
same space as that containing the specimens
Note 1 to entry: The term ‘global exposure temperature’ is frequently abbreviated to ‘exposure temperature’.
3.9
time constant (of a standard specimen)
measure of time taken for the temperature of a standard specimen to approach the exposure
volume temperature
3.10
temperature deviation
δT
d
calculated difference in the exposure temperature from the intended value due to the
combination of the temperature difference, temperature fluctuation and the error in the
measurement of temperature
Note 1 to entry: Examples for calculation of temperature deviation are given in Annex B
3.11
ventilation
continuous passage of pre-heated air through the oven chamber
3.12
air speed
air movement in m/s within the oven chamber
3.13
single-chamber oven
oven with one electrically heated and ventilated chamber and with the ability to maintain the
global exposure temperature in its exposure volume
IEC CDV 60216-4 © IEC 2026
3.14
oven chamber
interior volume of a single-chamber oven providing the space for exposing test specimens or
accommodating an iso-box
3.15
vapor volume
entire air volume within an oven, including the interior volume of the oven chamber as well as
remaining air volume in the oven system (e.g. tubes, ventilators,…)
3.16
iso box
metal box with a close fitting door, mounted in the oven chamber and used as an exposure
chamber to reduce the temperature deviation present in the unmodified oven chamber
4 Constructional requirements
4.1 General
The oven shall be soundly constructed of suitable materials designed for continuous operation
over the whole of the allowable temperature range.
All electrical and other ancillary fittings shall be readily accessible for maintenance purposes.
NOTE 1 The construction might be fitted with equipment to switch off the oven and preferably sound an alarm when
the temperature of the thermostatically controlled medium deviates from the allowable temperature range or if the
supply of ventilating air fails
NOTE 2 This standard does not cover all safety aspects. Additional information may be found in the IEC IEC 60335
(all parts).
4.2 Mechanical requirements
The materials of construction of the oven chamber and the interior fittings shall be chosen as
to not influence the properties of the specimens.
NOTE Aluminium alloys and stainless steel have been found suitable in many cases. Copper based alloys and any
materials that may give off interfering volatiles over the temperature range of the oven, for example some silicone
resins, must not be used.
The interior of the oven shall be constructed of suitable corrosion­-resistant, non-absorbent
material, so fabricated that any joints are leak-proof and not subject to corrosion. The interior
surfaces shall be easy to clean.
Attention shall be given to ensure that the door to the oven chamber is provided with an efficient
seal and that any gasket materials used do not influence the properties of the specimens.
4.3 Specimen chambers for multi-chamber ovens
The ovens shall consist of at least two open-topped, approximately cylindrical chambers with
appropriate lids, mounted with their axis approximately vertical. Each lid shall form an effective
seal with the chamber: the leakage of ventilating air from the lid seal shall be no more than 5 %
of the flow rate of ventilating air to the specimen chamber.
NOTE 1 Some types of 'O' ring seals have been found to be satisfactory.
Unless otherwise specified, the individual chambers shall have a minimum diameter of 35 mm
and a minimum length of 200 mm.
IEC CDV 60216-4 © IEC 2026
The materials of construction of the chambers, their lids and their internal parts shall not contain
any copper, copper alloy or any material that may give off interfering volatiles over the
temperature range of the oven, for example some silicone resins.
The design shall be such as to permit the chambers to be easily cleaned after each test.
The chambers shall be mounted in a thermostatically controlled heat transfer medium: for
example in a metal block, a liquid or 'sand' bath, a saturated vapour bath or in an air circulating
oven. Examples of typical designs are given in Figure D.1 and Figure D.2.
NOTE 2 The performance of air circulating ovens in this context is usually poorer than the alternative systems.
Examples of multi-chamber ovens are given in Annex D.
4.3.1 Iso-box
The iso-box is an optional device placed in the oven chamber to reduce the temperature
deviation.
The construction shall be such that the requirements for temperature fluctuation and
temperature difference are met throughout more than 50 % of the space inside the iso-box when
it is mounted in any chosen oven. The rate of ventilation shall conform with the requirements.
NOTE Boxes made from aluminium alloy sheet have been found to be satisfactory.
The iso-box shall have a door which shall be close-fitting without any sealing gasket.
All air that enters the oven as ventilating air shall pass through the iso-box in such a manner
as to produce turbulence.
4.4 Ventilation
The oven chamber shall be provided with a supply of pre-heated ventilating air, passing the
chamber at one side and being exhausted through another. Wherever possible, the ventilating
air shall be directed in such a manner as to produce mixing of the ventilated air throug hout the
chamber.
NOTE Pre-heated air is only required for the oven chamber. Cold air (based on the air exchange) can enter into the
vapor volume without pre-heating.
In forced convection ovens, the air speed does have a higher influence on the results of a
thermal aging program than the rate of ventilation. The air speed shall be in accordance with
5.5.
The rate of ventilation available shall be in accordance with 5.4.
Consideration shall be given to ensure adequate purity of the incoming ventilating air to
minimize influence on the results.
If specified, inlet vents shall enable air to be supplied from controlled sources.
The construction shall be fitted with equipment to switch off the oven and preferably activate
an alarm when the supply of ventilating air fails.
It is recommended that the exhaust from the oven chamber be vented to outside atmosphere,
but precautions should be taken to ensure that volatiles produced by ageing specimens do not
damage health or the environment.
IEC CDV 60216-4 © IEC 2026
If multiple chambers are used, the incoming air shall be directed to the cylindrical wall of the
chamber in such a manner as to produce turbulent flow throughout the cell and the general
design shall be to minimize recirculation of the ventilating air within each chamber. In order to
prevent cross-contamination of volatile components, ventilating air from one chamber shall not
come into contact with specimens in any other chamber. It is recommended that the exhaust
from the chambers be vented to outside atmosphere, but precautions shall be taken to ensure
that volatiles produced by the ageing specimens do not damage health or the environment.
4.5 Specimen mounting arrangements
Provision shall be made for supporting/suspending and positioning specimens within the
exposure volume. The specimens shall neither touch each other nor touch the chamber walls.
The specimens and supports shall not occupy more than 25 % of the cross-sectional area of
the chamber in any one plane, nor occupy more than 10 % of the effective working volume of
the chamber.
If there is an expectation in practice that any of these maxima could be exceeded, the supplier
and purchaser should agree with the user on whether dummy loads should be used during the
assessment of performance.
4.6 Temperature control and indicator systems
The temperature in the exposure volume shall be controllable to the limits given in Clause 5.
The oven chamber shall be fitted with a minimum of two temperature sensors (numbered 1 and
2). Before installation, the sensors 1 and 2 shall be adjusted by a calibrated reference (sensor
3) to give a maximum desired value deviation within ±1,0 K. The difference in reading between
the two sensors as a function of temperature shall be recorded.
Sensor 3 shall have a maximum uncertainty of ± 0,5 K.
Temperature sensor 1 shall be mounted in a convenient manner, and used to indicate the
chamber temperature.
NOTE 1 It is has been found usefull, that the temperature is ecorded during the whole test procedure. The readout
also allows early identification of any malfunction in the system.
Temperature sensor 2 shall be mounted as close
...