oSIST prEN IEC 62990-1:2026

SLOVENSKI STANDARD
01-oktober-2026
Zrak na delovnem mestu - 1. del: Detektorji plina - Zahteve za delovanje
detektorjev strupenih plinov
Workplace atmospheres - Part 1: Gas detection equipment - Performance requirements
of detectors for toxic gases
Arbeitsplatzatmosphäre - Teil 1: Gasmessgeräte - Anforderungen an das
Betriebsverhalten von Geräten für die Messung toxischer Gase
Atmosphères des lieux de travail – Partie 1: Equipement de détection de gaz –
Exigences d’aptitude à la fonction des détecteurs de gaz toxiques
Ta slovenski standard je istoveten z: prEN IEC 62990-1:2026
ICS:
13.040.30 Kakovost zraka na delovnem Workplace atmospheres
mestu
13.320 Alarmni in opozorilni sistemi Alarm and warning systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

31/1981/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 62990-1 ED2
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2026-08-14 2026-11-06
SUPERSEDES DOCUMENTS:
31/1948/CD, 31/1965/CC
IEC TC 31 : EQUIPMENT FOR EXPLOSIVE ATMOSPHERES
SECRETARIAT: SECRETARY:
United Kingdom Mr Tom Stack
OF INTEREST TO THE FOLLOWING COMMITTEES: HORIZONTAL FUNCTION(S):

ASPECTS CONCERNED:
SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING
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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:
Workplace atmospheres – Part 1: Gas detection equipment – Performance requirements of detectors for
toxic gases
PROPOSED STABILITY DATE: 2030
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IEC CDV 62990-1 © IEC 2026
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 7
4 General requirements . 9
4.1 Overview . 9
4.2 Design . 9
4.2.1 General . 9
4.2.2 Indicators and means of indication . 9
4.2.3 Alarm signal(s) . 10
4.2.4 Fault signals . 10
4.2.5 Special state indication . 10
4.2.6 Adjustments . 10
4.2.7 Battery-powered equipment . 10
4.2.8 Software-controlled equipment . 10
4.3 Marking . 10
4.4 Instructions . 10
5 Test methods . 11
5.1 General . 11
5.2 General requirements for tests . 11
5.2.1 Samples and sequence of tests . 11
5.2.2 Preparation of equipment before testing . 11
5.3 Normal conditions for test . 11
5.3.1 General . 11
5.3.2 Test gas(es) . 11
5.3.3 Flow rate for test gases . 12
5.3.4 Power supply . 12
5.3.5 Temperature . 12
5.3.6 Pressure . 12
5.3.7 Humidity . 12
5.3.8 Acclimation time . 12
5.3.9 Orientation. 12
5.3.10 Communications options . 12
5.4 Tests . 12
5.4.1 General . 12
5.4.2 Unpowered storage . 12
5.4.3 Vibration . 12
5.4.4 Drop test . 13
5.4.5 Calibration kit . 13
5.4.6 Linearity . 13
5.4.7 Alarm set-point(s) . 13
5.4.8 Stability . 13
5.4.9 Gas concentrations above the upper limit of indication . 13
5.4.10 Poisons and other gases . 13
5.4.11 Temperature . 13
IEC CDV 62990-1 © IEC 2026
5.4.12 Pressure (equipment with sensors only) . 13
5.4.13 Humidity of test gas . 14
5.4.14 Air velocity (diffusion equipment only). 14
5.4.15 Flow rate (aspirated equipment only) . 14
5.4.16 Warm-up time . 14
5.4.17 Time of response . 14
5.4.18 Time of recovery . 14
5.4.19 Sampling probe . 14
5.4.20 Operation at or below the lower limit of measurement (Type O2-DE
only) . 14
5.4.21 Extended operation in test gas (Type TX only) . 14
5.4.22 Orientation. 15
5.4.23 Battery capacity for battery-powered equipment . 15
5.4.24 Power supply variations for externally powered equipment . 15
5.4.25 Electromagnetic immunity . 15
5.4.26 Fault signal tests . 15
5.4.27 Software controlled equipment . 16
5.4.28 Environmental protection . 16
5.4.29 Time-weighted average (TWA) function . 17
6 Uncertainty of measurement and lower limit of measurement . 17
6.1 General . 17
6.2 Method of calculation of uncertainty of measurement . 17
6.2.1 Basic concept . 17
6.2.2 Sources of uncertainty . 19
6.3 Method of calculation of lower limit of measurement . 24
6.4 Acceptance criteria . 24
6.4.1 Uncertainty of measurement . 24
6.4.2 Lower limit of measurement . 25
6.5 Relation between uncertainty and accuracy . 25
Annex A (normative) Gas specific performance requirements . 26
Annex B (normative) Acceptance criteria for Type TX-HM . 28
B.1 Type TX-HM equipment . 28
Bibliography . 31

Table 1 – Factors to be considered in the expanded uncertainty estimate . 18
Table A.1 – Gas specific performance requirements . 26
Table B.1 – Acceptance criteria for Type TX-HM equipment . 28

IEC CDV 62990-1 © IEC 2026
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
Workplace atmospheres –
Part 1: Gas detection equipment –
Performance requirements of detectors for toxic gases

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 62990-1 © 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.
IEC shall not be held responsible for identifying any or all such patent rights.
IEC 62990-1 has been prepared by Joint Working Group (JWG) 45 of IEC technical committee
31: Equipment for explosive atmospheres in cooperation with ISO technical committee 146: Air
quality, sub-committee 2: Workplace atmospheres. It is an International Standard.
It is published as a dual logo standard.
This second edition cancels and replaces the first edition published in 2019. This edition
constitutes a technical revision. Users of this document are advised that interpretation sheets
clarifying the interpretation of this document can be published. Interpretation sheets are
available from the IEC webstore and can be found in the “history” tab of the page for each
document.
This edition includes the following significant technical changes with respect to the previous
edition:
a) Transferred all requirements for Type TX-SM (Safety Monitoring) from the document to IEC
60079-29-0;
b) Aligned major technical requirements for Type TX-HM (Health Monitoring) with IEC 60079-
29-0.
The text of this International Standard is based on the following documents:
Draft Report on voting
XX/XX/FDIS XX/XX/RVD
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 www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
A list of all parts in the IEC 62990 series, published under the general title Workplace
atmospheres, 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 webstore.iec.ch in the data related to the
specific document. At this date, the document will be
– reconfirmed,
– withdrawn, or
– revised.
IEC CDV 62990-1 © IEC 2026
INTRODUCTION
This part of IEC 62990 specifies general requirements for construction, testing and performance
of equipment intended to measure the concentration of toxic gas and vapour in workplace
atmospheres and other industrial and commercial applications. The perfor mance requirements
are intended to apply under environmental conditions present at the site of operation.
Although a wide range of environmental conditions are encountered in practice, this document
specifies requirements that have to be fulfilled by gas detection equipment when tested under
prescribed laboratory conditions.
This document applies to the type of equipment: Health Monitoring (Type TX-HM).
Requirements for type of equipment Safety Monitoring (SM) are moved to the IEC 60079-29-0
[1]. For a given measurement task of Type TX-HM equipment the range over which the
requirements must be met depends on the occupational exposure limit value. However, for most
toxic gases and vapours the occupational exposure limit values have not been harmon ized at
the international level. Therefore, it was decided to use a reference value instead of the
occupational exposure limit value for the performance tests. The list of reference values is given
in Annex A. The reference values chosen are equal to or close to the occupational exposure
limit values used in different countries but are intended to be used only for type testing
equipment without any legal implications.
Electrical equipment used for the direct detection and direct concentration measurement of toxic
gases and vapours generate readings in clean air (nominally zero), which vary with
environmental conditions and time. This document therefore includes test met hods and
requirements for acceptable variations in measured values at application of zero gas and of
defined test gases.
General and performance requirements for gas detection equipment including additional
function for detecting flammable gas and/or oxygen and/or toxic gases in areas for safety
monitoring, are set out in IEC 60079-29-0 [1]. The IEC 60079-29-0 standard includes a
bibliography of relevant standards that can provide assistance when applying IEC 62990 -1.
Consideration needs to also be given to the following relevant international standards:
IEC 60079-29-2, Explosive atmospheres - Part 29-2, Gas detectors - Selection, installation, use
and maintenance of detectors for flammable gases and oxygenIEC 60079-29-2 [2]
IEC 62990-2, Workplace atmospheres - Part 2: Gas detectors - Selection, installation, use and
maintenance of detectors for toxic gases and vapoursIEC 62990-2
IEC 60079-29-3, Explosive atmospheres - Part 29-3, Gas detectors - Guidance on functional
safety of fixed gas detection systemsIEC 60079-29-3 [3].
IEC CDV 62990-1 © IEC 2026
1 Scope
This part of IEC 62990 specifies general requirements for design, function and performance,
and describes the test methods that apply to portable, transportable, and fixed equipment for
the detection and concentration measurement of toxic gases and vapours in workplace
atmospheres.
NOTE The term gas detection equipment is often referred to as the term gas detector.
This document is applicable to continuously sensing equipment whose primary purpose is to
provide an indication, alarm and/or other output function the purpose of which is to indicate the
presence of a toxic gas or vapour in the atmosphere and in some cases to initiate automatic or
manual protective action(s). It is applicable to equipment in which the sensor generates an
electrical signal when gas is present.
This document applies to Type TX-HM (Health Monitoring) 'occupational exposure' equipment:
For occupational exposure measurement, the performance requirements are focused on
uncertainty of measurement of gas concentrations in the region of Occupational Exposure Limit
Values (OELV). The upper limit of measurement will be defined by the manufactur er in
accordance with 4.2.1.
For equipment used for sensing the presence of multiple gases this document applies only to
the part for occupational exposure measurement of toxic gas or vapour.
This document is not applicable to equipment:
– with samplers and concentrators such as sorbents or paper tape having an irreversible
indication;
– used for the measurement of gases and vapours related to the risk of explosion;
– used for the measurement of oxygen;
– used for medical applications;
– used only in laboratories for analysis or measurement;
– used only for process monitoring or control purposes (such as a gas analyser);
– used in the domestic environment;
– used in environmental air pollution monitoring;
– used for flue gas analysis;
– used for sampling systems external to the gas detection equipment;
– used for open-path (line of sight) area gas measurement;
– used for ventilation control in car parks or tunnels.
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.
IEC 60068-2-6, Environmental testing - Part 2-6: Tests - Test Fc: Vibration (sinusoidal)
IEC 60079-0, Explosive atmospheres - Part 0: Equipment - General requirements
IEC 60079-29-0, Explosive atmospheres - Part 29-0: Gas detection equipment - General
requirements and test methods
IEC CDV 62990-1 © IEC 2026
IEC 60529, Degrees of protection provided by enclosures (IP Code)
IEC 61000-4-29, Electromagnetic compatibility (EMC) - Part 4-29: Testing and measurement
techniques - Voltage dips, short interruptions and voltage variations on d.c. input power port
immunity tests
IEC 61326-1, Electrical equipment for measurement, control and laboratory use - EMC
requirements - Part 1: General requirements
IEC 62990-2, Workplace atmospheres - Part 2: Gas detectors - Selection, installation, use and
maintenance of detectors for toxic gases and vapours
3 Terms and definitions
All definitions of IEC 60079-29-0 [1] apply. For the purposes of this document, the following
additional terms and definitions apply.
ISO and IEC maintain terminology 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
gas properties
3.1.1
occupational exposure limit value
OELV
limit of the time-weighted average of the concentration of a chemical agent in the air within the
breathing zone of a worker in relation to a specified reference period
Note 1 to entry: The term "limit value" is often used as a synonym for "occupational exposure limit value", but the
term "occupational exposure limit value" is preferred because there is more than one limit value (for example,
biological limit value and occupational exposure limit value).
Note 2 to entry: Occupational exposure limit values (OELVs) are often set for reference periods of 8 h, but can also
be set for shorter periods or concentration excursions.
[SOURCE: ISO 18158:2016, 2.1.5.4, modified (Note 2 to entry is shortened)]
3.1.2
reference value
value used as the basis to specify requirements such as
measuring range, resolution and alarm set point
Note 1 to entry: The term reference value is used in this document because for most toxic gases and vapours the
occupational exposure limit values have not been harmonized at the International level.
3.1.3
time-weighted average concentration
TWA concentration
concentration of gas in air averaged over a reference period
3.1.4
reference period
specified period of time for which the occupational exposure limit value of a chemical agent
applies
IEC CDV 62990-1 © IEC 2026
Note 1 to entry: The reference period is usually 8 h for long-term measurements and 15 min for short-term
measurements.
[SOURCE: ISO 18158:2016, 2.1.5.7, modified (term "biological agent" deleted as not relevant
to the current document)]
3.2
signals and alarms
3.2.1
TWA alarm set point
setting of the equipment at which the measured time weighted average
concentration will cause the equipment to initiate an indication, alarm or other output function
3.3
uncertainty
3.3.1
expanded uncertainty
U
quantity defining an interval about a result of a measurement, expected to encompass a large
fraction of the distribution of values that could reasonably be attributed to the measurand
[SOURCE: ISO 18158:2016, 2.4.2.5]
3.3.2
measurand
particular quantity subject to measurement
[SOURCE: ISO 18158:2016, 2.3.8]
3.3.3
coverage factor
k
numerical factor used as a multiplier of the combined standard uncertainty in order to obtain an
expanded uncertainty
3.3.4
non-random uncertainty
uncertainty associated with non-random errors
3.3.5
random uncertainty
uncertainty associated with random errors
3.3.6
zero uncertainty
quantity defining an interval about zero expected to encompass a large fraction of the
distribution of values that could reasonably be attributed to the measurement in clean air
Example of zero uncertainty:
IEC CDV 62990-1 © IEC 2026
Note 1 to entry: In the Figure above, the mean value of the measured values in clean air is not equal to zero to
illustrate that there can be an offset due to drift. The mean value can be above or below zero.
4 General requirements
4.1 Overview
The requirements of the corresponding clause for overview in IEC 60079-29-0 [1] shall apply.
Where there is no clause in this standard corresponding to a clause in IEC 60079-29-0 [1] the
requirements are not applicable.
4.2 Design
4.2.1 General
The requirements of the corresponding clause for general in IEC 60079-29-0 [1] shall apply. In
addition, for Type TX-HM equipment the upper limit of measurement shall be equal to or greater
than 2 times the reference value (See Table A.1). The requirement for the lower limit of
measurement is described in 6.4.2.
4.2.2 Indicators and means of indication
4.2.2.1 Indicators
The requirements of the corresponding clause for indicators in IEC 60079-29-0 [1] shall apply.
4.2.2.2 Visual indicators
The requirements of the corresponding clause for visual indicators in IEC 60079-29-0 [1] shall
apply.
4.2.2.3 Display and other outputs for indication
The requirements of the corresponding clause for display and other outputs for indication in IEC
60079-29-0 [1] shall apply.
In addition, for Type TX-HM equipment the resolution shall be 10 % of the reference value or
better.
NOTE See also 5.2.2.
4.2.2.4 Suppression of indication
The requirements of the corresponding clause for suppression of indication in IEC 60079-29-0
[1] shall apply.
IEC CDV 62990-1 © IEC 2026
In addition, the maximum suppression threshold value for Type TX-HM shall be 5 % of the
reference value in Table A.1.
4.2.3 Alarm signal(s)
4.2.3.1 General
The requirements of the corresponding clause for general in IEC 60079-29-0 [1] shall apply.
4.2.4 Fault signals
The requirements of the corresponding clause for fault signals in IEC 60079-29-0 [1] shall apply
with the following modification.
A measured value below zero (for example, caused by drift) shall be indicated by a fault signal
at no less than minus four times the lower limit of measurement or −10 % of the upper limit of
measurement, whichever is closer to zero.
4.2.5 Special state indication
The requirements of the corresponding clause for special state indication in IEC 60079-29-0 [1]
shall apply.
4.2.6 Adjustments
The requirements of the corresponding clause for adjustments in IEC 60079-29-0 [1] shall apply.
4.2.7 Battery-powered equipment
The requirements of the corresponding clause for battery-powered equipment in IEC 60079-29-
0 [1] shall apply.
4.2.8 Software-controlled equipment
The requirements of the corresponding clause for software-controlled equipment in IEC 60079-
29-0 [1] shall apply.
4.3 Marking
The requirements of the corresponding clause for marking in IEC 60079-29-0 [1] with exception
of e) shall apply with the following modification.
The marking shall include (as replacement of e)): "62990-1".
4.4 Instructions
The requirements of the corresponding clause for instructions in IEC 60079-29-0 [1] shall apply,
and the specific instruction to read the procedures described in IEC 62990-2 shall be included.
In addition, any information for use of equipment as a type TX-HM shall be included, as well as
the following information:
a) details of operational limitations, performance claimed by the manufacturer and special
features including, where applicable, the following:
1) information on how times of response and times of recovery vary with temperature,
humidity, and ambient air velocity or flow rate of the aspirated gas;
2) the averaging period for instruments measuring TWA concentration;
IEC CDV 62990-1 © IEC 2026
5 Test methods
5.1 General
The requirements of the corresponding clause for general in IEC 60079-29-0 [1] shall apply.
5.2 General requirements for tests
5.2.1 Samples and sequence of tests
The requirements of the corresponding clause for samples and sequence of tests in IEC 60079-
29-0 [1] shall apply with the following modifications.
Three instead of two test samples shall be used.
In addition, the TWA test as described in 5.4.29 shall be performed.
For gas detection control unit and separate gas detection control unit with at least three inputs
for Type TX-HM, the tests may be performed using one unit only.
5.2.2 Preparation of equipment before testing
5.2.2.1 General
The requirements of the corresponding clause for general described in IEC 60079-29-0 [1] shall
apply with the following modification.
Type TX-HM equipment having connection facilities for more than three remote sensors, only
three remote sensors need to be subjected to the tests.
5.2.2.2 Mask for calibration and test
The requirements of the corresponding clause for mask for calibration and test in IEC 60079-
29-0 [1] shall apply.
5.3 Normal conditions for test
5.3.1 General
The test conditions specified in 5.3.2 to 5.3.10 shall be used for all tests, unless otherwise
stated.
5.3.2 Test gas(es)
5.3.2.1 General
The requirements of the corresponding clause for general in IEC 60079-29-0 [1] shall apply.
5.3.2.2 Type TX
The requirements of the corresponding clause for Type TX in IEC 60079-29-0 [1] shall apply
with the following modifications.
For Type TX-HM the standard test gas shall have a volume fraction equal to the reference value
specified in Table A.1. For gases not included in Table A.1, a value agreed between the
manufacturer and the test laboratory considering the occupational exposure limit value shall be
used and documented in the test report.
IEC CDV 62990-1 © IEC 2026
5.3.3 Flow rate for test gases
The requirements of the corresponding clause for flow rate for test gases in IEC 60079-29-0 [1]
shall apply.
5.3.4 Power supply
The requirements of the corresponding clause for power supply in IEC 60079-29-0 [1] shall
apply.
5.3.5 Temperature
The requirements of the corresponding clause for temperature in IEC 60079-29-0 [1] shall apply.
5.3.6 Pressure
The requirements of the corresponding clause for pressure in IEC 60079-29-0 [1] shall apply.
5.3.7 Humidity
The requirements of the corresponding clause for humidity in IEC 60079-29-0 [1] shall apply.
5.3.8 Acclimation time
The requirements of the corresponding clause for acclimation time in IEC 60079-29-0 [1] shall
apply.
5.3.9 Orientation
The requirements of the corresponding clause for orientation in IEC 60079-29-0 [1] shall apply.
5.3.10 Communications options
The requirements of the corresponding clause for communications options in IEC 60079-29-0
[1] shall apply.
5.4 Tests
5.4.1 General
The requirements of the corresponding clause for general in IEC 60079-29-0 [1] shall apply with
the following modifications.
The TX-HM equipment shall meet the applicable acceptance criteria of Annex B.
In addition, to determine the performance requirements for gases not listed within Table A.1,
the general limit value guidelines of Table A.1 along with performance requirements justified by
the test laboratory shall be followed. The performance requirements shall be described in the
test report.
5.4.2 Unpowered storage
The requirements of the corresponding clause for unpowered storage in IEC 60079-29-0 [1]
shall apply.
5.4.3 Vibration
The requirements of the corresponding clause for vibration in IEC 60079-29-0 [1] shall apply
with the following modification.
IEC CDV 62990-1 © IEC 2026
Divergent, for Type TX-HM the alarm set point shall be set at 80 % of the standard test gas
volume fraction.
5.4.4 Drop test
The requirements of the corresponding clause for drop test in IEC 60079-29-0 [1] shall apply.
5.4.5 Calibration kit
The requirements of the corresponding clause for calibration kit in IEC 60079-29-0 [1] shall
apply.
5.4.6 Linearity
Each indication shall be taken after a time interval equal to 10 times the time of response t(50)
for test gas application and equal to 10 times the time of recovery t(50) for clean air application,
as specified in the instructions. Expose the equipment to test gases with the following volume
fractions of the standard test gas: 0,1 (except if not practicable as stated below); 0,5; 1; 2; 5
(or 90 % of the upper limit of measurement if 5 times is outside the measuring range). For each
test gas volume fraction, expose the equipment to clean air and then the test gas and repeat
this cycle a total of six times. In the case of gases which are very difficult to handle at low
volume fractions, the lowest possible test gas volume fraction below the standard test gas
volume fraction shall be used instead of 0,1. The lowest test gas volume fraction shall not
exceed 0,2 times the standard test gas volume fraction.
NOTE Concentrations greater than 5 times the reference value are not considered relevant to the calculation of
relative expanded uncertainty of Type HM equipment.
Calculate the lower limit of measurement as specified in 6.4.2 using the indications in clean air
taken in conjunction with the test gas volume fractions up to and including two times the
standard test gas volume fraction. Calculate for each test gas volume fraction, the relative
expanded uncertainty as specified in 6.2.2.15.
5.4.7 Alarm set-point(s)
The requirements of the corresponding clause for alarm set-point(s) in IEC 60079-29-0 [1] shall
apply.
5.4.8 Stability
The requirements of the corresponding clause for stability in IEC 60079-29-0 [1] shall apply.
5.4.9 Gas concentrations above the upper limit of indication
The requirements of the corresponding clause for gas concentrations above the upper limit of
indication in IEC 60079-29-0 [1] shall apply.
5.4.10 Poisons and other gases
The requirements of the corresponding clause for poisons and other gases in IEC 60079-29-0
[1] are not applicable.
5.4.11 Temperature
The requirements of the corresponding clause for in IEC 60079-29-0 [1] shall apply.
5.4.12 Pressure (equipment with sensors only)
The requirements of the corresponding clause for pressure (equipment with sensors only) in
IEC 60079-29-0 [1] shall apply with following modifications.
IEC CDV 62990-1 © IEC 2026
Tests shall be performed at pressures of (80 ± 0,5) kPa, (90 ± 0,5) kPa, (100 ± 0,5) kPa (110 ±
0,5) kPa, and (120 ± 0,5) kPa. The 120 kPa pressure level may be reduced to 110 kPa if the
instructions specify that the equipment is not intended for use above the 110 kPa.
Calculate the differences between the measured values in standard test gas for each 10 kPa
step from 80 to 90 kPa, 90 to 100 kPa, 100 to 110 kPa and 110 to 120 kPa (if tested) for the
calculation of the uncertainty according to 6.2.2.4.
5.4.13 Humidity of test gas
The requirements of the corresponding clause for humidity of test gas in IEC 60079-29-0 [1]
shall apply.
5.4.14 Air velocity (diffusion equipment only)
The requirements of the corresponding clause for air velocity (diffusion equipment only) in IEC
60079-29-0 [1] shall apply.
5.4.15 Flow rate (aspirated equipment only)
The requirements of the corresponding clause for flow rate (aspirated equipment only) in IEC
60079-29-0 [1] shall apply.
5.4.16 Warm-up time
The requirements of the corresponding clause for warm-up time in IEC 60079-29-0 [1] shall
apply using the settings c) for the alarm set point.
5.4.17 Time of response
The requirements of the corresponding clause for time of response in IEC 60079-29-0 [1] shall
apply using the case b).
5.4.18 Time of recovery
The requirements of the corresponding clause for time of recovery in IEC 60079-29-0 [1] shall
apply using the case b).
5.4.19 Sampling probe
The requirements of the corresponding clause for sampling probe in IEC 60079-29-0 [1] shall
apply.
5.4.20 Operation at or below the lower limit of measurement (Type O2-DE only)
The requirement of the corresponding clause for operation at or below the lower limit of
measurement (Type O2-DE only) in IEC 60079-29-0 [1] are not applicable.
5.4.21 Extended operation in test gas (Type TX only)
5.4.21.1 Portable equipment
The requirements of the corresponding clause for portable equipment in IEC 60079-29-0 [1]
shall apply.
5.4.21.2 Fixed and transportable equipment
The requirements of the corresponding clause for fixed and transportable equipment in IEC
60079-29-0 [1] shall apply.
IEC CDV 62990-1 © IEC 2026
5.4.22 Orientation
5.4.22.1 Portable equipment
The requirements of the corresponding clause for portable equipment in IEC 60079-29-0 [1]
shall apply.
5.4.22.2 Fixed and transportable equipment
The requirements of the corresponding clause for fixed and transportable equipment in IEC
60079-29-0 [1] shall apply.
5.4.23 Battery capacity for battery-powered equipment
5.4.23.1 General
The requirements of the corresponding clause for general in IEC 60079-29-0 [1] shall apply with
adjustable alarm set point setting per item c).
5.4.23.2 Tests
The requirements of the corresponding clause for tests in IEC 60079-29-0 [1] shall apply.
5.4.24 Power supply variations for externally powered equipment
5.4.24.1 General
The requirements of the corresponding clause for general in IEC 60079-29-0 [1] shall apply with
adjustable alarm set point setting per item c).
5.4.24.2 Tests
The requirements of the corresponding clause for testsin IEC 60079-29-0 [1] shall apply.
5.4.25 Electromagnetic immunity
5.4.25.1 General
The requirements of the corresponding clause for general in IEC 60079-29-0 [1] shall apply with
adjustable alarm set point setting per item c).
5.4.25.2 Tests
The requirements of the corresponding clause for tests in IEC 60079-29-0 [1] shall apply.
5.4.25.3 Performance criteria
The requirements of the corresponding clause for perfromance criteria in IEC 60079-29-0 [1]
shall apply.
5.4.26 Fault signal tests
5.4.26.1 General
The requirements of the corresponding clause for general in IEC 60079-29-0 [1] shall apply.
5.4.26.2 Low voltage and power interruption
The requirements of the corresponding clause for low voltage and power interruption in IEC
60079-29-0 [1] shall apply.
IEC CDV 62990-1 © IEC 2026
5.4.26.3 Field wiring faults
The requirements field wiring faults in IEC 60079-29-0 [1] shall apply.
5.4.26.4 Disruption of digital communication
The requirements of the corresponding clause for disruption of digital communication in IEC
60079-29-0 [1] shall apply.
5.4.26.5 Measured values below zero
5.4.26.5.1 General
The requirements of the corresponding clause for general in IEC 60079-29-0 [1] shall apply.
5.4.26.5.2 Procedure 1
The requirements of the corresponding clause for procedure 1 in IEC 60079-29-0 [1] shall apply.
5.4.26.5.3 Procedure 2
The requi
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