prEN ISO 10298

SLOVENSKI STANDARD
01-februar-2026
Plinske jeklenke - Plini in zmesi plinov - Določanje strupenosti plinov in njihovih
zmesi za izbiro izhodnega priključka ventila na jeklenki (ISO/DIS 10298:2025)
Gas cylinders - Gases and gas mixtures - Determination of toxicity for the selection of
cylinder valve outlets (ISO/DIS 10298:2025)
Gasflaschen - Gase und Gasgemische - Bestimmung der Toxizität zur Auswahl von
Ventilausgängen (ISO/DIS 10298:2025)
Bouteilles à gaz - Gaz et mélanges de gaz - Détermination de la toxicité pour le choix
des raccords de sortie de robinets (ISO/DIS 10298:2025)
Ta slovenski standard je istoveten z: prEN ISO 10298
ICS:
23.020.35 Plinske jeklenke Gas cylinders
71.100.20 Industrijski plini Gases for industrial
application
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 10298
ISO/TC 58/SC 2
Gas cylinders — Gases and gas
Secretariat: AFNOR
mixtures — Determination of
Voting begins on:
toxicity for the selection of cylinder
2025-12-22
valve outlets
Voting terminates on:
2026-03-16
Bouteilles à gaz — Gaz et mélanges de gaz — Détermination de
la toxicité pour le choix des raccords de sortie de robinets
ICS: 71.100.20
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.
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USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
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NOTIFICATION OF ANY RELEVANT PATENT
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Reference number
ISO/DIS 10298:2025(en)
DRAFT
ISO/DIS 10298:2025(en)
International
Standard
ISO/DIS 10298
ISO/TC 58/SC 2
Gas cylinders — Gases and gas
Secretariat: AFNOR
mixtures — Determination of
Voting begins on:
toxicity for the selection of cylinder
valve outlets
Voting terminates on:
Bouteilles à gaz — Gaz et mélanges de gaz — Détermination de
la toxicité pour le choix des raccords de sortie de robinets
ICS: 71.100.20
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 2025
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
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Published in Switzerland Reference number
ISO/DIS 10298:2025(en)
ii
ISO/DIS 10298:2025(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Determination of toxicity . 2
4.1 General .2
4.2 Test method .2
4.2.1 Test procedure.2
4.2.2 Results for pure gases . . .2
4.3 Calculation method.2
Annex A (informative) Selection of an LC value for a particular gas . 4
Annex B (informative) LC values for toxic gases and toxic vapours used in gas mixtures . 7
Bibliography .12

iii
ISO/DIS 10298:2025(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 not received notice of (a)
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Any trade name used in this document is information given for the convenience of users and does not
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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 58, Gas cylinders, Subcommittee SC 2, Cylinder
fittings.
This fourth edition cancels and replaces the third edition (ISO 10298:2018), which has been technically
revised.
The main changes are as follows:
— Update of Annex B to include new toxic gases which are being added to ISO 14456;
— Some LC values have been updated;
— Incorporated Addendum 1 into Clause 4.3.
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/DIS 10298:2025(en)
Introduction
ISO 5145 specifies the dimensions of different valve outlets for different compatible gas groups. These
compatible gas groups are determined according to practical criteria defined in ISO 14456.
These criteria are based on certain physical, chemical, toxic and corrosive properties of the gases. In
particular, the tissue corrosiveness is considered in this document.
The aim of this document is to assign for each gas a classification category that takes into account the toxicity
by inhalation of the gas. For gas mixtures containing toxic components a calculation based on the method
specified in the GHS is proposed.
Since the publication of the first edition of ISO 10298, this International Standard has been used for other
purposes than the selection of cylinder valve outlets, e.g. providing toxicity data for the classification of gas
and gas mixtures according to the international transport regulations and according to the classification
of dangerous substances regulations, which since 2003 is under the umbrella of the Globally Harmonized
System (GHS).
v
DRAFT International Standard ISO/DIS 10298:2025(en)
Gas cylinders — Gases and gas mixtures — Determination of
toxicity for the selection of cylinder valve outlets
1 Scope
This document lists the best available acute-toxicity data of gases taken from a search of the current
literature to allow the classification of gases and gas mixtures for toxicity by inhalation.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 10286 and the following apply.
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/
3.1
lethal concentration 50
LC
concentration of a substance in air exposure to which, for a specified length of time, it is expected to cause
the death of 50 % of the entire defined experimental animal population after a defined time period
Note 1 to entry: See Annex A for the selection of this LC value.
3.2
toxicity level
level of toxicity of gases and gas mixtures
Note 1 to entry: In ISO 14456, the toxicity level is divided into three groups:
— Subdivision 1: non toxic [LC > 5 000 ppm (volume fraction)]
— Subdivision 2: toxic [200 ppm (volume fraction) < LC ≤ 5 000 ppm (volume fraction)]
— Subdivision 3: very toxic [LC ≤ 200 ppm (volume fraction)]
These subdivisions are sometimes used in transport regulations.
where
LC values correspond to 1 h exposure to gas;
ppm (volume fraction) indicates parts per million, by volume.
Note 2 to entry: In the GHS, the inhalation toxicity levels are:

ISO/DIS 10298:2025(en)
Category 1: Fatal if inhaled 0 ppm < LC ≤ 100 ppm (volume fraction)
Category 2: Fatal if inhaled 100 ppm (volume fraction) < LC ≤ 500 ppm (volume fraction)
Category 3: Toxic if inhaled 500 ppm (volume fraction) < LC ≤ 2 500 ppm (volume fraction)
Category 4: Harmful if inhaled 2 500 ppm (volume fraction) < LC ≤ 20 000 ppm (volume fraction)
Note 3 to entry: In GHS, the LC values correspond to 4 hours exposure. Consequently, the LC50 values given in
Annex B (see 4.2.2) need to be divided by 2 (i.e. 41/ ). The reasoning behind the division by 2 is given in A.2.
3.3
lethal dose 50
LD
amount of a material, given all at once, which causes the death of 50 % of a group of test animals
3.4
lethal concentration low value
LC
LO
lowest concentration of a substance in air, other than the LC , which was reported in the original reference
paper as having caused death in humans or animals
4 Determination of toxicity
4.1 General
Toxicity may be determined through a test method (4.2) for gas mixtures where the data for the components
exist, or through a calculation method (4.3).
For reasons of animal welfare, inhalation toxicity tests geared only for the classification of gas mixtures
should be avoided if the toxicity of each of the components is available. In this case, toxicity is determined in
accordance with 4.3.
4.2 Test method
4.2.1 Test procedure
When new toxicity data are being considered for inclusion in this document, an internationally recognized
[43]
test method such as OECD TG 403 should be used.
NOTE For this document, LC is equivalent to 1 h exposure to albino rats.
4.2.2 Results for pure gases
The toxicity of pure gases is listed in Annex B, in which LC values correspond to 1 h exposure. Some of
these values have been estimated in accordance with Annex A.
4.3 Calculation method
The LC value of a gas mixture is calculated using Formula 1:
LC = (1)
C
i
∑
i
LC
50i
where
C is the mole fraction of the ith toxic component present in the gas mixture;
i
LC is the lethal concentration of the ith toxic component [LC < 5 000 ppm (by volume)].
50i 50
ISO/DIS 10298:2025(en)
After the LC of the gas mixture has been calculated, this mixture is classified in accordance with 3.2.
NOTE Potential synergistic effects are not considered in Formula 1.

ISO/DIS 10298:2025(en)
Annex A
(informative)
Selection of an LC value for a particular gas
A.1 General
When collecting data from the open literature on the acute inhalation toxicity of gases, some difficulties
are experienced. For example, taking into account the very early years of publication, one cannot expect to
get results of standardized tests. Moreover, data from reporting sources have to be validated with respect
to their details in handling and summarizing information. Furthermore, there is a lack of information on
inhalation toxicity for several gases. Thus, particular attention is needed to incorporate all the available
facts to complete the toxicological characteristics of gases.
A.2 Time adjustment
In inhalation toxicity tests, the dose-response relationship can be described by Formula A.1:
W = c ⋅ t (A.1)
where
W is a constant which is specific for any given effect, e.g. the deaths of 50 % of the animals exposed;
c ⋅ t is the applied dose expressed as the product of concentration and exposure time.
This equation, called Haber's rule, is applicable as long as the biological half-life of the substance in question
is reasonably longer than the exposure time.
For gases and vapours with appreciable rates of detoxification or excretion over the time in question, it was
found that the relationship between concentration and time is better described by Formula A.2.
0,5
W = c ⋅ t (A.2)
When extrapolating from 4 h to 1 h, Formula A.2 predicts lower LC values than does Haber's rule. To be on
the safe side, this principle was applied by the UN Transport Recommendations in adopting the conversion
factor 2 (i.e. 41/ ) to allow classification of materials on the basis of 1 h LC data. On the other hand,
Haber's rule predicts a lower LC when going from a 1-h to a 4-h LC . To make use of all the available data
50 50
on acute inhalation toxicity under the different exposure schemes, a more generalized version was applied.
Using 1 h as the point of reference,
— going up from shorter periods, linear extrapolation was preferred;
— coming down from longer periods, the conversion factor xhh/1 was used.
However, test results for a period less than 0,5 h were not used, as this was deemed unreliable.
A.3 Choice of animal
Since data on humans, if available, are usually not sufficient to derive any dose-response relationship,
laboratory animals are used to investigate the toxicity of substances on warm-blooded animals.
Unless there are counter indications, such as extraordinarily high or low susceptibility of the rat compared
to other animals or humans, the rat is the preferred species in the most common toxicity tests. Therefore,

ISO/DIS 10298:2025(en)
LC data in rats are the most likely to be found. If they are missing, data from animals close to the rat in
body weight are evaluated.
A.4 Adjustment for effects
Instead of LC , often the term LC is found in the reporting literature and in databases.
50 LO
Unfortunately, the use of this term is not consistent enough to make any assumptions as to whether the
LC is below or above that value. Nevertheless, it seems reasonable to make the same use of the LC as if it
50 LO
were information about an approximate lethal concentration (ALC). For the classification of gases, no higher
precision is required, but the calculation formula for gas mixtures requires a definite LC value to be set.
Another LC value has been taken as LC when additional information proved it plausible to do so.
A.5 Read across
Some substances had to be characterized as analogous to chemically related structures with known
physiological properties. Structure-activity relationships have been taken into consideration as far as
possible. Moreover, in several instances, the toxicological impact on the respiratory tract is based on
fundamental reactions such as the hydrolysis of different gases in the presence of moisture leading to the
same reactive principle.
A.6 Other routes of application
This route may only be used as a very last option.
Sometimes th
...