ISO 10156:1990
(Main)Gases and gas mixtures — Determination of fire potential and oxidizing ability for the selection of cylinder valve outlets
Gases and gas mixtures — Determination of fire potential and oxidizing ability for the selection of cylinder valve outlets
Gaz et mélanges de gaz — Détermination du potentiel d'inflammabilité et d'oxydation pour le choix des raccords de sortie de robinets
Plini in plinske mešanice - Določanje gorilne in oksidacijske sposobnosti za izbor izhodnih odprtin ventilov cilindrov
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IS0
1 O1 56
First edition
1990-1 2-1 5
Gases and gas mixtures - Determination of fire
potential and oxidizing ability for the selection
of cylinder valve outlets
Gaz et mélanges de gaz - Détermination du potentiel d'inflammabilité
et d'oxydation pour le choix des raccords de sortie de robinets
Reference number
IS0 1 O1 56: 1990( E)
---------------------- Page: 1 ----------------------
IS0 1 O1 56:1990(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
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, govern-
mental and non-governmental, in liaison with ISO, also take pari in the
work. IS0 collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
Drafi International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an Interna-
tional Standard requires approval by at least 75 % of the member bodies
casting a vote.
International Standard IS0 10156 was prepared by Technical Committee
ISO/TC 58, Gas cylinders.
Annex A forms an integral part of this International Standard.
8 IS0 1990
Ail rights reserved. No part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without
permission in writing from the publisher.
International Organlzation for Standardization
Case Postale 56 CH-I21 1 Geneve 20 Switzerland
Printed In Switzerland
ii
---------------------- Page: 2 ----------------------
IS0 I O1 561 990(E)
I nt roduct ion
The purpose of IS0 5145 is to establish practical criteria for the deter-
mination of outlet connections of gas cylinders of water capacity 150 li-
tres or less. These criteria are based on certain physical and chemical
properties of the gases, In particular, the flammability in air and the
oxidizing potential (with air as the reference) are considered.
One of the difficulties in the application of IS0 5145 resides in the fact
that it is at times difficult to know if a gas or gas mixture is flammable
in air or more oxidizing than air.
In fact,
in the case of pure gases, there is abundant data in the literature,
although conflicting results are to be found, depending upon the test
methods employed;
but, above all,
in the case of gas mixtures, data in the literature is often incomplete
or even non-existent.
With standardized test methods, it will be possible
to eliminate the ambiguities in the case of conflicting results in the
literature:
and, above all,
to supplement existing data (mainly in the case of gas mixtures).
In particular, the application of standardized test methods will eliminate
the ambiguities concerning mixtures in groups 1, 3, 4, 6, 7, 8, 9, 12, 13
and 15, such as they are defined in IS0 5145, since it is necessary to
know, in the case of those mixtures, whether or not they are flammable
in air and/or more or less oxidizing than air.
---------------------- Page: 3 ----------------------
___ __ - ~
IS0 1 O1 56:1990(E)
INTERNATIONAL STANDARD
Gases and gas mixtures - Determination of fire potential and
oxidizing ability for the selection of cylinder valve outlets
3 Definitions and symbols
1 Scope
This International Standard specifies two test meth-
j)
3.1 Definitions
ods for determining whether or not a gas is
flammable in air and whether a gas is more or less
For the purposes of this International Standard, the
oxidizing than air, respectively, with the aim of
following definitions apply:
eliminating difficulties entailed in the application of
IS0 5145.
3.1.1 gas or gas mixture flammable in air: A gas or
gas mixture which will ignite in air at atmospheric
NOTE 1 For certain special applications, such as special
pressure and a temperature of 20 OC.
gas mixtures produced to order (in small quantities), it
might prove relatively complex to apply the method
specified and to perform the special tests necessary to 3.1.2 lower flammability limit in air: The minimum
determine the flammability or oxidizing power of the gas
content of a gas or gas mixture in air at which the
mixture.
gas or gas mixture will ignite. This limit is deter-
mined at atmospheric pressure and 20 OC.
To avoid these difficulties, a simple method of calculation
is recommended to determine rapidly the type of con-
nection to be employed depending upon the character- 3.1.3 gas or gas mixture less oxidizing than air: A
istics (flammability, oxidizing power, etc.) of the gas
gas or gas mixture which is not able, at atmospheric
mixture and the characteristics of the pure substances
pressure, to support the combustion of substances
making up the mixture.
which are flammable in air.
3.2 Symbols
molar fraction of a flammable gas in a
Ai
mixture of gases
molar fraction of an inert gas in a mixture
2 Normative references
Bi
of gases
The following standards contain provisions which,
coefficient of oxygen equivalency
Ci
through reference in this text, constitute provisions
of this International Standard. At the time of publi-
ith flammable gas in a gas mixture
r;,
cation, the editions indicated were valid. All stan-
dards are subject to revision, and parties to
iih inert gas in a gas mixture
li
agreements based on this International Standard
n number of flammable gases in a gas
are encouraged to investigate the possibility of ap-
plying the most recent editions of the standards in- mixture
dicated below. Members of IEC and IS0 maintain
number of inert gases in a gas mixture
P
registers of currently valid International Standards.
of an inert gas
coefficient of equivalency
Ki
IS0 4589:1984, Plastics - Determination of
relative to nitrogen
flammability by oxygen index.
equivalent content of a flammable gas
A',
IS0 5145:1990, Cylinder valve outlets for gases and
gas mixtures - Selection and dimensioning. N2 nitrogen
1
---------------------- Page: 4 ----------------------
IS0 10156:1990(E)
maximum flammable-gas content for 4.2.2 Apparatus and materials
which a mixture of the flammable gas in
nitrogen is not flammable in air The apparatus (see figure 1) includes:
hydrogen
- a mixer;
carbon dioxide
- a tube in which the reaction takes place;
minimum concentration of an oxidizing
- an ignition system;
combustion gas, in a mixture with nitro-
gen, which will support combustion of a
- a system of analysis to determine the test-gas
test piece
composition.
helium
4.2.2.1 Preparation
argon
a) Test gas
neon
The test gas shall be prepared to represent the most
krypton
flammable composition that can occur in the normal
xenon
course of production. The criteria to be used in es-
tablishing the composition of the test gas are man-
sulfur dioxide
ufacturing tolerances, i.e. the test gas shall contain
the highest concentration of flammable gases en-
sulfur hexafluoride
countered in the normal manufacturing process and
the moisture content shall be less than or equal to
carbon tetrafluoride
10 ppm by volume. The test gas shall be thoroughly
octafluoropropane
mixed and carefully analysed to determine the exact
com position.
methane
b) Compressed air
nitrous oxide
The compressed air shall be analysed and shown to
lower flammability limit in air of a
be free of moisture.
flammable gas
oxygen
c) Test-gadair mixture
The compressed air and the gas to be tested are
mixed in a blender, controlling the flow rates, The
4 Flammability of gases and gas mixtures
air-flammable gas mixture shall be analysed using
in air
a chromatograph or a simple oxygen analyser.
4.2.2.2 Reaction tube
4.1 General
This tube shall be made of thick pyrex glass (e.g.
Gases and gas mixtures which are flammable shall
5 mm), with an inside diameter of at least 50 mm
be designated in accordance with IS0 5145:1990,
and a length at least five times the diameter.
annex A - category I - subdivision 2. Such gases
and gas mixtures have flammable limits in air. The
At one end of the tube, there shall be a cylindrical
following sub-clauses outline a test method and a
component designed to take:
calculation method for determining whether a gas
or gas mixture is flammable. In cases where the test
- an ignition spark plug, located about 50 mm from
result is different from that obtained by calculation,
the bottom of the tube;
the test result shall take precedence.
- an inlet for the gas mixture to be tested;
4.2 Test method
- a relief valve at the bottom of the pyrex tube
[see figure la)];
4.2.1 Principle
- two thermocouples, one located close to the ig-
nition system, the other located close to the top
The gas is mixed in the desired proportions with air.
of the tube, the purpose of these thermocouples
Then ignition energy is supplied in the form of an
being to allow easy detection of flame propa-
electric arc between two electrodes.
2
---------------------- Page: 5 ----------------------
IS0 10156:199O(E)
gation [see figure la)] (alternatively, gas ignition indicates that the flammability limit is close. In
may be observed by an experienced operator in this case, repeat the test at least five times. If, in
one of these repeat tests, the flame rises up the
a dark room);
tube, it shall be considered that the flammability
limit has been reached, i.e. the test gas is
- a safety device to minimize the risk of de-
struction of the tube in the event of an explosion flammable.
(preferably located close to the ignition system).
c) The flame rises slowly up the tube at 10 cm/s to
The tube and its accessories shall always be very
50 cm/s. In this case, it shall be considered that
clean in order to avoid any impurities, and partic-
the limit has been reached, i.e. the test gas is
ularly moisture resulting from a preceding test or
flammable.
from exposure to the atmosphere, from affecting the
determination.
d) The flame rises up the tube very rapidly. In this
case, the test gas is flammable.
The gas mixture is vented at the top of the reaction
tube by a tube fitted with a shut-off valve.
NOTES
This apparatus is located inside a ventilated metal
2 Instead of flowmeters, other appropriate devices, such
chamber, one side of which has a window made of as metering pumps, etc., can be used.
high-strength transparent material.
3 With mixtures containing hydrogen, the flame is almost
colourless. In order to confirm the presence of such
Prior to ignition, the composition of the mixture shall
flames, the use of temperature-measuring probes is re-
be tested by analysing the gas leaving the reaction
commended (see 4.2.2.2).
tube [see figurela), analysis at point 21 to ensure
that the tube has been properly purged.
4 Although it is beyond the scope of this International
Standard, if a precise value is required for the lower
4.2.2.3 Ignition system
flammability limit of the test gas, then repeated tests must
be carried out, varying the flammable-gas content until
A spark generator (e.g. 15 kV) shall be used which
the threshold point is reached between ignition and no
can supply sparks (across a 5 mm electrode gap, for ignition of the flammable gas.
instance) with an energy of 10 J per spark.
4.4 Key points concerning safety
4.3 Procedure
Tests shall be carried out by trained and competent
Care shall be taken when carrying out flammability
personnel working in accordance with authorized
tests to ensure that the explosive range is avoided.
procedures (see also 4.3). The reaction tube and
This can be done by commencing the experimental
flowmeter shall be adequately screened to protect
work at “safe” concentrations of flammable gas in
the personnel in the event of an explosion. Person-
air (“safe” = below the expected lower flammable
nel shall wear safety glasses. During the ignition
limit). Subsequently, the initial gas concentration
sequence, the reaction tube shall be open to the at-
can be slowly increased until ignition occurs.
mosphere and isolated frorn the gas supply. Care
shall also be taken during the analysis of the test
Blend the desired mixture using the flowmeter (the
gas or mixture.
efficiency of this step shall be checked by analysis).
Close the gas inlets simultaneously. Just prior to
ignition, ensure that the outlet valve (if there is one)
4.5 Results for pure gases
is opened, to bring the mixture to atmospheric
pressure.
A list of flammable gases is given in annex A to-
gether with some lower flammability limits. These
There are several possible results:
values have been obtained using similar test equip-
ment to that described in 4.2.2.
a) No combustion: the test-gas mixture is not
flammable in air at this concentration. In this
case, repeat the test at a slightly higher concen- 4.6 Calculation method
tration.
This method is limited to gas mixtures produced in
small quantities in cylinders to indicate if flammable
b) Partial combustion: a flame begins to burn
around the spark plug, and then goes out. This in air.
3
---------------------- Page: 6 ----------------------
IS0 10156:1990(E)
4.6.1 Mixtures containing n flammable gases and p A,F, + . +Ail$+ . + A,&+
inert gases
+ (KlB, + . + KiBi + . + K,B,)N,
The composition of a mixture of this kind can be ex-
Taking the sum of all the component gas fractions
pressed as follows:
to be equal to 1, the expression for the composition
A $, + . . . + A& + . . . + AnFn + B,I, + . + Biii +
becomes:
+ . + Bp$
where
Ai and Bi are the molar fractions of the ith
where
flammable gas and the ith inert gas,
respectively:
designates the ith flammable gas;
6
designates the ith inert gas;
4
is the equivalent flammable-gas content.
n is the number of flammable gases;
Table2 gives values for the maximum content Tci of
flammable gas which, in a mixture with nitrogen,
0
is the number of inert gases.
P
gives a composition which is not flammable in air.
Expressed mathematically, this condition for the
The composition of the mixture is re-expressed in
mixture not being flammable in air is
terms of an equivalent composition in which all the
inert-gas fractions are converted into their nitrogen
equivalent, using
...
SLOVENSKI STANDARD
SIST ISO 10156:1996
01-maj-1996
3OLQLLQSOLQVNHPHãDQLFH'RORþDQMHJRULOQHLQRNVLGDFLMVNHVSRVREQRVWL]DL]ERU
L]KRGQLKRGSUWLQYHQWLORYFLOLQGURY
Gases and gas mixtures -- Determination of fire potential and oxidizing ability for the
selection of cylinder valve outlets
Gaz et mélanges de gaz -- Détermination du potentiel d'inflammabilité et d'oxydation
pour le choix des raccords de sortie de robinets
Ta slovenski standard je istoveten z: ISO 10156:1990
ICS:
23.020.30 7ODþQHSRVRGHSOLQVNH Pressure vessels, gas
MHNOHQNH cylinders
71.100.20 Industrijski plini Gases for industrial
application
SIST ISO 10156:1996 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
SIST ISO 10156:1996
---------------------- Page: 2 ----------------------
SIST ISO 10156:1996
IS0
1 O1 56
First edition
1990-1 2-1 5
Gases and gas mixtures - Determination of fire
potential and oxidizing ability for the selection
of cylinder valve outlets
Gaz et mélanges de gaz - Détermination du potentiel d'inflammabilité
et d'oxydation pour le choix des raccords de sortie de robinets
Reference number
IS0 1 O1 56: 1990( E)
---------------------- Page: 3 ----------------------
SIST ISO 10156:1996
IS0 1 O1 56:1990(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
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, govern-
mental and non-governmental, in liaison with ISO, also take pari in the
work. IS0 collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
Drafi International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an Interna-
tional Standard requires approval by at least 75 % of the member bodies
casting a vote.
International Standard IS0 10156 was prepared by Technical Committee
ISO/TC 58, Gas cylinders.
Annex A forms an integral part of this International Standard.
8 IS0 1990
Ail rights reserved. No part of this publication may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying and microfilm, without
permission in writing from the publisher.
International Organlzation for Standardization
Case Postale 56 CH-I21 1 Geneve 20 Switzerland
Printed In Switzerland
ii
---------------------- Page: 4 ----------------------
SIST ISO 10156:1996
IS0 I O1 561 990(E)
I nt roduct ion
The purpose of IS0 5145 is to establish practical criteria for the deter-
mination of outlet connections of gas cylinders of water capacity 150 li-
tres or less. These criteria are based on certain physical and chemical
properties of the gases, In particular, the flammability in air and the
oxidizing potential (with air as the reference) are considered.
One of the difficulties in the application of IS0 5145 resides in the fact
that it is at times difficult to know if a gas or gas mixture is flammable
in air or more oxidizing than air.
In fact,
in the case of pure gases, there is abundant data in the literature,
although conflicting results are to be found, depending upon the test
methods employed;
but, above all,
in the case of gas mixtures, data in the literature is often incomplete
or even non-existent.
With standardized test methods, it will be possible
to eliminate the ambiguities in the case of conflicting results in the
literature:
and, above all,
to supplement existing data (mainly in the case of gas mixtures).
In particular, the application of standardized test methods will eliminate
the ambiguities concerning mixtures in groups 1, 3, 4, 6, 7, 8, 9, 12, 13
and 15, such as they are defined in IS0 5145, since it is necessary to
know, in the case of those mixtures, whether or not they are flammable
in air and/or more or less oxidizing than air.
---------------------- Page: 5 ----------------------
SIST ISO 10156:1996
---------------------- Page: 6 ----------------------
SIST ISO 10156:1996
___ __ - ~
IS0 1 O1 56:1990(E)
INTERNATIONAL STANDARD
Gases and gas mixtures - Determination of fire potential and
oxidizing ability for the selection of cylinder valve outlets
3 Definitions and symbols
1 Scope
This International Standard specifies two test meth-
j)
3.1 Definitions
ods for determining whether or not a gas is
flammable in air and whether a gas is more or less
For the purposes of this International Standard, the
oxidizing than air, respectively, with the aim of
following definitions apply:
eliminating difficulties entailed in the application of
IS0 5145.
3.1.1 gas or gas mixture flammable in air: A gas or
gas mixture which will ignite in air at atmospheric
NOTE 1 For certain special applications, such as special
pressure and a temperature of 20 OC.
gas mixtures produced to order (in small quantities), it
might prove relatively complex to apply the method
specified and to perform the special tests necessary to 3.1.2 lower flammability limit in air: The minimum
determine the flammability or oxidizing power of the gas
content of a gas or gas mixture in air at which the
mixture.
gas or gas mixture will ignite. This limit is deter-
mined at atmospheric pressure and 20 OC.
To avoid these difficulties, a simple method of calculation
is recommended to determine rapidly the type of con-
nection to be employed depending upon the character- 3.1.3 gas or gas mixture less oxidizing than air: A
istics (flammability, oxidizing power, etc.) of the gas
gas or gas mixture which is not able, at atmospheric
mixture and the characteristics of the pure substances
pressure, to support the combustion of substances
making up the mixture.
which are flammable in air.
3.2 Symbols
molar fraction of a flammable gas in a
Ai
mixture of gases
molar fraction of an inert gas in a mixture
2 Normative references
Bi
of gases
The following standards contain provisions which,
coefficient of oxygen equivalency
Ci
through reference in this text, constitute provisions
of this International Standard. At the time of publi-
ith flammable gas in a gas mixture
r;,
cation, the editions indicated were valid. All stan-
dards are subject to revision, and parties to
iih inert gas in a gas mixture
li
agreements based on this International Standard
n number of flammable gases in a gas
are encouraged to investigate the possibility of ap-
plying the most recent editions of the standards in- mixture
dicated below. Members of IEC and IS0 maintain
number of inert gases in a gas mixture
P
registers of currently valid International Standards.
of an inert gas
coefficient of equivalency
Ki
IS0 4589:1984, Plastics - Determination of
relative to nitrogen
flammability by oxygen index.
equivalent content of a flammable gas
A',
IS0 5145:1990, Cylinder valve outlets for gases and
gas mixtures - Selection and dimensioning. N2 nitrogen
1
---------------------- Page: 7 ----------------------
SIST ISO 10156:1996
IS0 10156:1990(E)
maximum flammable-gas content for 4.2.2 Apparatus and materials
which a mixture of the flammable gas in
nitrogen is not flammable in air The apparatus (see figure 1) includes:
hydrogen
- a mixer;
carbon dioxide
- a tube in which the reaction takes place;
minimum concentration of an oxidizing
- an ignition system;
combustion gas, in a mixture with nitro-
gen, which will support combustion of a
- a system of analysis to determine the test-gas
test piece
composition.
helium
4.2.2.1 Preparation
argon
a) Test gas
neon
The test gas shall be prepared to represent the most
krypton
flammable composition that can occur in the normal
xenon
course of production. The criteria to be used in es-
tablishing the composition of the test gas are man-
sulfur dioxide
ufacturing tolerances, i.e. the test gas shall contain
the highest concentration of flammable gases en-
sulfur hexafluoride
countered in the normal manufacturing process and
the moisture content shall be less than or equal to
carbon tetrafluoride
10 ppm by volume. The test gas shall be thoroughly
octafluoropropane
mixed and carefully analysed to determine the exact
com position.
methane
b) Compressed air
nitrous oxide
The compressed air shall be analysed and shown to
lower flammability limit in air of a
be free of moisture.
flammable gas
oxygen
c) Test-gadair mixture
The compressed air and the gas to be tested are
mixed in a blender, controlling the flow rates, The
4 Flammability of gases and gas mixtures
air-flammable gas mixture shall be analysed using
in air
a chromatograph or a simple oxygen analyser.
4.2.2.2 Reaction tube
4.1 General
This tube shall be made of thick pyrex glass (e.g.
Gases and gas mixtures which are flammable shall
5 mm), with an inside diameter of at least 50 mm
be designated in accordance with IS0 5145:1990,
and a length at least five times the diameter.
annex A - category I - subdivision 2. Such gases
and gas mixtures have flammable limits in air. The
At one end of the tube, there shall be a cylindrical
following sub-clauses outline a test method and a
component designed to take:
calculation method for determining whether a gas
or gas mixture is flammable. In cases where the test
- an ignition spark plug, located about 50 mm from
result is different from that obtained by calculation,
the bottom of the tube;
the test result shall take precedence.
- an inlet for the gas mixture to be tested;
4.2 Test method
- a relief valve at the bottom of the pyrex tube
[see figure la)];
4.2.1 Principle
- two thermocouples, one located close to the ig-
nition system, the other located close to the top
The gas is mixed in the desired proportions with air.
of the tube, the purpose of these thermocouples
Then ignition energy is supplied in the form of an
being to allow easy detection of flame propa-
electric arc between two electrodes.
2
---------------------- Page: 8 ----------------------
SIST ISO 10156:1996
IS0 10156:199O(E)
gation [see figure la)] (alternatively, gas ignition indicates that the flammability limit is close. In
may be observed by an experienced operator in this case, repeat the test at least five times. If, in
one of these repeat tests, the flame rises up the
a dark room);
tube, it shall be considered that the flammability
limit has been reached, i.e. the test gas is
- a safety device to minimize the risk of de-
struction of the tube in the event of an explosion flammable.
(preferably located close to the ignition system).
c) The flame rises slowly up the tube at 10 cm/s to
The tube and its accessories shall always be very
50 cm/s. In this case, it shall be considered that
clean in order to avoid any impurities, and partic-
the limit has been reached, i.e. the test gas is
ularly moisture resulting from a preceding test or
flammable.
from exposure to the atmosphere, from affecting the
determination.
d) The flame rises up the tube very rapidly. In this
case, the test gas is flammable.
The gas mixture is vented at the top of the reaction
tube by a tube fitted with a shut-off valve.
NOTES
This apparatus is located inside a ventilated metal
2 Instead of flowmeters, other appropriate devices, such
chamber, one side of which has a window made of as metering pumps, etc., can be used.
high-strength transparent material.
3 With mixtures containing hydrogen, the flame is almost
colourless. In order to confirm the presence of such
Prior to ignition, the composition of the mixture shall
flames, the use of temperature-measuring probes is re-
be tested by analysing the gas leaving the reaction
commended (see 4.2.2.2).
tube [see figurela), analysis at point 21 to ensure
that the tube has been properly purged.
4 Although it is beyond the scope of this International
Standard, if a precise value is required for the lower
4.2.2.3 Ignition system
flammability limit of the test gas, then repeated tests must
be carried out, varying the flammable-gas content until
A spark generator (e.g. 15 kV) shall be used which
the threshold point is reached between ignition and no
can supply sparks (across a 5 mm electrode gap, for ignition of the flammable gas.
instance) with an energy of 10 J per spark.
4.4 Key points concerning safety
4.3 Procedure
Tests shall be carried out by trained and competent
Care shall be taken when carrying out flammability
personnel working in accordance with authorized
tests to ensure that the explosive range is avoided.
procedures (see also 4.3). The reaction tube and
This can be done by commencing the experimental
flowmeter shall be adequately screened to protect
work at “safe” concentrations of flammable gas in
the personnel in the event of an explosion. Person-
air (“safe” = below the expected lower flammable
nel shall wear safety glasses. During the ignition
limit). Subsequently, the initial gas concentration
sequence, the reaction tube shall be open to the at-
can be slowly increased until ignition occurs.
mosphere and isolated frorn the gas supply. Care
shall also be taken during the analysis of the test
Blend the desired mixture using the flowmeter (the
gas or mixture.
efficiency of this step shall be checked by analysis).
Close the gas inlets simultaneously. Just prior to
ignition, ensure that the outlet valve (if there is one)
4.5 Results for pure gases
is opened, to bring the mixture to atmospheric
pressure.
A list of flammable gases is given in annex A to-
gether with some lower flammability limits. These
There are several possible results:
values have been obtained using similar test equip-
ment to that described in 4.2.2.
a) No combustion: the test-gas mixture is not
flammable in air at this concentration. In this
case, repeat the test at a slightly higher concen- 4.6 Calculation method
tration.
This method is limited to gas mixtures produced in
small quantities in cylinders to indicate if flammable
b) Partial combustion: a flame begins to burn
around the spark plug, and then goes out. This in air.
3
---------------------- Page: 9 ----------------------
SIST ISO 10156:1996
IS0 10156:1990(E)
4.6.1 Mixtures containing n flammable gases and p A,F, + . +Ail$+ . + A,&+
inert gases
+ (KlB, + . + KiBi + . + K,B,)N,
The composition of a mixture of this kind can be ex-
Taking the sum of all the component gas fractions
pressed as follows:
to be equal to 1, the expression for the composition
A $, + . . . + A& + . . . + AnFn + B,I, + . + Biii +
becomes:
+ . + Bp$
where
Ai and Bi are the molar fractions of the ith
where
flammable gas and the ith inert gas,
respectively:
designates
...
IS0
NORME
I O1 56
I NTE R NATIONALE
Première édition
1990-1 2-1 5
Gaz et mélanges de gaz - Détermination du
potentiel d’inflammabilité et d’oxydation pour le
choix des raccords de sortie de robinets
Gases and gas mixtures - Determination of fire potential and oxidizing
ability for the selection of cylinder valve outlets
Numéro de référence
IS0 10156:1990(F)
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IS0 10156:1990(F)
Avant-propos
L’ISO (Organisation internationale de normalisation) est une fédération
mondiale d’organismes nationaux de normalisation (comités membres
de I’ISO). L’élaboration des Normes internationales est en général
confiée aux comités techniques de l‘lS0. Chaque comité membre inté-
ressé par une étude a le droit de faire partie du comité technique créé
à cet effet. Les organisations internationales, gouvernementales et non
gouvernementales, en liaison avec I’ISO participent également aux tra-
vaux. L’ISO collabore étroitement avec la Commission électrotechnique
internationale (CEI) en ce qui concerne la normalisation électrotech-
nique.
Les projets de Normes internationales adoptés par les comités techni-
ques sont soumis aux comités membres pour vote. Leur publication
comme Normes internationales requiert l’approbation de 75 % au moins
des comités membres votants.
La Norme internationale IS0 10156 a été élaborée par le comité techni-
que ISO/TC 58, Bouteilles à gaz.
L’annexe A fait partie intégrante de la présente Norme internationale.
8 is0 1990
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Organisation internationale de normalisation
Case Postale 56 CH-I21 1 Genève 20 Suisse
imprimé en Suisse
ii
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IS0 1 O1 56:1990(F)
lntroduct ion
L’ISO 5145 définit les critères pratiques de choix des raccords de sortie
de robinets de bouteilles à gaz de capacité en eau inférieure ou égale
à 150 L. Ces critères reposent sur certaines propriétés physico-
chimiques des gaz et en particulier leur inflammabilité à l’air ou leur
potentiel d’oxydation (par référence à l’air).
L’un des problèmes posés par I’ISO 5145 vient du fait qu’il est parfois
difficile de déterminer si un gaz ou un mélange de gaz est inflammable
à l’air ou plus oxydant que l’air.
En fait,
pour les gaz purs, la bibliographie abonde en résultats mais ils sont
parfois contradictoires selon les méthodes d’essai employées;
et surtout,
pour les mélanges de gaz, les données bibliographiques sont sou-
vent soit incomplètes, soit inexistantes.
Avec des méthodes d’essai normalisées, il devrait être possible
d‘éliminer les ambiguïtés soulevées par les contradictions des don-
nées bibliographiques;
et surtout,
de compléter les données inexistantes (principalement pour les mé-
langes de gaz).
L’utilisation de méthodes d’essai normalisées devraient en particulier
éliminer les ambiguïtés relatives aux mélanges des groupes 1, 3, 4, 6,
7, 8, 9, 12, 13 et 15 définis dans 1’1S0 5145 puisqu’il est nécessaire dans
le cas de ces mélanges de déterminer s’ils sont ou non inflammables
à l’air et plus ou moins oxydants que l’air.
iii
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I
I NORME INTERNATIONALE IS0 I O1 56:1990(F)
Gaz et mélanges de gaz - Détermination du potentiel
d’inflammabilité et d’oxydation pour le choix des raccords de
sortie de robinets
3 Definitions et symboles
0 1 Domaine d’application
La présente Norme internationale prescrit deux
3.1 Définitions
méthodes d‘essai servant à déterminer si un gaz est
ou non inflammable à l’air et si un gaz est plus ou
Pour les besoins de la présente Norme internatio-
moins oxydant que l’air, dans le but d‘éliminer les
nale, les définitions suivantes s’appliquent.
difficultés soulevées par l’application de I’ISO 5145.
3.1.1 mélange de gaz Inflammable à t’air: Mélange
NOTE 1 Dans certains cas, comme par exemple les
qui peut s’enflammer dans de l’air à la pression at-
mélanges de gaz spéciaux fabriqués sur commande (en
mosphérique et à une température de 20 OC.
petites quantités), il peut s’avérer assez complexe de
mettre en œuvre la méthode prescrite et de réaliser les
essais spéciaux de détermination de l’inflammabilité ou 3.1.2 limite Inférieure d’inflamma~llité A l’air: Limite
du potentiel d’oxydation du mélange.
minimale à laquelle un produit peut s’enflammer.
Cette limite est déterminée à la pression atmos-
Pour contourner la difficulté, il est recommandé d’avoir
phérique et à 20 OC.
recours à une méthode de calcul simple, permettant de
déterminer rapidement le type de raccord à employer en
fonction des caractéristiques du gaz (inflammable, oxy- 3.1.3 gaz ou mélange de gaz moins oxydant que
dant, etc.) et des caractéristiques des substances pures l’air: Gaz ou mélange de gaz qui ne peut pas, à la
dont le gaz est composé.
pression atmosphérique, supporter la combustion
de substances inflammables à l’air.
e
3.2 Symboles
2 References normatives
fraction molaire d’un gaz inflammable
Les normes suivantes contiennent des dispositions Ai
dans un mélange de gaz
qui, par suite de la référence qui en est faite,
constituent des dispositions valables pour la pré-
fraction molaire d’un gaz inerte dans un
ni
sente Norme internationale. Au moment de la pu-
mélange de gaz
blication, les éditions indiquées étaient en vigueur.
Toute norme est sujette à révision et les parties
ci coefficient d ’équ ivale nce en oxygène
prenantes des accords fondés sur la présente
Norme internationale sont invitées à rechercher la I;E ième gaz inflammable dans un mélange
possibilité d’appliquer les éditions les plus récentes de gaz
des normes indiquées ci-après. Les membres de la
‘i $me gaz inerte dans un mélange de gaz
CE1 et de I’ISO possèdent le registre des Normes
internationales en vigueur à un moment donné.
n Nombre de gaz inflammables dans un
mélange de gaz
IS0 4589:1984, Plastiques - Essais de réaction au feu
- Détermination de l‘indice d‘oxygène.
nombre de gaz inertes dans un mélange
P
de gaz
IS0 5145:1990, Raccords de sortie de robinets de
coefficient d’équivalence entre gaz iner-
bouteilles à gaz et mélanges de gaz - Choix et
Ki
dimensionnement. tes et azote
1
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IS0 10156:199O(F)
teneur équivalente d‘un gaz inflammable 4.2 Méthode d’essai
azote
4.2.1 Prlnclpe
teneur maximale en gaz inflammable qui,
Mélange d’un gaz à de l’air dan les DroDortion
en mélange avec de l’azote, donne une
désirées, et production, à l‘aide d‘un arc‘ électrique,
composition qui n’est pas infiammable à
établi entre deux électrodes, de l’énergie néces-
l’air
saire à l’inflammation.
hydrogène
4.2.2 Apparelllage et produits
dioxyde de carbone
concentration minimale d’un gaz oxydant
L’appareillage (voir figure 1) comprend:
de combustion dans un mélange avec
l’azote, qui favorisera la combustion des
- un mélangeur;
éprouvettes
- un tube où se produit la réaction;
hélium
- un système d’allumage;
argon
- 0
un système d’analyse de la composition des gaz.
néon
krypton
4.2.2.1 Préparation
xénon
a) Gaz d’essai
dioxyde de soufre
Le gaz d’essai préparé doit représenter la compo-
hexafluorure de soufre
sition la plus inflammable rencontrée en fabrication
normale. Les critères servant à définir la compo-
tétrafluorure de carbone
sition du gaz d’essai sont les tolérances de fabrica-
tion: le gaz d‘essai doit ainsi renfermer la
octafl uoropropane
concentration la plus élevée de gaz inflammables
rencontrée dans le cours normal de la fabrication
méthane
et une teneur en humidité inférieure ou égale à
protoxyde d’azote 10 ppm en volume. Le gaz d’essai doit être
homogénéisé et soigneusement analysé pour avoir
limite inférieure d’inflammabilité dans
une composition précise.
l’air d’un gaz inflammable
b) Gaz comprimé
oxygène
Après analyse il doit être démontré que le gaz 0
comprimé est absolument exempt d’humidité.
c) Mélange gaz d‘essai/air
4 Inflammabillté à l’air des gaz et
L’air comprimé et le gaz à essayer sont mélangés
dans un mélangeur dynamique en contrôlant les
mélanges de gaz
débits. L’analyse du mélange se fait à l‘aide d’un
chromatographe ou d’un analyseur d’oxygène sim-
ple.
4.1 Généralités
4.2.2.2 Tube pour les essais
Les gaz et mélanges de gaz inflammables doivent
Ce tube doit être en pyrex (par exemple 5 mm), d’un
être identifiés conformément à l‘lS0 5145:1990, an-
diamètre intérieur au moins égal à 50 mm et d’une
nexe A - catégorie I - subdivision 2. Ces gaz et
longueur au moins égale à cinq fois le diamètre.
mélanges de gaz ont des limites d’inflammabilité à
Au fond du tube, un élément cylindrique doit renfer-
l’air. Les paragraphes qui suivent exposent les mé-
mer:
thodes permettant de déterminer si un gaz ou un
mélange de gaz est inflammable. Dans les cas où le
- la bougie d‘allumage située à environ 50 mm de
résultat d‘essai est différent. de celui obtenu par
la base du tube:
calcul, le résultat d’essai aura la préséance.
2
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IS0 10156:1990(F)
- l‘entrée du mélange de gaz à essayer;
b) Combustion partielle: une flamme commence à
brûler autour de la bougie d’allumage puis
- un robinet de purge [voir figure la)];
s’éteint. C’est le signe que la limite d’inflamma-
bilité est proche. L’essai doit être répété cinq
- deux thermocouples, l‘un près du système d’al-
fois. Si, dans l’un des cas, la flamme monte dans
lumage, l’autre près du sommet du tube. Ces le tube, c’est le signe que la limite d’inflamma-
thermocouples servent à détecter la propagation bilité est atteinte et donc que le gaz d’essai est
de la flamme [voir figure la)]. II est aussi possi- inflammable.
ble de charger un personnel expérimenté d’ob-
server l’allumage dans une pièce sombre;
c) La flamme monte lentement dans le tube à une
vitesse de quelque 10 cm/s à 50 cm/s. II est
- un système de sdcurité réduisant le risque de
consldéré que la limite d’inflammabilité est at-
destruction du tube en cas d‘explosion (situé de teinte et donc que le gaz d‘essai est inflamma-
préférence près du système d’allumage). ble.
Le tube et ses accessoires doivent être très propres
d) La flamme monte dans le tube très rapidement.
pour éviter les effets d’impuretés ou de restes
Dans ce cas, le gaz d’essai est inflammable.
d’humidité d’une précédente combustion ou expo-
NOTES
sition à l’atmosphère.
2 On peut remplacer les débitmètres par d’autres dis-
Le mélange de gaz à essayer est évacué par le haut
positifs appropriés, tels que pompes doseuses, débitmè-
du tube équipé d‘un robinet d’isolement.
tres masslques, etc.
Le montage est placé à l’intérieur d’une enceinte
3 Pour les mélanges contenant de l’hydrogène, les
métallique ventilée dont l’un des côtés est constitué
flammes sont presque incolores. Pour vérifier dans ce cas
d’une vitre en matériau transparent extrêmement
la présence de flamme, il est recommandé d’utiliser des
résistant .
sondes thermométriques (voir 4.2.2.2).
Avant d’allumer le mélange on détermine sa com-
4 II sort du domaine de la présente Norme internationale
position par analyse du gaz s’échappant du tube
de spécifier une valeur précise de limite inférieure d’in-
d‘essai [figurela), analyse au point 23 afin de véri-
flammabilité, mais si cela s’avérait nécessaire, il faudrait
fier que le tube a été convenablement purgé. (en faisant varier la teneur en
effectuer plusieurs essais
gaz inflammable) jusqu’à ce qu’on ait atteint le seuil entre
inflammation et non-inflammation du gaz.
4.2.2.3 Système d’allumage
Le générateur d’étincelles utilisé (par exemple
4.4 Polnts-clés concernant la sécurité
15 kV) peut faire passer (dans un entrefer de 5 mm
des électrodes, par exemple) des étincelles d’une
Les essais doivent être réalisés par du personnel
énergie individuelle de 10 J.
entraîné et compétent respectant les procédures
autorisées (voir aussi 4.3). Le tube à essai et le dé-
4.3 Mode opératoire
bitmètre doivent être convenablement blindés pour
protéger le personnel en cas d’explosion. Le per-
Veiller pendant les essais d’inflammabilité à éviter
sonnel doit porter des lunettes protectrices. Pendant
la plage explosible. Pour cela, commencer I’expéri-
l’opération d’allumage, le tube à essai doit être ou-
mentation à des concentrations ((sûres)) de gaz in-
vert à l’air libre et isolé de l‘alimentation en gaz.
flammable dans l’air (&Ire>, = inférieure à la limite
L’analyse du gaz ou mélange de gaz doit se faire
inférieure d’inflammation pro ba b I e). Puis augmenter
avec soin.
lentement la concentration initiale jusqu’à ce que
l’allumage se produise.
4.5 Résultats sur les gaz purs
Effectuer le mélange désiré à l’aide des débitmètres
(après vérification par analyse). Fermer simultané-
Les gaz inflammables sont énumérés dans
ment les entrées de gaz. Juste avant l’allumage,
l’annexe A avec pour certains leur limite inférieure
vérifier que le robinet de sortie (s’il existe) est bien
d’inflammabilité. Ces valeurs ont été obtenues avec
ouvert pour amener le mélange à la pression at-
un appareillage du type décrit en 4.2.2.
mosphérique.
II existe plusieurs résultats possibles:
4.6 Méthode de calcul
a) Aucune combustion: le mélange de gaz essayé
n’est pas inflammable à la concentration consi- L’usage de cette méthode se limite aux mélanges
répété à une concen- de gaz produits en bouteilles en petites quantités
dérée. L’essai doit être
tration légèrement plus élevée. pour vérifier s‘ils sont inflammables à l’air.
3
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IS0 I O1 56:1990(F)
4.6.1 Mélanges contenant n gaz inflammables et p AIFl + . + Ai& + . + A,F, +
gaz inertes
+ (KIR1 + . + KiBi + . + KpBp)N2
Le mélange s’exprime sous la forme suivante:
ce qui, après ajustement de la composition en une
somme de teneurs égale à 1, peut s’écrire
A$, + . +A&+ .I. +A,& + B,Z, + . + niri +
+ . + BPIp
où
où
Ai et Bi sont les fractions molaires d’un @me
gaz inflammable et ième gaz inerte,
respectivement;
...
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