Determination of explosion limits of gases and vapours and determination of the limiting oxygen concentration (LOC) for flammable gases and vapours

This European Standard specifies two test methods (method T and method B) to determine the explosion limits of gases, vapours and their mixtures, mixed with air. An air/inert gas mixture (volume fraction of the oxygen < 21 %) can be used as the oxidizer instead of air. In this European Standard, the term "air" includes such air/inert mixtures. This European Standard applies to gases, vapours and their mixtures at atmospheric pressure for temperatures up to 200 °C.
This European Standard specifies in addition the method for determining the LOC of mixtures consisting of flammable gas or vapour, air and inert gas at atmospheric pressure and temperatures from ambient temperature to 200 °C.
NOTE: This method was previously specified in EN 14756.

Bestimmung der Explosionsgrenzen von Gasen und Dämpfen und Bestimmung der Sauerstoffgrenzkonzentration (SGK) für brennbare Gase und Dämpfe

Diese Europäische Norm legt zwei Prüfverfahren (Verfahren T und Verfahren B) zum Bestimmen der Explosionsgrenzen von Gasen, Dämpfen und deren Gemischen, in Mischung mit Luft oder einer Luft-/Inertgas-Mischung (Volumenanteil Sauerstoff < 21 %), fest. Dieses Dokument gilt für Gase, Dämpfe und deren Gemische bei Umgebungsdruck und Temperaturen von Raumtemperatur bis 200 °C.

Détermination des limites d'exposivité des gaz et vapeurs et détermination de la concentration limite en oxygène (CLO) des gaz et des vapeurs inflammable

La présente Norme européenne spécifie deux méthodes d'essai (la méthode T et la méthode B) pour déterminer les limites d'explosivité de gaz, de vapeurs et de mélanges de gaz et de vapeurs mélangés à l'air, ou d'un mélange d'air et de gaz inerte (fraction volumique de l'oxygène < 21 %) ainsi que la concentration limite en oxygène. La présente Norme européenne s’applique aux gaz, aux vapeurs et à leurs mélanges à la pression atmosphérique pour des températures jusqu’à 200 °C.

Ugotavljanje mej eksplozivnosti plinov in hlapov ter ugotavljanje mejne koncentracije kisika (LOC) za vnetljive pline in pare

Ta evropski standard določa dve preskusni metodi (metodo T in metodo B) za ugotavljanje mej eksplozivnosti plinov, hlapov in njihovih mešanic, zmešanih z zrakom. Namesto zraka je kot oksidant mogoče uporabiti mešanico zraka in inertnega plina (delež prostornine kisika < 21 %). Izraz »zrak« v tem evropskem standardu vključuje take mešanice zraka/inertnega plina. Ta evropski standard se uporablja za pline, hlape in njihove mešanice pri atmosferskem tlaku in temperaturah do 200 °C. Ta evropski standard določa tudi metodo za ugotavljanje mejne koncentracije kisika pri mešanicah vnetljivih plinov ali hlapov, zraka in inertnega plina pri atmosferskem tlaku in temperaturah od temperature okolja do 200 °C.  OPOMBA: Ta metoda je bila predhodno določena v standardu EN 14756.

General Information

Status
Published
Public Enquiry End Date
30-Jul-2014
Publication Date
21-Mar-2017
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
24-Jan-2017
Due Date
31-Mar-2017
Completion Date
22-Mar-2017

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SLOVENSKI STANDARD
SIST EN 1839:2017
01-april-2017
1DGRPHãþD
SIST EN 14756:2007
SIST EN 1839:2013
Ugotavljanje mej eksplozivnosti plinov in hlapov ter ugotavljanje mejne
koncentracije kisika (LOC) za vnetljive pline in pare

Determination of explosion limits of gases and vapours and determination of the limiting

oxygen concentration (LOC) for flammable gases and vapours
Bestimmung der Explosionsgrenzen von Gasen und Dämpfen und Bestimmung der
Sauerstoffgrenzkonzentration (SGK) für brennbare Gase und Dämpfe
Détermination des limites d'exposivité des gaz et vapeurs et détermination de la
concentration limite en oxygène (CLO) des gaz et des vapeurs inflammable
Ta slovenski standard je istoveten z: EN 1839:2017
ICS:
13.230 Varstvo pred eksplozijo Explosion protection
SIST EN 1839:2017 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 1839:2017
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SIST EN 1839:2017
EN 1839
EUROPEAN STANDARD
NORME EUROPÉENNE
January 2017
EUROPÄISCHE NORM
ICS 13.230 Supersedes EN 14756:2006, EN 1839:2012
English Version
Determination of the explosion limits and the limiting
oxygen concentration(LOC) for flammable gases and
vapours

Détermination des limites d'explosivité des gaz et Bestimmung der Explosionsgrenzen und der

vapeurs et détermination de la concentration limite en Sauerstoffgrenzkonzentration (SGK) für brennbare

oxygène (CLO) des gaz et des vapeurs inflammables Gase und Dämpfen
This European Standard was approved by CEN on 7 November 2016.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this

European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references

concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN

member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by

translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management

Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,

Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2017 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 1839:2017 E

worldwide for CEN national Members.
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SIST EN 1839:2017
EN 1839:2017 (E)
Contents Page

European foreword ....................................................................................................................................................... 5

Introduction .................................................................................................................................................................... 6

1 Scope .................................................................................................................................................................... 7

2 Normative references .................................................................................................................................... 7

3 Terms and definitions ................................................................................................................................... 7

4 Test methods .................................................................................................................................................... 9

4.1 General ................................................................................................................................................................ 9

4.2 Method T (“tube” method) ........................................................................................................................ 10

4.2.1 Detailed method ........................................................................................................................................... 10

4.2.2 Reagents and materials .............................................................................................................................. 10

4.2.3 Apparatus ........................................................................................................................................................ 11

Table 1 — Maximum permissible uncertainty of measurement for the amount of test

substance in the test mixture ................................................................................................................... 12

Figure 1 — Scheme of the ‘tube’ apparatus for determining the explosion limits respc.

Limiting oxygen concentration ............................................................................................................... 12

4.2.4 Preparation of the test mixture .............................................................................................................. 13

4.2.5 Procedure........................................................................................................................................................ 13

4.3 Method B (“bomb” method)...................................................................................................................... 14

4.3.1 Principle .......................................................................................................................................................... 14

4.3.2 Reagents and materials .............................................................................................................................. 14

4.3.3 Apparatus ........................................................................................................................................................ 14

4.3.4 Preparation of the test mixture .............................................................................................................. 16

4.3.5 Procedure........................................................................................................................................................ 17

4.3.6 Determination of explosion limits ......................................................................................................... 17

4.3.7 Determination of the limiting oxygen concentration ..................................................................... 18

4.4 Determination of the limiting oxygen concentration ..................................................................... 18

4.4.1 Metering devices and additional equipment ..................................................................................... 18

4.4.2 Procedure........................................................................................................................................................ 19

Figure 2 — Short procedure scheme for the determination of the LAC ................................................. 20

Figure 3 — Extended procedure scheme for the determination of the LAC .......................................... 21

4.5 Recording of results .................................................................................................................................... 22

4.5.1 General ............................................................................................................................................................. 22

4.5.2 Determination of explosion limits ......................................................................................................... 22

4.5.3 Determination of the limiting oxygen concentration ..................................................................... 23

5 Verification ..................................................................................................................................................... 23

6 Test report ...................................................................................................................................................... 23

Annex A (normative) Method for determination of the explosion limits and limiting oxygen

concentration of substances that are difficult to ignite ................................................................. 25

A.1 Background .................................................................................................................................................... 25

A.2 Explanation .................................................................................................................................................... 25

A.2.1 Explosion criterion — flame detachment ............................................................................................ 25

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EN 1839:2017 (E)

A.2.2 Degree of halogenation ............................................................................................................................... 25

A.3 Apparatus ........................................................................................................................................................ 25

A.3.1 Test vessel ....................................................................................................................................................... 25

A.3.2 Reagents and materials .............................................................................................................................. 26

A.3.3 Ignition source ............................................................................................................................................... 26

A.3.4 Equipment for preparing the test mixture .......................................................................................... 26

A.4 Safety equipment .......................................................................................................................................... 26

A.5 Preparation of the test mixture ............................................................................................................... 26

A.6 Procedure ........................................................................................................................................................ 27

A.6.1 Determination of LEL and UEL ................................................................................................................. 27

A.6.2 Determination of LOC .................................................................................................................................. 27

Annex B (informative) Conversion of the values for the explosion limits ............................................ 28

B.1 Abbreviations and symbols ....................................................................................................................... 28

B.2 Substance characteristics of air ............................................................................................................... 28

B.3 Definitions ....................................................................................................................................................... 29

B.4 Mixture preparation .................................................................................................................................... 29

B.5 Conversion ...................................................................................................................................................... 30

Table B.1 — Formulas for the conversion .......................................................................................................... 31

Annex C (informative) Examples to describe flame detachment ............................................................. 32

Annex D (informative) Example of recommended evaporator equipment .......................................... 33

Figure D.1 — Evaporator equipment for producing test mixtures from liquid flammable

substances ....................................................................................................................................................... 33

Annex E (normative) Safety measures ............................................................................................................... 35

E.1 General ............................................................................................................................................................. 35

E.2 General safety measures ............................................................................................................................ 35

E.3 Additional safety measures concerning the tube method ............................................................. 35

Annex F (informative) Examples of the determination of the LOC .......................................................... 36

F.1 Example 1: determination of the LOC – short procedure ............................................................... 36

Figure F.1 — Determination of the LAC of a ternary system of n-hexane, air and nitrogen at

100 °C and ambient pressure ................................................................................................................... 36

F.2 Example 2: determination of the LOC – extended procedure ....................................................... 36

Figure F.2 — Determination of the LAC of a ternary system of hydrogen, air and nitrogen at

20 °C and ambient pressure ...................................................................................................................... 37

Annex G (normative) Verification ........................................................................................................................ 38

Table G.1 — Data for verification of the apparatus with respect to the lower explosion limit ...... 38

Table G.2 — Data for verification of the apparatus with respect to the upper explosion limit ...... 38

Annex H (informative) Example of a form expressing the results ........................................................... 40

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EN 1839:2017 (E)
Annex I (informative) Significant Changes between this European Standard and

EN 1839:2012 and EN 14756:2006 ........................................................................................................ 42

Table I.1 — The significant changes with respect to EN 1839:2012 and EN 14756:2006 ................ 42

Annex ZA (informative) Relationship between this European Standard and the essential

requirements of Directive 2014/34/EU aimed to be covered ..................................................... 43

Table ZA.1 — Correspondence between this European Standard and Annex II of Directive

2014/34/EU ................................................................................................................................................... 43

Bibliography ................................................................................................................................................................. 44

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SIST EN 1839:2017
EN 1839:2017 (E)
European foreword

This document (EN 1839:2017) has been prepared by Technical Committee CEN/TC 305 “Potentially

explosive atmospheres - Explosion prevention and protection”, the secretariat of which is held by DIN.

This document supersedes EN 14756:2006, and EN 1839:2012.

This European Standard shall be given the status of a national standard, either by publication of an

identical text or by endorsement, at the latest by July 2017, and conflicting national standards shall be

withdrawn at the latest by January 2018.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document has been prepared under a mandate given to CEN by the European Commission and the

European Free Trade Association, and supports essential requirements of EU Directive(s).

For relationship with EU Directives, see informative Annex ZA, which is an integral part of this

document.

According to the CEN-CENELEC Internal Regulations, the national standards organisations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,

Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,

France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,

Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Turkey and the United Kingdom.
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SIST EN 1839:2017
EN 1839:2017 (E)
Introduction

The hazard of an explosion can be avoided by preventing the formation of explosive mixtures of gases

and/or vapours with air. To do so, the explosion limits (also known as “flammability limits”) or the

limiting oxygen concentration of the flammable substance need to be known. These limits depend

mainly on:
— the properties of the flammable substance;
— temperature and pressure;
— size and shape of the test vessel;
— ignition source (type, energy);
— the criterion for self-propagating combustion;
— the inert gas (in case of the limiting oxygen concentration).

To obtain reliable and comparable results it is necessary to standardize the conditions for determining

the explosion limits resp. the limiting oxygen concentration (i.e. apparatus and procedure). However, it

is not possible to provide one single method that is suitable for all types of substances. For practical

reasons, it is preferable to use apparatus that can also be used for the determination of other explosion

characteristics. This European Standard, therefore, details two methods, namely, the tube method

(method T) and the bomb method (method B). In general, the tube method gives a wider explosion

range. Differences in the explosion limits and limiting oxygen concentration determined by the two

methods can vary by up to 10 % relative.

For substances which are difficult to ignite, only a modified tube method is suitable. This is described in

Annex A.
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EN 1839:2017 (E)
1 Scope

This European Standard specifies two test methods (method T and method B) to determine the

explosion limits of gases, vapours and their mixtures, mixed with air or an air / inert gas mixture

(volume fraction of the oxygen < 21 %) and the limiting oxygen concentration. This European Standard

applies to gases, vapours and their mixtures at atmospheric pressure for temperatures up to 200 °C.

2 Normative references

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. For dated references, only the edition cited applies. For undated

references, the latest edition of the referenced document (including any amendments) applies.

EN 13237:2012, Potentially explosive atmospheres - Terms and definitions for equipment and protective

systems intended for use in potentially explosive atmospheres
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
flammable substance

substance in the form of gas, vapour or mixtures of these, able to undergo an exothermic reaction with

air or air / inert gas mixture when ignited
[SOURCE: EN 13237:2012, 3.37, modified]
3.2
explosion range

range of the concentration of a flammable substance or mixture of substances in air, within which an

explosion can occur, respectively range of the concentration of a flammable substance or mixture of

substances in mixture with air / inert gas, within which an explosion can occur, determined under

specified test conditions
[SOURCE: EN 13237:2012, 3.22, modified]
Note 1 to entry: The explosion limits are not part of the explosion range
3.3
lower explosion limit
LEL
lowest concentration of the explosion range
[SOURCE: EN 13237:2012, 3.19.1, modified]

Note 1 to entry: Those concentrations are given at which an explosion just fails during the tests.

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EN 1839:2017 (E)
3.4
upper explosion limit
UEL
highest concentration of the explosion range
[SOURCE: EN 13237:2012, 3.19.2, modified]

Note 1 to entry: Those concentrations are given at which an explosion just fails during the tests.

3.5
limiting air concentration
LAC

maximum air concentration in a mixture of a flammable substance, air and an inert gas, in which an

explosion will not occur

Note 1 to entry: LAC is usually expressed as molar fraction in % or volume fraction in % (for conversion of units

see Annex B).

Note 2 to entry: The LAC does not depend only on the flammable gas or vapour, but also on the inert gas used.

3.6
limiting oxygen concentration
LOC

maximum oxygen concentration in a mixture of a flammable substance, air and an inert gas, in which an

explosion will not occur
[SOURCE: EN 13237:2012, 3.49, modified]

Note 1 to entry: LOC is usually expressed as molar fraction in % or volume fraction in % (for conversion of units

see Annex B)

Note 2 to entry: The LOC does not depend only on the flammable gas or vapour, but also on the inert gas used.

Note 3 to entry: LOC is calculated from the measured LAC
3.7
inert gas
gas that does not react with the test substance or oxygen
3.8
explosion region

area inside the boundary curve formed by the explosion limits of a flammable substance in various

mixtures with air and inert gas
[SOURCE: EN 13237:2012, 3.15, modified]

Note 1 to entry: In many cases the apex of the boundary curve corresponds to the limiting air concentration,

LAC.
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EN 1839:2017 (E)
3.9
explosion criterion — flame detachment

in method T there are two alternate criteria for explosion (self-propagating combustion): i) the

detachment and upward movement of the flame from the spark gap for at least 100 mm, or ii) the

formation of a halo which either reaches the top of the tube, or reaches a minimum height of 240 mm

Note 1 to entry: Throughout the duration of the ignition spark, test mixtures, whose test substance content lies

just outside the explosion range, may exhibit a luminous phenomenon (referred to as a “halo”) above the spark

gap which does not detach from the latter (see Annex C). For some test substances (e.g. halogenated

hydrocarbons), this luminous phenomenon can occupy a large portion of the test vessel. The formation of a halo

alone is not considered to count as an ignition of the test mixture unless it reaches the top of the tube or a

minimum height of 240 mm.
3.10
explosion criterion — pressure rise

in method B, the criterion for an explosion (self-propagating combustion) is the generation of explosion

overpressure which is equal to or greater than the overpressure created by the ignition source alone in

air plus (5 ± 0,1) % of the initial pressure
3.11
vapour
gaseous phase emanating or being emanated from a liquid

Note 1 to entry: If not otherwise mentioned, the term “gas” in this standard also includes such vapours but not

mists.
3.12
oxidizer
air or an air / inert gas mixture (volume fraction of the oxygen < 21 %)
3.13
sample

substance or mixture of substances for which explosion limits are to be determined

3.14
test substance

sample in the gaseous state; in the case of liquid samples, after complete evaporation

3.15
test mixture
mixture of test substance and air or air / inert gas
4 Test methods
4.1 General

The determination consists of a series of ignition tests which are carried out with test mixtures whose

test substance content is varied when determining the explosion limits and with test mixtures whose

test substance content and inert gas content is varied when determining the limiting oxygen

concentration..

For organic substances which consist exclusively of carbon, hydrogen and oxygen (with the exception of

peroxides), the LEL can be roughly estimated. At 20 °C, the LEL, in many cases, is approximately half the

test substance content of the stoichiometric composition in air. The temperature dependence of the LEL

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SIST EN 1839:2017
EN 1839:2017 (E)

has to be taken into account. Up to 200 °C, the LEL decreases more or less linearly between 30 % and

50 % of the value estimated for 20 °C.
There is currently no method which readily estimates the UEL.

When it is established that a given test mixture will not ignite, it is recommended that the quantitative

composition of the non-ignited test mixture flowing out of the test vessel is analysed in order to

determine whether any errors have arisen either with the metering devices or due to leakage.

4.2 Method T (“tube” method)
4.2.1 Detailed method

The test mixture flows through the cylindrical test vessel from the bottom upwards to the top until the

contents previously in the test vessel have been completely replaced. Then, under quiescent conditions,

an ignition is initiated using a series of induction sparks. It is observed whether or not flame

detachment occurs. When determining the LEL or the UEL (explosion criterion — flame detachment)

the test substance content of the test mixture is varied stepwise until an ignition of the mixture just fails

or until it is established that there is no explosion range.. When determining the LOC the test substance

content of the test mixture as well as the inert gas content is varied stepwise until an ignition of the

mixture just fails.
4.2.2 Reagents and materials

4.2.2.1 Air, which shall be free of water (≤0,1 mol% water vapour absolute) and oil (≤0,1 g / m

oil)
If synthetic air is used, it has to be stated in the report.

4.2.2.2 Inert gases, the purity of the inert, or the mixture of inerts, shall be 99,8 % mol. or better

If a mixture of inerts is used, the composition of the mixture shall be stated in the test report.

4.2.2.3 Flammable substances, which may be either a single substance or a defined mixture of

substances or a process sample (of known or unknown composition)

When a single substance or a defined mixture of substances is used, the purity of each substance shall

be 99,8 % mol. or better. In the case of a mixture of substances or a process sample of known

composition, the precision of the composition shall be stated in the test report. For a process sample

with unknown composition, the sample shall be defined as precisely as possible (e.g. process

conditions).

If the flammable gas is derived from a liquid containing more than one component, the gas phase

composition can differ from the composition of the liquid phase. When large volumes of the gas are

removed, the composition of both the liquid and gas phases can change with time. For these reasons,

the test sample shall be taken from the liquid phase.

4.2.2.4 Heat-resistant, chemically inert material for gaskets and adhesive mountings

Sample containers shall be kept closed before and after sampling to avoid changes in the sample

composition within the container (e.g. loss of volatile components from mixtures). If a sample container

contains a mixture with both gaseous and liquid phases present, the mixture composition of the two

phases will be different. Under such conditions, it is recommended that the test substance sample be

removed from the liquid phase. If the sample is taken from the gaseous phase, account shall be taken of

the difference in composition.
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EN 1839:2017 (E)
4.2.3 Apparatus
4.2.3.1 Test vessel

The test vessel is an upright cylindrical vessel made of glass or other transparent material (e.g.

polycarbonate) with an inner diameter of (80 ± 2) mm and a minimum length of 300 mm.

The vessel is equipped with an inlet pipe with a three-way valve for the test mixture, located at the

bottom, and an outlet pipe and pressure vent in the upper part.

The bottom and top may be made of other material. However, the material shall be free of any catalytic

effect and resistant to corrosion from the test mixture or the reaction products.

4.2.3.2 Ignition source

A series of induction sparks between two electrodes is used as the ignition source.

The electrodes shall end (60 ± 1) mm above the bottom of the test vessel.

Stainless steel is a suitable material for the electrodes. The electrodes shall be pointed rods with a

diameter of maximum 4 mm. The angle of the tips shall be (60 ± 3)°. The distance between the tips shall

be (5 ± 0,1) mm. The electrodes shall be mounted in the vessel so that they are gas tight at the highest

explosion pressures generated during the test. The mounting shall be resistant to both heat and the test

mixture, and also provide adequate electrical resistance from the test vessel body

...

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