EN 14756:2006

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

This European Standard specifies 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.

Bestimmung der Sauerstoffgrenzkonzentration (SGK) für brennbare Gase und Dämpfe

Diese Europäische Norm legt das Verfahren zur Bestimmung der SGK von Gemischen aus brennbarem Gas
oder Dampf mit Luft und Inertgas bei Atmosphärendruck und Temperaturen von Umgebungstemperatur bis
200 °C fest.

Détermination de la concentration limite en oxygène (CLO) des gaz et des vapeurs inflammable

La présente Norme européenne spécifie la méthode permettant de déterminer la CLO de mélanges constitués
de gaz ou de vapeurs inflammables, d’air et de gaz inerte, à la pression atmosphérique et à des températures
allant de la température ambiante à 200 °C.

Ugotavljanje mejne koncentracije kisika (LOC) za vnetljive pline in hlape

General Information

• Status: Withdrawn
• Publication Date: 14-Nov-2006
• Withdrawal Date: 10-Jan-2017
• ICS: 13.230 - Explosion protection
• Technical Committee: CEN/TC 305 - Potentially explosive atmospheres - Explosion prevention and protection
• Drafting Committee: CEN/TC 305/WG 1 - Test methods for determining the flammability characteristics of substances (provisional title)
• Current Stage: 9960 - Withdrawal effective - Withdrawal
• Completion Date: 11-Jan-2017
• Directive: 2014/34/EU - Directive 2014/34/EU Of The European Parliament And Of The Council of 26 February 2014 on the harmonisation of the laws of the Member States relating to equipment and protective systems intended for use in potentially explosive atmospheres (recast)
• Directive: 94/9/EC - Directive 94/9/EC of the European Parliament and the Council of 23 March 1994 on the approximation of the laws of the Member States concerning equipment and protective systems intended for use in potentially explosive atmospheres
• Mandate: M/BC/CEN/92/46 - Standardization mandate assigned to CEN/CENELEC concerning equipment and protective systems intended for use in potentially explosive atmospheres
• Ref Project: SIST EN 14756:2007 - Determination of the limiting oxygen concentration (LOC) for flammable gases and vapours

Relations

• Replaced By: EN 1839:2017 - Determination of the explosion limits and the limiting oxygen concentration(LOC) for flammable gases and vapours
• Effective Date: 08-Jun-2022

Standards Content (Sample)

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Ugotavljanje mejne koncentracije kisika (LOC) za vnetljive pline in hlapeBestimmung der Sauerstoffgrenzkonzentration (SGK) für brennbare Gase und DämpfeDétermination de la concentration limite en oxygene (CLO) des gaz et des vapeurs inflammableDetermination of the limiting oxygen concentration (LOC) for flammable gases and vapours13.230Varstvo pred eksplozijoExplosion protectionICS:Ta slovenski standard je istoveten z:EN 14756:2006SIST EN 14756:2007en01-april-2007SIST EN 14756:2007SLOVENSKI
STANDARD
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 14756November 2006ICS 13.230 English VersionDetermination of the limiting oxygen concentration (LOC) forflammable gases and vapoursDétermination de la concentration limite en oxygène (CLO)des gaz et des vapeurs inflammableBestimmung der Sauerstoffgrenzkonzentration (SGK) fürbrennbare Gase und DämpfeThis European Standard was approved by CEN on 2 October 2006.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2006 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14756:2006: ESIST EN 14756:2007

Examples of the determination of the LOC.13 A.1 Example 1: Determination of the LOC – short procedure.13 A.2 Example 2: Determination of the LOC – extended procedure.14 Annex ZA (informative)
Relationship between this European Standard and the Essential Requirements of EU Directive 94/9/EC.15 Bibliography.16 Figures Figure 1 — Explosion area for a ternary system of test substance, air and inert gas.7 Figure 2 — Short procedure scheme for the determination of the LAC.10 Figure 3 — Extended procedure scheme for the determination of the LAC.11 Figure A.1 — Determination of the LAC of a ternary system of n-hexane, air and nitrogen at 100 °C and ambient pressure.13 Figure A.2 — Determination of the LAC of a ternary system of hydrogen, air and nitrogen at 20 °C and ambient pressure.14 Tables Table ZA.1 — Correspondence between this European Standard and Directive 94/9/EC.15
1 Scope This European Standard specifies 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. 2 Normative references The following referenced documents are indispensable for the application 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. EN 1839:2003, Determination of explosion limits of gases and vapours 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 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, determined under specified test conditions NOTE 1 LAC is usually expressed as molar fraction in % or volume fraction in % (for conversion of units see EN 1839:2003, Annex F). NOTE 2 The LAC does not depend only on the flammable gas or vapour, but also on the inert gas used. 3.2 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 NOTE 1 LOC is usually expressed as molar fraction in % or volume fraction in % (for conversion of units see EN 1839:2003, Annex F) NOTE 2 The LOC does not depend only on the flammable gas or vapour, but also on the inert gas used. 3.3 test substance substance or mixture of substances for which the LOC is to be determined NOTE The test substance is usually a flammable gas or the vapour generated by the complete evaporation of a flammable liquid. 3.4 test mixture mixture of test substance, air and inert gas SIST EN 14756:2007

Key 1 explosion area 2 apex 3 stoichiometric line x molar fraction in % IN inert gas TS test substance a air Figure 1 — Explosion area for a ternary system of test substance, air and inert gas 4 Test apparatus The standard test apparatuses for determination of the LOC are described in EN 1839. For practical reasons there are two methods for the determination of the explosion limits, a tube method (T) and a bomb method (B). A specific apparatus is specified for each method, both of which are suitable for the determination of the LOC. It shall be clearly stated which of the two methods was used, as the apparatus and test procedure may influence the LOC value. For the purposes of this European Standard the oxygen concentration shall be measured by means of a calibrated oxygen analyser with a precision of a molar fraction of 0,1 % oxygen (e.g. paramagnetic analyser, gas chromatography etc.).
the flammable substance may be:  a single substance or a defined mixture of substances;  a process sample (of known or unknown composition). When a single substance or a mixture of substances is used, the purity of each substance shall be a molar fraction of 99,8 % 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. In the case of a process sample of unknown composition, the sample shall be defined as well as possible (e.g. process conditions, lower explosion limit). 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 quantities of the gas are drawn off, 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. 6 Test method 6.1 Principle Ignition trials with defined test mixtures according to EN 1839 (method (T) or (B)) are carried out in order to obtain the explosion area or a part of the explosion area for a ternary system of test substance, air and inert gas. By increasing incrementally the fraction of inert gas in the test mixtures the limiting air concentration, LAC, is obtained. From the measured LAC the LOC is calculated according to the following equation: LACLOC209,0= (1) 6.2 Procedures 6.2.1 General Two different methods are described for the determination of the LAC, an extended procedure and a short procedure. The short procedure may be applied if the LAC is at the apex of the explosion area, which is mostly the case. The extended procedure shall be applied if the LAC is given by a tangent on the UEL branch. The criterion for the decision "short procedure" or "extended procedure" is given by Equation (2). ()Lair,xUEL–1008,0≤ (2) where Lair,x is the air fraction at the explosion limit, as molar fraction in %, measured according to step 2. SIST EN 14756:2007
...