SIST EN 14756:2007
(Main)Determination of the limiting oxygen concentration (LOC) for flammable gases and vapours
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 oxygene (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, a la pression atmosphérique et a des températures
allant de la température ambiante a 200 °C.
Ugotavljanje mejne koncentracije kisika (LOC) za vnetljive pline in hlape
General Information
Relations
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
SIST EN 14756:2007
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
EN 14756:2006 (E) 2 Contents Page Foreword.3 Introduction.4 1 Scope.5 2 Normative references.5 3 Terms and definitions.5 4 Test apparatus.7 5 Reagents and materials.8 6 Test method.8 6.1 Principle.8 6.2 Procedures.8 6.2.1 General.8 6.2.2 Short procedure.9 6.2.3 Extended procedure.11 6.3 Oxygen analysis.12 7 Verification of the test apparatus.12 8 Safety precautions.12 9 Test report.12 Annex A (informative)
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
SIST EN 14756:2007
EN 14756:2006 (E) 3 Foreword This document (EN 14756:2006) 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 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 May 2007, and conflicting national standards shall be withdrawn at the latest by May 2007. 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 Directive(s), see informative Annex ZA, which is an integral part of this document. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: 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. SIST EN 14756:2007
EN 14756:2006 (E) 4 Introduction This European Standard describes a method for the experimental determination of the limiting oxygen concentration (LOC) of mixtures consisting of flammable gas or vapour, air and inert gas. The LOC is the maximum concentration of oxygen in a mixture at which an explosion cannot occur at any fuel concentration. Explosion protection by "inerting" is based on the LOC. SIST EN 14756:2007
EN 14756:2006 (E) 5
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
EN 14756:2006 (E) 6 3.5 inert gas gas that does not react with the test substance or oxygen 3.6 explosion range range of concentration of a flammable substance or mixture of substances in air within which an explosion can occur 3.7 explosion limit limit of the explosion range or of the explosion area NOTE 1 Explosion limits (lower explosion limits, LEL, and upper explosion limits, UEL) are determined according to EN 1839. At the explosion limits flame propagation does not occur. The explosion limits are not part of the explosion range or explosion area. NOTE 2 Explosion limits means also the limits where the test mixture contains additional fractions of inert gas. 3.8 explosion area area inside the boundary curve formed by the explosion limits of a flammable substance in various mixtures with air and inert gas NOTE 1 See Figure 1. NOTE 2 In many cases the boundary curve has an apex, which corresponds to the limiting air concentration, LAC. SIST EN 14756:2007
EN 14756:2006 (E) 7
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.).
SIST EN 14756:2007
EN 14756:2006 (E) 8 5 Reagents and materials Air: the air shall be free of water and oil. If
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