EN 14373:2005

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Explosion suppression systemsSistemi za dušenje eksplozijSystemes de suppression d'explosionExplosions-Unterdrückungssysteme13.230Varstvo pred eksplozijoExplosion protectionICS:SIST EN 14373:2006enTa slovenski standard je istoveten z:EN 14373:200501-februar-2006SIST EN 14373:2006SLOVENSKI
STANDARD
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 14373October 2005ICS 13.230 English VersionExplosion suppression systemsSystèmes de suppression d'explosionExplosionsunterdrückungs-SystemeThis European Standard was approved by CEN on 16 August 2005.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, 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© 2005 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14373:2005: E

Page Foreword.5 1 Scope.6 2 Normative references.6 3 Terms and definitions.7 4 Explosion suppression.10 4.1 General.10 4.2 Influencing factors.11 4.2.1 General.11 4.2.2 The explosion hazard.11 4.2.3 The explosion suppressant.12 4.2.4 The suppression system.12 4.2.5 Interrelation.12 5 General requirements for explosion suppression components.13 5.1 Detection.13 5.1.1 General.13 5.1.2 Optical detection.13 5.1.3 Pressure detection.13 5.2 Suppressant.13 5.3 HRD-suppressors.14 5.4 Control and Indicating Equipment, CIE.15 6 Requirements for the design of an explosion suppression system.15 6.1 General.15 6.2 Hazard definition.15 6.3 Determination of the pred, max as a function of relevant influencing parameters.16 6.3.1 General.16 6.3.2 Validation by testing in one volume.16 6.3.3 Validation by testing in a second volume.22 6.3.4 Elongated enclosures.22 6.3.5 Pipes.23 6.3.6 Occupied spaces.23 6.4 Validation of system design guidelines.23 6.4.1 General.23 6.4.2 Design nomograph.24 6.4.3 Mathematical model for design.25 6.5 Special applications.26 6.5.1 Suppression combined with venting.26 6.5.2 Venting combined with suppression.27 6.5.3 Suppression combined with reduced oxygen concentrations.27 6.5.4 Partial volumes.27 6.5.5 Segregated volumes.28 6.5.6 Obstructed volumes.28 6.6 Test report.29 7 Safety integrity of explosion suppression systems.30 7.1 General.30 7.2 Measures to avoid and control systematic faults.30 7.3 Control of electric connections.30 7.4 Indicators and messages CIE.30 7.5 Energy supply.31 8 Instructions for installation, commissioning and maintenance.31

Development of nomograph type design guidelines.35 A.1 General.35 A.2 Design nomograph.35 Annex ZA (informative)
Relationship between this European Standard and the Essential Requirements of EU Directive 94/9/EC of 23 March 1994.39 Bibliography.42 Figures: Figure 1 — Pressure behaviour versus time for a normal and suppressed explosion.11 Figure 2 — Effectiveness of suppressant.14 Figure 3 — Pressure behaviour and pressure rate of pressure rise versus concentration for a normal and suppressed explosion.17 Figure 4 — Maximum reduced explosion pressure, pred, max behaviour versus maximum explosion constant, Kmax.18 Figure 5 — Maximum reduced explosion pressure, pred, max
behaviour versus activation pressure, pa.20 Figure 6 — Maximum reduced explosion pressure, pred, max behaviour versus number of HRD-suppressors, HRDs20 Figure 7 — Maximum reduced explosion pressure, pred, max behaviour versus dispersion agent pressure ps.21 Figure 8 — Design nomograph for a specific explosion suppression system.24 Figure 9 — Calculated maximum reduced explosion overpressure versus measured maximum reduced explosion overpressure for pred, max values up to 0,5 bar.25 Figure 10 — Calculated maximum reduced explosion overpressure versus measured maximum reduced explosion overpressure for pred, max values above 0,5 bar.26 Figure 11 — Example of an enclosure where an explosive concentration prevails only in the lower section.28 Figure A.1— Design nomograph for a specific explosion suppression system.36 Figure A.2 — Design guideline for a fuel range.37 Figure A.3 — Volume limits of the design guideline for a fuel range.37

dispersion device device fitted on a HRD-Suppressor and designed to spread the suppressant throughout the volume to be protected 3.14 enclosure
3.14.1 compact enclosure cubic enclosure enclosures having a length (height) to diameter ratio of less than 2 3.14.2 elongated enclosures enclosures with length (height) to diameter ratio of 2 to 10 3.14.3 pipe construction with a ratio length (height) to diameter greater than 10 3.15 combination systems
3.15.1 suppression combined with venting system combining the technology of explosion suppression with explosion venting 3.15.2 venting combined with suppression system designed to minimise flame ejection out of an explosion vent 3.15.3 reduced oxygen concentration combined with suppression system where a reduced oxygen concentration is used to minimise the explosion intensity and suppression is used to suppress the reduced explosion intensity 3.16 design strength of enclosure p (plant strength)
3.16.1 explosion resistant enclosures enclosures and equipment, inclusive of attached pipelines, which are designed in accordance with CEN-regulation, such that the expected explosion pressure can be withstood without permanent deformation 3.16.2 explosion shock resistant enclosures enclosures and equipment, inclusive of attached pipelines, which are designed in accordance with CEN-regulation such that they will resist the anticipated overpressure of an explosion. Unlike the criteria for explosion resistant enclosures, with explosion shock resistant enclosures some plastic deformation is allowable. In designing these enclosures, a higher utilisation of the strength of the material of construction is assumed

Key 1 Activation of the suppression system 2 Closed enclosure explosion 3 Suppressed explosion Y Explosion overpressure p, in bar X Time t, in s Figure 1 — Pressure behaviour versus time for a normal and suppressed explosion For most practical applications of explosion suppression the worst case maximum suppressed explosion pressure, pred, max that can result is determined. Provided that this suppressed explosion pressure is lower than the process equipment design strength and provided further that suppression is achieved with a sufficient margin of safety, effective explosion suppression can be assured. 4.2 Influencing factors 4.2.1 General The effectiveness of an explosion suppression system depends on the parameters listed in 4.2.2 to 4.2.4. 4.2.2 The explosion hazard a) Volume of enclosure (free volume, V); b) shape of enclosure (surface area and length (height) to diameter ratio); c) explosible material (gas, dust, flammable liquids, mixtures thereof); d) homogeneity and intrinsic turbulence of the explosive atmosphere; e) induced turbulence caused by interaction of the combustion wave with internal obstacles and reflected pressure waves; f) initial pressure; g) temperature condition; h) explosibility parameters of explosible materials: 1) maximum explosion overpressure, pmax;

Key 1 Less effective suppressant 2 Effective suppressant 3 Very effective suppressant X pa (bar) Y pred, max (bar) Figure 2 — Effectiveness of suppressant The application of a suppressant is dependent upon how effective it is at suppressing an explosion. Testing shall be used to determine the effectiveness and performance of the suppressant, thus quantifying the applicability of the suppressant. The following parameters shall be considered when selecting a suppressant: a) any adverse reaction with the process products; b) toxicity levels of the suppressant relating to occupational exposure limits; c) temperature stability of the suppressant. In addition the following properties shall be taken into account where necessary: d) Will the suppressant have to be food compatible? e) Will the suppressant cause the onset of corrosion? f) Is the suppressant environmentally friendly? g) Can the suppressant be easily removed from the process? 5.3 HRD-suppressors HRD-suppressors are available in a range of sizes. Suppressant is stored in a container which is typically pressurised. A rapidly actuated container opening mechanism provides almost instantaneous unimpeded release for the suppressant, which is expelled by propelling agent and discharged through an appropriate dispersion device, if required, into the process equipment. HRD-suppressors that utilise a large diameter outlet have superior suppression capability over those that rely on high dispersion agent pressure alone to expel the suppressant agent. The HRD-suppressor and the dispersion system have an important influence on suppression effectiveness. The performance of HRD-suppressors with specific mounting adapters and dispersion system as appropriate shall be proven through tests (Clause 6). The number and distribution of HRD-suppressors are dependent upon the geometric size and shape of the enclosure to be protected and are crucial to achieving the best suppression performance. The application of HRD-suppressor(s) shall allow for the most effective discharge of suppressant, taking into account the following:

1. series 250 g m-3, 500 g m-3, 750 g m-3
2. series
500 g m-3
3. series
500 g m-3
a) b) Key 1 unsuppressed explosion 2 suppressed explosion NOTE The activation pressure pa and the number of suppressors (suppressant charge) are constant. Figure 3 — Pressure behaviour and pressure rate of pressure rise versus concentration for a normal and suppressed explosion The suppression system shall be prepared (dispersion agent pressure, suppressant charge) and installed on the test apparatus in accordance with the manufacturer‘s recommendations. 6.3.2.1.2 Variation of maximum explosion constant, Kmax To determine the range (limit) of application of a particular explosion suppression system against explosion hazards in a chosen test volume, a series of evaluations shall be undertaken against different explosions of increasing severity by varying Kmax (see Figure 4).

Key X ×sbarm maxK Y pred,max (bar)
NOTE The activation pressure pa and the number of HRD-suppressors (suppressant charge) are constant. Figure 4 — Maximum reduced explosion pressure, pred, max behaviour versus maximum explosion constant, Kmax The variation of Kmax values shall be obtained as follows: a) Dust as a fuel: Using dusts with different Kmax values or by using the same dust and varying the ignition delay time, tv, and the concentration, C, to obtain different rates of pressure rise in order to simulate different Kmax values. b) Gas as a fuel: Evaluating the performance of a suppression system in tests with propane will be satisfactory for vapours of many industrial solvents. Where the burning characteristics of the gas or vapour are greater than that of propane, the performance of the suppression system shall be evaluated using a test gas or vapour with equal or higher explosion characteristics. For turbulent conditions, the standard turbulence test method with turbulence varied by varying the ignition delay shall be used (see EN 26184-3). c) Hybrid mixtures as a fuel: For hybrid mixtures, the gas under turbulent conditions and the dust are investigated separately, and the worst case taken as the criterion for the efficacy of the suppression system (see EN 26184-3). d) Mists as a fuel: For mists a test procedure analogous to that used for dust shall be chosen. It is necessary to confirm that the test methodology used produces a mist with droplet size distribution equivalent to or smaller than occurs in the plant equipment for such testing to be considered valid (see also EN 26184-3).
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