Explosion prevention and protection in underground mines - Equipment and protective systems for firedamp drainage

This standard specifies the requirements for equipment for firedamp drainage. That equipment can consist of ventilators, pressure generators and safety facilities. This standard also specifies requirements for the installation and monitoring of this equipment.

Explosionsschutz in untertägigen Bergwerken - Geräte und Schutzsysteme zur Absaugung von Grubengas

Diese Norm legt Anforderungen für Geräte und Schutzsysteme zur Absaugung von Grubengas aus Bergwerken fest. Sie enthält auch Anforderungen für die Einrichtung und die Überwachung dieser Geräte und Schutzsysteme (siehe EN 1127-2).
Diese Norm gilt nicht für die Verwertung von Grubengas im Anschluss an die Absperrvorrichtung zur Verwertung.

Protection contre l'explosion dans les mines souterraines - Appareils et systemes de protection destinés au captage du grisou

La présente norme spécifie les exigences pour les appareils et systemes de protection destinés au captage du grisou dans les mines. Elle contient également les exigences relatives a la mise en place et la surveillance de ces appareils et systemes de protection (voir EN 1127-2).

Preprečevanje eksplozij in zaščita v podzemnih rudnikih - Oprema in zaščitni sistemi za odvajanje jamskega plina

General Information

Status
Published
Publication Date
20-Jun-2007
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
14-Jun-2007
Due Date
19-Aug-2007
Completion Date
21-Jun-2007

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Explosion prevention and protection in underground mines - Equipment and protective systems for firedamp drainageProtection contre l'explosion dans les mines souterraines - Appareils et systemes de protection destinés au captage du grisouExplosionsschutz in untertägigen Bergwerken - Geräte und Schutzsysteme zur Absaugung von GrubengasTa slovenski standard je istoveten z:EN 14983:2007SIST EN 14983:2007en;fr;de73.100.203UH]UDþHYDOQDVentilation, air-conditioning and illumination equipment13.230Varstvo pred eksplozijoExplosion protectionICS:SLOVENSKI

STANDARDSIST EN 14983:200701-julij-2007

EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 14983March 2007ICS 73.100.20 English VersionExplosion prevention and protection in underground mines -Equipment and protective systems for firedamp drainageProtection contre l'explosion dans les mines souterraines -Appareils et systèmes de protection destinés au captagedu grisouExplosionsschutz in untertägigen Bergwerken - Geräte undSchutzsysteme zur Absaugung von GrubengasThis European Standard was approved by CEN on 13 January 2007.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 CEN 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 translationunder the responsibility of a CEN member into its own language and notified to the CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium, Bulgaria, 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© 2007 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14983:2007: E

EN 14983:2007 (E) 2 Contents Page Foreword..............................................................................................................................................................4 Introduction.........................................................................................................................................................5 1 Scope......................................................................................................................................................6 2 Normative references............................................................................................................................6 3 Terms and definitions...........................................................................................................................6 4 Equipment and protective systems for firedamp drainage...............................................................8 4.1 General....................................................................................................................................................8 4.2 Borehole standpipes.............................................................................................................................8 4.3 Drainage pipes for seals and stoppings...........................................................................................12 4.4 Water separators at drainage points.................................................................................................12 4.5 Firedamp pipes....................................................................................................................................12 4.5.1 General requirements for firedamp pipes.........................................................................................12 4.5.2 Measuring points for measuring equipment in firedamp drainage pipes......................................13 4.6 Pressure vessels in firedamp drainage plant...................................................................................13 4.7 Exhausters............................................................................................................................................13 4.7.1 Requirements for exhausters.............................................................................................................13 4.7.2 Reserve exhausters.............................................................................................................................14 4.7.3 Location of exhausters.......................................................................................................................14 4.8 Venting of the drained firedamp.........................................................................................................14 4.9 Explosion prevention systems for pipelines....................................................................................15 4.9.1 Explosion barriers...............................................................................................................................15 4.9.2 Non-flammable firedamp vent pipe outlets and flame arrester outlets..........................................15 4.9.3 Reserve container and operating state.............................................................................................16 4.10 Requirements for the design of electrical safety devices...............................................................16 4.11 Electrostatic ignition risks..................................................................................................................16 5 Instructions for installation and use..................................................................................................17 Annex A (informative)

Installation and use of firedamp drainage system..................................................18 A.1 General..................................................................................................................................................18 A.2 Work on firedamp pipes......................................................................................................................18 A.3 Measures to be taken when gas levels fall below or exceed limit values during firedamp drainage................................................................................................................................................19 A.4 Failure or shutdown of exhausters....................................................................................................19 Annex B (informative)

Monitoring of firedamp drainage system.................................................................20 B.1 Examination and inspection by competent persons.......................................................................20 B.2 Measurement of the drained firedamp mixture and pressure.........................................................20 B.2.1 Measurements taken by hand............................................................................................................20 B.2.2 Fixed monitoring equipment..............................................................................................................20 B.3 Documentation.....................................................................................................................................21 B.4 Firedamp circuit plan..........................................................................................................................21 Annex C (informative)

Requirements for location of exhausters.................................................................22 Annex D (informative)

Requirements for gas removal equipment for abandoned surface outlets..........23 Annex E (informative)

Example for calculation of t90 path............................................................................27 E.1 General..................................................................................................................................................27 E.2 Example for calculation of t90-path...................................................................................................27 Annex ZA (informative)

Relationship between this
European
Standard and the Essential Requirements

of EU Directive 94/9/EC.............................................................................................29

EN 14983:2007 (E) 3 Bibliography......................................................................................................................................................31

Figures Figure 1 —

Example of connection of roof borehole to collector pipe when measurement and control are accessible..............................................................................................................................................9 Figure 2 — Example of connection of roof borehole to collector pipe when measurement and control are not accessible.....................................................................................................................................10 Figure 3 — Example of connection of floor borehole to collector pipe when measurement and control are accessible............................................................................................................................................11 Figure 4 — Example of connection of floor borehole to collector pipe when measurement and control are not accessible.....................................................................................................................................12 Figure 5 — Example of explosion prevention system for pipelines with one firedamp vent pipe..........15 Figure D.1 — Passive gas removal equipment (Type II)...............................................................................25 Figure D.2 — Passive gas removal equipment (Type III)..............................................................................26 Figure E.1 — Schematic arrangement of a t90-path.....................................................................................28 Tables Table D.1 — Requirements for gas removal equipment for abandoned surface outlets..........................24 Table ZA.1 — Correspondence between the European Standard and Directive 94/9/EC.........................29

EN 14983:2007 (E) 4 Foreword This document (EN 14983:2007) 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 shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by September 2007, and conflicting national standards shall be withdrawn at the latest by September 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, Bulgaria, 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 the United Kingdom.

EN 14983:2007 (E) 5 Introduction Firedamp drainage is a technical process for selected gas removal, the purpose of which is to reduce the risks presented by inflammable gas and air mixtures. Firedamp drainage is therefore a measure for preventive explosion protection.

In the mining industry, firedamp is drained from the underground workings of gassy mines, from boreholes and abandoned mine workings to ensure that mine workers are not exposed to the risks associated with the occurrence of an explosive atmosphere at their place of work. In this case, the explosion risk results from unacceptable accumulations of firedamp occurring in the waste areas and cavities left in the in the rock strata after the coal has been extracted from the coal seam. In such cases, the need to drain these accumulations, and the complexity of the drainage system, depends on the amount of firedamp produced by the coal and the likelihood of it occurring in explosive quantities in the mine roadways and coal face. Examples of situations that might cause firedamp to move in dangerous concentrations from the waste area or cavities into the mine roadways: a breakdown of the mine ventilation system or a sudden reduction in the underground atmospheric pressure. National legislation in EU coal mining member countries requires workers to be withdrawn to a safe place if firedamp levels attain a specific nationally defined value in the general body of mine air. Firedamp drainage is therefore often used in gassy mines in an attempt to ensure that the concentration of firedamp in the general body of mine air is kept well below this critical level, even during abnormal situations such as those described above.

Once the accumulations of firedamp have been drained from the affected areas, it is usually discharged to the mine surface, but in some cases it is discharged into the mine return ventilation system. In systems where the firedamp is brought to the mine surface, it is discharged to the atmosphere through an earthed metallic discharge stack or pressurized and delivered to a utilisation system, such as a gas-fired boiler.

In abandoned mines, firedamp drainage is used

¾ to prevent gas pressure building up and gas issuing at the surface in an uncontrolled manner, and ¾ to protect workers at an adjacent nearby mine or ¾ to allow it to be utilized, for example by burning it in a gas-fired boiler to produce heat or to generate electricity.

EN 14983:2007 (E) 6 1 Scope This standard specifies the requirements for equipment and protective systems for firedamp drainage at mines. It also contains requirements for the construction and monitoring of this equipment and protective systems (see EN 1127-2). This standard does not apply to firedamp utilization systems beyond the utilization shut-off device. 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 1127-2:2002, Explosive atmospheres — Explosion prevention and protection — Part 2: Basic concepts and methodology for mining

EN 1710:2005, Equipment and components intended for use in potentially explosive atmospheres in underground mines EN 1333, Flanges and their joints — Pipework components — Definition and selection of PN EN 12874, Flame arresters — Performance requirements, test methods and limits for use EN 13237:2003, Potentially explosive atmospheres — Terms and definitions for equipment and protective systems intended for use in potentially explosive atmospheres

prEN 15089, Explosion isolation systems prEN 61024-1, Protection of structures against fire, explosion and life hazards EN 61508 (all parts), Functional safety of electrical/electronic/programmable electronic safety-related systems 3 Terms and definitions For the purposes of this document, the terms and definitions given in EN 1127-2:2002 and EN 13237:2003 and the following apply:

3.1 electrostatic leakage resistance electrical resistance measured between an object and earth

3.2 active explosion isolation system system which is designed to be activated by a detector and control and indicating equipment (CIE) which are inherent parts of the system and stop explosions from travelling through pipelines or limit destructive effects of the explosion

[prEN 15089:2004, 3.12.1]

3.3 starting by-pass temporary and specific by-passing of a safety device when starting the exhauster of a firedamp drainage plant

EN 14983:2007 (E) 7

3.4 design pressure pd pressure at the top of each chamber of the pressure equipment chosen for the derivation of the calculation pressure of each component2

[EN 764-1:2004, 3.10]

3.5 pressure pressure relative to atmospheric pressure, i.e. gauge pressure. As a consequence, vacuum is designated by a negative value

[EN 764-1:2004, 3.3]

3.6 flame arrester device fitted to the opening of an enclosure or to the connecting pipework of a system of enclosures and whose intended function is to allow flow, but prevent the transmission of flame

NOTE This device should not be confused with a fire barrier, which is ineffective in case of explosion.

[EN 13237:2003, 3.41]

3.7 firedamp any potentially explosive mixture of flammable gases naturally occurring, which may form a hazardous mixture when combined with air

NOTE As firedamp mainly consists of methane, in mining practice, the terms “firedamp” and “methane” are frequently used as synonyms.

[EN 1127-2:2003, 3.1]

3.8 firedamp collector pipe gas pipes connected directly to one or more boreholes or gas drainage points

3.9 firedamp mains pipe gas pipes connected to more than one gas collector pipe

3.10 extinguishing system system that is used to discharge suppressant agent to extinguish flame and keep it from propagating into the vent pipe

3.11 technically leaktight made in such a way that no changes in gas composition occur.

NOTE 1 Gas pipes, items of plant and equipment, including all detachable and non-detachable connections can be technically leaktight. NOTE 2

The term “technically leaktight” means that diffusion through statically stressed seals can occur.

EN 14983:2007 (E) 8
3.12 t90-path distance between the monitoring position and the shut-off device

NOTE This distance depends on the measured gas/air mixture, taking account of the velocity of flow, the response time (according to EN 61779-1) of the measurement device, the tripping time and the closing time of the rapid shut-off device; the response time is the time taken to achieve 90% of the final indication.

4 Equipment and protective systems for firedamp drainage 4.1 General Electrical and mechanical equipment used in firedamp drainage shall not pose an explosion risk. For this reason: ¾ equipment used in the firedamp drainage systems where flammable gas is likely to occur shall be explosion protected either Group I Category M1 or M2, or, if on the surface, Group II Category 1 or 2; ¾ where measuring equipment is in direct contact with firedamp/air concentration within the explosive range (e.g. the purity measuring instruments), it shall be category M1 ignition protected. In surface installations, Group II, Category 1 equipment may be used; ¾ the drainage system shall have a facility to allow it to be shut down, usually automatically, where the concentration of extracted firedamp in the pipework reaches a prescribed limit, taking into account the response time of the monitoring equipment and the t90-path (see Annex E). NOTE 1 Care is needed during start-up of the firedamp drainage system when the pipework will be full of air and will at some stage pass through the explosive range. NOTE 2 Normally, the explosive range for firedamp/air mixtures is specified within a range of about 5 % by volume to

15 % by volume methane. Automatic shut down usually takes place when a methane concentration reaches a level of approx. 22 % by volume. 4.2 Borehole standpipes Standpipes shall be made in such a way that devices (Y- or T-pieces) for the insertion of borehole probes can be attached to them. The standpipe shall have connection facilities to allow it to be connected, it shall be made in such a way and arranged so that no reduction in cross-section occurs, and should contain a suitable facility for measuring the volume flow and vacuum pressure where the boreholes are accessible for measuring and taking firedamp samples, e.g. a measuring section (see Figures 1 to 4).

EN 14983:2007 (E) 9
Key d
Diameter 1
Borehole standpipe 2
Flexible hose suitable for the required flow and pressure 3
T-piece 4
Connection for water separator 5
Facility for measurements 6
Facility for measurements 7
Measuring section 8
Collector pipe 9
Shut off device Figure 1 —

Example of connection of roof borehole to collector pipe when measurement and control are accessible

EN 14983:2007 (E) 10
Key 1
Borehole standpipe 2
Flexible hose suitable for the required flow and pressure 3
Collector pipe 4
Shut-off device 5

Suitable connection for collector pipe Figure 2 — Example of connection of roof borehole to collector pipe when measurement and control are not accessible

EN 14983:2007 (E) 11
Key d
Diameter 1
Borehole standpipe 2
Flexible hose suitable for the required flow and pressure 3
T-piece 4
Connection for water separator 5
Facility for measurements 6
Facility for measurements 7
Measuring section 8
Shut-off device 9
Collector pipe

Figure 3 — Example of connection of floor borehole to collector pipe when measurement and control are accessible

EN 14983:2007 (E) 12
Key 1
Borehole standpipe 2
Flexible hose suitable for the required flow and pressure 3 Collector pipe 4
Shut-off device 5
Suitable connection for collector pipe 6

Water separator Figure 4 — Example of connection of floor borehole to collector pipe when measurement and control are not accessible 4.3 Drainage pipes for seals and stoppings When firedamp drainage pipes are installed in seals and stoppings to drain methane, pipes shall be of sufficient diameter, equipped with devices for controlling firedamp flows and be monitored in accordance with 4.2. The requirements of 4.2 are to be applied accordingly for gas measuring devices in seals and stoppings. 4.4 Water separators at drainage points Where water is a problem, water separators should be provided between the drainage points and the measuring sections. These separators shall be made in such a way that they can separate any water that collects in the gas pipe without allowing the admission of the ambient atmosphere. 4.5 Firedamp pipes 4.5.1 General requirements for firedamp pipes Firedamp pipes and their fittings (e.g. shut-off devices, controls, borehole connections) shall comply at least with the nominal pressure stage PN 6 (see EN 1333). This strength rating is sufficient provided that the permissible operating pressure in the gas drainage plant, based on the design of the exhauster and/or regulating equipment, does not exceed 0,3 bar. Firedamp pipes shall only be fitted with pipe connections which are deemed suitable and necessary for operation and control purposes. Shut-off devices shall be provided in firedamp pipes in such a way that each branch pipe can be shut off independently. With the exception of the drainage points, all pipes shall be manufactured exclusively from materials suitable for the transportation of methane underground.

EN 14983:2007 (E) 13 Firedamp pipes shall be installed in such a manner as to be protected from damage. Where necessary, vertical firedamp pipes shall be secured by the fitting of expansion pieces. Firedamp pipes are to be positioned in such a way that any water which collects in the pipes can be removed. Connections for water separators are to be provided at the lowest points and in the transfer zone between the horizontal and the vertical pipe sections. Where required, firedamp pipes are to be protected from the effects of frost and freezing. 4.5.2 Measuring points for measuring equipment in firedamp drainage pipes Measuring points shall be provided at all places where the gas collector pipe joins a firedamp drainage main and where the firedamp main enters a mine shaft. A damping section of at least 10 ´ d shall be maintained in front of the measuring point, and a further damping section of at least 5 ´ d behind it. Measuring points in firedamp main pipes, installed for monitoring pipes for leakage, shall be sited at a minimum distance of 70 ´ d behind points where the firedamp collector pipes join. The dimensions of the measuring points shall be determined on the basis of the measuring equipment being installed. 4.6 Pressure vessels in firedamp drainage plant Where pressure vessels are used in firedamp drainage plants the design pressure pd of pressure vessels shall be at least 6 bar pressure. NOTE Systems operating below 0,5 bar pressure are not considered to be pressure systems. 4.7 Exhausters 4.7.1 Requirements for exhausters Each exhauster shall have a manufacturer’s certificate stating that its housing has withstood a water-pressure test for at least a 6 bar design pressure. NOTE For further information see Directive 97/23/EC of the European Parliament and of the Council of 29 May 1997 on the approximation of the laws of the Member States concerning pressure equipment. For materials of exhausters, requirements for fans according to EN 1710:2005, 5.3 have to be applied.

Where exhausters operate below 0,5 bar pressure, they shall be tested in accordance with the manufacturer's requirements. Exhausters shall be fitted with a temperature limiting device at the gas exit side according to the maximum permissible operating temperature recommended by the manufacturer, unless other technical measures can be used to prevent the permissible operating temperatures from being exceeded. The limiting device shall be adjusted so that the maximum permissible compression temperature specified by the manufacturer cannot be exceeded. Fluid-ring exhausters shall be monitored so that they are shut down automatically and immediately in the event of fluid deficiency. At the same time as this shut-down, an audible and visual warning signal shall also be emitted at the permanently manned position (see A.4). Exhausters (e.g. rotary compressors, fluid-ring exhausters and discharge nozzles) and pipe mains shall be designed so that a sufficient vacuum is available at each firedamp drainage point. Where practicable, exhausters shall be fitted additionally with:

EN 14983:2007 (E) 14 ¾ inlet and outlet gas pressure monitors; ¾ indicators showing the state of all inlet, outlet and bypass valves; ¾ mechanical fault monitoring (including driving motor) including an audible and visual warning signal; ¾ indicators showing the state of power supply to driving motors. All devices intended to automatically cut off power supply shall be designed so that they can only be reset at the location of the exhauster. The control system shall ensure, that exhausters cannot be started unless the outlet valve is open, and if the outlet valve closes while the exhauster is running the exhauster is shut down. 4.7.2 Reserve exhausters Exhausters shall be designed in such a way that they can be changed easily due to maintenance or after breakdown. NOTE The number of exhausters should be sufficient to cater for the maximum expected volume of firedamp, and additional capacity should be provided for periods when exhausters would be unavailable. 4.7.3 Location of exhausters Exhausters for firedamp drainage are, in principle, to be installed above ground. The place of installation is subject to the regulations which apply to areas where there is a risk of fire and explosion. Examples of requirements for the location of exhausters are given in Annex C. Firedamp which is released into the water collector tanks of liquid-ring exhausters shall be removed in a safe manner. If necessary, an explosion barrier is to be provided at the discharge end. 4.8 Venting of the drained firedamp Where firedamp is vented underground, the point of discharge shall have a dilution chamber around it, so located that when firedamp discharge is taking place the concentration of firedamp at the dilution chamber outlet does not exceed a value which has to be defined taking into account the LEL of methane and the local explosion safety requirements. NOTE The values are normally defined in national regulations. Firedamp drainage plants above ground shall be provided with a firedamp pipe which allows the firedamp to be vented to the atmosphere (firedamp vent pipe). In practice, the mouth of the surface firedamp vent pipe shall be defined by a risk assessment, but it shall be: ¾ at a minimum distance of 20 m, measured radially, from surface shafts and any areas presenting a fire or explosion hazard. This shall not apply to the location of an exhauster); ¾ at least 10 m above ground level and 3 m above any buildings sited within a radius of 20 m. Any possible ingress of water into drainage pipes shall be considered. Firedamp vent pipe outlets on the surface shall be protected against risks from lightning.

EN 14983:2007 (E) 15 4.9 Explosion prevention systems for pipelines 4.9.1 Explosion barriers Explosion barriers (flame arrestors according to EN 12874 or active explosion isolation systems according to prEN 15089) shall be provided: ¾ at firedamp vent outlets, designed and located to prevent an explosion at the vent outlet propagating in the direction of the exhauster; ¾ in the drainage pipes between the pressure generator and the mine, designed and located to prevent an explosion at the exhauster propagating in the direction of the mine. It is acceptable to dispense with the installation of an explosion barrier between the exhauster and the mine provided that the exhauster is of the water-filled fluid-ring non-sparking type,

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