CEN/TR 16829:2016

SLOVENSKI STANDARD
01-februar-2017
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Fire and explosion prevention and protection for bucket elevators
Brand- und Explosionsschutz für Becherwerke
Prévention et protection contre l'incendie et l'explosion des élévateurs à godets
Ta slovenski standard je istoveten z: CEN/TR 16829:2016
ICS:
13.220.20 3RåDUQD]DãþLWD Fire protection
13.230 Varstvo pred eksplozijo Explosion protection
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

CEN/TR 16829
TECHNICAL REPORT
RAPPORT TECHNIQUE
August 2016
TECHNISCHER BERICHT
ICS 13.220.40; 13.230; 53.040.10
English Version
Fire and explosion prevention and protection for bucket
elevators
Prévention et protection contre l'incendie et Brand- und Explosionsschutz für Becherwerke
l'explosion des élévateurs à godets

This Technical Report was approved by CEN on 13 July 2015. It has been drawn up by the Technical Committee CEN/TC 305.

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, 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
© 2016 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 16829:2016 E
worldwide for CEN national Members.

Contents Page
European foreword . 3
1 Scope . 4
2 Normative references . 4
3 Terms and definitions . 5
4 Bucket elevators . 6
4.1 General . 6
4.2 Bucket elevator types . 6
5 Fire and explosion hazards. 6
5.1 General . 6
5.2 Explosion hazards . 7
5.2.1 Presence of explosive atmospheres . 7
5.2.2 Presence of potential ignition sources . 8
5.2.3 Effect of ignition: smouldering product, fire, explosion, propagation of explosion . 10
5.2.4 Risk assessment . 10
5.3 Fire hazards . 10
6 Fire and explosion prevention and protection of bucket elevators . 11
6.1 General . 11
6.2 Fire prevention and protection . 12
6.2.1 Fire prevention . 12
6.2.2 Fire protection . 12
6.3 Explosion prevention and protection . 13
6.3.1 Prevention of explosive atmospheres . 13
6.3.2 Prevention of ignition sources . 14
6.3.3 Protective measures . 19
7 Information for use . 19
7.1 Markings . 21
Annex A (informative) Examples/types of bucket elevators . 22
Annex B (informative) Guidance on explosion venting . 28
Annex C (informative) Guidance on explosion suppression . 33
Annex D (informative) Example of an ignition hazard assessment . 36
Annex E (informative) Example of a nameplate . 61
Annex F (informative) Guidance for assessing the probability of generating explosive
atmospheres . 62
Bibliography . 63
European foreword
This document (CEN/TR 16829:2016) has been prepared by Technical Committee CEN/TC 305
“Potentially explosive atmospheres – Explosion prevention and protection”, the secretariat of which is
held by DIN.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent
rights.
1 Scope
This European Technical Report applies to bucket elevators that may handle combustible products
capable of producing potentially explosive atmospheres of dust or powder inside the bucket elevator
during its operation. The precautions to control ignition sources will also be relevant where the product
in the bucket elevator creates a fire risk but not an explosion risk.
For the purposes of this report, a bucket elevator is defined as an item of bulk material handling
equipment that carries material in powder form or as coarse products such as whole grain, wood chips
or flakes, in a vertical direction by means of a continuous movement of open containers.
This Technical Report specifies the principles of and guidance for fire and explosion prevention and
explosion protection for bucket elevators.
Prevention is based on the avoidance of effective ignition sources, either by the elimination of ignition
sources or the detection of ignition sources.
Explosion protection is based on the application of explosion venting, explosion suppression or
explosion containment and explosion isolation rules specifically adapted for bucket elevators. These
specific rules may be based on agreed test methods.
This European Technical Report does not apply to products that do not require atmospheric oxygen for
combustion.
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 1127-1:2011, Explosive atmospheres — Explosion prevention and protection — Part 1: Basic concepts
and methodology
EN 13237, Potentially explosive atmospheres — Terms and definitions for equipment and protective
systems intended for use in potentially explosive atmospheres
EN 13463-1, Non-electrical equipment for use in potentially explosive atmospheres — Part 1: Basic
method and requirements
EN 13463-5, Non-electrical equipment intended for use in potentially explosive atmospheres — Part 5:
Protection by constructional safety 'c'
EN 13463-6, Non-electrical equipment for use in potentially explosive atmospheres — Part 6: Protection
by control of ignition source 'b'
EN 14373, Explosion suppression systems
EN 14460, Explosion resistant equipment
EN 14797, Explosion venting devices
EN 14491, Dust explosion venting protective systems
EN 15089, Explosion isolation systems
EN 60079-10-2, Explosive atmospheres — Part 10-2: Classification of areas — Combustible dust
atmospheres
EN ISO 12100, Safety of machinery — General principles for design — Risk assessment and risk reduction
(ISO 12100)
ISO 281, Rolling bearings — Dynamic load ratings and rating life
IEC/TS 60079-32-1, Explosive atmospheres — Part 32-1: Electrostatic hazards, Guidance
VDI 2263-1, Dust fires and dust explosions; hazards, assessment, protective measures; test methods for the
determination of the safety characteristic of dusts
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN 13237, EN 15089 and the
following apply.
Note 1 to entry: The zones for the classification of hazardous areas are defined in Directive 1999/92/EC.
3.1
volume
3.1.1
bucket elevator leg volume
internal volume of pipe section connecting head to the boot
3.1.2
bucket elevator head volume
internal volume above the leg connection, including outlet section and excluding the volume of the
pulley
Note 1 to entry: Attached chutes are not included.
3.1.3
bucket elevator boot volume
internal volume below the leg connection, including inlet section and excluding the volume of the pulley
3.2
vent spacing
distance between vents measured from centre to centre
3.3
bucket spacing
distance between buckets measured from centre to centre
3.4
combustible dust
finely divided solid particles, 500 μm or less in nominal size, which may be suspended in air, may settle
out of the atmosphere under their own weight, which can burn or glow in air, and may form explosive
mixtures with air at atmospheric pressure and normal temperatures
4 Bucket elevators
4.1 General
Bucket elevators are described as bulk materials handling equipment, conveying material in a vertical
direction by means of a continuous movement of open containers. A bucket elevator consists of three
main parts: the boot where the material enters the equipment, the leg or legs where the material is
transported upwards and the head where the material is discharged. The most common type of bucket
elevators generally use open containers fixed to a moving belt or chains. In case of a single leg bucket
elevator the belt moves upwards and returns in the same leg. In a twin-leg bucket elevator the
returning of the belt occurs in a second leg.
Bucket elevators require special attention since they have been involved in dust explosions and they
have many potential ignition sources. The most common ignition sources are due to mechanical
problems, for example due to friction between the belt and the casing, heating up of mechanical rotating
parts on elevator head and boot, impact of damaged buckets or foreign objects. These mechanical
problems may also create explosive atmospheres: impact or vibrations will cause dust deposits in the
legs to fall down and create an explosive atmosphere. Therefore if, during normal operation, there is no
explosive dust-air mixture present inside a bucket elevator, mechanical problems are still likely to
cause an explosion.
NOTE Maintenance related ignition sources like hot work are also very common.
Even if an ignition source does not cause an explosion it may result in a fire and spread quickly because
the leg of a bucket elevator acts as a chimney.
Fire and explosion protection of bucket elevators requires special attention. A bucket elevator might be
considered as two volumes (head and boot) between which there are one or two long ducts (the legs).
The information (see EN 14491) for flame accelerations inside a long duct, however, cannot be applied.
The buckets do affect flame acceleration: especially metal buckets which will cool the flame (and reduce
flame acceleration). But the buckets also form repeated obstacles which cause increased turbulence and
hence promote flame accelerations. Plastic buckets may become part of the fuel for a fire.
4.2 Bucket elevator types
There are many types of bucket elevators. Casing types include twin leg, single leg, and “Z” type. The
buckets can be attached to either a belt or a chain and can be made from metal or plastic.
Typical examples
...