www bzfxw com BRITISH STANDARD BS EN 617 2001 Continuous handling equipment and systems — Safety and EMC requirements for the equipment for the storage of bulk materials in silos, bunkers, bins and ho[.]
Mechanical hazards
Mechanical hazards shall be safeguarded by guards.
To ensure operator safety from crushing and shearing hazards, it is essential to implement appropriate safety distances as outlined in EN 349:1993, EN 294:1992, and EN 811:1996 This includes the use of hinged or slidable guards, fixed enclosing guards, fixed distance guards, or interlocking guards.
Guards must adhere to EN 953 standards and can be constructed from either perforated or imperforate sheets In the case of perforated designs, it is essential to maintain safety distances to ensure that danger areas are not accessible.
Covers or guards must be capable of supporting a uniformly distributed force of 1,500 N over an area of 0.2 m x 0.2 m, ensuring that deformation does not exceed 1% of any reference dimension and that there is no contact with moving parts Additionally, these guards should be replaceable after loading.
The guards are designed to endure a force of 150 N uniformly distributed over an area of 0.2 m by 0.2 m, ensuring deformation remains below 1% of any reference dimension and preventing contact with moving parts Additionally, they can be reused after loading.
NOTE The design of guards should enable spillage to be cleared without removal of guards.
Fixed enclosing guards must comply with section 3.2.1 of EN 953:1997, ensuring they are securely attached using captive fastenings that require a tool for installation If guards are removable, they should be easily replaceable without the need to dismantle other components Additionally, guards must be designed to remain closed only when properly fastened.
Openings in fixed enclosing guards shall conform with EN 294:1992, Tables 3, 4 or 6 and EN 811:1996, Table 1.
Fixed distance guards must comply with section 3.2.2 of EN 953:1997 and should be securely installed using captive type fastenings These guards can only be fixed and fastened with the use of a tool Additionally, the safety distance established by fixed distance guards must adhere to the specifications outlined in EN 294:1992, Table 2.
Hinged guards, such as doors, on totally enclosed sections must adhere to the attachment type and opening direction specified in EN 953 If the opening and compartment are spacious enough for a person to enter, the panel must be operable from the inside without the need for a key or tool Additionally, openings must comply with the standards outlined in EN 294:1992, Tables 3, 4, or 6, and EN 811:1996, Table 1.
Interlocking guards shall be in accordance with 3.5 of EN 953:1997, shall be securely fixed in position and shall use interlocking devices in accordance with EN 1088: 1995, 4.2.1.
If a guard is intended to be opened during operation to allow viewing of a danger zone:
1) safety distance of EN 294:1992, Tables 2, 3, 4, 6 and EN 811:1996, Table 1 shall be met ; or
An additional fixed guard must be installed to prevent access to danger points, utilizing materials such as perforated plates or wire mesh This guard should adhere to the safety distances outlined in EN 294:1992, Table 4, and EN 811:1996, Table 1.
Hinged or slidable guards shall be self closing and self locking.
5.1.2.2 Access guards for maintenance or repair out of operation
If access guards for maintenance or repair out of operation are intended to be opened more frequently than once every eight hours they shall be interlocked with guards.
Access guards for maintenance or repair that are not intended to be opened more than once every eight hours must be operated using a tool or key.
If there are hinged or slidable guards they shall be retained open by a positive engagement device.
5.1.2.3 Access guards for maintenance or repair in special operating modes
Access guards for maintenance and repair in specific operating modes must be fixed, hinged, or slidable These guards should be secured in an open or closed position by a positive engagement device and must allow for tool-free or keyless opening from the inside.
The chute and telescoping pipe system must be equipped with a safety mechanism to avoid unintentional lowering or lifting of the articulated section, as well as to prevent any kickback from manually operated cranks.
The device for adjusting the movable part must be positioned to eliminate the need for the operator to be underneath the equipment Additionally, the movement range in all directions should be restricted by safety devices to maintain a minimum gap in accordance with EN 349:1993, Table 1 (body and head).
To ensure safety in equipment operation, devices must be strategically positioned or designed to prevent bulk materials from falling on operators and to avoid the risk of operators being crushed by vehicles, particularly in traffic zones.
NOTE The operator can also be the driver of the lorry.
When transporting bulk materials away from a silo using vehicles, manufacturers must ensure that the minimum horizontal distances between the silo structure and the designated traffic and working areas are properly designed.
Vertical : Minimum vertical height shall be 2,1 m.
NOTE This should take into account the vehicle to be loaded.
30 km/ h 300 mm 300 mm 500 mm 700 mm
30 km/ h 300 mm 300 mm 700 mm 700 mm with :
W Working area w1, w2 Length of obstacles in direction T d1, d2 Minimal horizontal distances v Maximal intended velocity (see 7.2.3) b Maximum intended width of the vehicles
To ensure safety for non-rail vehicles, it is essential to maintain minimum horizontal distances, which can be protected by wheel guides such as steps, curbs, or guard rails These safety features must be of sufficient height, exceeding 0.2 meters, and possess adequate stability.
Figure 2 – Minimal horizontal safety distances d 1 , d 2
Electrical hazards
The electrical equipment shall be provided in accordance with all applicable clauses of EN 60204-1:1997, together with the particular requirements below.
For equipment operating under electrical supply conditions that fall outside the specifications of EN 60204-1:1997, section 4.3, or prEN 60204-11:1997, clause 4, the manufacturer must implement required design modifications, ensure necessary safety measures, and clearly outline any operational restrictions in the operating manual.
Electrical equipment encompasses a variety of components such as materials, fittings, devices, appliances, fixtures, and apparatus that are integral to electrical installations This includes electronic devices, disconnection mechanisms from the power supply, and all wiring extending from the silo to the disconnection point.
To ensure safety during maintenance on a silo or its electrical equipment, it is essential to implement measures that prevent unexpected start-up and electric shock, in accordance with EN 1037 and sections 5.4 and 5.5 of EN 60204-1:1997 Additionally, a disconnecting device must be installed that meets the criteria outlined in sections 5.3.2a), b), c), or d) and 5.3.3 of EN 60204-1:1997.
In a system where the silo is divided into separate sections, each section must have its own supply and be capable of being isolated This isolation is essential to facilitate maintenance and work within each individual section.
Electrical equipment may have live parts even after the disconnecting device is turned off, often due to interconnections within storage equipment It is essential to mark, identify, or protect these parts against direct contact as necessary, in accordance with sections 5.3.5 and 6.2 of EN 60204-1:1997.
The supplier must choose and install equipment that is appropriate for the specific working environment Electrical equipment enclosures, such as cabinets and boxes, should offer adequate protection; indoors, they require a minimum protection rating of IP 22, while motors need at least IP 23 For outdoor installations exposed to liquid, a minimum protection rating of IP 54 is necessary, in accordance with EN 60529.
Equipment shall be designed to withstand the vibration normally occurring on silos, without failing to danger.
When designing a silo for conditions that exceed the specifications outlined in EN 60204-1:1997, such as extreme ambient temperatures, humidity, altitude, or corrosive environments, the manufacturer must consider these factors in the design process.
Wiring practices in silos and between silos and disconnection means must comply with EN 60204-1:1997, specifically sections 13 and 14 This includes proper identification techniques and wiring methods for both internal and external enclosures To enhance safety, wiring outside enclosures should be kept away from combustible materials and protected from mechanical damage If such positioning is unavoidable, appropriate protective measures must be implemented, such as using armoured cables, rigid metal conduits, flexible conduits, electrical metallic tubing, or metal raceways.
Electrostatic charges can pose hazards such as shock and fire When individuals are at risk from these charges, appropriate protective measures must be implemented, including earth bonding, brush contact, or discharge elements for moving items.
NOTE Provisions for electrostatic hazards are under consideration by CENELEC/TC44X.
Where equipotential connection between the equipment (e.g vehicles, container) is provided, charging and discharging shall only be possible after this equipotential connection is efficient.
Electromagnetic compatibility (EMC)
5.3.1 is related to the EMC Directive, 5.3.2 to the Machinery Directive.
The equipment must comply with the generic emission standard EN 50081-1, ensuring that electromagnetic disturbances do not exceed specified levels Additionally, it should possess adequate immunity to electromagnetic disturbances, allowing it to function correctly under conditions outlined in EN 61000-6-2 Manufacturers are responsible for designing, installing, and wiring the equipment and its sub-assemblies according to supplier recommendations to prevent unintended operations caused by electromagnetic disturbances.
To ensure optimal performance, it is crucial to avoid any sequencing, timing, or counting errors, maintain speed variations within +/- 20% of the discharge equipment, and ensure the proper functioning of interlocking devices Additionally, the duration of starting operations should not increase or decrease by more than 10%, and the capability for non-safety-related fault detection must remain intact.
Section 4.4.2 of EN 60204-1:1997 outlines measures to minimize generated disturbances and mitigate their effects on equipment Manufacturers must declare any performance degradation or loss of function related to performance criteria "A" and "B" as specified in EN 61000-6-2 Additionally, any temporary loss of function permitted under performance criteria "C" must also be disclosed by the manufacturer.
5.3.2 Safety requirements related to EMC
The equipment must possess adequate immunity to electromagnetic disturbances, ensuring safe operation as intended It should not pose any danger or fail when subjected to specified levels and types of disturbances.
According to EN 61000-6-2, manufacturers must design, install, and wire equipment and sub-assemblies while considering the recommendations from sub-assembly suppliers This approach is essential to prevent electromagnetic disturbances from causing unsafe operations or failures that could pose a danger.
EMC immunity testing results will be determined based on specific performance criteria outlined in EN 61000-6-2 It is essential that all performance criteria, including A and B, ensure no loss or degradation of performance that could pose a danger Critical failures to avoid include unexpected start-ups, blocking of emergency stop commands, and inhibition of safety or interlocking devices related to ultimate-position switch circuits.
Interlocking switches, emergency stop devices, level control systems, discharge control systems, and start/stop circuits are all interconnected in safety-related control systems According to section 5.9.3.4, any decrease in fault detection capability of these systems, which utilize electronic components, must be considered, especially when selecting devices as outlined in the previous clauses.
Information on measures to reduce the effects of electromagnetic disturbances is given in 4.4.2 of EN 60204-1:1997.
Thermal hazards
Where materials stored or any part of the equipment itself which, on contact with persons, can lead to burns or scalds, following measures shall be taken :
To maintain maximum temperature limits, the following standards apply: for non-intentional contact, the temperature specified in annex B of prEN 13202:1998 for a contact time of 0.5 seconds must be adhered to; for accessible parts of the system, the temperature defined by EN 563 for a contact time of 1 second is required; and for components operated by hand, the temperature set by EN 563 for a contact time of 1 minute should be observed.
When maximum temperature above mentioned cannot be maintained the following provisions shall be considered : cooling : insulation ; safety distances (see EN 294:1992, Table 1 excluded).
Hazards generated by radiation
Lasers which may be used e.g as level indicators in silos or for special measurements, shall comply with
Laser of class 3B and 4 shall only be used where lower classes are not sufficient due to local conditions.
To mitigate risks associated with the heating of bulk materials in silos, it is essential to continuously monitor the temperature of the materials Effective measures to prevent overheating include the use of reflective surfaces on the exterior, proper insulation, and the installation of cooling equipment.
Hazards generated by bulk materials handled and stored in the storage equipment
The manufacturer shall take into consideration the characteristics of the bulk materials (see introduction
NOTE For the description of bulk materials see FEM 2.581/2.582 (see Bibliography).
5.6.1 Hazards resulting from contact with or inhalation of harmful gases, and dusts
Equipment shall be so designed and constructed as to be suitable for operation in the intended environmental conditions.
The housing shall be properly sealed and, where necessary, provided with a correctly designed gas or dust extraction device (see EN 626-1).
Where harmful dusts could be exhausted to the atmosphere (e.g pneumatic charging) filter(s) shall be provided.
If the equipment may be required to store finely divided materials (dusts), with a possible hazard of fire and explosion, see annex D (informative).
Hazards generated by neglected ergonomic principles in machine design (mismatch of machinery
5.7.1 Inadequacy with human hand-arm or foot-leg anatomy
Control actuators shall be situated in such positions where they easily can be reached (see Figure 5 for an operator which is intended to stay).
Key a Less or up to 0,5 m b More than 0,9 m c Less than 1,5 m d Working area e Area for manual control actuators
Figure 5 – Positions for manual control actuators (operator is intended to stay)
They shall be designed in order to be operated with acceptable forces (less than 150 N).
5.7.2 Neglected use of personal protection equipment
If safety gloves are intended to be worn, the control actuators shall be designed so that they can be operated under this conditions.
The minimum free space required around control devices is essential for safe operation: a) 50 mm for handles needing over 50 N of force; b) 25 mm for handles requiring up to 50 N; c) 10 mm between rows of push buttons or switches; d) 15 mm between individual push buttons; and e) 100 mm for pedals.
Lighting of workplaces shall comply with prEN 12464.
Hazard combinations
Covering each individual hazard is sufficient for covering combinations of hazards. e c b a d
Hazards caused by failure of energy supply, braking down of machinery parts and others functional
5.9.1 Failure of energy supply (of energy and/or control circuits)
Discharge systems included their drives shall be designed so as to prevent unintended movement and unintended modification of the flow rate setting.
To prevent overflow, the flow rate setting must be accurately designed The gate system should effectively interrupt the flow as quickly as possible to prevent flooding, potentially utilizing an additional gate for enhanced control.
Manual interruption of the flow shall be possible in case of failure of the power supply or of the control system.
5.9.2 Unexpected ejection/retention of bulk materials
To minimize issues such as flooding, irregular flow behavior (including core flow and rat-holing) in non mass-flow silos, and arching, the design of the silo must be carefully considered Key factors influencing this design include the type of material and its flow properties, the shape and slope of the walls, the friction characteristics, the positions and dimensions of discharge openings, the discharge rate, and the use of flow aid devices.
5.9.3 Measures for protection against hazards arising from unsuitability, failure or malfunction of safety related parts of control
Safety-related controls and circuits encompass various systems, including ultimate-position switch circuits, interlocking switch circuits, emergency stop device circuits, level control system circuits, discharge control system circuits, and start and stop circuits.
Safety related parts shall be designed, selected, located, and/or protected to meet the intended site conditions and the various applications of the equipment e.g ice build-up.
The switching arrangements of mechanically actuated switches shall be of positive opening operation in accordance with clause 3 of EN 60947-5-1:1997 (i.e "safety switches").
In the event that a safety device is activated, an automatic stop command will be issued, triggering either a category "0" or category "1" stop, depending on the design requirements (refer to section 9.2.2 of EN 60204-1:1997) Additionally, the stop function must adhere to the standards outlined in section 5.2 of EN 954-1:1996.
5.9.3.3 Transmission elements used for safety purposes
Transmission elements utilized for safety, as outlined in section 5.9.3.1, such as wiring, must be engineered to ensure that any failure or rupture does not lead to hazardous conditions This design requirement mandates that an automatic stop command is triggered in the event of such failures.
The design of control systems and equipment must utilize proven techniques and components, as outlined in EN 60204-1:1997 Safety-related parts of the control system should meet at least category 1 requirements per EN 954-1:1996 For safety-related applications involving programmable electronic equipment or electronic devices, compliance with at least category 2 is necessary Additionally, if these electronic systems are solely responsible for transmitting emergency stop commands, they must adhere to category 4 standards.
When the supply is switched-on, there shall be no movement of the machinery.
In case of a supply interruption or significant supply fluctuations, as well as control system faults or failures, it is essential to ensure that no hazardous situations arise, such as unintended start-ups or failure to stop, in accordance with EN 60204-1:1997 and EN 954-1:1996 standards.
Electronic control circuitry, software and adjustable safety devices/safety equipment shall not be accessible to unauthorised persons, e.g by use of access codes, special tools.
For prevention of unexpected start-up see EN 1037.
Start devices must be designed and installed to reduce the likelihood of accidental activation They should be easily accessible to the operator and clearly marked for visibility.
5.9.3.6 Stop function and stop control devices
Stop devices must be easily accessible to the operator at all control stations and should be clearly identifiable and visible The stop function should comply with category "0" or category "1" standards, depending on the design requirements, as outlined in EN 60204-1:1997, section 9.2.2.
NOTE Interlocking with possible other equipment should be considered.
Stop devices shall be of the impulse type After their actuation the appropriate part of the equipment, shall come to a stop and then remain in a stationary condition.
The stop function must be designed to prevent hazardous conditions, such as the dangerous discharge of materials If gates are utilized for discharging, they should close immediately after the stopping device is activated.
The emergency stop system shall be in accordance with EN 418 and shall be a category ”0” stop or category ”1” stop as appropriate to be compatible with the design (see 4.1.5 of EN 418:1992).
Emergency stop devices shall have positive operation, be self-latching.
Emergency stop devices must be installed at charging and discharging points where there is permanent access Refer to section 5.7.1 for the required height of these devices.
Emergency stop systems must be designed to prevent the creation of additional hazards, such as the complete emptying of a silo, which can occur if the operator is unable to close the gate during an emergency stop.
Hazards caused by (temporary) missing and/or incorrectly positioned safety related measures/means
There shall be separate disconnecting devices for each type of energy (hydraulic, pneumatic, and electric), see EN
5.10.1.1 Safe access to silo space B
To ensure safe access to silo space B, all disconnecting devices must be centralized near the access openings and should be lockable This requirement also extends to power-driven charging equipment.
For air cannon and other flow aid devices see 5.1.7.
If there is a risk to persons entering silo space B from material falling down from charging equipment even when the equipment is disconnected, there shall be special covers or guards.
5.10.1.2 Essential equipment and accessories for safe adjusting and/or maintaining
The equipment shall be designed so that, as far as possible, adjustment, lubrication and maintenance points are located outside danger areas (see clause 5 of EN 1037:1995).
For special maintenance or repair operations it can be necessary to provide other measures which can be one or a combination of the following :
Each piece of equipment must be isolated, and energy must be dissipated according to EN 1037:1995 Special operating modes include: a) hold-to-run devices for local control, b) remote control options, c) speed-limiting devices, and d) temporary movement-limiting control devices.
Cableless controls shall not be used.
If specific compensating measures have to be taken, the required material means shall be supplied with the equipment Mode selection means shall preclude any possibility of normal operation control.
6 Verification of safety and EMC requirements and /or measures
General
Safety requirements and/or measures of clauses 5 and 7 of this standard shall be verified according to the Table below, which covers :
1) Type verification, the intention of which being to ensure that the type complies with the requirements of this standard (the first section of the Table).
Individual verification aims to ensure that each unit meets all safety requirements of the standard prior to dispatch For assemblies completed on-site, any verification that could not be conducted before dispatch must be performed at the location of use.
The verification methods outlined in the table include: a) visual checks, aimed at confirming the presence of elements such as guarding, visual warning devices, and adequate documentation to meet standard requirements (indicated by the symbol "V"); b) measurements, which assess whether specified measurable parameters, including geometric dimensions, safety distances, isolation resistance of electric circuits, noise, and vibration, are satisfied (represented by the symbol "M"); and c) tests.
A functional test (symbol "FT") aims to verify that the equipment, including all safety devices, operates as intended during an unloaded working operation or normal cycle This test ensures that all functions meet the specified requirements and align with the technical documentation.
Loaded tests (symbol "LT" in the Table) are conducted beyond the scope of functional tests to determine the adequacy of strength, stability, and safety devices, as well as their adjustments The goal is to ensure that the results of these tests comply with the requirements outlined in the standard.
Specific verification and measurements, such as electrical assessments, EMC evaluations, and fire/explosion risk analyses, are conducted to determine if the stated parameters are met, ensuring compliance with electrical standards This process is denoted by the symbol "SV" in the table.
Type verification Individual verification clause visual checks measurement tests visual checks measurement tests
Special verification
To ensure compliance with EMC requirements outlined in section 5.3.1, manufacturers must adhere to the specified standards If testing the entire equipment is impractical due to its size, the manufacturer is responsible for confirming that all relevant sub-assemblies meet the 5.3.1 requirements Additionally, the manufacturer must ensure that these sub-assemblies are properly installed and wired to reduce the impact of disturbances on the equipment, limit generated disturbances, and follow any recommendations provided by the sub-assembly suppliers.
6.2.2 Verification of safety requirements related to EMC
To ensure compliance with EMC requirements outlined in section 5.3.2, preliminary and functional testing must be conducted If testing the entire machinery is impractical due to its size, the manufacturer is responsible for confirming that all relevant sub-assemblies meet the specified requirements Additionally, the manufacturer must ensure that these sub-assemblies are properly installed and wired to reduce disturbance effects, following the recommendations provided by the sub-assembly suppliers.
Operating instruction- Instruction handbook
The operating instruction handbook must comply with section 5.5 of EN 292-2:1991 and include details specified in section 1.7.4 of annex A to the same standard It should provide essential information regarding the intended usage conditions of the storage equipment, particularly concerning the bulk material that will be handled.
This article highlights essential flow properties, including bulk densities and friction angles, as well as geometric design data such as outlet diameter and wall slope of the converging section It also addresses the surface finish of interior walls, working and traffic areas, and operating conditions, particularly the charging and discharging processes of storage equipment Additionally, it discusses dust explosion characteristics in accordance with VDI 3673 and outlines maximum permissible environmental conditions like snow, wind, moisture, and temperature It is important to note that this handbook does not include procedures for entering the silo or the behavior of individuals inside it.
The instruction handbook emphasizes the importance of avoiding unintended use, including unauthorized modifications to critical components of the storage equipment specified in the contract, particularly concerning the stored materials Additionally, it warns against operating the system under conditions classified as abnormal, such as excessive moisture in bulk materials.
Where a programmable logic system is provided, the instruction handbook shall contain all the instructions necessary for modifications of programmes considered allowable by the manufacturer.
EN 60825-1 shall apply for the information for use.
7.1.2 Information about the installation of the storage equipment
When storage equipment is supplied unassembled, the manufacturer must provide detailed assembly specifications and drawings that include instructions for assembly and installation, various assembly phases, and the loads imposed by the equipment Additionally, it should specify the maximum weights, dimensions, and lifting points of the components, as well as the necessary lifting means and operating procedures Precautions such as anchoring and support details, along with electric, hydraulic, and pneumatic connections, must also be outlined The manufacturer should include checks to be performed during and after assembly, earth bonding requirements to mitigate electrostatic hazards, and any special equipment needed for assembly Furthermore, information regarding interfaces with other components of continuous handling systems and remaining verifications post-assembly should be provided.
7.1.3 Information for the use of the storage equipment
The instruction handbook must encompass essential information regarding operator training, the functions of controls, and detailed instructions for restarting the system It should also provide guidance on settings, adjustments, and modifications to computer software, as well as outline stopping modes and emergency stop locations Additionally, the handbook must include instructions for charging and discharging, highlight hazards associated with missing or improperly positioned safety measures, and offer information on temporary access means for charging openings exceeding 0.05 m.
The instruction handbook emphasizes that users must not alter the design or configuration of the equipment without prior consultation with the manufacturer or an authorized representative Following any modifications, recommissioning must adhere to clause 6 It is crucial to keep all working and traffic areas clear In environments where noise may hinder speech communication, specialized equipment such as phone boxes or designated rooms is required to facilitate undisturbed conversations among personnel Additionally, for work conducted in restrictive locations within storage equipment, such as silo space B, users must ensure the availability of special lamps and electrical tools, in accordance with IEC 60364-7-706.
7.1.4 Information for inspection and maintenance
The maintenance instruction handbook mandates that equipment must be maintained in proper working condition following the manufacturer's guidelines Regular inspections, adjustments, maintenance, and cleaning should be performed safely as per these instructions Any inspection or adjustment while the equipment is in motion must only occur with guards in place The removal of guards or neutralization of safety devices should adhere to the manufacturer's instructions, specifically referencing EN 292-2:1991 Additionally, repairs and the removal of protective enclosures or panels must only be conducted after the equipment is stopped and rendered inoperative by authorized personnel, following a safe system of work.
The instruction handbook must detail essential information regarding training, the importance of deactivating laser beams, and the designated anchorage points for personal protective equipment It should also outline the restricted use of access door opening mechanisms, the necessary precautions to authorize operations safely, and provide a list of wear parts along with their replacement frequency and conditions, such as wall lining thickness Additionally, the handbook should specify the measures required to establish maintenance or repair zones using protective devices, including the installation of temporary fencing or barriers.
The instruction handbook must outline the required regular inspections for bulk materials, detailing their maximum intervals Inspections should include explosion safety devices, bursting disks, and vents at least annually; vacuum prevention installations monthly; electronic, electrical, hydraulic, and pneumatic equipment annually; safety devices such as guards and interlocking devices monthly; spillage checks daily; stored bulk materials monthly; and filters monthly.
The instruction handbook shall give special advice if bulk materials to be stored are likely to create fire and/or explosion hazards (in accordance with 5.6.2).
Minimum marking
The storage equipment shall be marked with the following :
1) the name and address of the manufacturer ;
4) designation of series or type ;
6) names of bulk materials for which the storage equipment was designed ;
7) special notice if stored bulk materials are likely to create fire and / or explosion hazards (see 7.2.3) or dangerous or if noxious bulk materials are to be stored ;
8) capacity (volume) of silo space B ;
9) bulk densities for each bulk material handled ;
10) max allowed operating pressure, if necessary ;
11) max allowed vacuum pressure, if necessary ;
12) max and min allowed operation temperatures, if necessary ;
13) max and min allowed storage time (if relevant) for each bulk material handled ;
14) max and min allowed charging and/ or discharging rate (if relevant) for each bulk material handled ;
15) Further information is given in the Instruction Handbook.
Where relevant storage equipment with a nominal capacity up to 1 m 3 shall be marked at least with points 1 to 7 and 15 The points 10 to 14 shall only be mentioned if necessary.
All safety signs shall be in accordance with ISO 3864.
Safety signs must be provided as follows: a sign indicating the maximum intended velocity for vehicles in hazard zone F; a plate W10 if laser equipment is present; a plate P02 and/or W02 if the bulk material poses an explosive or flammable risk; and a plate W15 along with an additional sign if the charging opening cannot be permanently guarded.
”Cover the opening immediately after charging”; if there is an opening for access to silo space B a plate : P06 and an additional plate stating :
Unauthorised access is forbidden ; if mdd exceeds 4,0 m a plate (see 5.1.6.2): M09; if wearing of hearing protection is required: M03.
List of hazards according to EN 292-1
The risks associated with bulk material storage systems in silos differ significantly from those related to standard machinery as outlined in EN 292-1 and EN 929-2 Table A.1 highlights various types of hazards specific to these storage systems Additionally, hazard locations A - F are identified, with corresponding requirements and measures provided in section 5, along with relevant information detailed in clause 7.
Table A.1 - List of hazards according to EN 292-1 in comparison with annex 1 of the Machinery Directive
Hazards Significant Locations Typical hazard items or situations
1.1 Crushing yes C,D,E,F telescoping pipes, chutes, vehicles
1.2 Shearing yes B,C,D,E,F charging and discharging equipment, valves, gates
1.4 Entanglement yes C,D,E,F charging and discharging equipment
1.5 Drawing-in or trapping yes A,B,C,D silo inlets, inspection opening, sinking into or under bulk material, access into silo
1.6 Impact yes A,B,D,F vehicle under silo 5.1.3
1.9 High pressure fluid injection yes B air cannon 5.1.7
1.10 Ejection of parts (of machinery and processed materials / workpieces yes A,B,C,D,F safety devices (valves, vents, bursting discs, etc.), stored or conveyedbulk material
1.11 Loss of stability (of machinery and machine parts) yes A,B,C,D,E,F all the storage equipment parts, structure
1.12 Slip, trip and fall in relationship with machinery yes F platforms, floors, ladders, gangways, stairs, step
2.1 electrical contact direct or indirect yes B,C,D,E,F electrical equipment, means of disconnection, environment, wiring practices
2.2 electrostatic phenomena yes B,C,D,E,F between particles of bulk material, wall material etc.
2.3 thermal radiation or other phenomena such as projection of molten particles and chemical effects from short- circuits, overload etc. no
Hazards Significant Locations Typical hazard items or situations
2.4 external influence on electrical equipment yes C,D,E electromagnetic compatibility, charging, discharging, unexpected start-up, blocking of emergency stop
3.1 burns and scalds by possible contact of persons by flames or explosions and also by the radiation of heat sources yes A,B,C,D,E,F bulk material 5.4
3.2 health-damaging effects by hot or cold work environment yes B,F not dealt with
4 Hazards generated by noise, resulting in
4.1 hearing losses (deafness); other physiological disorders yes F working and traffic area Not dealt with
4.2 interference with speech communication, acoustic signals etc. yes C,D,E,F working and trafficarea, charging and discharging equipment, vibrators
5 Hazards generated by vibration (resulting in a variety of neurological and vascular disorders) no
6 Hazards generated by radiation, especially by
6.2 lasers yes B control system for special measurements
6.3 ionising radiation sources yes B,F level indicators Not dealt with
6.4 use of high frequency electromagnetic fields no
6.5 solar radiation yes A,B,F heating up of structure, bulk material and operator’s working area
7 Hazards generated by materials and substances processed, used or exhausted by machinery e.g.
7.1 contact or inhalation of harmful fluids, gases, mists, fumes and dusts yes A,B,C,D,E,F charging, discharging and additional equipment
7.2 fire and explosion yes A,B,C,D,E,F silo space B, during charging and discharging
7.3 biological and micro- biological (viral or bacterial) yes A,B,C,D,E,F operator’s working area Not dealt with
8 Hazards generated by neglecting ergonomic principles in machine design caused e.g by
8.1 unhealthy postures or excessive efforts yes B,F not dealt with
8.2 inadequacy with human hand- arm or foot- leg anatomy yes F working area, control actuators
Hazards Significant Locations Typical hazard items or situations
8.3 neglected use of personal protection equipment yes B,F use of gloves 5.7.2
8.4 inadequate area lightning yes F inside silo space B, operator’s working area, traffic area
8.5 mental overload or underload, stress no
8.6 human errors yes B,F entering silo space B with inadequate personnel, manual and equipment support
10 Hazards caused by failure of energy supply, breaking down of machinery parts and other functional disorders, e.g.
10.1 failure of energy supply yes C,D,E unintended movement of gates, overfilling, uncontrolled emptying
10.2 unexpected ejection of machine parts or fluids yes A,B,C,F flooding of bulk material, overfilling
10.3 failure, malfunction of control system yes A,B,C,D,E,F emergency stoppage, changing software
10.4 errors of fitting yes C,D,E system and equipment, design errors
10.5 overturn, unexpected loss of machine stability no
(temporary) missing and/ or incorrectly positioned safety related measures/ means, e.g. yes A,B,C,D,E,F maintenance 5.10.1.2,
11.1 all kind of guards yes A,B,C,D,E,F replaceable lids and grids, falling into or from silo
7.1.3, 5.1.1, 5.1.2.3, 5.1.6.1, 5.1.10, 7.2.3 11.2 all kinds of safety related
(protection ) devices yes A,B,C,D,E,F flooding of bulk material 7.1.3, 5.9.1
11.3 starting and stopping devices yes C,D,E,F starting and stopping equipment
11.4 safety signs and signals yes B,C,D,E,F noise, laser, velocity, unauthorised access, explosive atmosphere
11.5 all kinds of information and warning devices yes B,C,D,E,F silo plate, persons entering silo space B
11.6 energy supply disconnecting devices yes B,C,D,E entering silo space B, incorrect starting procedure for all conditions
11.7 emergency devices yes B,C,D,E equipment starting and material flowing before silo space is evacuated of personnel and also before any maintenance is completed in other locations
11.8 feeding / removal of workpieces no
11.9 essential equipment and accessories for safe adjusting and / or maintaining yes B,C,D,E opening of access or inspection doors during working process
11.10 equipment evacuating gases, etc. yes B,F gas, dust 5.6.1
VDI 2263:1992, Dust fires and dust explosions; hazards, assessment, protective measures.
VDI 3673-1:1995, Pressure venting of dust explosions.
Load and load combination assessment
The manufacturer must design the silo system structure to accommodate both internal and external loads, considering the potential for foreseeable overloading based on the system's characteristics.
Loads and load combinations due to the material flow in relation with the silo characteristics can be assessed on the basis e.g of : the measured bulk material flow properties ;
The article emphasizes the importance of several factors in silo design, including the detailed geometry of the silo structure, the frictional properties of the internal wall surfaces, the flow behavior of the bulk material, and the potential impact of mobile charging or discharging equipment such as grabs, ships, or wagons.
Designing for the worst conditions is essential for ensuring safety It is crucial to exercise great care when considering changes to the previously mentioned measures or discharge methods.
Mass flow minimises the hazard of loss of stability Non mass flow (core flow, arching, rat-holing, flooding) increases this risk.
Ear protection must be worn (M03) Safety hareness must be worn (M09)
No smoking and naked flames prohibited
No access for unauthorized persons
When storing finely divided materials, such as dusts, that pose a fire and explosion risk, it is essential to design the equipment in compliance with EN 1127-1 to effectively minimize these hazards.
Finely divided organic materials, whether natural or synthetic, can lead to dust explosions, and certain metal and inorganic substances are also capable of causing explosions However, powdered materials generally present a lower risk of serious explosions.
NOTE 1 Requirements for equipment intended for use in explosive atmospheres are under consideration by CEN/TC 305.
When conducting a hazard analysis and risk assessment for fire and explosion hazards in storage equipment, it is crucial to consider both upstream and downstream processes Fires originating in storage equipment can lead to explosions in adjacent processes, highlighting the interconnected nature of these hazards.
NOTE 3 Reference should be made to specific standards e.g VDI 2263 (see annex B).
NOTE 4 A method of test for possibly explosible materials is given in EN 26184-1.
To mitigate explosion risks associated with dust accumulation, it is essential to eliminate these dusts at their source, particularly at transfer points and within silos Additionally, the installation of explosion venting or suppression systems is recommended, especially in fully enclosed equipment.
To minimize the risk of fire or explosion, it is essential to position ignition sources, such as bearings and items with mechanical friction or impact, outside of dusty areas Additionally, utilizing electrical equipment that is appropriate for hazardous zones 20, 21, or 22, as outlined in IEC 61241-1-2, is crucial for safety.
The article emphasizes the importance of implementing anti-static measures and utilizing indicators to monitor critical conditions such as temperature, carbon monoxide, oxygen, and methane levels in silo space B Additionally, it highlights the necessity of employing speed and rotation detectors to mitigate the risk of sparks from malfunctioning mechanical components during the charging or discharging processes.
To minimize the consequences of fire and explosion, it is essential to implement effective strategies such as planning cooling systems and utilizing fire-resistant materials and firefighting devices Additionally, incorporating explosion vents, explosion suppression systems, and designing equipment to be pressure-resistant or pressure shock-resistant is crucial The use of inert gas blankets, particularly nitrogen, in fully enclosed equipment further enhances safety measures.
Explosion vents should be installed in the upper section of silo space B For guidance on the required spacing between vents and other related considerations, refer to VDI 3673 (see annex B).
Explosion vents shall be interlocking in accordance with 4.1.1 of EN 1088:1995 If they are opened, the charging / discharging equipment and other connected equipment shall stop automatically.
Relief valves, bursting panels, and doors must be strategically placed and designed to prevent the ejection of materials or devices into traffic or work areas during an explosion.
The system shall be designed to withstand, without failing, the maximum pressure which can arise in practice(including the pressure to initiate the explosion relief equipment).
NOTE 5 This requires a knowledge of the pressure strength of the equipment.
NOTE 6 Special attention should be paid if abrasive material is stored.
NOTE 7 For pressure relief calculation see VDI 3673.
Every workstation or passageway must have a minimum of two exits to ensure safety These exits should be strategically positioned to prevent individuals from becoming trapped during a fire or explosion.
Relationship of this document with EC Directives
This European Standard has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association and supports essential requirements of following EC Directives :
Machinery Directive 98/37/EC, amended by Directive 98/79/EC.
Compliance with this standard provides one means of conforming with the specific essential requirements of the Directive concerned and associated EFTA regulations.
WARNING Other requirements and other EC Directives may be applicable to the products falling within the scope of this standard.
Table ZA.1 – Clauses/subclauses of this European Standard addressing essential requirements of
Number (as given in annex A) appropriate clauses/subclauses of
Design of machinery to facilitate its handling 1.1.5 -
Failure of the power supply 1.2.6 5.9.1
Risk of break-up during operation 1.3.2 5.1.9
Risks due to falling or ejected objects 1.3.3 5.1.8, 5.1.6.1, 5.1.10
Risks due to surface, edges or angles 1.3.4 -
Risks related to combined machinery 1.3.5 -
Risks related to variations in the rotational speed of tools
Number (as given in annex A) appropriate clauses/subclauses of
Prevention of risks related to moving parts 1.3.7 5.1.3, 5.1.5, 5.1.6.1
Choice of protection against risks related to moving parts
Required characteristics of guards and protection devices
Special requirements for protection devices 1.4.3 5.1.2.3
Energy supply other than electricity 1.5.3 5.10.1.2
Emissions of dust, gases, etc 1.5.13 5.6.1
Risk of being trapped in a machine 1.5.14 5.1.6, 5.1.6.1, 5.1.6.2,
Risk of slipping, tripping or falling 1.5.15 5.1.10
Access to operating position and servicing points 1.6.2 5.1.10
Clauses of this European Standard which address Principal Protection Requirements of the EU Electro-magnetic compatibility Directive 89/336/EEC
The following clauses of this standard are likely to support requirements of the EMC Directive 89/336/EC:
Compliance with this standard provides one means of conforming with the specific essential requirements of the Directive concerned and associated EFTA regulations.
WARNING Other requirements and other EU Directives may be applicable to the products falling within the scope of this standard.
ENV 1991-1:1994, Eurocode 1: Basis of design and actions on structures – Part 1: Basis of design.
ENV 1991-4:1995, Eurocode 1: Basis of design and actions on structures – Part 4: Actions on silos and tanks. DIN 1055-6:1987, Design loads for buildings – Part 6: Loads in silo bins.
P Martens (Hrsg.) Silo- Handbuch, Ernst & Sohn, Berlin 1988, ISBN 3-433-01037-4.
Dr H Wright & Associates, 100 Steps in Bunker Design, Wilkinson & Wright, Stockton-on-Tees, UK, 1984, ISBN 0 9509573 0 5
6 NF P 22-630:1992, Constructions métalliques – Silos en acier – Calcul des actions dans les cellules
7 FEM 2.381:1986, Specific characteristics of bulk products as applicable to storage in silos; Determination and representation of flow characteristics.
8 FEM 2.581:1991, Properties of bulk materials.
9 FEM 2.582:1991, General properties of bulk materials and their symbolisation.