ATEX Non-Electrical Certification
ATEX Non-electrical certification has always been part of ATEX Certification, however, the fact that even Zone 1 certification could be ‘self certified’ for non-electrical equipment (with the resulting file lodged with a Notified Body) has meant that there has been little control as to the depth and accuracy of the assessment. It is likely however that IECEx will add non-electrical to their schemes scope this year (2013) and that will be the end of non-electrical ‘self certification’ for many manufacturers!
Non-electrical equipment can cause explosion by friction, impact, static, hot surfaces and many other methods; all equipment designed to be used in Explosive Atmospheres should have been risk assessed to assure that this can not happen, but in Europe it is the law that this must be done (under the ATEX Directive) and the methodology for doing the assessment and protecting ignition capable parts has been well defined in the form of ‘Standards’.
Many manufacturers buy electrical equipment that is certified for use in potentially explosive atmospheres and assemble rigs, skids or systems that that also include non-electrical potential ignition sources (these can even be the materials of construction such as plastic or metals with high magnesium content). All of these factors must be assessed when CE Marking the package under the ATEX Directive.
It is likely that these requirements will eventually become mandatory for IECEx Certification (it is currently being scheduled for introduction towards the end of 2013) and even North America approval as the non-electrical requirements are now in IEC Standards
Overview of the requirements for ATEX non-electrical equipment
The ATEX Directive 94/9/EC provides for the first time Essential Health and Safety Requirements for non-electrical equipment intended for use in potentially explosive atmospheres and equipment intended for use in environments which are potentially explosive due to dust hazards and protective systems and for devices intended for use outside explosive atmospheres which are required for or contribute to the safe functioning of equipment or protective systems with respect to risks of explosion. This is an increase in scope compared to existing national regulations.
Essential health and safety requirements: equipment, protective systems and safety devices must satisfy the relevant essential health and safety requirements set out in Annex C of Directive 94/9/EC. The requirements take into account the intended use of the products and changes in technological knowledge as far as possible, with immediate utilisation. They include general measures requiring manufacturers to take steps to prevent the formation of explosive atmospheres by the equipment, protective system or safety device; to prevent the ignition of an explosive atmosphere by electrical and non-electrical sources; and to ensure that, should an explosion occur, it can be halted immediately or limited in range. Other aspects covered include:
a) Energy levels (temperature, pressure, friction, electromagnetic fields etc) with ATEX non-electrical parts,
b) Constructional variants within the ATEX non-electrical equipment,
c) Operating conditions or working cycles including their variations (start, stop, load),
d) Influences of the ambience (temperature, pressure, humidity, energy supply etc.),
e) Material parameters or their interdependencies
f) Interdependencies with components or other pieces of ATEX non-electrical equipment,
g) Interdependencies with persons (including misuse which can reasonably be anticipated),
h) Combinations of malfunctions.
In general it is the manufacturer’s responsibility to take those measures necessary to verify conformity to the EC Directive 94/0/EC. This implies a risk assessment for the ATEX non-electrical equipment and in some cases the procedure relating to product quality assurance.
Certification Types and Methods for ATEX Non-Electrical
For all ATEX Categories (Zones) the manufacturer of the equipment must conduct a risk assessment and create a ‘Technical File’ if he wishes to comply with the Directive (and affix the CE Marking). For Category 1, a Notified Body must do the assessment, for Category 2 the manufacturer may do the assessment themselves but they have to ‘lodge’ the Technical File with a Notified Body. For Category 3 the manufacturer may hold the Technical File internally.
Currently, Under IECEx, no self certification is permitted (Test and Certification is always conducted by a suitably qualified and reviewed test and certification body) ATEX defines the EN 13463 mechanical series of standards used to demonstrate compliance to the directive and gain ATEX Non-Electrical Certification. EN 13463-1 is the generic standard which should be used as the basis, however others existing for specific ATEX non-electrical equipment.
Typical Information required to conduct an ATEX non-electrical assessment
A document would be required to confirm the global specification & environment for where the equipment will be used and in what environments (E.g Zone, Gas Group, T Class, and Ambient Temperature).
|External Zone Requirement||II A,B,C – or IIIA, B C Temperature and zone etc.|
|Internal Zone* (POE)||Material, %- Classification|
|Environmental Contamination risk||Ingress, chemical attack, corrosion|
|Ambient Range of Environment||Low and high temperatures expected, icing etc.|
|Operating Conditions of ATEX Non-Electrical parts||Type of facility|
|Level of maintenance available||Skill level and frequency|
|Level of supervision available||Skill level and frequency|
|Monitoring of ATEX Non-Electrical parts||Continuous, automatic or intermittent|
|Other||Other relevant information|
ATEX Non-Electrical Equipment Schedule:
Depending on the apparatus being certified the equipment schedule can vary from a number of components to thousands. It is critical when compiling this schedule that all items are correctly identified and categorized, for example, electrical, mechanical, hydraulic, pneumatic, lubricants & fluids.
Instructions & Certification Drawings for ATEX Non-Electrical equipment :
The initial package for review should contain the instructions and diagrams necessary for the manufacture, putting into service, maintenance, inspection, checking of correct operation and, where appropriate, repair of the equipment. Once the risk assessment has been performed and the safety measures additional documentation will need added which gives a full and correct specification of the explosion safety aspects of the equipment.
Results of Verification & Tests forATEX Non-Electrical equipment :
Verifications and tests are intended to verify that the equipment conforms to the relevant requirements of the applied European Standard for the type of ignition protection concerned. In the initial stages of the assessment we are generally only concerned with the maximum surface temperature of the equipment in relation to the parameters agreed in the scope.
Ignition Hazard Assessment for ATEX Non-Electrical equipment:
The EU Council Directive on the Approximation of the Laws of the member states relating to Machinery (89/392/EEC) demands in its Annex I Section 1.5.7 that “Machinery shall be so designed and constructed to avoid any risk of explosions”.
The ATEX Non-Electrical Standard (EN13463-1) also states that “All equipment and all parts of it shall be subjected to a formal documented hazard analysis that identifies and lists all of the potential sources of ignition by the equipment and the measures to be applied to prevent them becoming effective.’’
To demonstrate compliance with the above we use EN1127-1 as the reference standard. This standard describes the basic concepts and methodology of explosion prevention and protection.
In order that we may conduct the required risk assessment as detailed in EN1127-1 we must first establish where the equipment will be used and what safety factors need to be applied. When this has been established, a detailed and formal hazard identification can be conducted and suitable protective measures applied as appropriate.
Tests may be omitted if it is judged to be unnecessary, in which case the justification for its omission shall be recorded in the technical file.
It should be noted that where safety devices or protective systems are used to prevent hazards occurring, the ATEX Safety Systems Standard should be used.
Apparatus is divided into Equipment groups: I for mining and II for surface industries and into categories M1and M2 for mining and category 1, 2 and 3 for all other industries. The categories provide respectively, very high, high and normal levels against ignition. The categories should be viewed as delivering the level of priority which is obtained by applying the existing protection techniques (Ex ‘c’, Ex ‘k’ Ex ‘p’ etc.)
Definition of Categories /EPLs for ATEX Non-Electrical Equipment
Category 1 Equipment (Zone 0) Ga, Da
Must not have ignition sources that can become effective even in the event of a rare malfunction. Equipment in this category is intended for use in areas in which explosive atmospheres caused by mixtures of air and gases , vapours or mists or by air/dust mixtures are present continuously for long periods or frequently.
Category 2 Equipment (Zone 1) Gb, Db
May have effective ignition sources (with a malfunction applied) protected by a concept listed in EN113463-1. Equipment in this category is intended for use in areas in which explosive atmospheres caused by gases, vapours, mists or air/dust mixtures are likely to occur.
Category 3 Equipment (Zone 2) Gc, Dc
Must also be protected by a concept when ignition capable (relative to the gas or dust) in normal operation. Equipment in this category is intended for use in areas in which explosive atmospheres caused by gases, vapours, mists or air/dust mixtures are not likely to occur.
The categories in normal practice are equated to the suitability for Zones. Apparatus will be marked with the grouping and category in addition to the marking required by the individual protection.
Example ATEX Non-Electrical Assessment of a ‘bearing’ for Zone 1 or Zone 2
Bearings are selected based on the equipment’s intended duty and the following items have been considered (slow moving case where dynamic load not considered):
XXXX Newton’s (617lb) static load, manufacturers maximum (Cr, Dynamic Load Rating) is over YYYY Newton’s (25% capacity)
Since the bearing is not subject to axial load the equivalent load Pr = Fr Therefore applying a service factor of 1.2 for a steady load:
Fr =XXXX x 1.2 (static) = Pr = YYYY C/P Ratio = Z
For Speed up to XXRPM, the bearing life is 20 000 hours.
The maintenance (replacement) level has been set at 15 000h
Note- exactly the same assessment would be required for each bearing for Zone 2, as the bearing must be proven to be rated correctly even in normal operation. Other assessments such as the affect of temperature on lubricants etc. will also need to be considered. For example:
- Lubrication Mineral CLP 220
- Ambient temperature 40 °C
- Oil temperature 57 °C
Maximum upper operating temperature (from datasheet) 80°C
Maximum upper operating temperature (from datasheet) 0°C
It should be noted that it is quite common to find lubricants that are not suitable for the normal ATEX/IEC ambient range of -20°C to +40°C
For more information or help with ATEX Non-electrical certification please contact us