CERTIFICATION OF EQUIPMENT FOR USE IN POTENTIALLY EXPLOSIVE ATMOSPHERES What do I Really Have to Do ?

UK ’ S IMPLEMENTATION OF ATEX 1999/92/EC – ATEX 137 – Implemented as The Dangerous Substances and Explosive Atmospheres Regulations 2002 (DSEAR) – Social Directive 94/9/EC – ATEX 100 – Implemented as the Equipment and Protective Systems for Use in Potentially Explosive Atmospheres Regulations 1996 (EPS) – Trade Directive

DUTIES UNDER DSEAR Conduct Risk Assessment relating to Explosive Atmospheres and their potential threat to people – hazards from flammable gases and vapours and combustible dusts Conduct Area Classification – define locations of Hazardous Areas in the workplace Employ suitable Safety Management systems to ensure that an adequate level of explosion safety is maintained

SUPPLIER RESPONSIBILITIES UNDER EPS Assess risks associated with equipment to demonstrate it is safe for use Ensure that equipment supplied for use in areas defined as hazardous by the customer is suitably certified for the type of hazardous area in which it will be installed Must consider all potential ignition sources – e.g. flames, sparks, static, etc – not just electrical ignition sources

Supplier ’ s Responsibilities (cont) Ensure equipment is suitably labelled Maintain a technical file and quality records re production Provide instructions for Installation, Maintenance, Inspection and Use

Operator ’ s Responsibilities when Ordering – Tell the supplier what classification of hazardous area the equipment will be installed in – Tell the supplier if the equipment is to be connected to other equipment which may contain an explosive atmosphere – Tell the supplier what material the equipment will handle (if it is processing material) and provide information on material properties

Information on Material Properties As a minimum – Whether the material can support an explosion (gas or dust) – Physical characteristics – Gas – autoignition temperature – Dust - Layer Ignition Temperature & Minimum Cloud Ignition Temperature Other data which the supplier may need to request (depending on how equipment is to be protected) – Minimum Ignition Energy – Explosion Indices

CUSTOMER MUST PROVIDE INFORMATION ON HAZARDOUS AREAS WHAT IS A HAZARDOUS AREA? “A place in which an explosive atmosphere may occur in sufficient quantities to require special precautions to protect the health and safety of the workers concerned is deemed to be hazardous” “A place in which an explosive atmosphere is not expected to occur in such quantities to require special precautions is deemed to be non-hazardous within the meaning of these Regulations”

HAZARDOUS AREA DEFINITIONS UNDER DSEAR Zone 0 (20):A place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas, vapour or mist (or dust) is present continuously or for long periods or frequently. Zone 1 (21):A place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas, vapour or mist (or dust) is likely to occur in normal operation occasionally. Zone 2 (22):A place in which an explosive atmosphere consisting of a mixture with air of flammable substances in the form of gas, vapour or mist (or dust) is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

Problems re Classification of Hazardous Areas Customers tend to be conservative and “over-classify” hazardous areas Customers may not have classified hazardous areas Zone 0/20 & 1/21 require that explosive concentrations are present in normal operation (e.g. >20,000ppm or 50g/m 3 ) Majority of workplaces will be no worse than Zone 2/22 (and may be safe) Need to include the new equipment in the evaluation of workplace hazardous areas – ideally operator would consult with supplier Be prepared to challenge the customer’s area classification

Classification of Gas Hazardous Areas Tendency is to be too conservative (e.g. extent of flammable atmosphere above flammable liquids will generally be small) Historical “Flameproof” areas might not be zone 1 Take credit for ventilation

EXPLOSIVE DUST ATMOSPHERE A cloud of 40 g/m 3 of coal dust in air is so dense that a glowing 25W light bulb can hardly be seen through a dust cloud of 2m thickness

CLASSIFICATION OF EQUIPMENT You have agreed with your customer what the hazardous areas are – what do you now have to do to classify your equipment

Certification of Equipment for Use in Hazardous Area 1. Equipment which does not handle hazardous material – only need to address the potential for the equipment to ignite a surrounding explosive atmosphere 2. Equipment which handles hazardous material – have to address control of explosion risks inherent to the equipment, the potential to ignite a surrounding explosive atmosphere, and the potential to ignite an explosive atmosphere in connected equipment

Equipment Classification to EPS Category 3 – equipment which does not represent an ignition source in normal operation – suitable for use in zone 2 (22) area Category 2 – equipment which does not create an ignition source in normal operation, or in the event of a foreseeable malfunction – suitable for use in zone 1 (21) and 2 (22) areas Category 1 – equipment which does not create an ignition source even in the event of a rare malfunction – suitable for use in zone 0 (20, 1 (21) and 2 (22) areas

Authority to Classify Category 3 – self certification by supplier Category 2, non-electrical ignition sources – self certification by supplier (technical file to be sent to a Notified Body) Category 2, electrical ignition sources (or internal combustion engines) – certification by Notified Body Category 1 – certification by Notified Body Have to be clear if the equipment is certified for Gases (G) or Dusts (D) or both (G/D)

Equipment from Outside the EC For equipment manufactured in the EC the supplier is responsible for the certification When equipment is imported from outside the EC it must still be certified, and either the EC agent (if there is one), or the EC customer has to take on the responsibilities of the supplier

Certification of Equipment Have to consider the Machinery Directive as well as EPS Do risk assessment for Machinery Directive first, then move on to EPS Machinery Directive requires a demonstration that the equipment is safe for intended use – requires consideration of inherent explosion hazards – may determine that equipment requires explosion protection Having completed the Machinery Directive risk assessment conduct an Ignition Hazard Assessment for EPS

Explosion Protection Devices Equipment Intended to provide protection against explosion affects, or to prevent explosion propagation from an item of equipment to another are “explosion protection devices” and must be Certified under EPS (by a notified body) Examples are : – Relief panels – Suppression Systems – Explosion Barrier Valves – etc

Let ’ s look at how to classify the two types of equipment (that which does not handle a flammable material and that which does)

Equipment which does not handle Hazardous Material Machinery Directive assessment will concentrate on basic health and safety requirements (e.g. guarding) and will not touch on EPS matters Ignition Hazard Assessment required to categorise equipment depending on its ability to ignite a surrounding explosive atmosphere

Ignition Hazard Assessment Systematically review the operation of the equipment to identify conditions when ignition sources could arise Consider all potential sources of ignition (e.g. electrical & mechanical sparks, friction / hot surfaces, static) Consider normal (intended) operation first Identify foreseeable malfunctions and decide whether these could create ignition sources (considering ignition of a surrounding explosive atmosphere) Identify rare malfunctions (e.g. two simultaneous malfunctions) and decide whether these could create ignition sources BS EN provides a methodology

Possible Outcomes of Ignition Hazard Assessment 1. Equipment provides an ignition source in normal operation – can’t certify under EPS (need to look at measures to remove the ignition source) 2. Equipment provides an ignition source as a result of a foreseeable malfunction – self certify as Category 3 3. Equipment provides an ignition source as a result of a rare malfunction – self certify as Category 2 (if no electrical ignition sources). If machine has some electrical components then invite Notified Body to certify, or use pre-certified category 1 or 2 electrical components in the assembly - lodge technical file with Notified Body 4. Equipment does not provide an ignition source in the event of a rare malfunction – invite Notified Body to certify as category 1

Further Considerations Creation of sparks or hot surfaces inside equipment may ignite a surrounding explosive atmosphere if there is no isolation Have to consider how the equipment might be used (abused) by the customer – may need some additional controls to prevent inadvertent incorrect use – or some warnings in instructions provided with the machine

Equipment Handling a Hazardous Material Conduct Machinery Directive Risk Assessment – Identify causes of explosive atmosphere within equipment – Look for possible sources of ignition of any such atmospheres – Determine whether ignition sources can be adequately controlled – Decide whether explosion protection is needed (will depend on overall risk – frequency and consequences) – Define explosion protection controls Complete Ignition Hazard Assessment in relation to an explosive atmosphere surrounding the equipment, and any explosive atmospheres in items which will be connected to the equipment, taking into account controls defined by the Machinery assessment

Implications of Internal Ignitions Ignition of an explosive atmosphere within an item of equipment may create an ignition source to an explosive atmosphere surrounding the equipment, if there is no isolation e.g. assessment of components on the outside of the equipment might allow Category 2, but internal ignition from a foreseeable malfunction would reduce this to Category 3 if flame can propagate from inside to outside Isolation devices will be “explosion protection devices” under EPS and will have to be certified by a notified body

Transfer of Ignition Sources to Connected Equipment “Internal” classification of machine (i.e. likelihood of ignition sources to up- and down- stream equipment) may be different to external classification If internal classification is not compatible with hazardous area classification for connected items will have to advise the customer that the connected items require explosion protection

Key Problems with the Regulations Many suppliers are not confident enough to self certify equipment Operators tend to overstate the hazardous areas Difficult to take into account the different ignition and combustion properties of different materials Assistance from Notified bodies can be expensive

EXAMPLE – Hammer Mill Zone 22 workplace, Category 3D mill required as a minimum But internal explosive atmosphere in normal operation identified by the Machinery Risk Assessment, and possible ignition source in the event of a malfunction Large volume grist hopper – consequences of explosion could be severe Explosion protection required EPS certified explosion barriers required to prevent explosion protection to connected equipment (which might also contain explosive atmospheres)

So if my risk assessment determines that my equipment requires explosion protection what can I do ?

Explosion Protection Explosion Containment – design plant for maximum explosion pressure Explosion Suppression – install extinguishing system Explosion Venting – provide weak panel to relieve pressure Explosion Isolation – prevent explosion propagation In all cases would have to use Certified Devices approved by a Notified Body

MYTH Existing equipment must be replaced by ATEX approved equipment Equipment on the market before 1 st July 2003 exempt from EPS (ATEX 100) – i.e. already installed, second hand or in stores Equipment must be safe for use in hazardous areas – e.g. old “Ex” rated electrical equipment in gas/liquid zones & suitable ‘IP’ rating for dust zones – suitable surface temperatures in both cases

MYTH Existing protective systems must be replaced by ATEX certified systems Protective systems on the market before 1 st July 2003 are exempt from EPS – Aluminium panels secured by nylon bolts – Explosion Doors with Brixon Latches OK to retain so long as they provide effective protection

OTHER AREAS OF CONFUSION Maintenance of Certified Equipment – Under EPS Suppliers must provide essential information for operation and maintenance – qualified technicians should be able to perform all necessary maintenance Refurbishing Old Equipment – Can legitimately refurbish equipment back to its original state without having to certify it – only have to certify if functionality is changed Use of Plastic in Hazardous areas – No restriction in zone 2/22 areas

SUMMARY Operator is responsible for Area Classification and must tell the Supplier what classification of hazardous area equipment will be required to operate in, and whether it will be connected to hazardous areas in other equipment Be prepared to challenge the Customer’s area classification Most equipment will be going into zone 2 (22) areas at worst, so can self certify Conduct Machinery Assessment first to define any explosion controls, then conduct Ignition Hazard Assessment Suppliers should provide instructions for safe operation which should cover maintenance as well