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Practical guide to the classification of potentially explosive areas Extract from the ATEX Directives 94/9 and 99/92

2006 edition


Garages

Description

These are car repair shops. Legislative changes: Modification V1 in new appendix to Guide CEI 31-35

Risk of explosion

Garages are no longer considered areas with risk of explosion if: 1) the only flammable substance is fuel in tanks 2) fuel tanks are not filled or emptied 3) no cars are leaking fuel 4) natural or forced ventilation is installed in accordance with the provisions of Italian Ministerial Decree 01/02/86 5) all car engines are off 6) only standardized/serviced cars are allowed access 7) only parking and manoeuvring are allowed 8) flammable substances are in such low quantities that there is no risk of an explosive atmosphere; 9) no work is carried out on the fuel circuits.

Fire risk

When it is necessary to disassembly the fuel pump (that can be found inside the tank), the possible contact between the pump live electrical wires could generate sparkles. Even if the tank has been emptied, fumes and the little fuel remained inside can be sufficient to provoke an explosion or to set a fire. In case of a car explosion, the fire that is generated can easily reach other vehicles, thus provoking other explosions.

Environmental stress

The exhaust emissions contain carbon monoxide (1-15%), carbon dioxide, unburnt petrol fumes, chloride and lead bromide. Lead is spread outside in organic and inorganic compounds through the exhaust emissions. Therefore, it is clear that the absorption risk of carbon monoxide and other substances present in rivers is higher in underground garages and in environments with insufficient ventilation.

Palazzoli – Practical guide to classification - 2Ex Garages - 2005/06 Note – The 3Ex practical guide on thermal power plants has been substituted by guide No. 15Ex

2


Painting/body shops

Description

These are places for spraying liquid paint containing flammable solvents, which could form explosive atmospheres by mixing with the air. These paints have the following symbol on their packaging:

Risk of explosion

The areas around the spray gun and painted objects during drying are the emission sources. These are classified depending on the components of the most hazardous paints used, according to method specified in Standard CEI EN 60079-10. As a general rule, the flow rate of air ventilating the environment must be at least 60 m3 /h per litre/h of sprayed paint. In this case, again as a general rule, Zone 1 is the area inside the spray and drying booths, or if the room is large, the areas surrounding the emission source for a safe distance of 2-3 m. If there is medium ventilation with good margin, the rest of the room can be classified as Zone 2 and should have EEx-n equipment.

Fire risk

According to Italian Ministerial Decree 16-02-82, all areas where over 500 kg of flammable or combustible paints are used or stored and all painting laboratories and workshops which use flammable or combustible paints and employ more than 5 people, are activities requiring inspections by the Fire Service, which then issues a Fire Prevention Certificate. According to Standard CEI 64-8/7, the places where these activities take place are considered high risk areas in the event of fire, regardless of their classification as areas with risk of explosion. As a minimum requirement, all sparking electrical components, except for small devices of up to 16A, must have at least IP4X protection.

Environmental stress

Painting and body shops should be considered high-stress environments due to the risks of penetration by solid and liquid bodies and of exposure to polluting and corrosive atmospheres. Components with high protection against these stresses are therefore recommended in these cases. Equipment with a protection level of at least IP55 (or IP66 if it is positioned in such as way that it can be accidentally sprayed with paint). As a general rule, these environments can be classified under the normalized group of environmental classes IE 33, according to Standard CEI EN 60721-3-3.

Palazzoli - Practical guide to classification - 4Ex Painting shops - 2005/06

3


Petrol stations

Description

Petrol stations supply fuel to the public in outdoor areas.

Risk of explosion

Petrol stations represent a specific example of classification in the Guide CEI 31-35/A (example GD7). This guide specifies the following hazardous areas: • petrol pumps: Zones 1 are the areas inside the pump, the slot for the pump gun and the area around the degasser vent down to the ground for a distance of 10 cm. Zones 2 are all the external parts of the above Zones 1 extended vertically down to the ground and horizontally for 20 cm; • tank filling pipe; Zone 1 is the part inside the pipe; Zone 2 extends over the cover of the pipe for a horizontal distance of 20 cm, beyond the perimeter of the pipe and for a vertical height of 10 cm; • underground tank pipe vent; Zone 2 extends in all directions around the mouth of the breather pipe for 75 cm. The above specifications are indicative as the classification must be made for each individual case following the criteria specified by Standard CEI EN 60079-10. EEx-n equipment is acceptable in Zone 2. Self service petrol stations should have the above equipment throughout the area under the shelter, as users filling up their cars may accidentally spill petrol which then evaporates.

Fire risk

Fixed petrol stations for both public and private use are listed in point 18 of Italian Ministerial Decree 16-2-82 as one of the activities requiring Fire Prevention Certification. According to section 751 of Standard CEI 64-8 Fifth edition, these stations are therefore classified as high risk areas in the event of fire due to the presence of flammable material. Regardless of their classification as Zones 0, 1 or 2 with risk of explosion, the minimum requirement is that all sparking components must have at least IP4X protection (except for small devices of up to 16A ).

Environmental stress

Petrol stations should be considered high-stress environments due to their exposure to bad weather and polluting and corrosive exhaust fumes. All components should have at least IP55 protection with enclosures made of aluminium or thermosetting resin. As a general rule, they can be classified in the normalized group of environmental classes IE 41, according to Standard CEI EN 60721-3-4.

Palazzoli - Practical guide to classification - 5Ex Petrol stations - 2005/06

4


Chemical industries

Description

These are where many different types of substances are processed in order to obtain organic or inorganic chemical compounds. Gases, liquids, solids, gelatines or powders are often present, causing risks of explosion, fire and corrosion. These substances must be specified individually with the help of technicians supervising the production process, in order to choose the right electrical components.

Risk of explosion

All combustible gases and flammable liquids (i.e. with lower flash points than the ambient temperature or processing temperature). The risk level should be evaluated according to Standards CEI EN 60079-10 for liquids and gases and CEI EN50281-3 for dusts and powders. In the surrounding areas, the reactors, storage areas and conveyers and processing machinery are often classified as Zones 2 and Zones 22, extending a few metres around the second grade emission sources. This areas should have EEx n equipment for gases and liquids and EEx II 3D IP5X equipment for dusts. Areas with a high density of second grade emission sources should have the above equipment installed throughout the environment.

Fire risk

All environments with a fire load of more than 15 kg wood/m2 should be classified according to the method described in Annex B of section 751 of Standard CEI 64-8. If there is a fireproof compartment higher than 15, the environment should be considered a high risk area in the event of fire due to the presence of flammable or combustible material on the production line or in storage. In all cases, the above classification covers all departments or rooms destined for carrying out one or more of the activities listed in Italian Ministerial Decree 16-2-82 that require Fire Prevention Certification and systematic inspection by the Fire Service. Even if these areas are not classified as areas with risk of explosion, the minimum requirement is that all the equipment installed must have at least IP4X protection (except for small devices of up to 16A ).

Environmental stress

Chemical industries should be considered very high-stress environments due to the risks of exposure to polluting or corrosive atmospheres. All components should have highly resistant enclosures (made of aluminium or thermosetting resin with IP55 or higher protection). As a general rule, they can be classified under the normalized group of environmental classes IE 41, according to Standard CEI EN 60721-3-4.

Palazzoli - Practical guide to classification - 6Ex Chemical industries - 2005/06

5


Cereal silos

Description

Silos are used for storing cereals such as wheat, grain, rice and pulses. This produce is loaded and unloaded using mechanical equipment which can generate dusty atmospheres during manoeuvres.

Risk of explosion

Cereal dusts are extremely hazardous, due to both their grain size and their low specific weight. They can remain suspended in the area for quite a long time, generating a high risk of explosion. Areas with this risk should be classified due to this risk of explosion, according to the criteria specified in Standard CEI EN50281-3. This means evaluating the presence and extent of Zone 20, 21 and 22. Zone 20 is usually the entire area inside a silo; Zone 1 is adjacent to the loading and unloading points (loaders and hoppers); and Zones 22 are the areas bordering on these zones and cover a few metres. Zones 22 are also areas where dusts can accumulate in layers and therefore occasionally cause explosive atmospheres, as well as areas where easily torn packages are stored. Zones 20 allow EEx II 1 D IP6X equipment; Zones 21 allow EEx II 2D IP6X equipment; and Zones 22 allow EEx II 3 IP5X equipment. Socket-outlets must be interlocked.

Fire risk

The risk of fire can be determined by a fire load with compartments higher than 15 (>15 kg wood/m2). Cereal storage areas with a higher capacity than 500 quintals are included in the list of activities given in point 36 of Italian Ministerial Decree 16-02.82. They therefore require Fire Prevention Certification, and according to Standard CEI 64-8/7, can be classified as high risk environments in the event of fire due to the presence of flammable material. Therefore, regardless of their classification as areas with risk of explosion, these environments must have equipment with at least IP4X protection (or IP5X for dusty environments).

Environmental stress

Environments where there are silos for storing cereals etc. are usually outdoor and dusty areas where temperature changes can cause condensation. As a minimum requirement, IP54 protection should be installed if the area is exposed to bad weather, rain and jets of water. In areas where loading and unloading trucks have access, the conductor and equipment should be installed at least 1.60 metres from the ground. As a general rule, they can be classified under the normalized group of environmental classes IE 41, according to Standard CEI EN 60721-3-4.

Palazzoli - Practical guide to classification - 7Ex Cereal silos - 2005/06

6


Pharmaceutical industries

Description

These are laboratories which produce drugs by mixing, emulsifying and causing chemical reactions of organic compounds, which are usually highly flammable. All the raw materials or chemical compounds produced (whether finished or semifinished) must be specified in detail, as they can cause risks of explosion, fire, corrosion and even enter electrical enclosures.

Risk of explosion

All combustible dusts, combustible gases and flammable liquids (i.e. with a lower flash point than the ambient temperature or processing temperature) generate a risk of explosion. The risk level should be evaluated according to the criteria specified by Standards CEI EN 60079-10 for liquids and gases and CEI EN50281-3 for dusts. Allthe extraction points for sampling as well as all the loading and unloading mechanisms moving in the air are continuous or first grade emission sources. Therefore, according to ATEX Directive, they must be reduced to a minimum. In all areas containing tanks, conveyor systems and chemical reactors, there are inevitably second grade emission sources surrounded by Zone 2 (where there can be leaks of flammable gases or liquids) or Zone 22 (occasional emissions of combustible dusts). The extent of these zones is determined in each case according to the criteria specified by the above standards. This areas allow EEx n equipment for gases and liquids and EEx II 3D IP5X equipment for dusts. In laboratories with a high density of second grade emission sources, or where these sources are mobile or variable depending on the production process, EEx equipment is recommended throughout the environment.

Fire risk

Italian Ministerial Decree 16-02-82 (in point 59) requires Fire Prevention Certification and systematic inspection by the Local Fire Service in all factories and plants that manufacture and process pharmaceutical products using solvents and other flammable products, without limits as to the processing quantity or number of employees. All processing environments must be classified as high risk areas in the event of fire, whatever the fire load. These environments should have sparking devices with at least IP4X protection (except for small devices of up to 16A).

Environmental stress

Many departments of pharmaceutical industries are to be considered high-stress environments due to the risk of penetration of liquids and dusts in enclosures containing electrical devices. All components should have at least IP54 protection (IP55 in tiled rooms that are frequently washed). As general rule, they can be classified under the normalized group of environmental classes IE 34, according to Standard CEI EN 60721-3-3. Palazzoli - Practical guide to classification - 8Ex Pharmaceutical industries - 2005/06

7


Joiner y shops

Description

These are woodworking shops where shavings are removed (through cutting, milling, planing or drilling) using machines fitted with sawdust suction systems conforming to hygiene regulations. Minor manual adjustments do not generate considerable amounts of sawdust.

Risk of explosion

Shavings and sawdust are large pieces and therefore remain suspended in the air for few seconds in small areas around the emission sources. Wood dust in fine particles, usually removed with the suction machine, are much more hazardous. Only in particular cases and for limited periods can there be explosive atmospheres (e.g. when the suction pipes are clogged, there is a fault in the suction systems or the manual or automatic mechanisms fail to function). Emissions can therefore be considered second grade and the areas covering a few metres around the tools can be classified as Zones 22. It is highly unlikely to have leaks from suction systems operating under pressure. Zones 22 are also areas where dusts can accumulate in layers and occasionally cause explosive atmospheres, as well as the immediate surroundings of the sawdust bin and the areas where mobile or portable electric tools are used occasionally. Zones 22 allow EEx II 3 IP5X equipment and socket-outlets must be interlocked. The areas must be regularly cleaned, i.e. piles of sawdust must be removed to prevent it from generating an explosive environment.

Fire risk

The risk of fire can be determined by the fire load with compartments higher than 15 (>15kg wood/m2); wood storage areas with a higher capacity than 500 quintals are listed as one of the activities requiring Fire Prevention Certification under Italian Ministerial Decree 16.02.82. According to Standard CEI 64-8/7, they can be classified as high risk environments in the event of fire due to the presence of flammable material. Therefore, regardless of their classification as areas with risk of explosion, all sparking devices must have at least IP4X protection (except for small devices of up to 16A).

Environmental stress

Environments housing joineries are exposed to the risk of impact and the penetration of shavings. Minimum protection should be IP4X (against the penetration of small objects) and IK09 (against impacts). As a general rule, they can be classified under the normalized group of environmental classes IE 33, according to Standard CEI EN 60721-3-3.

Palazzoli - Practical guide to classification - 9Ex Joineries - 2005/06

8


Agricultural and food industries

Description

These are factories processing cereals, pulses, peanuts, cocoa, coffee and sugar, which can have the risk of explosion, fire and the presence of dust. Dairy industries are not included in this category.

Risk of explosion

The dusts that develop during the handling of cereals, dry vegetables, pulses, cocoa, sugar and coffee have ignition temperatures of between 350째C (sugar) and 470째C (wheat), and their risk level depends on the size of the particle and the specific weight. The areas where these substances are processed or stored must be classified in terms of their risk of explosion according to the criteria specified in Standard CEI EN50281-3. This means evaluating the presence and extent of Zones 20, 21 and 22. Zone 20 is usually the area inside the processing machinery and conveyors while Zone 21 is immediately adjacent to the loading and unloading points (conveyor belts and hoppers). Zones 22 are the areas surrounding the conveyors, the processing machinery and the storage areas, where dust can occasionally enter the atmosphere. Zones 22 allow EEx II 3 D IP5X constructions. In environments where there is a high density of sources of occasional dust emission, EEx II 3D IPX5 are recommended throughout the area.

Fire risk

Cereal mills and other milling facilities with a production of over 200 quintals a day, cereal and vegetable drying systems with storage areas with a capacity of over 500 quintals of dried products, as well as factories producing coffee substitutes, sugar and pasta factories with a daily production of over 500 quintals, and rice mills with potential daily production of over 100 quintals, are all considered, according to Italian Ministerial Decree 16-02-82, activities requiring Fire Prevention Certification and can be classified according to Standard CEI 64-8/7 as high risk environments in the event of fire due to flammable material. Therefore, regardless of their classification as areas with risk of explosion, all devices must have at least IP4X protection.

Environmental stress

Small objects and dusts are often present in agricultural and food industries. The minimum protection level should be IP5X. When equipment must be cleaned with water jets (in tiled rooms for example), electric components must be installed with a protection level of at least IP55, preferably with easily washable enclosures (made of thermosetting resin). As a general rule, they can be classified under the normalized group of environmental classes IE 34, according to Standard CEI EN 60721-3-3. Palazzoli - Practical guide to classification - 10Ex Agricultural and food industries - 2005/06

9


Oil refineries

Description

These are areas for processing and storing highly flammable substances (such as petrol), flammable substances (such as crude oil or fuels like diesel oil) and combustible fuels for furnaces and boilers.

Risk of explosion

Crude oil and petrol have a flash point under 0째C and therefore generate a high risk of explosion. All the parts inside the storage areas and processing containers are Zones 0. The parts near vents, sampling valves and loading and unloading points are usually Zones 1. Most manual and automatic valves and flanged fittings should be considered second grade emission sources with the risk of explosive atmosphere due to dripping and evaporation. The areas surrounding these elements are usually Zones 2, covering a metre around the puddle formed by dripping. These areas should be evaluated according to the method specified by Standard CEI EN 60079-10. EEx n equipment should be installed throughout the area. Wherever there is a lot of piping, they should be installed up to 1.5 metres over the highest source of emission.

Fire risk

According to Italian Ministerial Decree 16-02-82, all factories which produce, use or store over 500 kg of flammable or combustible liquids (either in storage or being processed), require inspections by the Fire Service and Fire Prevention Certification. According to Standard CEI 64-8/7, these are high risk areas in the event of fire, regardless of their classification as Zones 0, 1 or 2 with risk of explosion. All sparking electrical components in refineries must have at least IP4X protection.

Environmental stress

Oil refineries should be considered extremely high-stress environments due to the risk of exposure to polluting and corrosive atmospheres. Components must have very resistant enclosures (made of aluminium or thermosetting, with IP55 or higher protection). As a general rule, they can be classified under the normalized group of environmental classes IE 41, according to Standard CEI EN 60721-3-4.

Palazzoli - Practical guide to classification - 11Ex Oil refineries - 2005/06

10


Farms and zootechnical sector

Description

These are farms where agricultural produce (such as cereals, forage and vegetable) is harvested, processed and stored and where animals are farmed. Peculiarities: Farms are considered special environments in Standard CEI 64-8, section 705. All socket-outlets must be protected with a 30mA differential switch and fitted with a differential main switch with Idn of at least 500mA. Other specifications regard the areas where animals are kept, in which: - the contact voltage must be reduced to 25V; - there must be supplementary unipotential connections; - a unipotential system must be installed in the stables.

Risk of explosion

There may be the risk of explosion due to combustible dusts in areas where cereals, forage and pulses are dried, stored, processed and handled. These areas must be classified according to the criteria specified in Standard CEI EN50281-3. This involves evaluating the presence and extent of Zones 20, 21 and 22. Zone 20 is usually the area inside the machinery used for processing, lifting and handling agricultural produce or fertilizer. Zones 21 are the areas immediately adjacent to the above machinery. The areas bordering on these zones (covering a few metres) where there may be the occasional presence of dusty atmospheres, should be classified as Zone 22. Zones 22 allow EEx II 3 D IP5X equipment. In threshing floors, haylofts and other areas where occasional processing may release dust into the atmosphere, EEx equipment should be installed throughout the environment.

Fire risk

The risk of fire may be present in all farms and should be evaluated according to the criteria for calculating the fire load specified in Section 751 of Standard CEI 64-8, section 751. In there is a risk of fire, sparking devices must have at least IP 4X protection.

Environmental stress

Farms are high-stress environments especially in places exposed to bad weather (rain, dust and small objects). At least IP55 protection is therefore recommended. In particular, areas where large animals are kept require particular precautions against knocks, fouling and rodents (highly robust enclosures made of aluminium or hard resin are recommended). As a general rule, exposed areas can be classified in the normalized group of environmental classes IE 41, according to Standard CEI EN 60721-3-4, while stables fall under group IE 35 according to CEI EN 61721-3-3.

Palazzoli - Practical guide to classification - 12Ex Farms and zootechnical sector - 2005/06

11


Batter y charging areas (forklift trucks etc.)

Description

These are areas for charging lead and cadmium nickel batteries installed on forklift trucks and other electrically powered vehicles. These areas can be outdoors, generally under lean-to roofs or in warehouses.

Risk of explosion

Cadmium nickel or lead batteries can cause (at the end of charging or during charging that is too rapid) the dissociation of water into oxygen and hydrogen. This leads to the risk of explosion with first grade emission sources. The most hazardous situation is where batteries have covers with outlet holes which require a flow rate of ventilating air that can be calculated using the following formula: Q (m3/h)= 0,05 C Igas 10 –3 where C is the total capacity in Ah of the charging batteries and Igas is equal to approx. 50 mA for each ampere of rapid charging. The above specifications are indicative and both refer to Standard CEI EN 50272-2. The classification must be made in each case following the criteria specified by Standard CEI EN 60079-10 (see Italian Ministerial Decree 10 March 98 and the ATEX directive). For first grade emission sources and top grade ventilation with adequate margin, Zones 2 are within the distance:

d(mm) = 28.8 x 3 Igas 3 C These areas allow EEx-nR equipment, which features limited respiration and are therefore suitable for hydrogen, which is a highly flammable gas (group B). As an extra precaution, this equipment should be installed in the entire charging area of the batteries, right up to and including the ceiling, mainly because forklift trucks do not have a fixed position during charging, so areas cannot be defined by safety distances. In outdoor installations, ventilation is generally high with good margin and Zones 2 are limited.

Fire risk

In the open charging areas the subsequent damages to an explosion can be particularly high, either for the explosion violence or for the possibility to set fire to possible combustible materials present in the nearby areas (charging areas). Therefore, it is necessary to take into consideration all possible measures to reduce to marginal values the formation of possible explosive atmospheres.

Environmental stress

The electrolyte used in lead batteries is an aqueous solution of sulphuric acid, and the electrolyte used in cadmium nickel batteries is an aqueous solution of potassium hydroxide. Whenever there are leaks, there is a high risk of corrosion due to direct contact and the evaporation of corrosive gases. Electrical components must have acid and base resistant enclosures. Regardless of the explosion-proof protection used, EEx nR type limited respiration is also effective against the penetration of corrosive atmospheres inside the equipment..

Palazzoli - Practical guide to classification - 13Ex Battery charging areas (Forklift trucks etc.) - 2005/06

12


Distilleries / Breweries

Description

These are industrial or small environments for making and/or storing spirits with a high content of ethyl alcohol. This may involve distillation, mixing of hydroalcoholic infusions and bottling.

Risk of explosion

Pure ethyl alcohol has a flash point of 12째C, which increases gradually to 40 째C in alcohol/water mixtures at a ratio of 15% and 85%. Only beverages with low alcohol content can be considered non-flammable. The risk level should be evaluated according to the criteria specified in Standard CEI EN 60079-10. If the ventilation is high with adequate margin, first and second grade emission sources are surrounded by Zones 2. These areas allow EEx n equipment with temperature class T2 (the flash point of ethyl alcohol is 363째C). In areas with a high density of emission sources, or where these sources are mobile, EEx n equipment should be installed throughout the environment. According to the ATEX directive, continuous grade emission sources outside the machinery and watertight tanks, such as open top tanks or distillers with dripping, must be limited to a minimum and could generate Zone 0 if there is medium ventilation. These areas should only have electric components with intrinsic safety.

Fire risk

Fire Prevention Certification is necessary in all factories and plants which process or store more than 500 litres of alcohol (Italian Ministerial Decree 16-02-82 clause 12 and 13). These environments should be classified as high risk areas in the event of fire and require sparking devices with at least IP4X protection (except for small devices of up to 16A ).

Environmental stress

It is advisable to install electrical components with a protection level of at least IP54 in areas where hydroalcoholic infusions are produced using water and essences in powder form.

Palazzoli - Practical guide to classification - 14Ex Distilleries / Breweries - 2005/06

13


Heating plants (modification V2)

Description

These are boiler rooms where heating systems with a thermal power of more than 35kW are powered by methane gas and are used for providing heating and/or a hot water in public, commercial or industrial buildings. Plants with a power of less than 35 kW do not require boiler rooms and are not included in this description. Heating systems used for industrial processes are also excluded.

Risk of explosion

All environments containing methane-powered equipment, plants or services with a potential of over 35 kW are governed by the ATEX directive. The risk level should be evaluated according to the criteria specified in Standard CEI EN 60079-10. National or private suggestions and guides may also be referred to together with these criteria. The recent modification V2 to guide CEI 31-35 has generated a bit of confusion and has often been mistaken as an amendment, which would exclude most of the heating plants from ATEX obligations. This modification, however, is only an example referring to particular conditions that are not easy to verify (sufficient ventilation, emission holes measuring max. 0,25mm2, methane pressure at max. 4000Pa). Evaluating ventilation efficiency or measuring source emission holes is not an easy task, nevertheless it is the classifier’s responsibility by law. The basic principle is that if the heating plant conforms to the laws in force, it should be classified as Zone 2 in the worst possible case. One sure precaution is to install EEx n T1 equipment throughout the environment to avoid errors in underestimating the risk of explosion.

Fire risk

The boiler room is a high risk area in case of fire (Italian Ministerial Decree 16-02-82 clause 91 for a potential of over 116kW and Italian Ministerial Decree 12 April 96 for power of over 35kW). This means that the electric system must be planned considering this, regardless of whether there is the risk of explosion.

Environmental stress

The boiler room has no windows, so it is subject to temperature changes from -5 to + 45 °C with risks of condensation. It can therefore be classified under environmental class IE 35 (Standard CEI EN 60 721-3-3). There are excellent electrical components designed for this class with IP 44 protection or higher.

Palazzoli - Practical guide to classification - 15Ex Heating plants after V2 - 2005/06

14


Metalworking factories

Description

These are places where metals are machined to obtain semi-finished pieces such as ingots, bars and rods, drawn pieces, sheets and section bars. This includes blast furnaces, galvanic baths and crucibles for extracting metals from minerals and producing alloys and special steels.

Risk of explosion

There may be a risk of explosion in areas where machining can generate metal dusts, like cutting, polishing and sanding. Particularly hazardous metals are magnesium, aluminium and titanium, whose lowest dust flash point is a few tenths of a gram per m3. Less hazardous are ordinary metals like iron, zinc and copper. Explosive dust deriving from these metals is produced by particular machining techniques, which can be classified as Zones 22 in the areas outside the processing machinery. Zones 22 allows EEx equipment with dust protection of at least IP6X, designed in compliance with Standard CEI EN 50281-1-1 and with an enclosure temperature of max 250 째C. These devices must be installed in areas where metal dust can accumulate.

Fire risk

The risk of fire is not intrinsic in the areas where typical metalworking takes place, except for blast furnaces and other types of furnaces with solid, liquid or gaseous fuel, which could cause a risk of explosion. Areas between metal trestles of structures or on processing plants can be classified as limited conducting areas (Standard CEI 64-8 section 706). These areas require supplementary unipotential connections and all mobile services must be powered by socket-outlets which each have an insulating or safety transformer.

Environmental stress

The Environmental stress are characterized by the possible presence of condensation resulting from extreme temperature changes (especially in open warehouses), and by the risk of knocks and the presence of dust. As a general rule, warehouses only partially protected against the bad weather can be classified under the normalized group of environmental class IE 35, according to Standard CEI EN 60721-3-3, where IP55 protection is recommended.

Palazzoli - Practical guide to classification - 16Ex Metalworking factories - 2005/06

15


Waste treatment plants

Description

These are plants where solid waste is treated with or without physical, chemical, biological or heat processes, and temporarily stored and sorted, in compliance with Italian Legislative Decree 36/03. This description does not include old sites which accept waste banned by Article 6 of the above Legislative Decree (e.g. explosive, comburent, flammable, corrosive or contaminated waste). This description mainly refers to biodegradable waste treatment plants.

Risk of explosion

Waste treatment plants accepting biodegradable waste must, by law, be equipped with equipment for extraction, possible energy use or biogas channelling in a suitable combustion chamber with a temperature of at least 850째C. This extraction and treatment system must be kept running for as long as there is the formation of gas the site. The risk of explosion around these plants must be evaluated according to specifications of Standards CEI EN 60079-10. Zones 0 are usually the areas bordering on the plant, while Zones 1 regard sampling points, outlets, valve fittings compressors. Zones 2 cover a few metres around the second grade emission sources. EEx n equipment is acceptable in these areas. EEx n equipment should be installed for the sake of precaution in large waste treatment plants, where there could be unidentified biogas leaks through roofs or holes.

Fire risk

Waste with a heat value of over 13000 kJ/kg is no longer accepted in ordinary waste treatment plants and therefore the risk of fire is limited. In special sorting areas, there could be a fire load of over 15kg wood/m2 and a fireproof compartment of over 15. In this case, the environment should be considered a high risk area in the event of fire, so equipment with at least IP4X protection should be installed (except for small appliances of up to 16A) in compliance with section 751 of Standard CEI 64-8.

Environmental stress

Waste treatment plants should be considered as extremely high-stress environments due to the permanent exposure to polluting and corrosive atmospheres and the presence of rodents and birds as well as dust due to the frequent passage of vehicles on dug-up earth. As a general rule, outdoor areas can be classified in accordance with Standard CEI EN 60721-3-4 under group IE 42 with corrosive atmosphere 4C4. Components with highly resistant enclosures (made of aluminium or thermosetting, IP65 or higher) are recommended.

Palazzoli - Practical guide to classification - 17Ex Waste treatment plants - 2005/06

16


Textile or spinning factories

Description

These are factories where threads and/or textiles are made from animal, plant or synthetic fibres.

Risk of explosion

Depending the type of process and humidity levels, textile fibres can release combustible dusts into the environment and form explosive mixtures. Laws regarding health and safety in the workplace require suction and/humidification systems on processing machinery. Therefore, apart from very particular cases, emissions can be considered second grade and areas covering a few metres around points of possible emission or accumulation are classified as Zones 22 (see Standard CEI EN50281-3). Zones 22 allow EEx II 3 IP5X safety equipment with interlocked socketoutlets (see Standard CEI EN 50281.1.1). Weaving or spinning factories are usually packed with fully automated machinery which requires frequent adjustments and handling. Safety devices should be installed throughout the environment to prevent expensive and frequent adjustments.

Fire risk

Factories and plants which produce more than 50 quintals of textile fibres and textiles are listed by Italian Ministerial Decree 16.02.82 under no. 48 as activities requiring Fire Prevention Certification, and can be classified according to Standard CEI 64-8/7 as high risk areas in the event of fire due to the presence of flammable material. Therefore, regardless of whether these environments are classified as areas with the risk of explosion, sparking devices must have at least IP4X protection (except for small devices with max 16A).

Environmental stress

Environments containing textile machinery have the risk of knocks and penetration of fibres. The minimum protection level should be IP 44 with an IK 09 enclosure.

Palazzoli - Practical guide to classification - 18Ex Textile/spinning factories - 2005/06

17


Perfume production

Description

These are factories or laboratories where perfumes containing alcohol or other flammable substances are processed and/or bottled.

Risk of explosion

Perfumes are generally hydroalcoholic solutions of essences, and therefore should be considered as flammable liquids for the purposes of safety against explosions. Without going into further detail about the LEL and flash points, which vary depending on the chemical composition of the alcohol and the percentage of the solution, the most important precaution, according to the ATEX directive, is to minimize continuous grade emission sources outside tanks, mixers and airtight pipes. Continuous grade emission source include open top tanks, open funnels and mixers for non-flammable liquids. In compliance with the criteria specified in Standard CEI EN 60079-10, in the presence of these sources, Zone 1 or even Zone 0 could be present and therefore require EEx d and EEx i equipment. If there is high ventilation with adequate margin, there could be Zones 2 a few metres around the first and second grade emission sources (in the worst possible case). Zones 2 also surround Zones 0. EEx n T2 equipment is acceptable in Zones 2. In environments with a high density of emission sources, or where these sources are mobile (often in small laboratories), EEx n equipment should be installed throughout the environment.

Fire risk

Fire Prevention Certification is required in all factories and plants which process or store more than 500 litres of flammable liquid (Italian Ministerial Decree 16-02-82, clauses 12 and 13). These environments should be classified as high risk areas in the even of fire and require sparking devices with at least IP4X protection (except for small devices of up to 16A ).

Environmental stress

Electrical components with at least IP44 protection should be installed in environments where hydroalcoholic infusions are produced using water.

Palazzoli - Practical guide to classification - 19Ex Perfume production - 2005/06

18


Large kitchens

Description

These are where burners with a thermal power of over 35kW are powered by methane and used for cooking food in hotels, restaurants, hospitals, company canteens and any other similar environment (except for domestic use). Kitchens with a thermal power of less than 35 kW are not included in this description, as they are not governed by Italian Ministerial Decree 12-4-96. However, they are still governed by UNI CIG standards.

Risk of explosion

Large kitchens are usually powered by natural gas (methane) at a pressure of max 4000 Pa. Italian Ministerial Decree 12-4-96 specifies the minimum ventilation as the same of that of heating plants providing heating and hot water. Gas systems must be fitted with the necessary safety devices which ensure that the emission sources are second grade. The risk level must be evaluated according to the criteria specified in Standard CEI EN 60079-10. The recent modification V2 to guide CEI 31-35 is not directly applicable, but the conclusions are practically the same: these environments are not hazardous if the emission holes no larger than 0.25mm2 and high grade ventilation has sufficient margin; while in all other cases, there may be Zones 2 which require EEx n safety equipment, in compliance with Italian Ministerial Decree 12-4-96. Nevertheless, it is ultimately the classifier’s responsibility to decide what equipment to install. Conditions are generally more complex and varied than in boiler rooms, and ventilation is often more limited due to climatic factors or changes to adapt rooms to standards. One sure precaution is to install EEx n T1 equipment installed throughout the environment, as this prevents any error in underestimating the risk of explosion.

Fire risk

Very large kitchens are high risk areas in the event of fire (Italian Ministerial Decree 16-02-82 clause 91) due to potential of over 116kW; lower potential is evaluated according to the criteria specified in section 751 of Standard CEI 64-8.

Environmental stress

There is the risk of water spillage, condensate and the penetration of small solid bodies. Climatic conditions are moderately warm with a slightly aggressive atmosphere and slight mechanical risks. Large kitchens can therefore be classified in environmental class IE 33 (Standard CEI EN 60 721-3-3); electrical components with IP44 protection or higher are ideal for these environments.

Palazzoli - Practical guide to classification - 20x Large kitchens - 2005/06

19


Bakeries

Description

These are factories or small bakeries where flour can cause risks of explosion, fire and dust.

Risk of explosion

When flour is handled, the dust clouds generated have a flash point of approx. 450째C and accumulated layers have a flash point of approx. 220째C. The processing and storage areas must therefore be classified in terms of the risk of explosion according to the criteria specified in Standard CEI EN50281-3. This means evaluating the presence and extent of Zones 20, 21 and 22. Since the lowest flash points of the dust clouds can be estimated at around 100g/m3, hazardous areas can be found only where there is high turbulence inside machinery (mills). Zone 20 is the area inside these machines and Zone 21 is immediately adjacent to the flour loading and unloading points. In exceptional cases (e.g. a bag of flour falls and tears open), the remaining areas can be classified as Zones 22 due to the presence of flammable dust clouds. EEx II 3D IP5X equipment is acceptable in Zones 22. EEx II 3D IP5X equipment is recommended in all areas where flour is handled in paper bags or in other material that easily tears and in areas where it can accumulate in layers (around kneading tables and in mixers that are not airtight).

Fire risk

Cereal mills and other milling facilities which produce over 200 quintals a day, as well as storage rooms or processing areas with a capacity of over 500 quintals of flour, are listed as activities requiring Fire Prevention Certification, according to Italian Ministerial Decree 16-02-82. For lower quantities, the risk of fire due to inflammable material must be evaluated according to the fire load in compliance with the fire-prevention regulations in force (see section 751 of Standard CEI 64-8).

Environmental stress

In processing or storage areas, there may be an occasional presence of 0 or 00 grain flour. The minimum protection level in this case is IP 5X. When these areas are cleaned with water jets (e.g. in tiled rooms), electrical components with at least IP55 protection must be installed, preferably with easily washable enclosures (made of thermosetting resin).

Palazzoli - Practical guide to classification - 21Ex Bakeries - 2005/06

20


Mines and quarries without firedamp

Description

These are mines, quarries and other structures used for extracting and semiprocessing minerals which do not emit firedamp or dusts that cause risk of explosion.

Risk of explosion

The presence of firedamp (typical of carbon mines) generates a very high risk of explosion in mines, so Group I electrical safety devices are required. In mines without firedamp, in open air quarries and in surface structures, ordinary classification criteria provided by Standard CEI 60079-10 are adopted in the presence of gas, vapours or mists, and Standard CEI EN 50281-3 in the presence of dusts. The presence of gas in mines without firedamp is not typical of mining, while the presence of flammable dusts is quite probable due to combustible or flammable substances such as magnesium, phosphorous and sulphur minerals. Zones 20 must be reduced to a minimum, while Zones 21 can be identified as small areas adjacent to first grade emission sources, such as loading and unloading openings on hoppers, crushers and screens. Heaps and machines that can release dusts are rarely caused by faults and generally all areas a few metres away from first or continuous grade emission sources can be classified as Zones 22. These zones allow Ex II 3D IP 5X and IP 6X safety equipment. The presence of hazardous dusts in mine tunnels requires a special classification which is not included in the scope of this description or in Standard CEI EN 50281-3.

Fire risk

The risk of fire in mine tunnels is increased by the lack of air which can produce asphyxiation caused by smoke and even poisoning by carbon monoxide or other poisonous gases. This is avoided by taking measures, where suitable, against the ignition and spreading of fire specified in section 752 of Standard CEI 64-8 for environments with high risk of fire. Activities listed under this group include mining, processing or storage of minerals containing phosphorous, sulphur and magnesium (see clauses 31,32, 33 and 34 of Italian Ministerial Decree 16-02-82).

Environmental stress

Mine tunnels are subject to humidity, dripping of water, the presence of dust and risk of impact. Components with extremely resistant enclosures are recommended (made of aluminium or thermosetting resin, IP 55 or higher protection).

Palazzoli - Practical guide to classification - 22Ex Mines and quarries without firedamp - 2005/06

21


A selection of products from the ATEX systems catalogue / Zones 2 -22

Energy use Protection against explosions

II 3GD EEx nR - EEx nA

compositions

ULYSSE-EX series Interlocked socketoutlets with fuses Thermosetting material IP66 / IP67

Rated current (A)

16

Rated voltage (V)

N째 Pole

220

2P+T 3P+T 3P+N+T 2P+T 3P+T 3P+N+T 3P+T 3P+N+T

380 220

32

63

Palazzoli

380 380

Ref. h

6

ULYSSE-EX series Interlocked socketoutlets with circuit breaker Thermosetting material IP66 / IP67

CEE-EX series Watertight straight Plugs IP67

Palazzoli code

400126EX 400136EX 400146EX 400226EX 400236EX 400246EX 400336EX 400346EX

403126EX 403136EX 403146EX 403226EX 403236EX 403246EX 403336EX 403346EX

477303EX 477413EX 477423EX 477306EX 477416EX 477426EX 477416EX 477427EX

Palazzoli

Palazzoli

16-32A (1 module)

Cod. 415001EX (1 module)

63A (2 modules)

Container with blind cover IP66 e IP76

External dimensions

Palazzoli code

125x175x128 250x175x128

415001EX 415002EX

Cod. 415002EX (2 modules)

Quick attachment plates

External dimensions

Palazzoli code

125x500 250x500 375x500 500x500

415901 415902 415903 415904

Shunting Cod. 415901 (1 module)

Cod. 415902 (2 modules) UNI-EX series Cable glands in insulating material IP68

Threadi ng

Cod. 415903 (3 modules)

Cod. 415904 (4 modules)

22

Pg 7 Pg 9 Pg 11 Pg 13,5 Pg 16 Pg 21 Pg 29 Pg 36 Pg 42 Pg 48

UNI series Nuts in insulating material IP68

Palazzoli code

571107EX 571109EX 571111EX 571113EX 571116EX 571121EX 571129EX 571136EX 571142EX 571148EX

571207 571209 571211 571213 571216 571221 571229 571236 571242 571248

UNI-EX series Cable glands in insulating material IP68

Threadi ng

M 12 M 16 M 20 M 25 M 32 M 40 M 50 M 63

UNI series Nuts in insulating material IP68

Palazzoli code

581112EX 581116EX 581120EX 581125EX 581132EX 581140EX 581150EX 581163EX

581212 581216 581220 581225 581232 581240 581250 581263


Control

applications CAM-EX series CAM-EX series CAM-EX series Watertight switches in Watertight switches in Watertight switches thermosetting material thermos. material in aluminium with fuses - IP65 - IP67 IP65 - IP67 IP55 - IP67

Rated current (A)

16

25

40

Joinery shops

63

100 200 250 400 600

Poles

Palazzoli code

292101EX 292102EX 292103EX

2 3 4 6 2 3 4 6 2 3 4 6 2 3 4 6 4 4 4 4 4

292201EX 292202EX 292203EX

290521EX 290522EX 290523EX

292301EX 292302EX 292303EX

290641EX 290642EX 290643EX

292411EX 292412EX 292413EX

290762EX 290763EX

292503EX 292623EX 292703EX 292733EX

Farms

92x92 125x92 185x92 125x125 155x155 185x125 250x125 185x185 250x185 220x220 250x250 295x295 250x370 315x315 370x500 630x373 630x507

Palazzoli code

532005EX 532006EX 532015EX 532016EX 532017EX 532018EX 531911EX 531931EX 531940EX

511910EX 511911EX 511912EX 511913EX 150021EX 511917EX 511920EX 511921EX 511922EX 511923EX 511926EX

531942EX 531962EX

274302EX 274303EX 274304EX 274031EX 274032EX 274033EX

282402EX 282403EX 282404EX 272503EX 282603EX

284042EX 284043EX

282703EX

283073EX 283082EX

283053EX 283063EX

Lighting

RINO-EX series Watertight lighting fixtures in stainless steel Glass diffuser - IP66

TAIS-EX series ALUPRES-EX series Watertight containers Watertight containers in thermosetting in aluminium material IP65 / IP67 IP55 / IP67

External dimens. (mm)

262141EX 272142EX 272143EX 292144EX 272241EX 272242EX 272243EX 272344EX 272301EX 272302EX 272303EX 272304EX

293053EX 293063EX 292263EX

Shunting

Battery charging

CAM-EX series Watertight switches in aluminium with fuses IP55 - IP67

511927EX 511929EX 511930EX 511931EX

Electromagnetic power unit

Power W

1x18 2x18 3x18 1x36 2x36 3x36 1x54 2x54

Electronic power unit

Emergency

Palazzoli code

820101EX 820102EX 820103EX 820201EX 820202EX 820203EX

820131EX 820132EX 820133EX 820231EX 820232EX 820233EX 822961EX 822962EX

See the entire range of products for potentially explosive atmospheres on the ATEX systems catalogue

23

820111EX

820211EX


55094-05

If you wish to see the entire ATEX series, ask for the “ATEX SYSTEMS” catalogue at www.palazzoli.com

export@palazzoli.com

www.palazzoli.com

Palazzoli S.p.A. Via F. Palazzoli, 31 - 25128 Brescia, Italia Tel. +39 030 2015.1 - Fax +39 030 2015.258


ATEX guide line