le Fonti di Innesco o Sorgenti di Innesco, secondo la #EN1127-1, sono suddivise in tredici tipi:
CLASSIFICAZIONE AREE EX
Gruppo
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Categoria |
ZONA
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E'
adatto il tipo di materale |
Tempo
di situazione pericolosa /anno |
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zona |
zona
POLVERE D |
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I
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M1
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Due mezzi di protezione per assicurare il livello di sicurezza |
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Miniere
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M2
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Un mezzo di protezione |
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II
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1
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0
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20
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Ex
ia |
>
1000 ore |
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2
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1
|
21
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Ex
e, Ex d, Ex p, Ex m, Ex o, Ex ib |
10
> ore < 1000 |
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3
|
2
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22*
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Ex
nA, Ex nW, Ex nL, Ex nP, Ex nR |
<
10 ore |
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Superficie
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*
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Direttiva 94/9/CE – ATEX 95
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![]() ![]() ![]() Introduction Potentially In such areas there is a necessity to eliminate sources of ignition such as sparks, hot surfaces or static electricity which may ignite these mixtures. Where electrical equipment has to be used in these areas it must be so designed and constructed as to not create sources of ignition capable of igniting these mixtures. Before electrical equipment can be used in a potentially explosive atmosphere a representative sample has to be fully tested and certified by an independent authority such as BASEEFA in the U.K. or UL in the U.S.A. This information is intended as a guide only and further expert guidance should be sought before placing into service, maintaining or repairing any item of equipment in a Potentially Explosive Atmosphere. Where comparisons are shown between, for example, European and North American practice this may be an approximation and individual standards/codes of practice should be consulted for precise details. MEDC have spent 25 years Process plants are divided into Zones (European and IEC method) or Divisions (North American method) according to the likelihood of a potentially explosive atmosphere being present.
Groups (plus dusts and fibres) There are two main gas groups, Group I – Mining only and Group II – Surface Industries These categories are used in European and I.E.C. groupings. Group I is concerned only with underground mining where methane and coal dust are present. Group II gases occurring in surface industries, are sub-grouped according to their volatility. This enables electrical equipment to be designed to less onerous tolerances if it is to be used with the least volatile gases.
Note : North Hot Many MEDC
e.g. Butane has an ignition temperature of 365 degrees Centigrade, equipment used in the vicinity of this gas would need a T rating of T2 or higher.
Different techniques are used to prevent electrical equipment from igniting explosive atmospheres. There are restrictions on where these different types of equipment can be used as follows :
* This type of protection is only recognised
by National Authorities, not as a European-wide type of protection.
International and national standards are
published giving details of requirements for the safe use of Electrical Equipment in Potentially Explosive Atmospheres as follows :
All Explosion-proof electrical Any spare parts used should be purchased from the original Manufacturer and repairs should be carried out by the Manufacturer or under his supervision, in order that the item remains in conformance with the certification documents.
All Electrical Equipment, intended for use in a Potentially Explosive Atmosphere, should be certified as suitable for such use. The methods of obtaining certification differ in detail, see below, between each certifying body or group of bodies (e.g. CENELEC). Basically this process consists of supplying a representative sample of the equipment along with a set of drawings to a recognised test/certification body e.g. BASEEFA who in turn test the equipment against a recognised Standard e.g. EN50018 and issue a Certificate. The user of the equipment can then refer to this Certificate to enable him to safely put the item into service in a zone appropriate to the Certification. European After the above date the ATEX Directive comes into force throughout the EEC. This becomes a mandatory requirement for all equipment intended for use in a hazardous area. The fundamental difference between current practice and ATEX certification is that ATEX addresses the essential safety requirements for hazardous area equipment and uses Standards as part of the method of conforming to these. Amongst other documentation required by certifying authorities will be Technical Manuals in order that the user is informed of installation methods etc. ALL EQUIPMENT, BOTH ELECTRICAL AND MECHANICAL, INTENDED TO BE PUT INTO SERVICE WITHIN THE EEC AFTER 1ST July 2003, WILL HAVE TO HAVE BEEN CERTIFIED IN ACCORDANCE WITH THE ATEX DIRECTIVE. In practice this means re-certification of all currently certified electrical equipment. MEDC have started this process and all relevant equipment will be covered by the implementation date of 1st July 2003. It should be noted also that MECHANICAL equipment is covered by the ATEX Directive so for the first time items such as gearboxes will have to carry ATEX certification. The equipment coding will be as the current practice plus an additional code as follows: ExII2G i.e. Ex – Explosion proof in accordance with ATEX. II – Group II surface industries.
G – suitable for atmospheres containing gas ( D is suitable for atmospheres containing dusts). Equipment will be European Practice The method is basically When certified, an E – European Ex – Explosion-proof d – flameproof II – Group II B – gas group T4 – temperature North American Sample equipment The equipment is After successful The product is marked
Most countries outside Europe or North America use the IEC Standards as a basis for their own national standards. The Russian Federation certifies There is a scheme in place which will when fully adopted allow for internationally recognised certification to become a reality, this is the IEC EX SCHEME. This uses the IEC standards and IEC recognised test and certification bodies to issue mutually recognised test reports and certificates. The scheme is in its infancy and its level of success cannot yet be measured.
2 digits are used to
North American practice
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