hazardous area classification
TRANSCRIPT
Dattatray K. Nikam Instrument Engineer
Hazardous Area Classification
LET US MAKE OUR REFINERIES SAFER!!!
WARNING: This guide is not intended to replace published standards, codes of practice or other relevant publications. This is for External used only.
Dattatray K. Nikam Instrument Engineer
Hazardous Area Classification Definitions of hazardous Area Definition 1: Petroleum Rule, 1976 An area shall be deemed to be hazardous area where petroleum having flash point below 65°C or any flammable gas or vapour in concentration capable of ignition is likely to be present. Definition 2: IS 5572 Hazardous area is an area in which an explosive gas atmosphere is present or likely to be present, in quantities such as to require special precautions for the construction, installation and use of electrical apparatus. Q. Why Zoning is required? Ans: To provide or decide the protection and selection.
i. Leak Potential & Presence of Ignition Sources. ii. Hazardous properties of hydrocarbons. iii. Safe selection (& optimisation) of Electrical Equipment.
Hazardous areas are defined by three main criteria:
• The type of hazard • The likelihood of the hazard being present in flammable concentrations • The ( auto) ignition temperature of the hazardous material
The hazard will be in the form of a gas, vapour, dust or fibre. Hazardous Area Classification (HAC) is as follows: Definitions of hazardous area are different as per IEC and NEC.
NEC IEC DESRIPTION DEFINITION
Zone 0 Highly Flammable for long period Flammable atmosphere present continuously (Typically 1000 hours / year).
Div 1
Zone 1 Flammable during normal operation
Flammable atmosphere present intermittently (Typical 10 & 1000 hours / year).
Div 2 Zone 2
Most Safer Zone Flammable atmosphere present abnormally (typically as a result of a process fault condition) (Typically less than 10 hours / year).
Zone 0 – Typical Areas (Continuous grade)
• Closed process vessels
• Storage tanks
• Closed containers
• Areas containing open tanks of volatile, flammable liquid Q. How to identify Zone 1 areas?
Ans: 1. Flammable gas or vapour concentration is likely to exist in the air under normal operating conditions. 2. Flammable atmospheric concentration is likely to occur frequently because of maintenance, repairs or leakage.
3. Flammable liquid or vapour piping system (containing valves, meters, or screwed or flanged fittings) is in an inadequately ventilated area. 4. The area below the surrounding elevation or grade is such that flammable liquids or vapors may accumulate.
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Dattatray K. Nikam Instrument Engineer
Zone 1 – Typical Area
• Imperfectly fitting peripheral seals on floating roof tanks.
• Inadequately ventilated pump rooms for flammable gas or volatile, flammable liquids.
• Oily waste water sewer / basins
• Loading / unloading gantries of hazardous products.
Zone 2 – Typical Areas (Secondary grade)
• The system handling flammable liquid or vapour is in an adequately ventilated area and is so designed and operated that the explosive or ignitable liquids, Vapours or gases will normally be confined within closed containers or closed systems from which they can escape only during abnormal conditions such as accidental release of a gasket or packing
• The flammable vapours can be conducted to the location as through trenches, pipes or ducts
• Locations adjacent to Zone 1 areas
• Pressurized rooms where flammable gas / vapour can enter in the case of failure of positive mechanical ventilation
Safe Areas – Typical areas The following locations are considered safe from the point of view of electrical installation
• Area where the piping system is without valves, fittings, flanges or similar appurtenances.
• Areas where flammable liquids or vapors are transported only in suitable containers or vessels.
• Areas where permanent ignition sources area present like area where combustion gases are present, for example flare pits,tips,other open flames 7 hot surfaces.
• Diesel Generator shed room /shed having adequate ventilation
• GT installation meeting the ventilation (12 ACPH), pressurization (0.5 mbar) and flange (not more than one pair of flanges inside the turbine room) requirements.
HAC Comparison
• North America (NFPA / API/ NFPA 70E or NEC) • Hazardous Areas:
• Division I- Z0 + Z1 • Division II- Z2
• Hazardous Locations • Class I-Flammable Gases / Vapour • Class II- Combustible dust • Class III- Combustible fibers or flyings
• Gas / vapour grouping • A, B, C, D, E, F & G
• Japan
• Hazardous Areas - Classes 1, 2 & 3
• Gas / vapour groups - G1, G2, G3, G4, G5 & G6
An experienced process engineer’s judgement in visualizing leak scenarios and classifying hazardous areas is the most CRUCIAL factor in the HAC exercise
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Dattatray K. Nikam Instrument Engineer
HAC-RELEVANT INTERNATIONAL STANDARDS
• API RP 500- Area Classification of Petroleum Installations • IEC 79-10 :1995 -Electrical Apparatus for Explosive Gas Atmospheres, part 10 Classification of hazardous areas • IP Part 15, 1990- Area Classification Code for Petroleum Installations • BS EN 60079-10, : 1996 -Electrical Apparatus for Explosive Gas Atmospheres, part 10 Classification of hazardous
areas • BS 5345, 1983-Selection, installation and maintenance of electrical apparatus for use in potentially explosive
atmospheres (other than mining applications or explosive manufacturing), part 2, Recommendations for particular industrial situations
SELECTION OF ELECTRICAL EQUIPMENT IN HAZARDOUS AREAS
• Selection Criteria
– Gas Grouping (based on ignition energy)
– Temperature Classification
– Classified Zones
IEC Gas Grouping
Mining Surface Industry
Group I Group II
IIA IIB IIC Methane
Propane Ethylene Hydrogen/Accetylene
180 Microjoules 60 Mircojoules 20 Mircojoules
NEC Gas Grouping
Group A Group B Group C Group D
Acetylene Hydrogen Ethylene Propane
20 Mircojoules 20 Mircojoules 60 Mircojoules 180 Mircojoules
Temperature Classes: Hot surfaces can ignite explosive atmospheres. To guard against this all Electrical Equipment intended for use in a potentially explosive atmosphere is classified according to maximum surface temp. it will reach in service. This temperature is normally based on a surrounding ambient temperature of 40°C (102°F).This temp. can then be compared to the ignition temp of the gas(es) which may come into contact with the equipment & a judgment reached as
to the suitability of the equipment to be used in that area
T-Class Max. Surface temperature in °C
T1 450°C
T2 300°C
T3 200°C
T4 135°C
T5 100°C
T6 85°C
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Dattatray K. Nikam Instrument Engineer
The bigger the T-number the lower is the ignition temperature of the hazard. So equipment to be installed in hazardous areas where the hazard has temperature class T5 or T6 must be ensured not to get hot. Electrical equipment is marked with a T-Class. The T-Class on the equipment states that the equipment will not provide an ignition capable surface hotter than the temperature represented by the stated T-Class. For equipment in hazardous areas, the bigger the T-Number on the equipment the less hot it will get. RECOMMENDED PROTECTION METHODS
• TYPES OF PROTECTION - EXPLOSION-PROTECTION METHODS / EQUIPMENT -Popular types
Ex-proof (Flameproof )(EX d)
Intrinsically Safe (Ex i )
Increased Safety (Ex e )
Non-Sparking (Ex n )
Pressurization (Ex p )
- OTHER TYPES OF EXPLOSION-PROTECTION –Not so Popular types
• DEFINITIONS OF DIFFERENT PROTECTIONS
1. Ex‘d ‘Flameproof Equipment A type of protection in which the parts can ignite an explosive atmosphere are to be placed in an enclosure, which can withstand the pressure developed during internal explosion of an explosive mixture, and which prevents the transmission of the explosion to the explosive atmosphere surrounding the enclosure.
US- Explosion-Proof, UK- Flame-Proof, GERMANY - Pressure-Proof
- Assumption:
• Flammable gases / vapours, if present in atmosphere will enter the enclosure • The apparatus will be selected, installed, operated and maintained within the acceptable ratings. The maintenance and use of FLP equipment shall be so that its safety will not be impaired, is the responsibility of the user • The electric circuit of the FLP equipment will have all required protection devices
• Sparking which will ignite a flammable gas or vapour, may occur at any part of the equipment
contained in the enclosure in normal operation due to an internal fault due to insulation failure, etc.
Powder filled Ex ‘q’ type
Oil immersed Ex ‘o’ type
Special Ex ‘s’ type
EX d typical marking: EEx d IIB T5
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- REQUIREMENTS:
• Contain internal explosion
• Explosion cannot be transmitted outside enclosure
• External temperature of enclosure below ignition temperature of surrounding gases
• Similar to NEC® "explosion proof"
• Cable fittings must have 5 threads engaged
• Internal and external ground screw
- Enclosures
EX d typical marking: EEx d IIB T5
Round junction box with cable
glands
32 Amp 380v receptable Control station start-stop
Round junction box with cable
glands
Dattatray K. Nikam Instrument Engineer
2. Ex ‘e’ INCREASED SAFETY EQUIPMENT Electrical apparatus produces no sparks in normal operation and is conservatively designed to reduce changes of abnormal occurrences which could cause sparks of temperatures with sufficient energy to ignite a specific flammable atmosphere.
- Construction Method: Stringiest construction methods to ensure that no sparks, excessive temperature are produced
• Careful terminal design • Use of good quality insulation material • Use of special materials to protect the enclosure against impact, ingress of dust & moisture • Can be used for I, II A, B, C gas groups • Permitted for us in T1, T2, T3 classes only • Terminal with minimum IP 54 ingress protection
- Requirements:
� Must use high impact resistant materials FRP, or GRP will not hold static charge � Cannot produce arcs or sparks � Has special air and line leakage and creepage distances � Use I EC non-loosen connection � Minimum IP 54 ingress rating � Control internal and external temperature. External should not exceed T6 (85°C)
EX d typical marking: EEx e IIA T3
Increased safety fixture 18, 36 or 58
Round junction box
with cable glands
16 amp, 24 v receptacle Control station, start-
Dattatray K. Nikam Instrument Engineer
JUNCTION BOX
Weatherpro
of seal in Approved
cable
Approved locking
type terminals
SPECIAL TERMINAL BOX
No. of terminals is restricted
by dissipated power per ckt.
Approved internal
ground screw (4)
STRIPPING A CONNECTION
THE CONDUCTORS
INCORRECT
TERMINAL LOCK
Torque in unlocked position
Dattatray K. Nikam Instrument Engineer
3. Ex ‘i’ INTRINSICALLY SAFE EQUIPMENT & CIRCUITS
Electrical apparatus and its associated wiring which is located in the hazardous area has insufficient electrical or thermal energy under normal of abnormal condition to ignite the specific hazardous atmospheric mixture.
“Simple Apparatus” is defined as an apparatus which does not generate power exceeding 1.2 V, 100mA, 25
mW or 20 µ J, such as thermocouples, RTD, Contact, terminal strips, junction boxes, etc. They are not required to be certified and connected to the intrinsic safety loops without approvals.
Method: � Only electrical protective measure (protection technology by way of power limitation), the other
protective techniques use mechanical means to prevent ignition from electrical faults (max. 30 volts or 50 mA)
� Ex ‘i’ apparatus is the one which has all the circuits within intrinsically safe � Ex ‘i’ circuit is the one which has intrinsically safe barriers with Zenner diodes for power limitation � Minimum IP 20 ingress protection
Ex ib: Equipment shall be incapable of causing ignition in normal operation, with a single fault and with the following safety factors:
– 1.5 in normal operation and with one fault – 1.0 with one fault, if the equipment contains no unprotected switch contacts in parts likely to be
exposed to a potentially explosive atmosphere and the fault is self-revealing
Ex ia: Equipment shall be incapable of causing ignition in normal operation, with a Two fault.
EX i typical marking: EEx ia IIC T5 4. Ex ‘p’ PRESSURIZATION TYPE By maintaining positive pressure of clean air or inert gases inside an instrument enclosure with respect to an external atmosphere, the external atmosphere can not come in contact with sources if ignition inside. - PRESSURIZATION TYPE (Ex ‘p’) TYPES
� Dynamic Pressurization (DP) or pressurization by continuos circulation of protective gas
(purging) DP is a method of maintaining pressure in an enclosure in which after purging the protective gas is passed continuously through the enclosure at a pressure above that of the specified minimum and discharged to the outside atmosphere
� Static Pressurization or pressurization with leakage compensation Air supplied & pressurized
continuously from a non-hazardous area to avoid ingress of flammable gases / vapour inside the enclosure
- Pressurized Equipment � Ingress protection minimum IP 4X � Over pressure 1.5 times or 0.2 kPa � Material of construction should be flame retardant, self- extinguishing and should not be affected
by protective gas.
Dattatray K. Nikam Instrument Engineer
5. Ex ‘n’ NON-SPARKING TYPE EQUIPMENT Nonincendive circuits may contain components which spark under normal operation, but the energy released by such components limited in normal operation to values incapable of causing ignition. Non-sparking circuits contain no open sparking components (such as provided with hermetic sealing) during normal operation. In short SUBSTANTIAL COST SAVING
� Equipment construction in such a way that in normal operation, it is incapable of igniting a surrounding explosive atmosphere and a fault incapable of causing ignition
� Hermetically sealed type � Restricted breathing type � Careful design of terminals � Applications
– Tools – Equipment
6. Ex ‘q’ POWDER FILLED TYPE EQUIPMENT
� Equipment enclosure filled with quartz /sand so that in normal operating condition, any arc occurring within the enclosure of electrical equipment will not ignite the surrounding atmosphere
� No ignition shall be caused either by flame or by excessive temperature of the surfaces of the
enclosure
� Enclosure constructional features: o High mechanical strength o Ingress protection o Powder filled o Insulation of enclosed equipment
Dattatray K. Nikam Instrument Engineer
7. Ex ‘o’ OIL IMMERSED TYPE EQUIPMENT � Protection technique in which the equipment or its parts are immersed in oil in such a way that
an explosive atmosphere which, may be above the oil or outside the enclosure cannot be ignited.
� Oil used shall be mineral oil confirming to relevant standards
� Constructional features:
− Fully enclosed, leak-proof enclosure
− Oil level indicator � Transformers, Switch gears, Control gears
8. Ex‘s’ SPECIAL TYPE EQUIPMENT
� This is a concept that has been adopted to permit the certification of those types of equipment which by their nature, do not comply with the constructional or other requirements specified for equipment with established types of protection but which, nevertheless, can be shown, wherever necessary, by test to be suitable for use in hazardous areas in prescribed zones
� This concept permits flexibility on the part of certifying and assessment authorities in their approach to applications for certification of equipment the use of which would otherwise not permitted in hazardous areas on account of non-compliance with the requirements of standards for established types of protection. This allows flexibility of approach to innovative ideas and new designs, the development of which otherwise be obstructed.
� Examples:
− Factory sealed hand lamps, Encapsulation (Ex ‘m’ type), Gas detection apparatus
Equipment Code Description Suitable for zones...
Ex ia Intrinsic safety 'ia' 0, 1, 2
Ex ib Intrinsic safety 'ib' 1,2
Ex ic Intrinsic Safety 'ic' 2
Ex d Flameproof protection 1,2
Ex p Purge/pressurized protection 1,2
Ex px Purge/pressurized protection 'px' 1,2
Ex py Purge/pressurized protection 'py' 1,2
Ex pz Purge/pressurized protection 'pz' 2
Ex e Increased safety 1,2
Ex m Encapsulation 1,2
Ex ma Encapsulation 0,1,2
Ex mb Encapsulation 1.2
Ex o Oil immersion 1,2
Ex q Sand / powder (quartz) filling 1,2
Ex n Type - n protection 2
Ex s Special protection Normally 1 and 2
Dattatray K. Nikam Instrument Engineer
• INGRESS PROTECTION (IP)
First Digit Second Digit Ingress Protection
(IP) Protection against solid bodies Protection against Liquid
0 No Protection No Protection
1 Objects greater than 50 mm vertically dripped water
2 Objects greater than 12 mm Angled dripped water
3 Objects greater than 2.5 mm sprayed water
4 Objects greater than 1 mm splashes water
5 Dust- Protected water jets
6 Dust- Tight Heavy seas
7 - Effective immersion ( 1 meter )
8 - Indefinite immersion.
NEMA Standards
Type Description
Type 1 General Purpose – Indoor
Type 2 Drip - proof - Indoor
Type 3 Dust - tight, Rain - tight and Sleet (Ice) - resist - Outdoor
Type 3R Rain - proof and Sleet (Ice) - resistant - Outdoor
Type 3S Dust - tight, Rain - tight and Sleet (Ice) - proof-Outdoor
Type 4 Water - tight and Dust - tight - Indoor and Outdoor
Type 4X Water - tight Dust - tight and Corrosion resistant - Indoor and Outdoor
Type 5 - Superseded by Type 12 for control apparatus -
Type 6 Submersible, Water - tight, Dust - tight and Sleet (Ice) - resistant - Indoor and Outdoor
Type 7 Class I, Group A, B, C or D - Indoor Hazardous Locations, Air Break Equipment
Type 8 Class I. Group A, B, C or D - Indoor Hazardous Locations, Oil - immersed
Type 9 Class II, Group E, F or G - Indoor Hazardous Locations, Air Break Equipment
Type 10 Bureau of Mines
Type 11 Corrosion - resistant and Drip - proof Oil - immersed - Indoor Equipment
Type 12 Industrial use, Dust - tight and Drip - tight - Indoor
Type 13 Oil - tight and Dust - tight - Indoor
Dattatray K. Nikam Instrument Engineer
Indian Standards for Various Protection Techniques
IS 5571 Guide For Selection Of Electrical Equipment For Hazardous Areas
IS 5572 –Part I Classification of Hazardous Areas for Electrical Installations
IS 13408 Part I, II, III Code of Selection, Installation and Maintenance of Electrical Apparatus for Use in Explosive Atmospheres
IS 8239 Classification of Maximum Surface Temperature of Electrical Equipment for Use In Explosive Atmospheres
IS 6381 Construction and testing of Electrical Apparatus with type of protection ‘e’
IS 2148 Flameproof Enclosures of Electrical Apparatus
IS 13346 General Requirements for Electrical Apparatus for Explosive Gas Atmospheres
IS 5780 Specification For Intrinsically Safe Electrical Apparatus and Circuits
IS 8240 Guide for Electrical Equipment for Explosive Atmospheres
IS 2147 Degrees of Protection Provided by Enclosures For Low Voltage Switch Gear & Control Gear
IS 4691 Degrees of Protection Provided by Enclosures For Rotating Electrical Machinery
IS 8241 Methods of Marking for Identifying Electrical equipment for Explosive Atmospheres
IS 8224 Specification for Electric Lighting fitting for Explosive Atmospheres
IS 8289 Electrical Equipment with Type of Protection ‘n’
IS 7389 Specification for Pressurized Enclosures
IS 2206 (PART I,III) Specification for Flame proof Electric Light Fixtures
STATUTORY REGULATIONS & APPROVAL REQUIREMENTS Approval / Testing Agencies
CMRI (Central Mining Research Institute), Dhanbad, BIHAR
CCoE (Chief Controller of Explosives), Nagpur
BIS (Bureau Of Indian Standards)
DGMS (Director General Mine Safety), Dhanbad, BIHAR
DGFASLI (Director General of Factory Advice Service and Labour Instituites), Mumbai
Dattatray K. Nikam Instrument Engineer
Summary
� Types of Enclosure Protection
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� Enclosure Rating
� IP Protection
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� Certification Code
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� Types of Electrical Equipment Suitable for Use in Potentially Explosive Atmosphere
Useful References
Hazardous Area Classification & Selection of Electrical Equipment for Flammable Atmospheres by P.G.Sreejith (www.cholaaxa.com)
Flammable Facts MTLFF 03 Explosive Facts By STAHL www.medc.com
Dattatray K. Nikam Instrument Engineer
Types of Electrical Equipment Suitable for use in Potentially Explosive Atmospheres
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 :
.
European -
Area of use
Designation
Standard
IEC - Area
of use
Designation
Standard
USA - Area of use
Designation
Standard
Flameproof Enclosure – An
enclosure used to house
electrical equipment, which
when subjected to an internal
explosion will not ignite a
surrounding explosive
atmosphere.
Zones 1 & 2
EExd
EN50018
Zones 1 & 2
Exd
IEC60079-1
Class 1 Divisions 1 & 2
UL1203
Intrinsic Safety – A
technique whereby electrical
energy is limited such that any
sparks or heat generated by
electrical equipment is
sufficiently low as to not ignite
an explosive atmosphere.
Zones 0, 1 & 2
EExi
EN50020
Zones 1 & 2
Exi
IEC60079-11
Class 1
Divisions 1 & 2
UL913
Increased Safety – This
equipment is so designed as to
eliminate sparks and hot
surfaces capable of igniting an
explosive atmosphere.
Zones 1 & 2
EExe
EN50019
Zones 1 & 2
Exe
IEC60079-7
Purged and Pressurised –
Electrical equipment is housed
in an enclosure which is initially
purged to remove any
explosive mixture, then
pressurised to prevent ingress
of the surrounding atmosphere
prior to energisation.
Zones 1 & 2
EExp
EN50016
Zones 1 & 2
Exp
IEC60079-2
Class 1
Divisions 1 & 2
NFPA496
Encapsulation – A method of
exclusion of the explosive
atmosphere by fully
encapsulating the electrical
components in an approved
material.
Zones 1 & 2
EExm
EN50028
Zones 1 & 2
Exm
IEC60079-18
Oil Immersion – The
electrical components are
immersed in oil, thus excluding
the explosive atmosphere from
any sparks or hot surfaces.
Zones 1 & 2
EExo
EN50015
Zones 1 & 2
Exo
IEC60079-6
Class 1
Division 2
UL698
Powder Filling – Equipment is
surrounded with a fine powder,
such as quartz, which does not
allow the surrounding
atmosphere to come into
contact with any sparks or hot
surfaces.
Zones 1 & 2
EExq
EN50017
Zones 1 & 2
Exq
IEC60079-5
Dattatray K. Nikam Instrument Engineer
Non-sparking – Sparking
contacts are sealed against
ingress of the surrounding
atmosphere, hot surfaces are
eliminated.
Zone 2
EExn
EN50021
Zone 2
Exn
IEC60079-15
.
Special Protection –
Equipment is certified for use
in a Potentially Explosive
Atmosphere but does not
conform to a type of protection
listed above.
Zones 0, 1 & 2
*Exs
Zones 0, 1 &
2
Exs
* This type of protection is only recognised by National Authorities, not as a
European-wide type of protection.
Dattatray K. Nikam Instrument Engineer
Selection, Installation and Maintenance of Electrical Equipment Intended for use in Potentially Explosive Atmospheres
International and national standards are published giving details of requirements for the safe use
of Electrical Equipment in Potentially Explosive Atmospheres as follows :
. International U.K. U.S.A.
General Recommendations EC60079-14
BS5345:Part
1
N.E.C. Chapter
5
Classification of Hazardous Areas IEC60079-10 .
N.E.C. Chapter
5
Inspection and Maintenance of
Electrical Equipment IEC60079-1
Requirements for Flameproof
Enclosures IEC60079-14
BS5345:Part
3
N.E.C. Chapter
5
Requirements for Intrinsically
Safe Equipment IEC60079-14
BS5345:Part
4
N.E.C. Chapter
5
Requirements for Increased
Safety Equipment IEC60079-14
BS5345:Part
6
N.E.C. Chapter
5
Requirements for Purged and
Pressurised Equipment IEC60079-14
BS5345:Part
5
N.E.C. Chapter
5
Requirements for Non-Sparking
Equipment IEC60079-14
BS5345:Part
7 .
Requirements for Equipment
with Special Protection IEC60079-14
BS5345:Part
8
MEDC advise that all Explosion-proof electrical equipment is maintained, by suitably trained
personnel, in accordance with the Manufacturers' recommendations.
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.
The Certification Process
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 Practice – after 1st July 2003
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
Dattatray K. Nikam Instrument Engineer
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.
2 – category 2 equipment (suitable
.....for use in Zone 1) note:
Category 1 is suitable for Zone 0.
Category 3 is suitable for Zone 2.
G – suitable for atmospheres containing gas ( D is suitable for atmospheres containing dusts).
Equipment will be CE marked when certified to ATEX.
European Practice – Current – until 30th June 2003
The method is basically as above. In addition all electrical equipment intended for use in the
European Economic Community (EEC) must comply with Electromagnetic Compatibility
regulations (EMC) and manufacturers must issue, on request, an EC Declaration of Conformity in
accordance with the EMC regulations.
When certified, an item of equipment and its' certificate, carry a code e.g. EExdIIBT4. This can be
broken down as follows:
E – European certificate in accordance with harmonised standards
Ex – Explosion-proof electrical equipment
d – flameproof enclosure type of protection
II – Group II surface industries
B – gas group B
T4 – temperature class T4 (135 degrees centigrade surface temperature).
Dattatray K. Nikam Instrument Engineer
North American Practice
Sample equipment and supporting documentation are submitted to the appropriate authority e.g.
.U.L., F.M., C.S.A.
The equipment is tested in accordance with relevant standards for explosion protection and also for general electrical requirements e.g. light fittings.
After successful testing a listing is issued allowing the manufacturer to place the product on the
market.
The product is marked with the certification details such as the gas groups A,B,C,D the area of use e.g. Class 1 Division 1
World-wide Certification
Most countries outside Europe or North America use the IEC Standards as a basis for their own national standards.
The Russian Federation certifies equipment to GOST standards, these closely follow CENELEC practice.
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.
Ingress Protection
2 digits are used to denote the level of ingress protection that a piece of apparatus enjoys :–
(The first digit denotes the level of protection against solid objects and the second against
liquids)
. Solids . Liquids
0 No protection. 0 No protection.
1 Protected against solid objects
up to 50mm, e.g. hands.
1 Protected against vertically falling
drops of water.
2 Protected against solid objects
up to 12mm, e.g. fingers.
2 Protected against water spray up
to 15 degrees from vertical.
3 Protected against solid objects
up to 2.5mm, e.g. tools.
3 Protected against water spray up to
60 degrees from vertical.
4 Protected against solid objects
over 1mm, e.g. wires.
4 Protected against water sprays from
all directions.
5 Protected against dusts.
(No harmful deposits).
5 Protected against water jets from
all directions.
6 Totally protected against dust. 6 Protected against strong water jets
from all directions, e.g. Offshore.
. . 7 Protected against immersion between
15cm and 1m in depth.
8 Protected against long immersion
under pressure.
Dattatray K. Nikam Instrument Engineer
North American practice is to use NEMA standards to describe ingress protection, i.e.:
NEMA 3 is similar to IP 54
NEMA 4 is similar to IP 55
NEMA 4x is similar to IP 56
NEMA 6 is similar to IP 67