In the case of rectan ular wires, the test s al b car ied out on the largest side of the wire.. Resistan e to refrigerant is expres ed by the q antity of mater extracted f rom the co tin
General
This test is applicable to enamelled round wire with a nominal conductor diameter over 0,250 mm and to enamelled rectangular wire
The test is not suitable for round wires with a nominal conductor diameter up to and including 0,250 mm.
Resistance to solvents is expressed by the pencil hardness of the wire after solvent treatment.
Equipment
The following solvents shall be used:
• standard solvent as specified below, or
• solvent as agreed between purchaser and supplier
The standard solvent shall be a mixture of:
• 60 % by volume white spirit with maximum aromatic content of 1 8 %;
The pencil used must be a lead pencil with the specified hardness according to the relevant standard Prior to each test, the pencil point should be sharpened with a smooth-cut file to create a symmetrical angle of 60° around the lead axis, as illustrated in Figure 1.
Figure 1 – Pencil and specimen for solvent test
Procedure
A straight piece of wire, approximately 1 50 mm in length, shall be preconditioned for
The wire should be subjected to a temperature of (1 30 ± 3) °C in an oven with forced air circulation for a duration of (1 0 ± 1) min Following this, a significant length of the wire must be immersed in a standard solvent within a glass cylinder, maintaining a temperature of (60 ± 3) °C for (30 ± 3) min.
According to IEC 60851-4:2016, after removing the wire from the solvent, the hardness of the wire surface must be measured within 30 seconds.
To conduct the test, place the specimen on a smooth, hard surface as shown in Figure 1 For rectangular wires, perform the test on the largest side Position the pencil at an angle of approximately \(60^\circ \pm 5^\circ\) on the wire's surface, and apply a slow, steady pressure with a force of about \(5 \, \text{N} \pm 0.5 \, \text{N}\) along the wire.
Three tests shall be made It shall be reported if the coating is removed with exposure of the bare conductor
NOTE 1 This method can also be used for testing resistance to other fluids, for example oil
To assess the hardness of insulation, the hardness of the lead pencil that cannot remove the coating from the conductor's surface is used as a measure of the wire surface hardness, represented by pencil hardness Refer to Table 1 for the pencil hardness series.
General
This test is applicable to enamelled round wire
Resistance to refrigerant is expressed by the quantity of matter extracted from the coating of the wire and by the breakdown voltage after exposure to a refrigerant.
The data in this test method pertains specifically to monochlorodifluoromethane (refrigerant R-22) Additional refrigerants deemed suitable for this test are listed in Annex A When utilizing these alternative refrigerants, it is crucial to adhere to their critical data and follow the updated test conditions to ensure safety during the operation of the pressure vessel.
NOTE 2 Refrigerants like monochlorodifluoromethane and rinsing fluids like trichlorotrifluorethane (refrigerant
R 1 1 3) are ozone depleting chemicals (ODC) Refrigerant and rinsing fluid are agreed upon between customer and supplier.
Extraction
Principle
A siphon cup with the wire sample is positioned in a pressure vessel, where the extractable matter is assessed following the wire sample's exposure to refrigerant under high pressure and elevated temperature.
Equipment
The following equipment shall be used:
• siphon cup according to Figure 2, of 450 ml volume up to the siphoning level;
• pressure vessel of 2 000 ml volume with an internal diameter of approximately 1 00 mm and a pressure capacity of 200 bar (20 MPa), preferably of unwelded construction and provided with a controlled heating system;
• top closure of the vessel containing a condenser coil according to Figure 3;
• oven with forced air circulation
Figure 2 – Refrigerant extractable test siphon cup
Specimen 1 1
Eight wire samples each containing (0,6 ± 0,1 ) g of insulation shall be wound into coils of
The specimens must undergo degreasing and be conditioned in a forced air circulation oven at a temperature of (150 ± 3) °C for 15 minutes After allowing them to cool for 30 minutes, the combined weight of the eight specimens should be measured to the nearest 0.0001 g, yielding the total initial mass M1.
Procedure 1 1
The eight specimens must be positioned in the siphon cup, which is suspended (25 ± 5) mm below the condenser coil on the pressure vessel cover The pressure vessel should be assembled and filled with (700 ± 25) g of distilled refrigerant, ensuring it is free from lubricant It is essential to connect the condenser water supply and drain line, and the pressure vessel must be heated using a controlled heating system set to (75 ± 5) °C, or a lower temperature if necessary to meet critical pressure conditions Additionally, the water flow through the condenser should be regulated to achieve a reflux rate of 20 to 25 discharges per hour from the siphon cup.
The vessel's pressure must remain below 75% of the refrigerant's critical pressure It is essential to verify the functionality of the over-pressure control valve before use Additionally, the heating system should automatically shut down if the pressure surpasses 75% of the critical pressure or if water flow through the condenser coil is disrupted.
At the conclusion of the extraction period, it is essential to cool the pressure vessel The refrigerant must be extracted from the vessel and recovered using appropriate methods, such as a refrigerant compressor and recovery system Following this, the pressure should be released, allowing for the safe opening of the pressure vessel.
For the following operations, the rinsing fluid shall be distilled before use
The specimens and siphon cup must be rinsed with the specified rinsing fluid, which is then poured into the pressure vessel The vessel's walls should be cleaned with two consecutive rinses of 100 ml each After rinsing, the fluid should be evaporated to a level of (5 ± 1) mm from the bottom of the pressure vessel and collected safely.
The liquid sample is transferred to a pre-dried tared aluminum weighing dish, and the pressure vessel is rinsed with 15 ml of rinsing fluid, which is also added to the dish This mixture is then evaporated to dryness at a temperature of (150 ± 3) °C for a duration of 60 to 65 minutes After evaporation, the weighing dish is cooled to room temperature in a desiccator The dish containing the residue is weighed to the nearest 0.0001 g, and the original tared mass of the dish is subtracted The resulting difference gives the total residue mass \( M_2 \) of the matter extracted from the eight specimens.
The insulation on the coils must be removed using appropriate chemical methods that do not damage the conductor The bare conductors should then be dried at a temperature of (150 ± 3) °C for a duration of (15 ± 1) minutes and subsequently cooled to room temperature in a desiccator Finally, the conductors should be weighed to the nearest 0.0001 g, with the combined mass of the eight conductors representing the total conductor mass M3.
Result 1 2
The extractable matter shall be determined according to the following equation :
One test shall be made The masses M 1 , M 2 , M 3 , the refrigerant, rinsing fluid, temperature, pressure of the pressure vessel and the percentage extractable matter shall be reported.
Breakdown voltage 1 2
Principle 1 2
A specimen prepared in accordance with IEC 60851 -5:2008 is positioned in a pressure vessel as specified in section 4.3.2 The breakdown voltage is measured following the specimen's exposure to refrigerant under both pressure and elevated temperature conditions.
Procedure 1 2
The specimen must be conditioned in an oven at a temperature of (150 ± 3) °C for 4 hours before being placed in a pressure vessel This vessel should be assembled and filled with (1,400 ± 50) g of refrigerant Subsequently, the pressure vessel needs to be heated for a duration of (72 ± 1) hours, following the guidelines outlined in section 4.2.4.
At the conclusion of the exposure period, the pressure vessel must be cooled and discharged as outlined in section 4.2.4 Once the internal pressure drops below 2 bar (0.2 MPa) absolute, the pressure vessel can be opened, and the specimen should be removed within 25 seconds.
30 s, transferred to the oven at a temperature of (1 50 ± 3) °C The specimen shall remain in
According to IEC 60851-4:2016, the specimen should be placed in an oven for 10 minutes, with a tolerance of ±1 minute Once removed, it must cool to room temperature before measuring the breakdown voltage, as specified in section 4.4.1 of IEC 60851-5:2008.
Result 1 3
Five specimens shall be tested The five individual values shall be reported
General 1 3
This test is applicable to enamelled round wire and bunched wire
Solderability is expressed by the time of immersion of the specimen in a solder bath required to remove the coating and to coat the conductor with solder
Lead is classified as a hazardous substance by regulatory agencies, with primary exposure occurring through inhalation and ingestion It is essential to follow the guidelines outlined in the Material Safety Data Sheet (MSDS) for lead, tin, flux, and alcohol when using, handling, or disposing of these materials To meet environmental regulations, ensure adequate ventilation or forced exhaust of solder pot vapors and decomposition products from solderable insulations.
Safety warning: Thermal hazard – Care shall be exercised in removing test specimens from the solder pot to avoid skin burns.
Equipment 1 3
The following equipment shall be used:
A temperature-controlled solder bath must have a sufficient volume to maintain a consistent solder temperature when immersing specimens at the specified temperatures in the relevant standard The solder composition should consist of a mass ratio of 60% tin to 40% lead, or a lead-free alternative compliant with ISO 9453, as agreed upon by the customer and supplier Additionally, any dross formed on the solder's surface must be removed before each test, and the temperature should be adjustable within ± 5 °C of the standard's specified temperature.
NOTE 1 Copper corrosion is greater when using lead free solder when compared to a tin/lead composition
A specimen holder must securely support the wire under test, ensuring a minimum distance of 20 mm between the support points when submerged in solder (refer to Figure 4) The holder's material should prevent any contamination of the solder, and its dimensions must be designed to avoid significant temperature fluctuations in the bath during immersion.
NOTE 2 Contamination of the solder due to oxidation or from copper can affect the results
Figure 4 – Example of carrier for solderability test
Procedure 1 4
The specimen shall be held vertically over the centre of the bath maintained at the temperature as specified in the relevant standard The bottom end shall be lowered to
The specimen must be immersed at a depth of (35 ± 5) mm below the bath's surface, ensuring it is positioned within 10 mm of the temperature measurement point After the specified immersion duration outlined in the relevant specification sheet, the specimen should be moved sideways in the bath before being removed from the solder.
The tinned wire's surface must be inspected using a magnification of 6 to 10 times For wires with a nominal conductor diameter of up to 0.100 mm, the examination is limited to the central section of 25 ± 2.5 mm between the supports For wires exceeding 0.100 mm in diameter and for bunched wires, the inspection should focus on the lower 15 mm of the segment that is immersed in the pot.
Three specimens shall be tested The condition of the surface of the wire shall be reported.
6 Test 20: Resistance to hydrolysis and to transformer oil
General 1 4
This test is applicable to enamelled wire
Resistance to hydrolysis is expressed by appearance and adherence after exposure of the specimens to transformer oil in the presence of water under pressure and at elevated temperature
Resistance to transformer oil is expressed by breakdown voltage and flexibility after exposure of the specimens to transformer oil under pressure and at elevated temperature
Water can impact the coating through hydrolytic degradation or absorption If only absorption occurs, drying the specimen at 125 °C ± 3 °C for 30 minutes before the breakdown voltage test can restore the specimen Wires with a nominal conductor diameter ranging from 0.800 mm to 1.500 mm are typically easier to handle and test.
Round wire 1 5
Equipment 1 5
The following equipment shall be used:
• two glass tubes of 25 mm diameter and 300 mm length capable of being sealed;
• stainless steel pressure vessel of 400 ml to 500 ml volume with a pressure capacity of
6 × 1 0 6 Pa, preferably of unwelded construction and provided with a controlled heating system;
• transformer oil according to IEC 60296;
• paper according to IEC 60554-1 , type 1
Specimens 1 5
The following specimens shall be prepared:
• 1 2 straight pieces of wire with a length of approximately two-thirds of the internal height of pressure vessel;
Twisted pair specimens are prepared according to section 4.4.1 of IEC 60851-5:2008 for nominal conductor diameters up to 2,500 mm, while straight specimens are tested in accordance with section 4.5.1 of the same standard for nominal conductor diameters exceeding 2,500 mm.
Three mandrel-wound specimens were prepared following section 5.1.1 of IEC 60851-3:2009 for nominal conductor diameters up to and including 1,600 mm Additionally, three straight specimens were tested in accordance with section 5.2 of IEC 60851-3:2009 for nominal conductor diameters exceeding this limit.
Procedure 1 5
Six straight pieces of wire, prepared as per section 6.2.2, are positioned inside a pressure vessel along with de-aerated dry transformer oil, filling approximately (52.5 ± 2.5) % of the vessel's volume The pressure vessel is then sealed and subjected to heating.
The specimens should be subjected to a temperature of (1 50 ± 3) °C for a duration of (24 ± 1) hours, after which they must cool to room temperature before being opened Examination of the specimens will be conducted using normal vision Additionally, the test will be repeated by adding a quantity of water equal to (0.3 ± 0.1) % of the oil volume used in the pressure vessel.
One test shall be made Any changes in appearance and adherence shall be reported
According to section 6.2.2, the pressure vessel must include one twisted pair or straight specimen, three mandrel-wound or straight specimens, and additional wire pieces to meet the coating volume requirements specified in Table 2.
NOTE The total mass of wire in grams to provide the required volume of enamel can be calculated approximately by:
V is the volume of the pressure vessel in millilitres;
Y is the mass of 1 m of wire in grams; δ is the increase in diameter due to the coating in millimetres;
D is the overall diameter of the wire in millimetres
The pressure vessel must be filled according to the components and quantities listed in Table 2 Before adding the oil and paper, they should be dried, and the oil must be de-aerated at a pressure of 2 kPa for a duration of (16 ± 1) hours at a temperature of (90 ± 3) °C, or for (4 ± 0.30) hours.
Steel a a By agreement between purchaser and supplier
The sealed pressure vessel shall be heated to the class temperature of the wire ± 3 °C, or to
The pressure vessel must be heated to a temperature of (150 ± 3) °C and maintained for (1000 ± 10) hours After this period, it should cool to room temperature before being discharged and opened Out of the ten specimens, five will be tested for breakdown voltage at (105 ± 3) °C in air, following the guidelines of either 4.4.2 or 4.5.2 of IEC 60851-5:2008, based on the conductor diameter The remaining five specimens will undergo a drying process.
(1 25 ± 3) °C for (30 ± 5) min, allowed to cool to room temperature and then tested at
(1 05 ± 3) °C for breakdown voltage in air in accordance with either 4.4.2 or 4.5.2 of IEC 60851 -5:2008, depending on the conductor diameter
The three specimens shall be examined for cracks according to either 5.1 1 1 or 5.2 of IEC 60851 -3:2009, depending on the conductor diameter
One test shall be made The individual values of breakdown voltage and any cracks shall be reported.
Rectangular wire 1 6
Equipment 1 6
Equipment according to 6.2.1 shall be used.
Specimens 1 6
The following specimens shall be prepared:
• 1 0 straight pieces of wire with a length of approximately two-thirds of the internal height of pressure vessel;
• four U-shaped specimens prepared in accordance with 4.7.1 of IEC 60851 -5:2008;
Procedure 1 6
Each of the tubes shall be charged with five straight pieces of wire according to 6.3.2 and
80 ml de-aerated dry transformer oil To one of the tubes, (0,24 ± 0,01 ) ml of distilled water
According to IEC 60851-4:2016, two sealed tubes must be placed in an oven for 24 hours at a temperature of (150 ± 3) °C After this period, the tubes should be removed, allowed to cool to room temperature, and then opened for examination under normal vision.
One test shall be made Any changes in appearance and adherence shall be reported
The pressure vessel shall contain four U-shaped specimens, two mandrel bent specimens and extra pieces of wire to arrive at the volume of coating specified in Table 2
NOTE The total mass of wire in grams to provide the required volume of enamel can be calculated approximately by:
V is the volume of the pressure vessel in millilitres;
Y is the mass of 1 m of wire in grams; δ is the increase in thickness due to the coating in millimetres;
W is the overall width of the wire in millimetres;
T is the overall thickness of the wire in millimetres
The pressure vessel must be filled with oil and paper, which should be dried separately just before addition This process should occur at a maximum pressure of 2 kPa for a duration of (1 6 ± 1) hours at a temperature of (90 ± 3) °C, or alternatively for (4 ± 0.1) hours.
(1 05 ± 3) °C The sealed pressure vessel shall be heated to the class temperature of the wire ±3 °C, or to (1 50 ± 3) °C if class temperature is higher than 1 50 °C, and maintained for
The pressure vessel must be cooled to room temperature before being discharged and opened Two U-shaped specimens will be tested for breakdown voltage in air at (105 ± 3) °C, following the guidelines of IEC 60851-5:2008, section 4.7.2 The remaining two specimens will be dried at (125 ± 3) °C for (30 ± 5) minutes, cooled to room temperature, and subsequently tested for breakdown voltage in air at (105 ± 3) °C in accordance with the same IEC standard.
The mandrel-bent specimens shall be examined for cracks according to 5.1 2 of IEC 60851 -3:2009
One test shall be made The individual values of breakdown voltage and any cracks shall be reported
Annex A (informative) Alternative refrigerants to monochlorodifluoromethane
Table A.1 provides a list of alternative refrigerants to monochlorodifluoromethane (R 22) that have been found through investigation to be suitable for use in Test 1 6
For safety purposes and for their proper application during testing, observation of critical data in this table is recommended
Composition (Weight percent) Formula Boiling Point Critical
Consultation with the refrigerant manufacturer is recommended for updated information
IEC 60264 (all parts), Packaging of winding wires
IEC 6031 7 (all parts), Specifications for particular types of winding wires
IEC 60851 (all parts), Winding wires – Test methods
3 Essai 1 2: Résistance aux solvants 25 3.1 Généralités 25 3.2 Equipement 26 3.3 Procédure 26
4 Essai 1 6: Résistance aux réfrigérants 27 4.1 Généralités 27 4.2 Extraction 27 4.2.1 Principe 27 4.2.2 Equipement 27 4.2.3 Eprouvette 29 4.2.4 Procédure 29 4.2.5 Résultats 30 4.3 Tension de claquage 30 4.3.1 Principe 30 4.3.2 Procédure 30 4.3.3 Résultats 31
5 Essai 1 7: Brasabilité 31 5.1 Généralités 31 5.2 Equipement 31 5.3 Procédure 32
This article discusses the resistance to hydrolysis and transformer oil, detailing general information and specific methodologies for testing both circular and rectangular wire sections It includes sections on equipment, specimen preparation, and procedures for each wire type Additionally, it provides informative insights on alternative refrigerants for monochlorodifluoromethane and concludes with a bibliography for further reference.
The article includes several key figures and tables that illustrate important concepts in solvent testing and material properties Figure 1 depicts the solvent testing setup with a pencil and test tube, while Figure 2 shows a siphon container used for extraction with a refrigerant Figure 3 presents a condenser, and Figure 4 provides an example of a support for solderability testing Additionally, Table 1 lists pencil hardness values, and Table 2 details the volume of components involved in the experiments.
Tableau A.1 – Réfrigérants de remplacement pour le R 22 36
FILS DE BOBINAGE – MÉTHODES D’ESSAI –
The International Electrotechnical Commission (IEC) is a global standardization organization comprising national electrotechnical committees Its primary goal is to promote international cooperation on standardization issues in the fields of electricity and electronics To achieve this, the IEC publishes international standards, technical specifications, technical reports, publicly accessible specifications (PAS), and guides, collectively referred to as "IEC Publications." The development of these publications is entrusted to study committees, which allow participation from any interested national committee Additionally, international, governmental, and non-governmental organizations collaborate with the IEC in its work The IEC also works closely with the International Organization for Standardization (ISO) under conditions established by an agreement between the two organizations.
2) Les décisions ou accords officiels de l’IEC concernant les questions techniques représentent, dans la mesure du possible, un accord international sur les sujets étudiés, étant donné que les Comités nationaux de l’IEC intéressés sont représentés dans chaque comité d’études
3) Les Publications de l’IEC se présentent sous la forme de recommandations internationales et sont agréées comme telles par les Comités nationaux de l’IEC Tous les efforts raisonnables sont entrepris afin que l’IEC s'assure de l'exactitude du contenu technique de ses publications; l’IEC ne peut pas être tenue responsable de l'éventuelle mauvaise utilisation ou interprétation qui en est faite par un quelconque utilisateur final
4) Dans le but d'encourager l'uniformité internationale, les Comités nationaux de l’IEC s'engagent, dans toute la mesure possible, à appliquer de faỗon transparente les Publications de l’IEC dans leurs publications nationales et régionales Toutes divergences entre toutes Publications de l’IEC et toutes publications nationales ou régionales correspondantes doivent être indiquées en termes clairs dans ces dernières
5) L’IEC elle-même ne fournit aucune attestation de conformité Des organismes de certification indépendants fournissent des services d'évaluation de conformité et, dans certains secteurs, accèdent aux marques de conformité de l’IEC L’IEC n'est responsable d'aucun des services effectués par les organismes de certification indépendants
6) Tous les utilisateurs doivent s'assurer qu'ils sont en possession de la dernière édition de cette publication
7) Aucune responsabilité ne doit être imputée à l’IEC, à ses administrateurs, employés, auxiliaires ou mandataires, y compris ses experts particuliers et les membres de ses comités d'études et des Comités nationaux de l’IEC, pour tout préjudice causé en cas de dommages corporels et matériels, ou de tout autre dommage de quelque nature que ce soit, directe ou indirecte, ou pour supporter les cỏts (y compris les frais de justice) et les dépenses découlant de la publication ou de l'utilisation de cette Publication de l’IEC ou de toute autre Publication de l’IEC, ou au crédit qui lui est accordé
8) L'attention est attirée sur les références normatives citées dans cette publication L'utilisation de publications référencées est obligatoire pour une application correcte de la présente publication
9) L’attention est attirée sur le fait que certains des éléments de la présente Publication de l’IEC peuvent faire l’objet de droits de brevet L’IEC ne saurait être tenue pour responsable de ne pas avoir identifié de tels droits de brevets et de ne pas avoir signalé leur existence
La Norme internationale IEC 60851 -4 a été établie par le comité d’études 55 de l’IEC: Fils de bobinage
Cette troisième édition annule et remplace la deuxième édition parue en 1 996, l’Amendement 1 :1 997 et l’Amendement 2:2005 Cette édition constitue une révision technique
The current edition features significant technical updates compared to the previous version, including a revision of Test 16: Resistance to Refrigerants, a revision of Test 17: Brazability, and the introduction of a new Appendix A concerning alternative refrigerants for monochlorodifluoromethane (R 22).
Le texte de cette norme est issu des documents suivants:
Le rapport de vote indiqué dans le tableau ci-dessus donne toute information sur le vote ayant abouti à l'approbation de cette norme
Cette publication a été rédigée selon les Directives ISO/IEC, Partie 2
Une liste de toutes les parties de la série IEC 60851 , publiées sous le titre général Fils de bobinage – Méthodes d'essai, peut être consultée sur le site web de l’IEC
The committee has determined that the content of this publication will remain unchanged until the stability date specified on the IEC website at "http://webstore.iec.ch" in relation to the sought publication On that date, the publication will be
• remplacée par une édition révisée, ou
La série IEC 60851 constitue un élément d'un groupe de Normes internationales définissant les fils isolés utilisés dans les enroulements des appareils électriques:
1 ) Série IEC 60851 , Fils de bobinage – Méthodes d’essai;
2) Série IEC 6031 7, Spécifications pour types particuliers de fils de bobinage;
3) Série IEC 60264, Conditionnement des fils de bobinage
FILS DE BOBINAGE – MÉTHODES D’ESSAI –
La présente partie de l’IEC 60851 spécifie les essais de propriétés chimiques suivants:
• Essai 20: Résistance à l'huile de transformateur
Pour les définitions, les notes générales concernant les méthodes d'essai et les séries complètes des méthodes d'essai des fils de bobinage, voir l’IEC 60851 -1
The following documents are referenced normatively, either in whole or in part, within this document and are essential for its application For dated references, only the cited edition is applicable For undated references, the latest edition of the referenced document applies, including any amendments.
IEC 60296, Fluides pour applications électrotechniques – Huiles minérales isolantes neuves pour transformateurs et appareillages de connexion
IEC 60554-1 :1 977, Spécification pour papiers cellulosiques à usages électriques – Première Partie: Définitions et conditions générales
IEC 60851 -1 , Fils de bobinage – Méthodes d'essai – Partie 1: Généralités
IEC 60851 -3:2009, Fils de bobinage – Méthodes d'essai – Partie 3: Propriétés mécaniques
IEC 60851 -5:2008, Fils de bobinage – Méthodes d'essai – Partie 5: Propriétés électriques
ISO 9453, Alliages de brasage tendre – Compositions chimiques et formes
Cet essai est applicable au fil de section circulaire émaillé de diamètre nominal de conducteur supérieur à 0,250 mm ainsi qu'au fil de section rectangulaire émaillé
L’essai n’est pas adapté aux fils de section circulaire de diamètre nominal de conducteur jusqu’à 0,250 mm inclus
La résistance aux solvants est exprimée par la dureté-crayon du fil après l'action du solvant
Les solvants suivants doivent être utilisés:
• solvant normalisé comme spécifié ci-dessous, ou
• solvant agréé entre acheteur et fournisseur
Le solvant normalisé doit être un mélange de:
• 60 % en volume de white spirit contenant un maximum de 1 8 % d'aromatique;