SIST EN 14726:2005
(Main)Aluminium and aluminium alloys - Chemical analysis - Guideline for spark optical emission spectrometric analysis
Aluminium and aluminium alloys - Chemical analysis - Guideline for spark optical emission spectrometric analysis
This European Standard gives guidance on the criteria and the fundamental operation procedure governing the spark optical emission spectral analysis (S OES) of metal samples, beginning with sampling, through sample preparation to reporting the test, as well as the requirements of the whole spark source spectrometric procedure which shall be fulfilled with respect to:
observance of the agreed precision and trueness [ISO 3534 1, ISO 5725-1] of the analytical results with reference to the agreed sample or sample area;
traceability of the analytical results to the international base units - mass (kg) and amount of substance (mol);
proof of agreement between the spark spectrometric result and the average composition of the supplied metal sample within the given uncertainty [ISO 3534 1] of the analytical result;
comparability of the test results between different laboratories;
as far as possible, a trouble free operation of the spark spectrometer.
These guidelines refer to computer controlled simultaneously measuring spectrometers for the analysis of solid samples.
Aluminium und Aluminiumlegierungen - Chemische Analyse - Leitfaden für die optische Funkenemissionsspektralanalyse
4
Diese Europäische Norm gibt eine Anleitung zu den Kriterien und dem grundlegenden Verfahrensablauf, die
die optische Funkenemissionsspektralanalyse (F-OES) von Metallproben bestimmen, beginnend bei der
Probenahme über die Probenvorbereitung bis hin zum Prüfbericht sowie die Anforderungen an das
funkenspektrometrische Gesamtverfahren, die erfüllt werden müssen für
.die Einhaltung der vereinbarten Präzision und Richtigkeit der Prüfergebnisse [ISO 3541-1, ISO 5725-1]
mit Bezug auf die vereinbarte Probe oder den Probenbereich;
.die Rückführbarkeit der Prüfergebnisse auf die internationalen Grundeinheiten ? Masse (kg) und Stoff-menge
(mol);
.den Nachweis der Übereinstimmung zwischen dem funkenspektrometrischen Ergebnis und der durch-schnittlichen
Zusammensetzung der angelieferten Metallprobe innerhalb der angegebenen Unsicherheit
[ISO 3534-1] für das Prüfergebnis;
.die Vergleichbarkeit der Prüfergebnisse zwischen verschiedenen Laboratorien;
.einen möglichst störungsfreien Betrieb des Funkenspektrometers.
Diese Leitlinien beziehen sich auf rechnergesteuerte, simultan messende Spektrometer für die Analyse von fes-ten
Proben.
Aluminium et alliages d'aluminium - Analyse chimique - Directives pour l'analyse par spectrométrie d'émission optique a étincelles
La présente Norme européenne donne des orientations concernant les criteres et la procédure de fonctionnement
fondamentale régissant la spectrométrie d?émission optique a étincelles (SEO-E) appliquée a des échantillons
métalliques, en commençant par l?échantillonnage, pour passer ensuite a la préparation de l?échantillon et au
rapport d?essai ainsi qu?aux exigences de la mise en oeuvre complete de spectrométrie a étincelles qui doivent etre
observées eu égard :
- au respect de la fidélité et de la justesse convenues [ISO 3534-1, ISO 5725-1] des résultats de l?analyse par
référence a l?échantillon ou a la zone échantillon convenus ;
- au raccordement des résultats d?analyse aux unités de base internationales ? la masse (kg) et la quantité de
matiere (mol) ;
- a la preuve de conformité entre le résultat de la spectrométrie a étincelles et la composition moyenne de
l?échantillon de métal fourni, dans l?intervalle de confiance associé au résultat d?analyse [ISO 3534-1] ;
- a la comparaison des résultats d?essai entre différents laboratoires ;
- dans la mesure du possible, au fonctionnement sans incident du spectrometre a étincelles.
Ces directives se rapportent aux spectrometres simultanés pilotés par ordinateur pour l?analyse d?échantillons
représentatifs.
Aluminij in aluminijeve zlitine – Kemijske analize – Smernica za optično emisijsko spektrometrijsko analizo z iskro
General Information
Relations
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Aluminium und Aluminiumlegierungen - Chemische Analyse - Leitfaden für die optische FunkenemissionsspektralanalyseAluminium et alliages d'aluminium - Analyse chimique - Directives pour l'analyse par spectrométrie d'émission optique a étincellesAluminium and aluminium alloys - Chemical analysis - Guideline for spark optical emission spectrometric analysis77.120.10Aluminij in aluminijeve zlitineAluminium and aluminium alloys77.040.30Kemijska analiza kovinChemical analysis of metalsICS:Ta slovenski standard je istoveten z:EN 14726:2005SIST EN 14726:2005en01-december-2005SIST EN 14726:2005SLOVENSKI
STANDARD
SIST EN 14726:2005
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 14726September 2005ICS 77.120.10; 77.040.30 English VersionAluminium and aluminium alloys - Chemical analysis - Guidelinefor spark optical emission spectrometric analysisAluminium et alliages d'aluminium - Analyse chimique -Directives pour l'analyse par spectrométrie d'émissionoptique à étincellesAluminium und Aluminiumlegierungen - ChemischeAnalyse - Leitfaden für die optischeFunkenemissionsspektralanalyseThis European Standard was approved by CEN on 22 July 2005.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2005 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14726:2005: ESIST EN 14726:2005
EN 14726:2005 (E) 2
Contents Page Foreword.3 Introduction.4 1 Scope.5 2 Normative references.5 3 Terms and definitions.5 4 Symbols and abbreviations.5 5 Review and principle of test method.6 6 Consumables and calibration materials.6 6.1 Consumables.6 6.2 Reference material and recalibration samples.6 7 Testing equipment.7 7.1 Spark spectrometer.7 7.2 Equipment for sample preparation.8 8 Samples.8 8.1 Requirements on test samples.8 8.2 Sampling.8 9 Sample preparation.9 10 Operating conditions of the spectrometer.10 11 Taking measurements.10 12 Calibration and evaluation (methods of calculation).11 12.1 Fundamental principles.11 12.2 Standard and reference materials.12 12.3 Base calibration.13 12.4 Recalibration.14 12.5 Alloy group calibration with simultaneous calibration.16 13 Accuracy (precision and trueness).16 13.1 General.16 13.2 Possibility of error.16 13.3 Measuring and calibration uncertainty.17 13.4 Comprehensive investigation of accuracy.18 14 Inspection.19 14.1 General.19 14.2 Continuous supervision.19 14.3 Checking the analytical sample.19 14.4 Analytical capability.19 15 Availability of the analytical system.20 16 Test report.20 Annex A (informative)
Representative sparking area.21 Bibliography.22
SIST EN 14726:2005
EN 14726:2005 (E)
3 Foreword This European Standard (EN 14726:2005) has been prepared by Technical Committee CEN/TC 132 “Alumin-ium and aluminium alloys”, the secretariat of which is held by AFNOR. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by March 2006, and conflicting national standards shall be withdrawn at the latest by March 2006. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following coun-tries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Esto-nia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. SIST EN 14726:2005
EN 14726:2005 (E) 4
Introduction In optical atomic emission spectral analysis (OES) with excitation by electric spark discharges, (S-OES), a small portion of the sample is thermally atomized through the erosion of an electric spark. In the spark discharge, the aerosol is atomized, partially ionised and excited to emit optical radiation. The characteristic radiation for each element is used in OES for element detection and for the quantitative determination of the element contents. The test result obtained on a small test portion (mostly less than one milligram per spark spot) of one or more laboratory samples is referred either to a laboratory sample or to many tons of a melt or a cast product of aluminium or aluminium alloys. Cast structure and segregation interfere with measurement. S-OES is suitable for determining the chemical composition of metal samples as defined in technical specifications. S-OES serves as inspection, test and measuring equipment for alloy compositions to control and inspect the manufacturing and casting processes. For those purposes, laboratory samples are taken from the liquid metal after melting down of the alloying constituents and during casting in different process stages. Besides process inspection, S-OES, within the framework of a chemical-analytical service, facilitates the preparation of a test report which refers to the laboratory sample or to an agreed sample area of that sample. The testing equipment, including software used in the testing laboratories, is subject to change. Therefore, these guidelines describe the common principles. It gives guidance to specific criteria which should be met and the detailed documentation for the laboratory procedures to obtain traceable test results with uncertainty intervals. SIST EN 14726:2005
EN 14726:2005 (E)
5 1 Scope This European Standard gives guidance on the criteria and the fundamental operation procedure governing the spark optical emission spectral analysis (S-OES) of metal samples, beginning with sampling, through sample preparation to reporting the test, as well as the requirements of the whole spark source spectrometric procedure which shall be fulfilled with respect to: observance of the agreed precision and trueness [ISO 3534-1, ISO 5725-1] of the analytical results with refer-ence to the agreed sample or sample area; traceability of the analytical results to the international base units — mass (kg) and amount of substance (mol); proof of agreement between the spark spectrometric result and the average composition of the supplied metal sample within the given uncertainty [ISO 3534-1] of the analytical result; comparability of the test results between different laboratories; as far as possible, a trouble-free operation of the spark spectrometer. These guidelines refer to computer-controlled simultaneously measuring spectrometers for the analysis of solid samples. 2 Normative references The following referenced documents are indispensable for the application of this European Standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 12258-2:2004, Aluminium and aluminium alloys — Terms and definitions — Part 2: Chemical analysis EN 14361, Aluminium and aluminium alloys — Chemical analysis — Sampling from metal melts EN ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories (ISO/IEC 17025:2005) ISO 3534-1, Statistics — Vocabulary and symbols — Part 1: Probability and general statistical terms ISO 3534-2, Statistics — Vocabulary and symbols — Part 2: Statistical quality control ISO 5725-1, Accuracy (trueness and precision) of measurement methods and results — Part 1: General principles and definitions ISO Guide 30, Terms and definitions used in connection with reference materials 3 Terms and definitions For the purposes of this European Standard the terms and definitions given in EN 12258-2:2004 apply. 4 Symbols and abbreviations Symbols and formula signs are defined immediately by the relevant formulae. Abbreviations are put in brackets immediately after a term first appears in the text (e.g. S-OES). SIST EN 14726:2005
EN 14726:2005 (E) 6
5 Review and principle of test method a) Spark spectrometric measurement executed after mechanical preparation of the metal sample, which, if nec-essary, is taken from the metal melt. b) Evaluation of the measuring signal: 1) alloy calibration and universal calibration: with stored evaluation functions, which are evaluated by calibra-tion using reference material of a similar chemical composition; 2) master curve calibration: with recalculated evaluation functions after measuring reference material of known chemical composition. c) Evaluation and correction of measuring results as determined in preliminary testing or in accordance with data supplied by the manufacturer of the spectrometer. d) Control, documentation and statistical evaluation of all parameters which codetermine the uncertainty (ISO 3534-1) of the analytical results with reference to the mean chemical composition of the supplied sample (see clause 9) or with reference to the agreed sample area. 6 Consumables and calibration materials 6.1 Consumables 6.1.1 General The consumables shall be specified in the analytical procedures or in the handbook of the equipment according to the instructions of the equipment manufacturer or according to preliminary tests. 6.1.2 Feed gas of specified purity (argon for spectrometry, high purity, see instrument manufacturer recommen-dation). 6.1.3 Gas purification cartridge for the feed gas (if required to meet the instrument manufacturer specifications). 6.1.4 Cleaning brushes for the counterelectrode, if needed (the filaments should not contaminate the electrode to any measurable extent). 6.1.5 Particle trap for filtering the metal condensate out of the waste-gas stream. 6.1.6 Spare and expendable parts for the spark spectrometer in accordance with the manufacturer's instructions (e.g. counter electrode, insert for sample table). 6.2 Reference material and recalibration samples 6.2.1 General The reference materials (ISO Guide 30) and recalibration samples shall be listed and documented in the testing procedure. 6.2.2 Recalibration samples for drift correction (see clause 12). 6.2.3 Blank sample, high-purity aluminium or aluminium alloy based on high-purity constituents (e.g. AlSn30) (see clause 12). 6.2.4 Binary samples (if required e.g. for line interference correction (see clause 12)). 6.2.5 Calibration samples (see clause 12). SIST EN 14726:2005
EN 14726:2005 (E)
7 6.2.6 Analytical control samples (see clauses 12 and 13). 6.2.7 Spectrometer control samples (see 14.2). 7 Testing equipment 7.1 Spark spectrometer Optical atomic emission spectrometer with excitation by spark discharge, suitable for the chemical analysis of aluminium and aluminium alloys for major, minor and trace constituents. Spark spectrometers comprise the following main functional groups: a) system for atomization and excitation: 1) spark generator (spark source); 2) spark stand with counter electrode. b) spectral apparatus (system for spectral isolation or radiation splitting). c) system designed for radiation measurement (radiation detector). d) system for acquisition of the measured values, data processing and evaluation. NOTE In addition, there are units for power supply, gas supply, instrument control and supervision, for the further process-ing of analytical results, as well as input and output devices (keyboard, screen, printer, interface module). In the documentation of spark spectrometer testing equipment, at least the following information shall be recorded (see also EN ISO/IEC 17025): designation of device (including internal identification number); manufacturer, type designation, serial number; procurement documents; condition when received (e.g. new, used, reconditioned); date placed in service (provisional taking over and taking over or acceptance of the equipment); description of the equipment. The description of the equipment shall include the main properties and characteristic features of the equipment or give information about the relevant manufacturer's notes and instructions, as follows: type of spectrometer (e.g. computer-controlled simultaneous measuring spectrometer with 20 detector (meas-urement) channels for the analysis of .); spectral apparatus and range of wavelengths (e.g. vacuum polychromator with diffraction grating . lines/mm for wavelengths of .nm to . nm); mounting (type) of spectral apparatus (e.g. 1 metre Paschen-Runge mounting); list of measuring channels (element, wavelength, calibration range); spark stands, feed gas (sample table, type of counter electrode); spark source; computer with peripherals; software. SIST EN 14726:2005
EN 14726:2005 (E) 8
7.2 Equipment for sample preparation Lathes, milling machines, circular and band saws, a grinder or any suitable device can be used for the preparation of samples. For each machine, the following shall be documented: designation (if applicable, internal identification number), application range, manufacturer, type, serial number, date received and put into service, condition when received and equipment. The machine or cutting tool used for the final preparation of the analytical surfaces shall be able to machine reference samples as well as laboratory samples to the same conditions. Adjustable cutting speeds are advantageous for alloys of different hardness. 8 Samples 8.1 Requirements on test samples In the test samples, a defined area shall exist which represents the average chemical composition1). This area shall be sufficiently homogeneous with regard to the test portions. The relation to the average composition of the sample shall be proved, particularly in the case of samples with content gradients (segregations) — (see 8.2.2 and clause 13). An additional requirement for S-OES is, as far as possible, a similar cast structure in the reference sample and in the laboratory sample. Since reference samples are not available in any and every structural variation, an adapted structure shall be strived for during the production of the laboratory sample (for possible structural influences on the analytical result: see clause 13 and EN 14361). 8.2 Sampling 8.2.1 General The sampling as a procedural step before the spectral analysis plays an essential role in the trueness and precision of the analytical result. By means of sampling, compact (solid) laboratory samples, whose dimensions are suitable for preparation test samples for S-OES and whose chemical composition agree as far as possible with that of the material to be tested, are prepared. NOTE Since the analytical result refers to the average content of the laboratory sample supplied, uncertainties which result from differences between the laboratory samples and the average composition of the shipment, the cast product, the contents of the casting furnace or from variations in the casting process should also be taken into account during the determination of the process variance or of systematic process deviations. 8.2.2 Sampling of molten metal The sampling from metal melts shall be carried out according to EN 14361. For the chemical analysis of molten metals, liquid samples shall be normally taken by means of a ladle. The metal is subsequently cast to produce solid laboratory samples. Alternatively, samples can also be taken with a dip or suction sampler. The aim is to manufacture a laboratory sample with a known consistent cast structure and a good homogeneity and a distinct, definable test area which represents the respective average content of the complete sample for all analytes of the alloy types to be tested. The position and size of the representative sample area varies with the sampling conditions, as well as with the type of alloy and the analytes. The contents gradients are evaluated in preliminary tests by means of S-OES and the average contents of the sample determined using independent analytical methods without structural influences. For the simultaneous multi-element analysis of different alloy types, a mean analysis zone is determined and, if required, systematic deviations for individual analytes or alloy types are corrected.
1) The test result refers only to the effective test portion which is known as the vaporized fraction of the sample material which
gives the measured value. SIST EN 14726:2005
EN 14726:2005 (E)
9 NOTE 1 Cylindrical samples with ∅ 40 mm × 30 mm (∅ 55 mm × 30 mm) and disc samples with a central sprue, e.g. ∅ 50 mm × 10 mm or ∅ 55 mm × 4,5 mm (also called plate or mushroom sample) are frequently used. NOTE 2 The design of the mould should be optimised for minimized, reproducible and defined segregation characteristics. In general this is achieved by fast cooling and directional solidification. Easy handling minimizes individual sampling errors. 8.2.3 Sampling of finished and semi-finished products A piece, suitable for use on the spark stand, is mechanically separated (e.g. by sawing) from the metal part to be analysed (see NOTE 1). The piece thus cut off shall have a minimum thickness of approximately 1 mm with a plane surface or such that a plane surface can be machined or otherwise prepared, and large enough for a sealing edge to protrude over the opening of the sample table (exception: air stand). When using small samples, care should be taken to ensure that no overheating occurs due to sparking. NOTE 1 To check the sample's homogeneity using spark spectrometry, the piece of metal or ingot can be analysed at vari-ous locations (e.g. along the diagonal through the part); special attention should thus be given to areas susceptible to segrega-tion. A small piece of any finished or semi-finished product can never truly represent the whole and a sample of this type cannot be used to certify a cast. Lost or not properly cast samples means a lost cast, or one that can only be recovered by a conces-sion analysis with the agreement of the customer. NOTE 2 Possible systematic deviations due to structural differences to the reference material should be given attention dur-ing evaluation, or as uncertainty of the test results. A compromise with samples of sufficient size is to melt them in a small fur-nace under an inert gas to produce a laboratory sample similar to that normally used for S-OES. However, volatile elements, such as magnesium can be partially lost with this technique. NOTE 3 Mobile spark spectrometers facilitate the semi-quantitative analysis of difficult-to-transport finished and semi-finished products without taking a test sample, but the residual spark crater (spark spot) should be allowed. As a rule, sample preparation is omitted which means that the uncertainty of the test results is greater. Consequently, experience dictates that only identity (confusion) checks or materials sorting can be carried out. 9
Sample preparation For spark optical emission spectral analysis, a plane, flat surface in the representative area is produced on the sample by machining. Lathes and milling machines are used. During final fine machining, which is essential for the analysis, the cutting speed, cutting angle and cutting tool should be chosen in such a way that no sample material is raised above the machined surfaces and that no single hard grains are torn from a soft microstructure. A certain residual roughness (e.g. Rm 16 µm depth of roughness) promotes the formation of electric sparks (see manufacturer's instructions). The machined surface shall not be touched or otherwise contaminated. For the sample preparation of calibration samples, certified control samples and laboratory samples, the same technique with the same machining parameters shall be used so that a similar surface condition is achieved, unless preliminary tests demonstrate that the influence of the different machining techniques can be neglected compared to the other measuring errors. NOTE The influence of worn cutting tools can be examined by control samples during the inspection test. Inspection after machining: analytical surface shall be free from pores, cracks, inclusions and shrinkage cavities; geometric position of the analytical surface in the defined area of the sample shall be checked regularly by measuring the thickness of
the sample before and after machining. SIST EN 14726:2005
EN 14726:2005 (E) 10
10 Operating conditions of the spectrometer The operating conditions of the spectrometer shall be optimized. NOTE 1 In simultaneous spectrometers, the detector channels for the individual elements are pre-set by the spectral line table, which is mostly fixed by the apparatus manufacturer according to task definition (system requirements/specifications). Changes and expansions are only possible by modifying the spectrometer. The space requirement for a detector channel does not allow the combination of just any lines in a spectrometer of a given design. As a result, several optical spectrometer units are sometimes used in one instrument. NOTE 2 Information about possible interferences due to line overlap can be deduced from the spectral line reference table, whereby interferences as a result of lines being in a different order should also be considered. The measuring signal of the ana-lytical line is mostly related to a line of the main matrix element as the reference line. For trace analyses, sometimes the inten-sity of a background position is used as reference. NOTE 3 Other measuring conditions, such as spark parameters for pre-sparking and measurement sparking, flush time, pre-spark time, delay time, measurement period, possibly time-resolved intensity measurement, masking-out of the radiation from the plasma, high-voltage adjustment of the photomultiplier tubes, are as a rule adjusted by the apparatus manufacturer accord-ing to the measuring task or are optimized in accordance with the manufacturer's instructions. 11
Taking measurements Due to the different design of instruments and the different computer programs (software) for spectrometer control and measuring evaluation, the taking of a measurement, the inspection of the spectrometer and the auxiliary equipment as well as the maintenance of the instruments shall be carried out in accordance with the manufacturer's operating instructions and the technical manuals. NOTE These operating instructions should be transposed into procedure instructions which fit the relevant knowledge and skills of the service personnel and also include the individual analytical programs and operational processes. To that, the follow-ing points should be taken into account: a) start-up (restart): 1) checking before start-up (e.g. argon feed, exhaust-gas duct, cooling water, vacuum pump oil); 2) switch on spectrometer with all units (possibly vacuum valve); 3) start computer and analytical program; 4) check the instrument status is stable (e.g. vacuum, temperature, instrument profile); 5) inspection if the stable measuring state is achieved (e.g. measurement of suitable spectrometer control samples). b) switching off for repair: 1) back-up of software; 2) close vacuum valve or purge spectrometer with inert gas, if necessary; 3) shut off gas feed; 4) switch off electricity. c) execution of sparking (independent of sample type): 1) in case of manual operation: place sample, start measuring cycle, exclude bad sparking (e.g. intensity of the refer-ence line < 90 %; memory effect), clean counter electrode and possibly spark stand, number of sparkings (may vary according to sample type), method of averaging; 2) in case of instruments with sample handling systems (robots): position sample, start. d) drift correction or recalibration: 1) list of recalibration samples (setting-up samples); 2) procedure, criteria of decision for outliers, maximum allowable deviations; 3) responsibilities and documentation. SIST EN 14726:2005
EN 14726:2005 (E)
11 e) carrying out an analysis or check control analysis: 1) selection of analytical program (according to alloy or alloy group); 2) sample designation; 3) approval (concession) of analysis (criteria, responsibilities); 4) analytical report. f) fault detection and backdated corrective actions in the event of instrument malfunction: 1) spectrometer problems; 2) computer and software problems; 3) analytical problems (certifi
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