Liquid petroleum products - Determination of ignition delay and derived cetane number (DCN) of middle distillate fuels - Ignition delay and combustion delay determination using a constant volume combustion chamber with direct fuel injection

WARNING The use of this standard may involve hazardous materials, operations and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
This European Standard specifies a test method for the quantitative determination of ignition and combustion delays of middle distillate fuels intended for use in compression ignition engines. The method utilizes a constant volume combustion chamber with direct fuel injection into heated, compressed synthetic air. A dynamic pressure wave is produced from the combustion of the product under test. An equation is given to calculate the derived cetane number (DCN) from the ignition and combustion delays determined from the dynamic pressure curve.
This standard is applicable to middle distillate fuels, fatty acid methyl esters (FAME) and blends of diesel fuels and FAME .The method is also applicable to middle distillate fuels of non-petroleum origin, oil-sands based fuels, blends of fuel containing biodiesel material, diesel fuel oils containing cetane number improver additives and low-sulfur diesel fuel oils. However, users applying this standard especially to unconventional distillate fuels are warned that the relationship between derived cetane number and combustion behaviour in real engines is not yet fully understood.
This standard covers the ignition delay range from 2,47 ms to 4,09 ms and combustion delay from 3,71 ms to 6,74 ms (67 DCN to 39 DCN).
NOTE 1   The combustion analyser can measure shorter or longer ignition and combustion delays, but precision is not known.
NOTE 2   There is no information about how DCNs outside the 67 to 39 range compares to EN ISO 5165.
NOTE 3   For the purpose of this European Standard, the expression (% (V/V)) is used to represent the volume fraction (φ), and (% (m/m)) the mass fraction (ω).

Flüssige Mineralölerzeugnisse - Bestimmung des Zündverzugs und der abgeleiteten Cetanzahl (ACZ) von Kraftstoffen aus Mitteldestillaten - Bestimmung des Zündverzugs und des Verbrennungsverzugs in einer Verbrennungskammer mit konstantem Volumen und direkter Kraftstoffeinspritzung

Diese Europäische Norm legt ein Prüfverfahren zur quantitativen Bestimmung des Zündverzugs und des Verbrennungsverzugs von Kraftstoffen aus Mitteldestillaten, die in Dieselmotoren eingesetzt werden, fest. Dieses Verfahren nutzt eine Verbrennungskammer mit konstantem Volumen mit direkter Kraftstoffeinspritzung in erwärmte und komprimierte synthetische Luft. Durch die Verbrennung des zu prüfenden Produkts wird eine dynamische Druckwelle erzeugt. Eine Gleichung zur Berechnung der abgeleiteten Cetanzahl (ACZ) mit den anhand der dynamischen Druckkurve ermittelten Werten für den Zünd- und den Verbrennungsverzug ist angegeben.
Diese Europäische Norm gilt für Mitteldestillatkraftstoffe, Fettsäuremethylester (FAME) sowie Gemische aus Dieselkraftstoffen und FAME. Das Verfahren ist ebenfalls anwendbar auf Mitteldestillatkraftstoffe nicht mineralölstämmiger Herkunft, auf ölsandbasierte Kraftstoffe, auf Biodieselmaterial enthaltende Kraftstoffmischungen, auf Dieselkraftstoffe, welche Zündverbesserer enthalten und auf schwefelarme Dieselkraftstoffe. Anwender, die diese Norm im Besonderen auf alternative Destillatkraftstoffe anwenden, werden jedoch darauf hingewiesen, dass die Beziehung zwischen der abgeleiteten Cetanzahl und dem Verbrennungsverhalten in realen Motoren noch nicht völlig geklärt ist.
Diese Norm umfasst den Zündverzugsbereich von 2,47 ms bis 4,09 ms und den Verbrennungsverzugsbereich von 3,71 ms bis 6,74 ms (ACZ 67 bis ACZ 39).
ANMERKUNG 1   Das Verbrennungsprüfgerät kann einen kürzeren oder längeren Zündverzug und Verbrennungsverzug messen, die Präzision ist jedoch nicht bekannt.
ANMERKUNG 2   Es liegen keine Angaben zur Vergleichbarkeit von ACZ außerhalb des Bereiches von 67 bis 39 mit EN ISO 5165 vor.
ANMERKUNG 3   Für die Anwendung dieser Europäischen Norm wird der Volumenanteil () mit „% (V/V)“ und der Massenanteil () mit „% (m/m)“ angegeben.
WARNUNG — Die Anwendung dieser Norm kann die Anwendung gefährlicher Stoffe, Arbeitsgänge und Geräte mit sich bringen. Diese Norm gibt nicht vor, alle mit ihrer Anwendung verbundenen Sicherheitsprobleme anzusprechen. Der Anwender dieser Norm ist dafür verantwortlich, vorher ange¬messene Maßnahmen in Hinblick auf den Arbeitsschutz einzuleiten und die Anwendbarkeit einschränkender Vorschriften zu ermitteln

Produits pétroliers liquides — Détermination du délai d'inflammation et de l'indice de cétane dérivé (ICD) des distillats moyens — Détermination du délai d'inflammation et de combustion en utilisant une chambre à volume constant avec injection direct du carburant

La présente Norme européenne prescrit une méthode d'essai pour la détermination quantitative des délais d’inflammation et de combustion des distillats moyens utilisés comme carburants dans les moteurs à allumage par compression. Elle utilise une chambre de combustion à volume constant avec injection directe de carburant dans de l'air synthétique comprimé et chauffé. Une onde de pression dynamique est générée par la combustion du produit soumis à l'essai. Une équation est donnée pour calculer l'indice de cétane dérivé (ICD) à partir des délais d’inflammation et de combustion déterminés à partir de la courbe de pression dynamique.
La présente Norme européenne s'applique aux distillats moyens, aux esters méthyliques d’acides gras (EMAG) et aux mélanges de carburants diesel et d'EMAG. Elle est également applicable aux distillats moyens d'origine non pétrolière, aux carburants produits à partir de sables asphaltiques, aux mélanges de carburants contenant des biodiesel, aux carburants diesel contenant des additifs améliorateurs de cétane et aux carburants diesel à faible teneur en soufre. Cependant, l'attention des utilisateurs de cette norme, en particulier lorsqu’elle est appliquée aux distillats combustibles non conventionnels, est attirée sur le fait que la relation entre l'indice de cétane dérivé et les phénomènes de combustion dans les moteurs n’est pas encore parfaitement comprise.
La présente Norme européenne couvre les délais d'inflammation compris entre 2,47 et 4,09 ms et les délais de combustion compris entre 3,71 et 6,74 ms (ICD compris entre 67 et 39).
NOTE 1   L’analyseur de combustion peut mesurer des délais d’inflammation et de combustion plus longs ou plus courts, mais la fidélité n’est pas connue.
NOTE 2   Il n’y a pas d’informations sur la comparabilité des ICD hors de la gamme comprise entre 67 et 39 avec les valeurs obtenues suivant l’EN ISO 5165.
NOTE 3   Pour les besoins de la présente Norme européenne, les expressions « % (V/V) » et « % (m/m) » représentent respectivement les fractions volumique (φ) et massique (ω).
NOTE   Pour les besoins de la présente Norme européenne, les expressions « % (V/V) » et « % (m/m) » représentent respectivement les fractions volumique (φ) et massique (ω).
AVERTISSEMENT — L'utilisation de la présente Norme européenne peut impliquer l'intervention de produits, d'opérations et d'équipements à caractère dangereux. La présente Norme européenne n'est pas censée aborder tous les problèmes de sécurité concernés par son usage. Il est de la responsabilité de l'utilisateur de consulter et d'établir des règles de sécurité et d'hygiène appropriées et de déterminer l'applicabilité des restrictions réglementaires avant utilisation.

Tekoči naftni proizvodi - Ugotavljanje zakasnitve vžiga in izpeljanega cetanskega števila (DCN) v srednje destilatnih gorivih - Določevanje zakasnitve vžiga in sežiga z uporabo komore s konstantno prostornino z direktnim injiciranjem goriva

Ta evropski standard določa preskusno metodo za kvantitativno ugotavljanje zakasnitve vžiga v srednje destilatnih gorivih, namenjenih za uporabo v motorjih s kompresijskim vžigom. Pri tej metodi se uporablja komora s konstantno prostornino z direktnim injiciranjem goriva v segret in stisnjen sintetičen zrak. Med sežigom preskušanega izdelka nastane dinamičen tlačni val. Enačba pretvori zakasnitev vžiga in sežiga, ki se določi na podlagi krivulje dinamičnega tlaka, v izpeljano cetansko število (DCN). Ta metoda se uporablja za dizelska goriva, vključno z gorivi, ki vsebujejo metilne estre maščobnih kislin (FAME). Metoda se uporablja tudi za srednje destilatna goriva nenaftnega izvora, čeprav so uporabniki tega standarda opozorjeni, da povezava med lastnostmi vžiga in zmogljivostjo motorja pri nekonvencionalnih gorivih še ni v celoti pojasnjena. Standard zajema obseg zakasnitve vžiga od 2,8 ms do 6,5 ms in zakasnitve sežiga od 5,5 ms do 120 ms (65 DCN do 30 DCN). Vendar navedena točnost zajema le razpon od 60 do 35 DCN.

General Information

Status
Published
Publication Date
04-Aug-2015
Current Stage
9093 - Decision to confirm - Review Enquiry
Due Date
04-Mar-2021
Completion Date
23-Apr-2021

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Flüssige Mineralölerzeugnisse - Bestimmung des Zündverzugs und der abgeleiteten Cetanzahl (ACZ) von Kraftstoffen aus Mitteldestillaten - Bestimmung des Zündverzugs und des Verbrennungsverzugs in einer Verbrennungskammer mit konstantem Volumen und direkter KraftstoffeinspritzungProduits pétroliers liquides - Détermination due délai d'inflammation et de l'indice de cétane dérivé (ICD) des distillatsmoyens - Détermination due délai d'inflammation et de combustion par utiliser in une une chambre à volume constant avec injection direct de gazoleLiquid petroleum products - Determination of ignition delay and derived cetane number (DCN) of middle distillate fuels - Ignition delay and combustion delay determination using a constant volume combustion chamber with direct fuel injection75.160.20Liquid fuelsICS:Ta slovenski standard je istoveten z:EN 16715:2015SIST EN 16715:2015en,de01-oktober-2015SIST EN 16715:2015SLOVENSKI

STANDARD
SIST EN 16715:2015
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 16715
August 2015 ICS 75.160.20 English Version

Liquid petroleum products - Determination of ignition delay and derived cetane number (DCN) of middle distillate fuels - Ignition delay and combustion delay determination using a constant volume combustion chamber with direct fuel injection

Produits pétroliers liquides - Détermination du délai d'inflammation et de l'indice de cétane dérivé (ICD) des distillats moyens - Détermination du délai d'inflammation et de combustion en utilisant une chambre à volume constant avec injection directe de gazole

Flüssige Mineralölerzeugnisse - Bestimmung des Zündverzugs und der abgeleiteten Cetanzahl (ACZ) von Kraftstoffen aus Mitteldestillaten - Bestimmung des Zündverzugs und des Verbrennungsverzugs in einer Verbrennungskammer mit konstantem Volumen und direkter Kraftstoffeinspritzung This European Standard was approved by CEN on 20 June 2015.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre:
Avenue Marnix 17,

B-1000 Brussels © 2015 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 16715:2015 ESIST EN 16715:2015

EN 16715:2015 (E) 2 Contents Page European foreword .............................................................................................................................................3 Introduction .........................................................................................................................................................4 1 Scope ......................................................................................................................................................5 2 Normative references ............................................................................................................................5 3 Terms and definitions ...........................................................................................................................6 4 Principle ..................................................................................................................................................7 5 Reagents and materials ........................................................................................................................7 6 Apparatus ...............................................................................................................................................8 7 Sampling .................................................................................................................................................8 8 Apparatus assembly and installation ............................................................................................... 10 9 Preparation of apparatus ................................................................................................................... 10 9.1 System start-up and warm-up ........................................................................................................... 10 9.2 Standard operating and test conditions ........................................................................................... 10 10 Calibration, verification and quality control .................................................................................... 11 10.1 General ................................................................................................................................................. 11 10.2 Calibration ........................................................................................................................................... 11 10.3 Apparatus verification ........................................................................................................................ 12 10.4 Quality control (QC) ............................................................................................................................ 12 11 Test procedure .................................................................................................................................... 13 12 Calculation ........................................................................................................................................... 13 13 Expression of results ......................................................................................................................... 13 14 Precision .............................................................................................................................................. 14 14.1 General ................................................................................................................................................. 14 14.2 Repeatability ........................................................................................................................................ 14 14.3 Reproducibility .................................................................................................................................... 14 15 Test report ........................................................................................................................................... 15 Annex A (normative) Combustion analyser description ............................................................................... 16 A.1 General ................................................................................................................................................. 16 A.2 Apparatus description and assembly ............................................................................................... 16 A.3 Control and data acquisition ............................................................................................................. 18 Annex B (normative)

Operational details in support to the standard test procedure .............................. 19 B.1 General ................................................................................................................................................. 19 B.2 Cleaning procedure to prepare fuel system for calibration ........................................................... 19 B.3 Automatic calibration procedure ...................................................................................................... 19 B.4 Test sequence ..................................................................................................................................... 20 B.5 Unit shutdown ..................................................................................................................................... 22 Bibliography ..................................................................................................................................................... 23

SIST EN 16715:2015

EN 16715:2015 (E) 3 European foreword This document (EN 16715:2015) has been prepared by Technical Committee CEN/TC 19 “Gaseous and liquid fuels, lubricants and related products of petroleum, synthetic and biological origin”, the secretariat of which is held by NEN. 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 February 2016 and conflicting national standards shall be withdrawn at the latest by February 2016. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights. According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. SIST EN 16715:2015

EN 16715:2015 (E) 4 Introduction This European Standard is derived from joint standardization work within the Energy Institute and ASTM International. It is based on and technically equivalent with ASTM D7668 [1]. The described method is an alternative quantitative determination of the cetane number of middle distillate fuels intended for use in compression ignition engines. A correlation study between this method and EN ISO 5165:1998 [2] has been done and the results of this are incorporated in this European Standard. Research Report RR: D02-1771 [3]. The basis of this method is the derived cetane number (DCN) correlation equation as given in Clause 12. The on-going validation of the equation is monitored and evaluated through the existing American and European fuel exchange programs. The validation data will be reviewed by CEN/TC 19 with a frequency of at least every two years. As a result of the review, CEN/TC 19 may make the decision to, if necessary, modify the existing equation/correlation or develop a new one. As part of this review, the sample types will be examined, and if certain types are underrepresented, further steps may be taken to evaluate how they perform. The ignition delay (ID) and combustion delay (CD) values and the DCN value determined by this test method can provide a measure of the ignition characteristics of diesel fuel oil used in compression ignition engines. This test is for use by engine manufacturers, petroleum refiners and marketers, and in commerce as a specification aid to relate or match fuels and engines. This test is also applicable to non-conventional diesel fuels. For the moment the basics of one type of apparatus are described. Once more correlation data on different types of derived cetane number testing equipment is available, CEN/TC 19 will consider revising this European Standard. SIST EN 16715:2015

EN 16715:2015 (E) 5 1 Scope This European Standard specifies a test method for the quantitative determination of ignition and combustion delays of middle distillate fuels intended for use in compression ignition engines. The method utilizes a constant volume combustion chamber with direct fuel injection into heated, compressed synthetic air. A dynamic pressure wave is produced from the combustion of the product under test. An equation is given to calculate the derived cetane number (DCN) from the ignition and combustion delays determined from the dynamic pressure curve. This European Standard is applicable to middle distillate fuels, fatty acid methyl esters (FAME) and blends of diesel fuels and FAME. The method is also applicable to middle distillate fuels of non-petroleum origin, oil-sands based fuels, blends of fuel containing biodiesel material, diesel fuel oils containing cetane number improver additives and low-sulfur diesel fuel oils. However, users applying this standard especially to unconventional distillate fuels are warned that the relationship between derived cetane number and combustion behaviour in real engines is not yet fully understood. This European Standard covers the ignition delay range from 2,47 ms to 4,09 ms and combustion delay from 3,71 ms to 6,74 ms (67 DCN to 39 DCN). NOTE 1 The combustion analyser can measure shorter or longer ignition and combustion delays, but precision is not known. NOTE 2 There is no information about how DCNs outside the 67 to 39 range compare to EN ISO 5165. NOTE 3 For the purpose of this European Standard, the expression “% (V/V)” is used to represent the volume fraction (3), and “% (m/m)” the mass fraction (). WARNING — The use of this standard can involve hazardous materials, operations and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of users of this standard to take appropriate measures to ensure the safety and health of personnel prior to application of the standard, and fulfil statutory and regulatory requirements for this purpose. 2 Normative references The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN ISO 3170, Petroleum liquids - Manual sampling (ISO 3170) EN ISO 3171, Petroleum liquids - Automatic pipeline sampling (ISO 3171) EN ISO 3696, Water for analytical laboratory use - Specification and test methods (ISO 3696) ISO 1998-2, Petroleum industry - Terminology - Part 2: Properties and tests IP 537, Determination of the purity of Derived Cetane Number reference materials - Gas chromatography method SIST EN 16715:2015

EN 16715:2015 (E) 6 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 1998-2 and the following apply. 3.1 cetane number CN measure of the ignition performance of a diesel fuel in a standardized engine test on a scale defined by reference fuels Note 1 to entry: It is expressed as the percentage by volume of hexadecane (cetane) in a reference blend having the same ignition delay as the fuel for analysis. The higher the cetane number, the shorter the ignition delay. 3.2 ignition delay ID period of time, in milliseconds (ms), between the start of fuel injection and the start of combustion Note 1 to entry: In the context of this test method, the start of fuel injection is interpreted as the rise in the electronic signal that opens the injector and the combustion start is interpreted as the first increase of the chamber pressure during the combustion cycle, as measured by a pressure sensor in the combustion chamber. 3.3 combustion delay CD period of time, in milliseconds (ms), between the start of fuel injection and mid-point of the combustion pressure curve Note 1 to entry: In the context of this test method, the start of fuel injection is interpreted as the rise in the electronic signal that opens the injector and the combustion pressure curve mid-point is interpreted as the part of the pressure curve midway between the initial chamber pressure and the maximum pressure generated during the combustion cycle, as measured by a pressure sensor in the combustion chamber. The combustion delay CD measures the time between the injection of the sample and phase of combustion controlled by the diffusive mixing of the air and fuel. 3.4 derived cetane number DCN number calculated by using an equation that correlates a combustion analyser’s ignition and combustion delays to the cetane number 3.5 accepted reference value ARV value agreed upon as a reference for comparison Note 1 to entry: The value is derived as (1) a theoretical or established value, based in scientific principles, (2) an assigned value, based on experimental work of some national or international organization, or (3) a consensus value, based on collaborative experimental work under the auspices of a scientific or engineering group. 3.6 quality control sample QC sample stable and homogenous material(s) similar in nature to the materials under test, properly stored to ensure integrity, and available in sufficient quantity for repeated long-term testing 3.7 calibration reference fluid stable and homogenous fluid used to calibrate the performance of the combustion analyser SIST EN 16715:2015

EN 16715:2015 (E) 7 3.8 verification reference fluid stable and homogenous fluid used to verify the performance of the combustion analyser 4 Principle A test portion of the material under test is injected into a temperature and pressure controlled, constant volume combustion chamber, which has previously been charged with synthetic air of a specified quality. Each injection produces a compression ignition combustion cycle detected using a pressure sensor. The ignition delay and combustion delay are measured from the rise of the electronic signal that activates the injector solenoid to two specific points along the combustion pressure wave produced by the combustion cycle. A complete sequence comprises 5 preliminary injection cycles and 15 subsequent injection cycles used for the sample analysis. The ID and CD measurements for the last 15 injection cycles are statistically reviewed and the outlying ID’s and CD’s are eliminated using Peirce’s Criterion [4]. The remaining ID’s and CD’s are averaged to produce the ID and CD results. An equation is given to calculate the derived cetane number (DCN) from the ignition and combustion delays determined from the dynamic pressure curve. The DCN obtained by this procedure is an estimate of the cetane number (CN) obtained from the conventional large-scale engine test EN ISO 5165 [2]. 5 Reagents and materials 5.1 Calibration reference fluid, 40:60 mixture by weight of hexadecane and 2,2,4,4,6,8,8-heptamethylnonane, respectively, measured with an accuracy of 0,01 percent. For peroxide-free material the assigned IDARV is 2,96 ms and the assigned CDARV is 4,90 ms. 5.1.1 Hexadecane, minimum purity of 99,0 % (m/m). 5.1.2 2,2,4,4,6,8,8-Heptamethylnonane, minimum purity of 98,0 % (m/m). IMPORTANT — Hydrocarbons can form peroxides and other free radicals forming contaminants that can influence the ID and CD. Experience has found some 40:60 blends of hexadecane and 2,2,4,4,6,8,8-heptamethylnonane meeting the purity specification can contain peroxides and other free radically form contaminants. Typically, the peroxides and other free radically formed contaminants can be removed from the 40:60 mixture of hexadecane and 2,2,4,4,6,8,8-heptamethylnonane by subjecting the blend to activated 4 Å molecular sieves. 5.2 Verification reference fluid, methylcyclohexane (MCH) of a purity of minimum 99,0 % (m/m) to be used as the designated 11,0 ms ignition delay (IDARV) and the designated 17,0 ms combustion delay (CDARV) assigned accepted reference value material. If the initial purity is not known the purity shall be checked in accordance with IP 537. Even if the verification reference fluid meets the purity specification, it may not meet the Ignition and Combustion delay requirements (see Table 2). It is recommended to either pass the suspect MCH through a filter column to remove peroxide based impurities or to test a bottle of MCH that has been shown to meet the ID and CD requirements. It is recommended that each bottle of MCH is tested prior to its use as a verification reference fluid to confirm it is of acceptable quality. 5.3 Quality control sample, stable and homogenous distillate fuel, similar in nature to the materials under test (see 3.6). SIST EN 16715:2015

EN 16715:2015 (E) 8 5.4 Combustion charge air, a compressed synthetic air mixture containing (20,0 ± 0,5) % (V/V) oxygen with the balance nitrogen, less than 0,003 % (V/V) hydrocarbons, and less than 0,025 % (V/V) water. It is recommended that a quality control test be performed after an air cylinder has been changed. NOTE Oxygen content of combustion charge air can vary between batches (cylinders). Significant variation will lead to changes in ignition and combustion delay (higher oxygen content leads to shorter ignition and combustion delays). 5.5 Heptane, (n-Heptane) with a minimum purity of 99,5 % (m/m). 5.6 Water, unless otherwise specified, meeting the requirements of grade 3 of EN ISO 3696. 5.7 Coolant system fluid, 50:50 volumetric mixture of commercial grade ethylene glycol-type radiator antifreeze with water (5.6). 5.8 Compressed nitrogen, of minimum purity 99,9 % (V/V), capable of delivering a pressure of (0,6 to 1,0) MPa to the instrument. 6 Apparatus 6.1 Combustion analyser The apparatus is described in more detail in Annex A. For the installation and set-up procedures, and for detailed system description, refer to the manufacturer’s manual. The system described in this standard comprises a temperature and pressure controlled combustion chamber (6.1.1) with fluid cooling of designated areas, chamber inlet and exhaust valves and associated piping, an electronically controlled fuel injection system, a fuel delivery system, a recirculating coolant system, solenoids, sensors, controls and connection fittings for the compressed gas utilities. Figure 1 gives a schematic outline of the analyser. 6.1.1 Combustion chamber, a steel combustion chamber of capacity 0,473 l ± 0,005 l. Annex A gives further details. 6.1.2 Filter medium, a removable polytetrafluoroethylene filter with a 5 µm pore size is placed downstream from the sample vessel to filter particulate matter from the test portion. 7 Sampling 7.1 Unless otherwise specified, obtain samples in accordance with the procedures given in EN ISO 3170 or EN ISO 3171. 7.2 To minimize exposure to UV emissions that can induce chemical reactions, which may affect ignition and combustion delays measurement, collect and store samples in sample containers that are either constructed of materials that minimize light reaching the sample such as a dark brown bottle, metal can or containers that shall be wrapped or boxed in light-proof containers immediately after filling. If the fuel is not to be analysed within 24 h, retain in a dark, cool environment, and preferably under an inert gas. NOTE 1 Exposure of petroleum fuels to UV wavelengths of less than 550 nm for even a short period of time has been shown to affect ignition delay [5]. NOTE 2 The formation of peroxides and radicals, which affect the ignition delay and the combustion delay, is minimized when the sample is stored in the dark, under a nitrogen blanket in a cool environment. 7.3 Condition the diesel fuel oil sample before opening the storage container, so that it is at room temperature, typically 18 °C to 32 °C. SIST EN 16715:2015

EN 16715:2015 (E) 9 7.4 Inspect the sample for wax precipitation. If precipitants are present, bring the test sample to a temperature of at least 14 °C above the expected cloud point of the material being tested, taking care not to lose any lower boiling range components. Agitate the sample to return precipitants back in to the solution, ensuring the sample is homogeneous before proceeding.

Key Digital signals Analogue signals L1: upper level sensor T1: coolant temperature L2: lower level sensor T2: inner wall temperature TF: thermal fuse P1: fuel pressure M1: hydraulic pump P2: chamber dynamic pressure N1: injector P3: chamber static pressure V1: flush valve P4: nitrogen pressure V2: air inlet valve FR1: coolant flow rate V3: exhaust valve

Vx: nitrogen circuit valves

Analyser lines Analyser parts (no signal registration) AI: Air inlet CC: Combustion chamber CI: Coolant input F1, F2, F3: Filter CO: Coolant output M2: Multiplier EX: Air exhaust RD: Rupture disk NI: Nitrogen input S1: Safety valve SI: Sample inlet SV: Sample vessel

WB: Sample waste drain

H1: Clam shell heater Figure 1 — Schematic overview of combustion analyser SIST EN 16715:2015

EN 16715:2015 (E) 10 8 Apparatus assembly and installation Annex A gives more details on the apparatus assembly and installation. The apparatus requires placement on a bench with facilities for the hook-up of all utilities and gases. The user shall ensure compliance with all local and national codes. The apparatus requires an environment with a temperature of 10 °C to 35 °C. The exhaust gases shall be directed into a low suction pressure fume extraction system. 9 Preparation of apparatus 9.1 System start-up and warm-up 9.1.1 Open the valve at the source of the combustion charge air supply and adjust the pressure regulator as needed to provide the specification pressure (5.4). 9.1.2 Open the valve at the source of the nitrogen supply and adjust the pressure regulator as needed to provide the specification pressure (5.8). 9.1.3 Switch on power to the combustion analyser and the coolant pump. 9.1.4 After the chamber wall temperature has stabilized a chamber leakage test will be performed to determine the chamber leakage rate. Combustion chamber leakage rate shall be less than 0,75 kPa/s, as measured during the automated check of the sealing integrity of the combustion chamber. If the leakage test fails, a warning is issued. 9.1.5 For more details and in case of error messages refer to the manufacturer’s manual. 9.2 Standard operating and test conditions 9.2.1 Operation of the combustion analyser requires setting a series of testing variables to prescribed specifications. Some of these settings are established by the operator, others are operating conditions that are monitored or controlled by the computer software. 9.2.2 The set points for chamber wall temperature and the injection time are determined during the calibration procedure. 9.2.3 Check that the parameters are according to Table 1. Refer to manufacturer’s manual in case the parameters are outside the limits. Table 1 — Standard operating test conditions Parameter Limits Chamber static pressure (2,00 ± 0,02) MPa Chamber wall temperature Stability during the 15 injections 560 °C to 640 °C ± 0,2 °C Injector nozzle coolant temperature (50 ± 2) °C Injection Pressure (100 ± 1,5) MPa Injection time 2000 µs to 2700 µs SIST EN 16715:2015

EN 16715:2015 (E) 11 10 Calibration, verification and quality control 10.1 General Calibrate and verify the apparatus at each of the following occasions: — after it is installed and commissioned, — after replacement of critical parts or components of combustion chamber assembly, fuel injection system, fuel injection system instrument sensors, chamber static pressure or chamber dynamic pressure sensors, — after calibration of the chamber static pressure, or chamber dynamic pressure sensors, or — whenever QC sample determinations are not in statistical control, and the reasons for QC non-compliance have been suitably addressed. 10.2 Calibration 10.2.1 Clean the fuel system in accordance with B.2. 10.2.2 Bring the calibration reference fluid (5.1) to a temperature greater than 20 °C and agitate before use. 10.2.3 Remove the fuel reservoir cap and wash the stem and threads and the fuel reservoir with approximately 50 ml of the calibration reference fluid. Reinstall the fuel reservoir cap. 10.2.4 Flush the entire aliquot of the calibration reference fluid through the fuel system. Refer to the manufacturer’s instruction manual. 10.2.5 Charge the instrument with the calibration reference fluid (at least 160 ml) and wipe the stem and threads of the fuel reservoir cap with a clean dry towel and secure the fuel reservoir cap to the fuel reservoir. 10.2.6 Carry out the automatic calibration procedure (see B.3). If the average ID value or the average CD value is outside the acceptance limits, the combustion chamber inner surface temperature controller set-point is adjusted by the computer to change the combustion chamber wall temperature or the fuel injection period is adjusted by the computer to inject the appropriate quantity of fuel into the combustion chamber, or both. The automatic calibration procedure performed by the processor controlling the instrument is summarized in B.3. NOTE ID increases when the combustion chamber inner surface temperature decreases and vice versa. CD decreases when a larger sample volume is injected into the combustion chamber and vice versa. If the temperature controller set-point adjustment from the previous setting exceeds ± 4 °C or the injection period adjustment from the previous setting exceeds ± 100 diagnostic procedures to determine and remedy the problem are recommended. Refer to the instruction manual of the manufacturer. 10.2.7 The combustion analyser calibration is complete when the calibration reference fluid average delays are within the specified acceptance limits as given in Table 2. 10.2.8 W

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