Liquid petroleum products - Middle distillates and fatty acid methyl ester (FAME) fuels and blends - Determination of oxidation stability by rapid small scale oxidation test (RSSOT)

This European Standard specifies a method for the determination of the oxidation stability of middle distillate fuels, fatty acid methyl ester (FAME) fuel and blends thereof, under accelerated conditions, by measuring the induction period to the specified breakpoint in a reaction vessel charged with the sample and oxygen.
NOTE 1   For the purposes of this European Standard, the term “% (V/V)” is used to represent the volume fraction (φ).
NOTE 2   The induction period is used as an indication for the resistance of middle distillates, fatty acid methyl ester (FAME) fuels and blends thereof against oxidation. It should be recognized, however, that this correlation can vary markedly under different conditions with different FAMEs and diesel fuel blends.
NOTE 3   The presence of ignition improvers may lead to lower oxidation stability results determined by this method. It has for instance been observed that the addition of 2-ethyl hexyl nitrate (2EHN) can reduce the measured oxidation stability values.

Flüssige Mineralölerzeugnisse - Mitteldestillat- und Fettsäure-Methylester (FAME)-Kraftstoffe und -Mischungen - Bestimmung der Oxidationsstabilität mit beschleunigtem Oxidationsverfahren und kleiner Probenmenge (RSSOT)

Dieses Dokument legt ein Verfahren zur Bestimmung der Oxidationsstabilität von Mitteldestillat- und Fettsäure-Methylester (FAME)-Kraftstoffen und Mischungen aus beiden unter beschleunigten Bedingungen fest; dies geschieht durch Messung der Induktionszeit bis zum definierten Bezugspunkt, die in einem mit der Probe und mit Sauerstoff befüllten Reaktionsgefäß bei 140 °C ermittelt wird.
ANMERKUNG 1 Für die Zwecke dieses Dokuments wird zur Angabe des Volumenanteils (φ) einer Substanz der Ausdruck "% (V/V)" verwendet.
ANMERKUNG 2 Die Induktionszeit wird als ein Hinweis auf Oxidationsbeständigkeit von Mitteldestillat- und Fettsäure-Methylester (FAME)-Kraftstoffen und Mischungen aus beiden verwendet. Diese Korrelation kann in Abhängigkeit von verschiedenen FAMEs, Dieselkraftstoffgemischen und Bedingungen deutlichen Schwankungen unterliegen.
ANMERKUNG 3 Die Anwesenheit von Zündverbesserern kann bei diesem Verfahren zu niedrigeren Messwerten für die Oxidationsstabilität führen. Zum Beispiel wurde beobachtet, dass bei Zugabe von 2 Ethylhexylnitrat (2 EHN) die gemessenen Werte für die Oxidationsstabilität geringer ausfallen können. Einzelheiten siehe [6].
ANMERKUNG 4 Weiterführende Angaben zu den Präzisionsdaten bei einer Prüftemperatur von 120 °C siehe Anhang C.

Produits pétroliers liquides - Distillats moyens, esters méthyliques d'acides gras (EMAG) et leurs mélanges - Détermination de la stabilité à l'oxydation par méthode d'oxydation accélérée à petite échelle (RSSOT)

Le présent document définit une méthode pour la détermination, dans des conditions d’oxydation accélérée, de la stabilité à l’oxydation des distillats moyens, des esters méthyliques d’acides gras (EMAG) et de leurs mélanges. Elle est basée sur la mesure de la période d’induction à un point de rupture donné dans un récipient de réaction contenant l’échantillon et de l’oxygène.
NOTE 1 Pour les besoins du présent document, le terme "% (V/V)" est utilisé pour représenter la fraction volumique (φ).
NOTE 2 La période d’induction est considérée comme une indication pour la résistance des distillats moyens, des EMAG et de leurs mélanges à l’oxydation. Cette corrélation peut varier nettement selon les différentes conditions concernant les mélanges des divers EMAG et de carburant diesel.
NOTE 3 La présence d’additifs améliorants de cétane peut entraîner une minoration des résultats de stabilité à l’oxydation mesurée par cette méthode. Il a été observé par exemple que l’ajout de 2-éthyl hexyl nitrate (2-EHN) peut abaisser les valeurs mesurées de stabilité à l’oxydation. Voir [6] pour les détails.
NOTE 4 Pour plus d'informations sur les données de fidélité à une température d'essai de 120 °C, voir l'Annexe C.

Tekoči naftni proizvodi - Goriva na osnovi srednjih destilatov, metilnih estrov maščobnih kislin (FAME) in mešanic - Ugotavljanje oksidacijske stabilnosti z oksidacijskim preskusom rapidne male skale (RSSOT)

General Information

Status
Published
Public Enquiry End Date
30-Jun-2021
Publication Date
14-Nov-2022
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
02-Nov-2022
Due Date
07-Jan-2023
Completion Date
15-Nov-2022

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SLOVENSKI STANDARD
SIST EN 16091:2022
01-december-2022
Nadomešča:
SIST EN 16091:2012
Tekoči naftni proizvodi - Goriva na osnovi srednjih destilatov, metilnih estrov
maščobnih kislin (FAME) in mešanic - Ugotavljanje oksidacijske stabilnosti z
oksidacijskim preskusom rapidne male skale (RSSOT)

Liquid petroleum products - Middle distillates and fatty acid methyl ester (FAME) fuels

and blends - Determination of oxidation stability by rapid small scale oxidation test

(RSSOT)

Flüssige Mineralölerzeugnisse - Mitteldestillat- und Fettsäure-Methylester (FAME)-

Kraftstoffe und -Mischungen - Bestimmung der Oxidationsstabilität mit beschleunigtem

Oxidationsverfahren und kleiner Probenmenge (RSSOT)

Produits pétroliers liquides - Distillats moyens, esters méthyliques d'acides gras (EMAG)

et leurs mélanges - Détermination de la stabilité à l'oxydation par méthode d'oxydation

accélérée à petite échelle (RSSOT)
Ta slovenski standard je istoveten z: EN 16091:2022
ICS:
75.160.20 Tekoča goriva Liquid fuels
SIST EN 16091:2022 en,fr,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 16091:2022
---------------------- Page: 2 ----------------------
SIST EN 16091:2022
EN 16091
EUROPEAN STANDARD
NORME EUROPÉENNE
October 2022
EUROPÄISCHE NORM
ICS 75.160.20 Supersedes EN 16091:2011
English Version
Liquid petroleum products - Middle distillates and fatty
acid methyl ester (FAME) fuels and blends - Determination
of oxidation stability by rapid small scale oxidation test
(RSSOT)

Produits pétroliers liquides - Distillats moyens, esters Flüssige Mineralölerzeugnisse - Mitteldestillat- und

méthyliques d'acides gras (EMAG) et leurs mélanges - Fettsäure-Methylester (FAME)-Kraftstoffe und -

Détermination de la stabilité à l'oxydation par méthode Mischungen - Bestimmung der Oxidationsstabilität mit

d'oxydation accélérée à petite échelle (RSSOT) beschleunigtem Oxidationsverfahren und kleiner

Probenmenge (RSSOT)
This European Standard was approved by CEN on 19 September 2022.

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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and

United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 16091:2022 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN 16091:2022
EN 16091:2022 (E)
Contents Page

European foreword ............................................................................................................................................ 4

1 Scope .......................................................................................................................................................... 5

2 Normative references .......................................................................................................................... 5

3 Terms and definitions ......................................................................................................................... 5

4 Principle ................................................................................................................................................... 5

5 Reagents and materials ...................................................................................................................... 6

6 Apparatus ................................................................................................................................................ 6

7 Sampling and sample handling ........................................................................................................ 6

8 Performance check of the apparatus ............................................................................................. 6

9 Preparation of the apparatus ........................................................................................................... 7

10 Procedure ................................................................................................................................................ 7

11 Expression of results ........................................................................................................................... 8

12 Precision .................................................................................................................................................. 8

12.1 General...................................................................................................................................................... 8

12.2 Repeatability, r ...................................................................................................................................... 8

12.3 Reproducibility, R ................................................................................................................................. 8

13 Test report ............................................................................................................................................... 9

Annex A (normative) Apparatus description ........................................................................................... 10

A.1 General requirements ....................................................................................................................... 10

A.2 Assembly of apparatus ...................................................................................................................... 10

A.3 Reaction vessel .................................................................................................................................... 10

A.4 Screw cap ............................................................................................................................................... 10

A.5 Electric heater ...................................................................................................................................... 11

A.6 O-ring seals ............................................................................................................................................ 11

A.7 Valves ...................................................................................................................................................... 11

A.8 Pressure sensor ................................................................................................................................... 11

A.9 Temperature sensor .......................................................................................................................... 11

A.10 Connecting pipes ................................................................................................................................. 11

A.11 Cooling fan ............................................................................................................................................. 11

Annex B (informative) Determination of induction period ................................................................ 12

Annex C (informative) Test method and precision data at 120 °C ................................................... 13

C.1 Background ........................................................................................................................................... 13

C.2 Short description of the implementation of the RSSOT method using a reduced

measurement temperature of 120 °C .......................................................................................... 13

---------------------- Page: 4 ----------------------
SIST EN 16091:2022
EN 16091:2022 (E)

C.3 Precision ................................................................................................................................................ 13

C.3.1 General ................................................................................................................................................... 13

C.3.2 Repeatability, r .................................................................................................................................... 14

C.3.3 Reproducibility, R ............................................................................................................................... 14

C.4 Outcome of the ILS .............................................................................................................................. 14

Bibliography ....................................................................................................................................................... 15

---------------------- Page: 5 ----------------------
SIST EN 16091:2022
EN 16091:2022 (E)
European foreword

This document (EN 16091:2022) 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 April 2023, and conflicting national standards shall be

withdrawn at the latest by month April 2023.

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CEN shall not be held responsible for identifying any or all such patent rights.

This document supersedes EN 16091:2011.

In comparison with the previous edition EN 16091:2011, the following technical modifications have been

made:

a) addition of informative Annex C to include work that has been executed on a modified rapid small

scale oxidation method at 120 °C;

b) revision of Clause 8: the performance check of the apparatus and the recommended calibration

process have been merged into a single Clause 8.1;
c) Annex on the calibration process has been removed;
d) the document was revised editorially.

Any feedback and questions on this document should be directed to the users’ national standards body.

A complete listing of these bodies can be found on the CEN website.

According to the CEN-CENELEC Internal Regulations, the national standards organisations of the

following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,

Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,

Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North

Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the United

Kingdom.
---------------------- Page: 6 ----------------------
SIST EN 16091:2022
EN 16091:2022 (E)
1 Scope

This document specifies a method for the determination of the oxidation stability of middle distillate

fuels, fatty acid methyl ester (FAME) fuel and blends thereof, under accelerated conditions, by measuring

the induction period to the specified breakpoint in a reaction vessel charged with the sample and oxygen

at 140 °C.

NOTE 1 For the purposes of this document, the term “% (V/V)” is used to represent the volume fraction (φ).

NOTE 2 The induction period is used as an indication for the resistance of middle distillates, fatty acid methyl

ester (FAME) fuels and blends thereof against oxidation. This correlation can vary markedly under different

conditions with different FAMEs and diesel fuel blends.

NOTE 3 The presence of ignition improvers can lead to lower oxidation stability results determined by this

method. It has for instance been observed that the addition of 2-ethyl hexyl nitrate (2-EHN) can reduce the

measured oxidation stability values. See [6] for details.

NOTE 4 For further information on the precision data at a test temperature of 120 °C see Annex C.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. 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)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
3.1
breakpoint

point in the pressure-time curve, where the pressure in the vessel has dropped 10 % below the maximum

pressure achieved in the current test run
3.2
induction period

time elapsed between starting the heating procedure of the reaction vessel, charged with sample and

oxygen, and the breakpoint, measured in minutes
4 Principle

At ambient temperature, a known volume of a sample is placed in a reaction vessel charged with oxygen

to a pressure of 700 kPa ± 5 kPa. The reaction vessel is heated to 140 °C. The pressure in the vessel drops

as the oxygen is consumed during the oxidation of the sample. The pressure in the vessel is recorded at

intervals of 1 s until the breakpoint is reached. The elapsed time from start to the breakpoint is the

induction period at the test temperature of 140 °C ± 0,5 °C.
---------------------- Page: 7 ----------------------
SIST EN 16091:2022
EN 16091:2022 (E)

NOTE Work has been executed on the determination of oxidation stability by a modified rapid small-scale

oxidation method at 120 °C. The results thereof are given in Annex C.
5 Reagents and materials

5.1 Cleaning solvent, for the removal of oxidation residues from the test vessel, of suitable purity to

leave no residue on the apparatus.

NOTE Commercially available ethanol of approximately 95 % (V/V) purity was found to be suitable.

5.2 Oxygen, extra dry (<5 mg/kg water), commercially available, with a purity of not less than 99,6 %.

5.3 Cleaning tissues, lint-free for cleaning sensitive galvanic coated surfaces without scratching.

5.4 Verification fluid, hydrocarbon fuel, any hydrocarbon fuel with sufficient stability and a known

induction period may be used.

NOTE In general, verification fluid with a certified induction period is available from the manufacturer of the

apparatus.
6 Apparatus

6.1 Automatically controlled oxidation tester, comprising an oxidation reaction vessel containing:

— test sample cup capable of being rapidly heated;
— pressure sensor
...

SLOVENSKI STANDARD
oSIST prEN 16091:2021
01-junij-2021
Tekoči naftni proizvodi - Goriva na osnovi srednjih destilatov, metilnih estrov
maščobnih kislin (FAME) in mešanic - Ugotavljanje oksidacijske stabilnosti z
oksidacijsko metodo rapidne male skale

Liquid petroleum products - Middle distillates and fatty acid methyl ester (FAME) fuels

and blends - Determination of oxidation stability by rapid small scale oxidation method

Flüssige Mineralölerzeugnisse - Mitteldestillat- und Fettsäuremethylesterkraftstoffe und

Mischungen - Bestimmung der Oxidationsstabilität mit beschleunigtem Verfahren und

kleiner Probenmenge

Produits pétroliers liquides - Distillats moyens, esters méthyliques d'acides gras (EMAG)

et leurs mélanges - Détermination de la stabilité à l'oxydation par méthode d'oxydation

accélérée à petite échelle
Ta slovenski standard je istoveten z: prEN 16091
ICS:
75.160.20 Tekoča goriva Liquid fuels
oSIST prEN 16091:2021 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
oSIST prEN 16091:2021
---------------------- Page: 2 ----------------------
oSIST prEN 16091:2021
DRAFT
EUROPEAN STANDARD
prEN 16091
NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2021
ICS 75.160.20 Will supersede EN 16091:2011
English Version
Liquid petroleum products - Middle distillates and fatty
acid methyl ester (FAME) fuels and blends - Determination
of oxidation stability by rapid small scale oxidation
method

Produits pétroliers liquides - Distillats moyens, esters Flüssige Mineralölerzeugnisse - Mitteldestillat- und

méthyliques d'acides gras (EMAG) et leurs mélanges - Fettsäuremethylesterkraftstoffe und Mischungen -

Détermination de la stabilité à l'oxydation par méthode Bestimmung der Oxidationsstabilität mit

d'oxydation accélérée à petite échelle beschleunigtem Verfahren und kleiner Probenmenge

This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee

CEN/TC 19.

If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN 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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,

Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and

United Kingdom.

Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are

aware and to provide supporting documentation.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without

notice and shall not be referred to as a European Standard.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 16091:2021 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
oSIST prEN 16091:2021
prEN 16091:2021 (E)
Contents Page

European foreword ............................................................................................................................................ 3

1 Scope .......................................................................................................................................................... 4

2 Normative references .......................................................................................................................... 4

3 Terms and definitions ......................................................................................................................... 4

4 Principle ................................................................................................................................................... 5

5 Reagents and materials ...................................................................................................................... 5

6 Apparatus ................................................................................................................................................ 5

7 Sampling and sample handling ........................................................................................................ 5

8 Performance check of the apparatus ............................................................................................. 6

9 Preparation of the apparatus ........................................................................................................... 6

10 Procedure ................................................................................................................................................ 6

11 Expression of results ........................................................................................................................... 7

12 Precision .................................................................................................................................................. 7

12.1 General...................................................................................................................................................... 7

12.2 Repeatability, r ...................................................................................................................................... 7

12.3 Reproducibility, R ................................................................................................................................. 8

13 Test report ............................................................................................................................................... 8

Annex A (normative) Apparatus description ........................................................................................... 9

Annex B (normative) Calibration process ............................................................................................... 11

Annex C (informative) Determination of induction period .............................................................. 12

Annex D (informative) Test method and precision data at 120 °C ................................................. 13

Bibliography ....................................................................................................................................................... 15

---------------------- Page: 4 ----------------------
oSIST prEN 16091:2021
prEN 16091:2021 (E)
European foreword

This document (prEN 16091:2021) 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 document is currently submitted to the CEN Enquiry.
This document will supersede EN 16091:2011.

In comparison with the previous edition, the following technical modifications have been made:

a) A new Annex D was included to include work that has been executed on a modified rapid small scale

oxidation method at 120 °C;
b) The document was revised editorially.
---------------------- Page: 5 ----------------------
oSIST prEN 16091:2021
prEN 16091:2021 (E)
1 Scope

This document specifies a method for the determination of the oxidation stability of middle distillate

fuels, fatty acid methyl ester (FAME) fuel and blends thereof, under accelerated conditions, by measuring

the induction period to the specified breakpoint in a reaction vessel charged with the sample and oxygen.

NOTE 1 For the purposes of this document, the term “% (V/V)” is used to represent the volume fraction (φ).

NOTE 2 The induction period is used as an indication for the resistance of middle distillates, fatty acid methyl

ester (FAME) fuels and blends thereof against oxidation. This correlation can vary markedly under different

conditions with different FAMEs and diesel fuel blends.

NOTE 3 The presence of ignition improvers can lead to lower oxidation stability results determined by this

method. It has for instance been observed that the addition of 2-ethyl hexyl nitrate (2-EHN) can reduce the

measured oxidation stability values. See [6] for details.

NOTE 4 For further information on the precision data at a test temperature of 120 °C see Annex D.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. 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)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at https://www.electropedia.org/
3.1
breakpoint

point in the pressure-time curve, where the pressure in the vessel has dropped 10 % below the maximum

pressure achieved in the current test run
3.2
induction period

time elapsed between starting the heating procedure of the reaction vessel, charged with sample and

oxygen, and the breakpoint at 140 °C
---------------------- Page: 6 ----------------------
oSIST prEN 16091:2021
prEN 16091:2021 (E)
4 Principle

At ambient temperature, a known volume of a sample is placed in a reaction vessel charged with oxygen

to a pressure of 700 kPa ± 5 kPa. The reaction vessel is heated to 140 °C. The pressure in the vessel drops

as the oxygen is consumed during the oxidation of the sample. The pressure in the vessel is recorded at

intervals of 1 s until the breakpoint is reached. The elapsed time from start to the breakpoint is the

induction period at the test temperature of 140 °C ± 0,5 °C.

NOTE Work has been executed on the determination of oxidation stability by a modified rapid small scale

oxidation method at 120°C. The results thereof are given in Annex D.
5 Reagents and materials

5.1 Cleaning solvent, for the removal of oxidation residues from the test vessel, of suitable purity to

leave no residue on the apparatus.

NOTE Commercially available ethanol of approximately 95 % (V/V) purity was found to be suitable.

5.2 Oxygen, extra dry (<5 mg/kg water), commercially available, with a purity of not less than 99,6 %.

5.3 Cleaning tissues, lint-free for cleaning sensitive galvanic coated surfaces without scratching.

5.4 Verification fluid, hydrocarbon fuel, any hydrocarbon fuel with sufficient stability and a known

induction period may be used.

NOTE In general, verification fluid with a certified induction period is available from the manufacturer of the

apparatus.
6 Apparatus

6.1 Automatically controlled oxidation tester, comprising an oxidation reaction vessel containing:

— test sample cup capable of being rapidly heated;

— pressure sensor capable of measuring pressures of 1 kPa up to 2 000 kPa with a resolution of 1 kPa;

— temperature sensor with a resolution of 0,1 °C;
— pressure and temperature recording of 1 s.

The oxidation reaction vessel shall be fitted with filling and relief valves, meant to release the pressure,

and a fan to cool the vessel from test to ambient temperature.
The requirements for the apparatus are described in detail in Annex A.
6.2 Pipette, capable of delivering 5,0 ml ± 0,1 ml.
6.3 O-ring seals, see A.6.
7 Sampling and sample handling

Unless otherwise specified, samples shall be taken as described in EN ISO 3170 or EN ISO 3171.

Collect and store samples in an opaque container to minimize exposure to light.
---------------------- Page: 7 ----------------------
oSIST prEN 16091:2021
prEN 16091:2021 (E)
8 Performance check of the apparatus

8.1 Verify the correct operation of the equipment by following the procedure in Clause 10 using the

verification fluid (5.4).

8.2 If the induction period of the verification fluid does not meet specified time, repeat 8.1. If it fails a

second time, refer to the manufacturer's instructions.

8.3 Pressure and temperature are critical parameters. Proper calibration of the respective sensors

(see 6.1) is therefore important. Recalibrate the tester at least every 12 months for correct temperature

and pressure readings.

8.4 In view of general good laboratory practice and harmonization of test methods, calibration as in

Annex B is strongly recommended. As the calibration procedure for a pressure sensor is complicated and

difficult to be executed by an untrained lab technician, one may (in most cases sufficiently) rely on the

verification fluid (5.4).
9 Preparation of the apparatus
9.1 Remove the previous test portion by means of a pipette or similar device.
9.2 Remove the used “O-ring” seal and discard.

To avoid contamination of the new test, it is necessary to discard the used “O-ring” seal, because it can be

soaked with oxidation products from the previous test.

9.3 Wipe the sample cup, the seal groove and the cover with lint-free cleaning tissue (5.3) soaked with

cleaning solvent (5.1) until free of gum or other oxidation residues.

9.4 Allow the test sample cup and cover to dry in air and visually inspect for cleanliness.

NOTE Compressed air is generally unsuitable to accelerate the evaporation of solvent because it can contain

traces of oil that can influence the next test.
9.5 Insert a new "O-ring" seal (6.3).
10 Proce
...

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