SIST-TP CEN/TR 15138:2005

SLOVENSKI STANDARD
SIST-TP CEN/TR 15138:2005
01-november-2005
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Petroleum products and other liquids - Guide to flash point testing
Mineralölerzeugnisse und andere Flüssigkeiten - Leitfaden zur Bestimmung des
Flammpunktes
Produits pétroliers et autres liquides - Guide pour la détermination du point d'éclair
Ta slovenski standard je istoveten z: CEN/TR 15138:2005
ICS:
75.080 Naftni proizvodi na splošno Petroleum products in
general
SIST-TP CEN/TR 15138:2005 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TP CEN/TR 15138:2005

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SIST-TP CEN/TR 15138:2005
TECHNICAL REPORT
CEN/TR 15138
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
August 2005
ICS 75.080

English Version
Petroleum products and other liquids - Guide to flash point
testing
Produits pétroliers et autres liquides - Guide pour Mineralölerzeugnisse und andere Flüssigkeiten - Leitfaden
détermination du point d'éclair zur Bestimmung des Flammpunktes
This Technical Report was approved by CEN on 14 May 2005. It has been drawn up by the Technical Committee CEN/TC 19.
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 STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 15138:2005: E
worldwide for CEN national Members.

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Contents Page
Foreword .3
Introduction.4
1 Scope .5
2 Outline .5
3 Brief history.5
4 Flash and fire point, and sustained combustion and burning.5
5 Why are flash point tests required.6
6 Which flash point method should be used .6
7 Testing environment.9
8 Safety .9
9 Calibration and verification.9
10 Test samples .10
11 Instrumentation.11

12 Flash point testing effects.12
13 Test results.13
Annex A (informative) Major test methods used in specifications and regulations.14
Acknowledgements .15
Bibliography.16

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Foreword
This Technical Report (CEN/TR 15138:2005) 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.

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Introduction
This Technical Report has been written under the guidance and with the assistance of the CEN/TC 19 /
TC 139 (ISO/TC 28 / TC 35) Joint Working Group for Flash Point Methods and the Energy Institute
Flammability Panel ST B 4 with the aim of assisting laboratory managers and technicians, regulators,
specification writers and industry in the use, specification and application of flash point tests for liquids and
semi-solids.
The work is based on standards produced by the following organizations:
 CEN/TC 19 "Petroleum products, lubricants and related products"
 CEN/TC 139 "Paints and varnishes"
 ISO/TC 28 "Petroleum products"
 ISO/TC 35 "Paints and varnishes"
 ASTM D01.22 "Health and Safety"
 ASTM D02.08 B "Flammability Section"
 DIN Deutsches Institut für Normung
 EI ST B 4 Flammability Panel

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1 Scope
This Technical Report is not intended to be a comprehensive manual on flash point tests and the
interpretation of test results, however it covers the key aspects on these subjects.
The flash point test can be summarised as a procedure where a test portion is introduced into a temperature
controlled test cup and an ignition source is applied to the vapours produced by the test portion to determine if
the vapour / air mixture is flammable or at what temperature the vapour / air mixture is flammable.
2 Outline
There are many, slightly different, definitions of flash point, however the following definition is widely used in
standard test methods:
The lowest temperature of the test portion, corrected to a barometric pressure of 101,3 kPa, at
which the application of an ignition source causes the vapour of the test portion to ignite
momentarily and the flame to propagate across the surface of the liquid under the specified
conditions of test.
It is important to realise that the value of the flash point is not a physical constant but it is the result of a flash
point test and is dependent on the apparatus and procedure used. This fact is so important that a general
statement similar to the following will be incorporated into all the main flash point methods:
Flash point values are not a constant physical-chemical property of materials tested. They are a
function of the apparatus design, the condition of the apparatus used, and the operational
procedure carried out. Flash point can therefore only be defined in terms of a standard test
method, and no general valid correlation can be guaranteed between results obtained by different
test methods or with test apparatus different from that specified.
Due to the importance of flash point test results for both safety and regulatory purposes, the test method
identification should always be included with the test result.
In general specific products specifications indicate which standard test method should be employed.
3 Brief history
th
The discovery of petroleum and the increased use of flammable distillates in the 19 century, for lighting and
heating in place of animal and vegetable oils, led to a large number of explosions and other fire related
accidents.
Legislation, such as the UK Petroleum Act in 1862 and the German Petroleum Regulations in 1882, quickly
spread around the world and led to the development of many types of test instruments. The following list
shows the dates when the major surviving instruments were in a form probably recognisable today:
1870 – 1880 Abel closed cup, Pensky-Martens closed cup
1910 – 1920 Tag closed cup, Cleveland open cup
4 Flash and fire point, and sustained combustion and burning
The flash point is essentially the lowest temperature of the liquid or semi-solid at which vapours from a test
portion combine with air to give a flammable mixture and ‘flash’ when an ignition source is applied. Fire point,
combustibility and sustained burning tests all use open cup instruments.
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Fire point can be considered as the lowest temperature of the test portion at which vapour combustion and
burning commences when an ignition source is applied and thereafter is continuous and where the heat
produced is self sustaining and supplies enough vapours to combine with air and burn even after the removal
of the ignition source.
Sustained combustion and burning tests are usually carried out with the test portion at a fixed temperature
and tests whether vapour combustion and burning commences when an ignition source is applied and
thereafter is continuous and where the heat produced is self sustaining and supplies enough vapours to
combine with air and burn even after the removal of the ignition source.
5 Why are flash point tests required
The fundamental reason for the requirement of flash point measurements is to assess the safety hazard of a
liquid or semi-solid with regard to its flammability and then classify the liquid into a group. The lower the flash
point temperature the greater the risk. This classification is then used to warn of a risk and to enable the
correct precautions to be taken when using, storing or transporting the liquid.
Specifications quote flash point values for quality control purposes as well as for controlling the flammability
risk.
A change in flash point may indicate the presence of potentially dangerous volatile contaminants or the
adulteration of one product by another.
6 Which flash point method should be used
6.1 First considerations
Firstly, if a flash point method has been specified in a product specification or regulation, then that method
should be the first choice. If a number of alternative methods are specified then the choice will be influenced
by availability and other factors such as sample size requirements, speed of testing or precision. In certain
circumstances the choice of the stated referee method may be of special importance. Annex A gives an
overview of the most common methods and their use in specifications and regulations.
When testing specifically for contamination or contaminants, certain test methods and procedures are more
appropriate than others. In general an equilibrium test method is recommended for testing samples that may
contain traces of volatile contaminants.
When selecting a flash point method for incorporation into a product specification or regulation, it is important
that the product type is included in the scope of the test method and that the temperature range of the product
is covered by the test method. If the product is not included in the scope then the test may be unsuitable for
the product or the quoted precision does not apply. Where the scope of a test method is general or not
suitable it is recommended to contact an appropriate standardization body for advice.
When testing chemicals, mineral products or corrosive materials it is recommended to check that the test cup
material is suitable and will not produce flammable gases or be damaged by any possible chemical reaction.
6.2 Open or closed cup
There are two general classes of flash point tests: open cup and closed cup:
The open cup was initially developed to assess the potential hazards of liquid spillage. In this test a test
portion is introduced into a cup that is open at the top. An ignition source is passed horizontally over the
surface of the liquid, while the cup and liquid are being heated, to test if the vapours ‘flash’. If the test is
repeated at increasing test portion temperatures a point may be reached when the test portion continues to
burn without further application of the ignition source, this is the fire point. The precision of open cup tests is
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somewhat poorer than closed cup tests as the vapours produced by heating the test portion are free to
escape to the atmosphere and are more affected by local conditions in the laboratory. When open cup tests
are made at temperatures above ambient the result is usually higher than a result from a closed cup test due
to the reduced concentration of vapours.
The closed cup test contains any vapours produced and essentially simulates the situation where a potential
source of ignition is accidentally introduced into a container. In this test a test portion is introduced into a cup
and a close fitting lid is fitted to the top of the cup. The cup and test portion is heated and apertures are then
opened in the lid to allow air into the cup and the ignition source to be dipped into the vapours to test for a
flash.
The closed cup test predominates in specifications and regulations due to its better precision and ability to
detect contaminants.
6.3 Non-equilibrium, equilibrium and rapid equilibrium tests
These three types of tests and associated instruments are characterised by the level of temperature
stabilisation of the test portion and resultant vapours, and by the test portion size and test time.
Test methods such as Pensky-Martens, Tag, Abel and Cleveland are referred to as non-equilibrium tests as
the test temperature of the test portion is increased during the test and the temperature of the vapours is not
the same (not in equilibrium) as the test portion temperature when the ignition source is dipped at regular
intervals into the cup. This type of test has the advantage that it produces a definitive flash point result. Under
normal circumstances the increasing temperature is not a problem, but when volatile contaminants or
components are present the short time between each dip of the ignition source, combined with the rate of
temperature increase, does not allow enough time for flammable vapours to evolve and this may cause
unreliable results. For this reason non-equilibrium tests with lower rates of heating usually perform better than
those using higher rates of heating, when volatile contaminants or components are present in the test portion.
Equilibrium tests are preferred for liquids and semi-solids containing volatile components or contaminants and
for confirmatory purposes in regulations as the sample temperature is constant or is increased at a very slow
rate. This allows enough time for vapours to build up and for the vapours to be in equilibrium with the test
portion before the ignition source is dipped into the cup. The ignition source is dipped in the cup at different
test portion temperatures thus resulting in a measurement of a flash point, or the ignition source is dipped only
once to carry out a flash no flash test to check conformance against specifications and flammability criteria.
These equilibrium tests use any type of closed cup in a liquid bath and limits the difference of temperature
between the test portion and the liquid bath. The liquid bath is specified because it gives a very even
temperature distribution on the outside of the test cup thus ensuring that hot spots are not present on the cup
surface that could cause the localised increase of flammable vapours and thus a low flash point. Unfortunately
these procedures take a long time to complete.
Rapid equilibrium (small scale) tests are not primarily aimed to give the actual flash point of a test portion. The
test is a flash no flash test to determine if the test portion’s vapours flash at the test temperature. This is useful
for checking conformance against specifications and flammability criteria. The test cup is heated to the test
temperature, a small test portion is introduced into the cup, and when the test portion is deemed to be at the
test temperature, the ignition source is used to test for a ‘flash’. Actual flash point temperature is determined
by repeating the flash no flash test at different temperatures with a new test portion. The constant temperature
of the test cup ensures that the test portion cannot be overheated and that there is a reasonable time for
vapours to build up before the ignition source is applied.
6.4 Flash point automation
For a manual flash point test the operator is in control throughout the test and ensures that the temperature,
stirring and ignition requirements are met throughout the test and determines when and if a flash has occurred.
Some semi-auto instruments may assist the operator in detecting a flash or controlling the temperature, but
the operator is in control. This is why manual tests are the referee in cases of dispute.
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Automated flash point testers conform to all the specified requirements of the manual test method such as
dimensions, heating rate and flash detection, however the electronics, software and mechanics mimic the
manual operations. This may significantly reduce operator time but this does have the disadvantage that more
frequent validation of tester operation is required as the instrument operates mainly unattended and is more
complex.
Automatic flash point testers are not based on a manual test and often only key dimensions and parameters
are defined in a test method written just for this instrument type. A unique type of test may be advantageous to
the user but the complexity of the tester makes it difficult for conformance to the test method to be measured.
More frequent validation of the tester parameters and operation is required.
Some automated and automatic instruments are available with carousels that allow a number of tests to be
carried out unattended. This is particularly advantageous where large numbers of samples are tested.
However, accurate and reliable measurements may be compromised if the sample temperature does not meet
the recommendations stated in the test method. This is especially relevant to samples that are volatile or
contain volatile contaminants.
In general automated instruments are accepted in test methods provided that the instrument shows
conformation to the method requirements, including precision.
6.5 Correlation between methods
It is well known that open cup tests usually give higher flash point results than closed cup tests for test
temperatures above ambient. Some specifications list equivalent flash point methods and sometimes relative
bias information for specific products. However flash point methods employ different apparatus, heating and
stirring rates, procedures and sample handling which have an effect on relative biases, especially when the
liquid is volatile, or volatile contaminants or components are present. It is therefore not possible and not
correct to claim correlation or a fixed relative bias between different test methods for all test samples.
6.6 Precision
The precision of a flash point method is defined by repeatability (r) and reproducibility (R) at a 95 %
confidence level such that only 1 test in 20 would be expected to exceed the quoted figure.
The definitions for precision shown below are typical of those used in Flash Point test methods and are based
on the definitions given in EN ISO 4259 [1]
Repeatability
r
Difference between two test results obtained by the same operator with the same apparatus under constant
operating conditions, on identical test material would, in the long run, in the normal and correct operation of
the test method, exceed the given value in only one case in 20
Reproducibility
R
Difference between two single and independent test results obtained by different operators in different
laboratories on identical test material would
...