ASTM D93-20

Standard Test Methods for Flash Point by Pensky-Martens Closed Cup Tester

SIGNIFICANCE AND USE
5.1 The flash point temperature is one measure of the tendency of the test specimen to form a flammable mixture with air under controlled laboratory conditions. It is only one of a number of properties which must be considered in assessing the overall flammability hazard of a material.  
5.2 Flash point is used in shipping and safety regulations to define flammable  and combustible  materials. One should consult the particular regulation involved for precise definitions of these classifications.  
5.3 These test methods should be used to measure and describe the properties of materials, products, or assemblies in response to heat and an ignition source under controlled laboratory conditions and should not be used to describe or appraise the fire hazard or fire risk of materials, products, or assemblies under actual fire conditions. However, results of these test methods may be used as elements of a fire risk assessment which takes into account all of the factors which are pertinent to an assessment of the fire hazard of a particular end use.  
5.4 These test methods provide the only closed cup flash point test procedures for temperatures up to 370 °C (698 °F).
SCOPE
1.1 These test methods cover the determination of the flash point of petroleum products in the temperature range from 40 °C to 370 °C by a manual Pensky-Martens closed-cup apparatus or an automated Pensky-Martens closed-cup apparatus, and the determination of the flash point of biodiesel in the temperature range of 60 °C to 190 °C by an automated Pensky-Martens closed cup apparatus.
Note 1: Flash point determinations above 250 °C can be performed, however, the precision has not been determined above this temperature. For residual fuels, precision has not been determined for flash points above 100 °C. The precision of in-use lubricating oils has not been determined. Some specifications state a D93 minimum flash point below 40 °C, however, the precision has not been determined below this temperature.  
1.2 Procedure A is applicable to distillate fuels (diesel, biodiesel blends, kerosine, heating oil, turbine fuels), new and in-use lubricating oils, and other homogeneous petroleum liquids not included in the scope of Procedure B or Procedure C.  
1.3 Procedure B is applicable to residual fuel oils, cutback residua, used lubricating oils, mixtures of petroleum liquids with solids, petroleum liquids that tend to form a surface film under test conditions, or are petroleum liquids of such kinematic viscosity that they are not uniformly heated under the stirring and heating conditions of Procedure A.  
1.4 Procedure C is applicable to biodiesel (B100). Since a flash point of residual alcohol in biodiesel is difficult to observe by manual flash point techniques, automated apparatus with electronic flash point detection have been found suitable.  
1.5 These test methods are applicable for the detection of contamination of relatively nonvolatile or nonflammable materials with volatile or flammable materials.  
1.6 The values stated in SI units are to be regarded as the standard.  
1.6.1 Exception—The values given in parentheses are for information only.
Note 2: It has been common practice in flash point standards for many decades to alternately use a C-scale or an F-scale thermometer for temperature measurement. Although the scales are close in increments, they are not equivalent. Because the F-scale thermometer used in this procedure is graduated in 5 °F increments, it is not possible to read it to the 2 °C equivalent increment of 3.6 °F. Therefore, for the purposes of application of the procedure of the test method for the separate temperature scale thermometers, different increments must be used. In this test method, the following protocol has been adopted: When a temperature is intended to be a converted equivalent, it will appear in parentheses following the SI unit, for example 370 °C (698 °F). When a temperature is inte...

General Information

• Status: Published
• Publication Date: 31-Jul-2020
• ICS: 13.220.40 - Ignitability and burning behaviour of materials and products
• ICS: 75.080 - Petroleum products in general
• ICS: 75.160.20 - Liquid fuels
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.08 - Volatility

Relations

• Replaces: ASTM D93-19 - Standard Test Methods for Flash Point by Pensky-Martens Closed Cup Tester
• Effective Date: 01-Aug-2020
• Refers: ASTM D3941-20 - Standard Test Method for Flash Point by the Equilibrium Method With a Closed-Cup Apparatus
• Effective Date: 01-Jun-2020
• Refers: ASTM D56-16 - Standard Test Method for Flash Point by Tag Closed Cup Tester
• Effective Date: 01-Jun-2016
• Refers: ASTM D3941-14 - Standard Test Method for Flash Point by the Equilibrium Method With a Closed-Cup Apparatus
• Effective Date: 15-Dec-2014
• Refers: ASTM E1-13 - Standard Specification for ASTM Liquid-in-Glass Thermometers
• Effective Date: 01-May-2013
• Refers: ASTM D4057-06(2011) - Standard Practice for Manual Sampling of Petroleum and Petroleum Products
• Effective Date: 01-Jun-2011
• Refers: ASTM E1-07 - Standard Specification for ASTM Liquid-in-Glass Thermometers
• Effective Date: 01-Nov-2007
• Refers: ASTM D3941-90(2007) - Standard Test Method for Flash Point by the Equilibrium Method With a Closed-Cup Apparatus
• Effective Date: 01-Jun-2007
• Refers: ASTM E502-07 - Standard Test Method for Selection and Use of ASTM Standards for the Determination of Flash Point of Chemicals by Closed Cup Methods
• Effective Date: 15-Jan-2007
• Refers: ASTM E502-07e1 - Standard Test Method for Selection and Use of ASTM Standards for the Determination of Flash Point of Chemicals by Closed Cup Methods
• Effective Date: 15-Jan-2007
• Refers: ASTM E502-06a - Standard Test Method for Selection and Use of ASTM Standards for the Determination of Flash Point of Chemicals by Closed Cup Methods
• Effective Date: 15-Aug-2006
• Refers: ASTM E502-06 - Standard Test Method for Selection and Use of ASTM Standards for the Determination of Flash Point of Chemicals by Closed Cup Methods
• Effective Date: 15-Jun-2006
• Refers: ASTM E1-05 - Standard Specification for ASTM Liquid-in-Glass Thermometers
• Effective Date: 01-Nov-2005
• Refers: ASTM D56-05 - Standard Test Method for Flash Point by Tag Closed Cup Tester
• Effective Date: 01-May-2005
• Refers: ASTM E1-03a - Standard Specification for ASTM Liquid-in-Glass Thermometers
• Effective Date: 01-Nov-2003

Overview

ASTM D93-20: Standard Test Methods for Flash Point by Pensky-Martens Closed Cup Tester defines procedures for determining the flash point of petroleum products, biodiesel, and other related liquids. The flash point is a critical property for evaluating how materials form flammable mixtures with air under controlled conditions. This standard provides a uniform, reproducible method using the Pensky-Martens closed cup apparatus, enhancing regulatory compliance, product development, and safety management for flammable and combustible liquids.

Key Topics

• Flash Point Determination

  • Establishes minimum temperatures at which samples produce enough vapor to ignite in air, using controlled laboratory procedures.
  • Covers petroleum products within 40 °C to 370 °C and biodiesel (B100) from 60 °C to 190 °C.

• Applicability to Materials

  • Procedure A targets distillate fuels (e.g., diesel, kerosine), heating oil, turbine fuels, lubricating oils, and homogeneous petroleum liquids.
  • Procedure B is for residual fuel oils, used lubricating oils, mixtures with solids, or high-viscosity petroleum liquids.
  • Procedure C focuses on biodiesel (B100), using automated apparatus for improved detection of residual alcohol flash points.

• Test Apparatus

  • Specifies use of manual and automated Pensky-Martens closed cup testers, detailing requirements for temperature measurement, heating rate, and ignition source.

• Regulatory Significance

  • Flash point values are essential for material classification in shipping, storage, and handling, affecting compliance with safety and transport regulations.

• Limitations

  • The standard provides guidance under laboratory conditions only. It does not replicate actual fire scenarios but supports risk assessments by providing reliable data as one factor among many.

Applications

• Regulatory Compliance:

  • Supports compliance with transportation, storage, and workplace safety regulations for flammable and combustible liquids.
  • Essential for meeting local, national, and international safety standards regarding hazardous materials.

• Quality Control and Safety:

  • Used by manufacturers and quality assurance labs to certify the flash point of fuels and lubricants, ensuring that products meet specification requirements.
  • Assists in monitoring for contamination by more volatile or flammable substances.

• Product Development:

  • Aids in the development and certification of new petroleum and biodiesel blends, ensuring prescribed flash point thresholds are met.

• Hazard Assessment:

  • Provides reliable test data for elements of fire risk assessment, supporting industrial hygiene, storage planning, and accident prevention strategies.

• Sampling and Testing Procedures:

  • Describes rigorous methods for sample collection, preparation, and handling to prevent contamination and ensure accuracy.
  • Outlines procedures for verifying and calibrating test equipment.

Related Standards

• ASTM D56: Test Method for Flash Point by Tag Closed Cup Tester - suited for liquids with lower flash points.
• ASTM D3941: Flash Point by the Equilibrium Method With a Closed-Cup Apparatus - applicable to paints, resins, and similar materials.
• ASTM D4057 / D4177: Practices for Manual and Automatic Sampling of Petroleum and Petroleum Products.
• ASTM E1: Specification for ASTM Liquid-in-Glass Thermometers - details for temperature measurement devices used in testing.
• ISO Guide 34 / Guide 35: Competence of reference material producers and principles for certification, supporting standards referenced in quality control.

ASTM D93-20 remains a cornerstone standard for laboratories and industries handling petroleum products and biodiesel, providing essential data for safe, regulatory-compliant operations.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D93 − 20
Designation: 34/99
Standard Test Methods for
Flash Point by Pensky-Martens Closed Cup Tester
ThisstandardisissuedunderthefixeddesignationD93;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
INTRODUCTION
This flash point test method is a dynamic test method which depends on specified rates of heating
to be able to meet the precision of the test method. The rate of heating may not in all cases give the
precision quoted in the test method because of the low thermal conductivity of some materials. There
are flash point test methods with slower heating rates available, such as Test Method D3941 (for
paints, resins, and related products, and high viscosity products in the range of 0 °C to 110 °C), where
the test conditions are closer to equilibrium.
Flash point values 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.
1. Scope* 1.3 Procedure B is applicable to residual fuel oils, cutback
residua, used lubricating oils, mixtures of petroleum liquids
1.1 These test methods cover the determination of the flash
with solids, petroleum liquids that tend to form a surface film
point of petroleum products in the temperature range from
under test conditions, or are petroleum liquids of such kine-
40 °C to 370 °C by a manual Pensky-Martens closed-cup
matic viscosity that they are not uniformly heated under the
apparatus or an automated Pensky-Martens closed-cup
stirring and heating conditions of Procedure A.
apparatus, and the determination of the flash point of biodiesel
in the temperature range of 60 °C to 190 °C by an automated
1.4 Procedure C is applicable to biodiesel (B100). Since a
Pensky-Martens closed cup apparatus. flashpointofresidualalcoholinbiodieselisdifficulttoobserve
by manual flash point techniques, automated apparatus with
NOTE 1—Flash point determinations above 250 °C can be performed,
electronic flash point detection have been found suitable.
however, the precision has not been determined above this temperature.
For residual fuels, precision has not been determined for flash points
1.5 These test methods are applicable for the detection of
above 100 °C. The precision of in-use lubricating oils has not been
contamination of relatively nonvolatile or nonflammable ma-
determined. Some specifications state a D93 minimum flash point below
terials with volatile or flammable materials.
40 °C, however, the precision has not been determined below this
temperature.
1.6 The values stated in SI units are to be regarded as the
1.2 Procedure A is applicable to distillate fuels (diesel,
standard.
biodiesel blends, kerosine, heating oil, turbine fuels), new and
1.6.1 Exception—The values given in parentheses are for
in-use lubricating oils, and other homogeneous petroleum
information only.
liquids not included in the scope of Procedure B or Procedure
NOTE2—Ithasbeencommonpracticeinflashpointstandardsformany
C.
decades to alternately use a C-scale or an F-scale thermometer for
temperature measurement. Although the scales are close in increments,
they are not equivalent. Because the F-scale thermometer used in this
procedure is graduated in 5 °F increments, it is not possible to read it to
ThesetestmethodsareunderthejointjurisdictionofASTMCommitteeD02on
the 2 °C equivalent increment of 3.6 °F. Therefore, for the purposes of
Petroleum Products, Liquid Fuels, and Lubricants and are the direct responsibility
application of the procedure of the test method for the separate tempera-
of Subcommittee D02.08 on Volatility. In the IP, these test methods are under the
ture scale thermometers, different increments must be used. In this test
jurisdiction of the Standardization Committee.
method, the following protocol has been adopted: When a temperature is
Current edition approved Aug. 1, 2020. Published August 2020. Originally
approved in 1921. Last previous edition approved in 2019 as D93 – 19. DOI: intended to be a converted equivalent, it will appear in parentheses
10.1520/D0093-20. following the SI unit, for example 370 °C (698 °F). When a temperature
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D93−20
is intended to be a rationalized unit for the alternate scale, it will appear
3.1.4 equilibrium, n—in flash point test methods, the condi-
after “or,” for example, 2 °C or 5 °F.
tion where the vapor above the test specimen, and the test
1.7 This standard does not purport to address all of the
specimen are at the same temperature at the time the ignition
safety concerns, if any, associated with its use. It is the
source is applied.
responsibility of the user of this standard to establish appro-
3.1.4.1 Discussion—This condition may not be fully
priate safety, health, and environmental practices and deter-
achieved in practice, since the temperature may not be uniform
mine the applicability of regulatory limitations prior to use.
throughout the test specimen, and the test cover and shutter on
For specific warning statements, see 6.4, 7.1, 9.3, 9.4, 11.1.2,
the apparatus can be cooler or warmer.
11.1.4, 11.1.8, 11.2.2, and 12.1.2.
3.1.5 flash point, n—in flash point test methods, the lowest
1.8 This international standard was developed in accor-
temperature of the test specimen, adjusted to account for
dance with internationally recognized principles on standard-
variations in atmospheric pressure from 101.3 kPa, at which
ization established in the Decision on Principles for the
application of an ignition source causes the vapors of the test
Development of International Standards, Guides and Recom-
sample to ignite under specified conditions of test.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
4. Summary of Test Method
2. Referenced Documents
4.1 A brass test cup of specified dimensions, filled to the
2.1 ASTM Standards:
inside mark with test specimen and fitted with a cover of
D56 Test Method for Flash Point by Tag Closed Cup Tester
specified dimensions, is heated and the specimen stirred at
D3941 Test Method for Flash Point by the Equilibrium
specified rates, using one of three defined procedures (A, B, or
Method With a Closed-Cup Apparatus
C). An ignition source is directed into the test cup at regular
D4057 Practice for Manual Sampling of Petroleum and
intervals with simultaneous interruption of the stirring, until a
Petroleum Products
flash is detected (see 11.1.8). The flash point is reported as
D4177 Practice for Automatic Sampling of Petroleum and
defined in 3.1.5.
Petroleum Products
E1 Specification for ASTM Liquid-in-Glass Thermometers
5. Significance and Use
E300 Practice for Sampling Industrial Chemicals
5.1 The flash point temperature is one measure of the
E502 Test Method for Selection and Use of ASTM Stan-
tendency of the test specimen to form a flammable mixture
dards for the Determination of Flash Point of Chemicals
with air under controlled laboratory conditions. It is only one
by Closed Cup Methods
of a number of properties which must be considered in
2.2 ISO Standards
assessing the overall flammability hazard of a material.
Guide 34 General requirements for the competence of refer-
ence material producers
5.2 Flash point is used in shipping and safety regulations to
Guide 35 Reference material—General and statistical prin-
define flammable and combustible materials. One should con-
ciples for certification
sult the particular regulation involved for precise definitions of
these classifications.
3. Terminology
5.3 These test methods should be used to measure and
3.1 Definitions:
describe the properties of materials, products, or assemblies in
3.1.1 biodiesel, n—a fuel comprised of mono-alkyl esters of
response to heat and an ignition source under controlled
long chain fatty acids derived from vegetable oils or animal
laboratory conditions and should not be used to describe or
fats, designated B100.
appraise the fire hazard or fire risk of materials, products, or
3.1.2 biodiesel blends, n—a blend of biodiesel fuel with
assemblies under actual fire conditions. However, results of
petroleum-based diesel fuel.
these test methods may be used as elements of a fire risk
3.1.3 dynamic, adj—in petroleum products—in petroleum
assessment which takes into account all of the factors which
product flash point test methods—the condition where the
are pertinent to an assessment of the fire hazard of a particular
vapor above the test specimen and the test specimen are not in
end use.
temperature equilibrium at the time that the ignition source is
5.4 These test methods provide the only closed cup flash
applied.
point test procedures for temperatures up to 370 °C (698 °F).
3.1.3.1 Discussion—This is primarily caused by the heating
of the test specimen at the constant prescribed rate with the
6. Apparatus
vapor temperature lagging behind the test specimen tempera-
ture.
6.1 Pensky-Martens Closed Cup Apparatus (manual)
—This apparatus consists of the test cup, test cover and shutter,
stirring device, heating source, ignition source device, air bath,
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
and top plate described in detail in Annex A1. The assembled
Standards volume information, refer to the standard’s Document Summary page on
manual apparatus, test cup, test cup cover, and test cup
the ASTM website.
assembly are illustrated in Figs. A1.1-A1.4, respectively. Di-
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
4th Floor, New York, NY 10036, http://www.ansi.org. mensions are listed respectively.
D93−20
6.2 Pensky-Martens Closed Cup Apparatus (Automated) — 8.2 Ensure at least 75 mL of sample is available so there is
This apparatus is an automated flash point instrument that is sufficient material for the test. When obtaining a sample of
capable of performing the test in accordance with Section 11 residual fuel oil, the sample container shall be from 85 % to
(Procedure A), Section 12 (Procedure B), and Section 13 95 % full. For other types of samples, the size of the container
(Procedure C) of these test methods. The apparatus shall use
shall be chosen such that the container is not more than 85 %
the test cup, test cover and shutter, stirring device, heating full or less than 50 % full prior to any sample aliquot being
source, and ignition source device described in detail in Annex
taken. For biodiesel (B100) samples, a typical one liter
A1. container filled to 85 % volume is recommended.
6.3 Temperature Measuring Device—Thermometer having
8.3 Successive test specimens can be taken from the same
a range as shown in Table 1 and conforming to the require-
sample container. Repeat tests have been shown to be within
ments prescribed in Specification E1 or in Annex A3,oran
the precisions of the method when the second specimen is
electronic temperature measuring device, such as resistance
takenwiththesamplecontaineratleast50 %filled.Theresults
thermometers or thermocouples. The device shall exhibit the
of flash point determinations can be affected if the sample
same temperature response as the mercury thermometers.
volume is less than 50 % of sample container capacity.
6.4 Ignition Source—Natural gas flame, bottled gas flame,
8.4 Erroneously high flash points may be obtained if pre-
and electric ignitors (hot wire) have been found acceptable for
cautions are not taken to avoid the loss of volatile material. Do
use as the ignition source. The gas flame device described in
not open containers unnecessarily, to prevent loss of volatile
detailed in Fig. A1.4 requires the use of the pilot flame
material or possible introduction of moisture, or both. Avoid
described in A1.1.2.3. The electric ignitors shall be of the
storage of samples at temperatures in excess of 35 °C or 95 °F.
hot-wire type and shall position the heated section of the
Samplesforstorageshallbecappedtightlywithinnerseals.Do
ignitor in the aperture of the test cover in the same manner as
notmakeatransferunlessthesampletemperatureisatleastthe
the gas flame device. (Warning—Gas pressure supplied to the
equivalent of 18 °C or 32 °F below the expected flash point.
apparatus should not be allowed to exceed 3 kPa (12 in.) of
water pressure.)
8.5 Do not store samples in gas-permeable containers, since
volatile material may diffuse through the walls of the enclo-
6.5 Barometer—With accuracy of 60.5 kPa.
sure. Samples in leaky containers are suspect and not a source
NOTE3—Thebarometricpressureusedinthiscalculationistheambient
pressure for the laboratory at the time of the test. Many aneroid of valid results.
barometers, such as those used at weather stations and airports, are
8.6 Samples of very viscous materials shall be heated in
precorrected to give sea level readings and would not give the correct
reading for this test.
theircontainers,withlid/capslightlyloosenedtoavoidbuildup
of dangerous pressure, at the lowest temperature adequate to
7. Reagents and Materials
liquefy any solids, not exceeding 28 °C or 50 °F below the
expected flash point, for 30 min. If the sample is then not
7.1 Cleaning Solvents—Use suitable solvent capable of
completely liquefied, extend the heating period for additional
cleaning out the specimen from the test cup and drying the test
30 min periods as necessary. Then gently agitate the sample to
cup and cover. Some commonly used solvents are toluene and
provide mixing, such as orbiting the container horizontally,
acetone. (Warning—Toluene, acetone, and many solvents are
before transferring to the specimen cup. No sample shall be
flammable and a health hazard. Dispose of solvents and waste
heated and transferred unless its temperature is more than
material in accordance with local regulations.)
18 °Cor32 °Fbelowitsexpectedflashpoint.Whenthesample
has been heated above this temperature, allow the sample to
8. Sampling
cool until its temperature is at least 18 °C or 32 °F below the
8.1 Obtainasampleinaccordancewithinstructionsgivenin
expected flash point before transferring.
Practices D4057, D4177,or E300.
NOTE 4—Volatile vapors can escape during heating when the sample
container is not properly sealed.
NOTE 5—Some viscous samples may not completely liquefy even after
prolonged periods of heating. Care should be exercised when increasing
Supporting data regarding a variant of the cover locking mechanism have been the heating temperature to avoid unnecessary loss of volatile vapors, or
filed at ASTM International Headquarters and may be obtained by requesting heating the sample too close to the flash point.
Research Report RR:D02-1706. Contact ASTM Customer Service at
[e-mail].
TABLE 1 Temperature Measuring Device
Temperature Range Thermometer Number Temperature Range Thermometer Number
ASTM IP
−5 °C to 110 °C 9C (9F) −5 °C to 110 °C 15C
(20 °F to 230 °F)
+10 °C to 200 °C 88C (88F) +20 °C to 150 °C 101C
(50 °F to 392 °F)
+90 °C to 370 °C 10C (10F) +90 °C to 370 °C 16C
(200 °F to 700 °F)
D93−20
8.7 Samples containing dissolved or free water may be (SWSs) can be determined along with their control limits.
dehydrated with calcium chloride or by filtering through a These secondary materials can then be utilized for more
qualitative filter paper or a loose plug of dry absorbent cotton. frequent performance checks (see Annex A4).
Warming the sample is permitted, but it shall not be heated for
10.5 When the flash point obtained is not within the limits
prolonged periods or greater than a temperature of 18 °C or
stated in 10.3 or 10.4, check the condition and operation of the
32 °F below its expected flash point.
apparatus to ensure conformity with the details listed in Annex
A1,especiallywithregardtotightnessofthelid(A1.1.2.2),the
NOTE6—Ifthesampleissuspectedofcontainingvolatilecontaminants,
the treatment described in 8.6 and 8.7 should be omitted.
action of the shutter, the position of the ignition source
(A1.1.2.3), and the angle and position of the temperature
9. Preparation of Apparatus
measuring device (A1.1.2.4). After any adjustment, repeat the
test in 10.3 using a fresh test specimen, with special attention
9.1 Support the manual or automated apparatus on a level
to the procedural details prescribed in these test methods.
steady surface, such as a table.
10.6 The numerical values obtained during the verification
9.2 Tests are to be performed in a draft-free room or
check (10.3) shall not be used to provide a bias statement, nor
compartment.
shall they be used to make any correction to the flash points
NOTE 7—A shield, of the approximate dimensions 460 mm (18 in.)
subsequently determined using the apparatus.
squareand610 mm(24 in.)high,orothersuitabledimensions,andhaving
anopenfrontisrecommendedtopreventdraftsfromdisturbingthevapors
above the test cup.
PROCEDURE A
NOTE 8—With some samples whose vapors or products of pyrolysis are
objectionable, it is permissible to place the apparatus along with a draft
11. Procedure
shield in a ventilation hood, the draft of which is adjustable so that vapors
can be withdrawn without causing air currents over the test cup during the
11.1 Manual Apparatus:
ignition source application period.
11.1.1 Ensure that the sample container is filled to the
9.3 Prepare the manual apparatus or the automated appara-
volume capacity requirement specified in 8.2. Fill the test cup
tus for operation in accordance with the manufacturer’s in-
with the test specimen to the filling mark inside of the test cup.
structions for calibrating, checking, and operating the equip-
The temperature of the test cup and test specimen shall be at
ment. (Warning—Gas pressure should not be allowed to
least18 °Cor32 °Fbelowtheexpectedflashpoint.Iftoomuch
exceed 3 kPa (12 in.) of water pressure.)
testspecimenhasbeenaddedtothetestcup,removetheexcess
using a syringe or similar device for withdrawal of fluid. Place
9.4 Thoroughly clean and dry all parts of the test cup and its
the test cover on the test cup and place the assembly into the
accessories before starting the test, to ensure the removal of
apparatus. Be sure the locating or locking device is properly
any solvent which had been used to clean the apparatus. Use
engaged. If the temperature measuring device is not already in
suitable solvent capable of removing all of the specimen from
place, insert the device into its holder.
thetestcupanddryingthetestcupandcover.Somecommonly
11.1.2 Light the test flame, and adjust it to a diameter of
used solvents are toluene and acetone. (Warning—Toluene,
3.2 mm to 4.8 mm (0.126 in. to 0.189 in.), or switch on the
acetone, and many solvents are flammable. Health hazard.
electric igniter and adjust the intensity in accordance with the
Dispose of solvents and waste material in accordance with
manufacturer’s instructions. (Warning—Gas pressure should
local regulations.)
not be allowed to exceed 3 kPa (12 in.) of water pressure.)
(Warning—Exercise care when using a gas test flame. If it
10. Verification of Apparatus
should be extinguished it will not ignite the vapors in the test
10.1 Adjust the automated flash point detection system
cup, and the gas for the test flame that then enters the vapor
(when used) in accordance with the manufacturer’s instruc-
space can influence the result.) (Warning—The operator
tions.
should exercise and take appropriate safety precautions during
10.2 Verify that the temperature measuring device is in
the initial application of the ignition source, since test speci-
accordance with 6.3.
mens containing low-flash material can give an abnormally
strong flash when the ignition source is first applied.)
10.3 Verify the performance of the manual apparatus or the
(Warning—The operator should exercise and take appropriate
automated apparatus at least once per year by determining the
safety precautions during the performance of these test meth-
flash point of a certified reference material (CRM) such as
ods.The temperatures attained during these test methods, up to
those listed in Annex A4, which is reasonably close to the
370 °C (698 °F), are considered hazardous.) (Warning—As a
expected temperature range of the samples to be tested. The
safety practice, when using automated or manual apparatus, it
material shall be tested according to Procedure A of these test
is strongly advised, before heating the test cup and specimen,
methods and the observed flash point obtained in 11.1.8 or
to dip the ignitor to check for the presence of unexpected
11.2.2 shall be corrected for barometric pressure (see Section
volatile material.)
14).The flash point obtained shall be within the limits stated in
11.1.3 Apply the heat at such a rate that the temperature, as
Table A4.1 for the identified CRM or within the limits
indicated by the temperature measuring device, increases 5 °C
calculated for an unlisted CRM (see Annex A4).
to 6 °C (9 °F to 11 °F)⁄min.
10.4 Once the performance of the apparatus has been
verified, the flash point of secondary working standards NOTE 9—In practice the rate is not achieved immediately after
D93−20
application of the heat due to the thermal inertia in the apparatus.
containinghalogenatedhydrocarbons,suchas,methylenechlo-
ride or trichloroethylene, no distinct flash, as defined, is
11.1.4 Turn the stirring device at 90 r⁄min to 120 r⁄min,
observed. Instead a significant enlargement of the test flame
stirring in a downward direction. (Warning—Meticulous at-
(not halo effect) and change in color of the test flame from blue
tention to all details relating to the ignition source, size of test
to yellowish-orange occurs. Continued heating and testing of
flame or intensity of the electric ignitor, rate of temperature
these samples above ambient temperature can result in signifi-
increase, and rate of dipping the ignition source into the vapor
cant burning of vapors outside the test cup, and can be a
of the test specimen is desirable for good results.)
potential fire hazard. See Appendix X1 and Appendix X2 for
11.1.5 Application of Ignition Source:
more information.)
11.1.5.1 Ifthetestspecimenisexpectedtohaveaflashpoint
11.1.9 When the ignition source is a test flame, the appli-
of 110 °C or 230 °F or below, apply the ignition source when
cation of the test flame can cause a blue halo or an enlarged
the temperature of the test specimen is 23 °C 65°Cor41°F
flamepriortotheactualflashpoint.Thisisnotaflashandshall
6 9 °F below the expected flash point and each time thereafter
be ignored.
at a temperature reading that is a multiple of 1 °C or 2 °F.
11.1.10 When a flash point is detected on the first
Discontinue the stirring of the test specimen and apply the
application, the test shall be discontinued, the result discarded,
ignition source by operating the mechanism on the test cover
and the test repeated with a fresh test specimen. The first
whichcontrolstheshuttersothattheignitionsourceislowered
application of the ignition source with the fresh test specimen
into the vapor space of the test cup in 0.5 s, left in its lowered
shall be 23 °C 65°Cor41°F 6 9 °F below the temperature
position for 1 s, and quickly raised to its upward position.
at which a flash point was detected on the first application.
11.1.5.2 Ifthetestspecimenisexpectedtohaveaflashpoint
11.1.11 When a flash point is detected at a temperature
above 110 °C or 230 °F, apply the ignition source in the
which is greater than 28 °C or 50 °F above the temperature of
manner described in 11.1.5.1 at each temperature increase of
thefirstapplicationoftheignitionsource,orwhenaflashpoint
2 °C or 5 °F, beginning at a temperature of 23 °C 6 5°C or
is detected at a temperature which is less than 18 °C or 32 °F
41 °F 6 9 °F below the expected flash point. (Warning—As a
above the temperature of the first application of the ignition
safety practice, when using automated or manual apparatus, it
source, the result shall be considered approximate, and the test
is strongly advised that, for an expected flash point above
repeated with a fresh test specimen. Adjust the expected flash
130 °C, to dip the ignitor every 10 °C throughout the test until
point for this next test to the temperature of the approximate
the sample temperature reaches 28 °C below the expected flash
result.The first application of the ignition source with the fresh
point and then follow the prescribed dipping procedure. This
test specimen shall be 23 °C 65°Cor41°F 6 9 °F below the
practice has been shown to reduce the possibility of a fire, and,
temperature at which the approximate result was found.
on average, not to significantly affect the result. A limited
11.1.12 When the apparatus has cooled down to a safe
study has shown that this dipping practice has no observable
handlingtemperature,lessthan55 °C(130 °F),removethetest
effect on test method repeatability.)
coverandthetestcupandcleantheapparatusasrecommended
11.1.6 When testing materials to determine if volatile ma-
by the manufacturer.
terial contamination is present, it is not necessary to adhere to
the temperature limits for initial ignition source application as
NOTE 11—Exercise care when cleaning and positioning the lid assem-
stated in 11.1.5.
blysonottodamageordislocatetheflashdetectionsystemortemperature
measuring device. See the manufacturer’s instructions for proper care and
11.1.7 When testing materials where the expected flash
maintenance.
point temperature is not known, bring the material to be tested
and the tester to a temperature of 15 °C 65°Cor60°F 6 11.2 Automated Apparatus:
10 °F. When the material is known to be very viscous at this 11.2.1 The automated apparatus shall be capable of per-
temperature, heat the specimen to a starting temperature as forming the procedure as described in 11.1, including control
described in 8.6. Apply the ignition source, in the manner of the heating rate, stirring of the test specimen, application of
described in 11.1.5.1, beginning at least 5 °C or 10 °F higher the ignition source, detection of the flash point, and recording
than the starting temperature. the flash point.
11.2.2 Start the automated apparatus in accordance with the
NOTE 10—Flash Point results determined in an “unknown expected
manufacturer’s instructions. (Warning—Failure to install the
flash point mode” should be considered approximate. This value can be
sample temperature measuring device correctly, when using
used as the expected flash point when a fresh specimen is tested in the
standard mode of operation.
automated apparatus, can result in uncontrolled heating of the
test portion and potentially a fire. Some automated apparatus
11.1.8 Record as the observed flash point the reading on the
include provisions to avoid this occurrence.) The apparatus
temperature measuring device at the time ignition source
shall follow the procedural details described in 11.1.3 through
application causes a distinct flash in the interior of the test cup.
11.1.8.
The sample is deemed to have flashed when a large flame
appears and instantaneously propagates itself over the entire
PROCEDURE B
surface of the test specimen. (Warning—For certain mixtures
12. Procedure
12.1 Manual Apparatus:
Supporting data have been filed at ASTM International Headquarters and may
12.1.1 Ensure that the sample container is filled to the
beobtainedbyrequestingResearchReportRR:D02-1652.ContactASTMCustomer
Service at [e-mail]. volume capacity requirement specified in 8.2. Fill the test cup
D93−20
with the test specimen to the filling mark inside of the test cup. using a syringe or similar device for withdrawal of fluid. Place
The temperature of the test cup and test specimen shall be at the test cover on the test cup and place the assembly into the
least18 °Cor32 °Fbelowtheexpectedflashpoint.Iftoomuch apparatus. Be sure the locating or locking device is properly
testspecimenhasbeenaddedtothetestcup,removetheexcess engaged. If the temperature measuring device is not already in
using a syringe or similar device for withdrawal of fluid. Place
place, insert the device into its holder.
the test cover on the test cup and place the assembly into the
13.3 Light the test flame, and adjust it to a diameter of
apparatus. Be sure the locating or locking device is properly
3.2 mm to 4.8 mm (0.126 in. to 0.189 in.) or switch on the
engaged. If the temperature measuring device is not already in
electric igniter and adjust the intensity in accordance with the
place, insert the device into its holder.
manufacturer’s instructions. (Warning—Gas pressure should
12.1.2 Light the test flame and adjust it to a diameter of
not be allowed to exceed 3 kPa (12 in. of water pressure.)
3.2 mm to 4.8 mm (0.126 in. to 0.189 in.), or switch on the
(Warning—Exercise care when using a gas test flame. If it
electric igniter and adjust the intensity in accordance with the
should be extinguished it will not ignite the vapors in the test
manufacturer’s instructions. (Warning—Gas pressure should
cup, and the gas for the test flame that then enters the vapor
not be allowed to exceed 3 kPa (12 in.) of water pressure.)
space can influence the result.) (Warning—The operator
(Warning—Exercise care when using a gas test flame. If it
should exercise and take appropriate safety precautions during
should be extinguished it will not ignite the vapors in the test
the initial application of the ignition source, since test speci-
cup and the gas for the test flame that then enters the vapor
mens containing low-flash material can give an abnormally
space can influence the result.) (Warning—The operator
strong flash when the ignition source is first applied.)
should exercise and take appropriate safety precautions during
(Warning—The operator should exercise and take appropriate
the initial application of the ignition source, since test speci-
safety precautions during the performance of these test meth-
mens containing low-flash material may give an abnormally
ods.The temperatures attained during these test methods, up to
strong flash when the ignition source is first applied.)
370 °C (698 °F), are considered hazardous.)
(Warning—The operator should exercise and take appropriate
safety precautions during the performance of these test meth-
13.4 Apply the heat at such a rate that the temperature as
ods.The temperatures attained during these test methods, up to
indicated by the temperature measuring device increases
370 °C (698 °F), are considered hazardous.)
3.0 °C⁄min 6 0.5 °C⁄min.
12.1.3 Turn the stirring device at 250 r⁄min 6 10 r⁄min,
NOTE 13—In practice the rate is not achieved immediately after
stirring in a downward direction.
application of the heat due to the thermal inertia in the apparatus.
12.1.4 Apply the heat at such a rate that the temperature as
indicated by the temperature measuring device increases 1 °C
13.5 Turn the stirring device at 90 r⁄min to 120 r⁄min,
to 1.6 °C (2 °F to 3 °F)⁄min.
stirring in a downward direction. (Warning—Meticulous at-
tention to all details relating to the ignition source, size of test
NOTE 12—In practice the rate is not achieved immediately after
flame, rate of temperature increase, and rate of dipping the
application of the heat due to the thermal inertia in the apparatus.
ignition source into the vapor of the test specimen is desirable
12.1.5 Proceed as prescribed in Section 11, with the excep-
for good results.)
tion of the preceding requirements for rates of stirring and
heating.
13.6 Application of Ignition Source—The first test on the
sample shall use an expected flash point of 100 °C.
12.2 Automat
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D93 − 19 D93 − 20
Designation: 34/99
Standard Test Methods for
Flash Point by Pensky-Martens Closed Cup Tester
This standard is issued under the fixed designation D93; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
INTRODUCTION
This flash point test method is a dynamic test method which depends on specified rates of heating
to be able to meet the precision of the test method. The rate of heating may not in all cases give the
precision quoted in the test method because of the low thermal conductivity of some materials. There
are flash point test methods with slower heating rates available, such as Test Method D3941 (for
paints, resins, and related products, and high viscosity products in the range of 0 °C to 110 °C), where
the test conditions are closer to equilibrium.
Flash point values 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.
1. Scope*
1.1 These test methods cover the determination of the flash point of petroleum products in the temperature range from 40 °C
to 370 °C by a manual Pensky-Martens closed-cup apparatus or an automated Pensky-Martens closed-cup apparatus, and the
determination of the flash point of biodiesel in the temperature range of 60 °C to 190 °C by an automated Pensky-Martens closed
cup apparatus.
NOTE 1—Flash point determinations above 250 °C can be performed, however, the precision has not been determined above this temperature. For
residual fuels, precision has not been determined for flash points above 100 °C. The precision of in-use lubricating oils has not been determined. Some
specifications state a D93 minimum flash point below 40 °C, however, the precision has not been determined below this temperature.
1.2 Procedure A is applicable to distillate fuels (diesel, biodiesel blends, kerosine, heating oil, turbine fuels), new and in-use
lubricating oils, and other homogeneous petroleum liquids not included in the scope of Procedure B or Procedure C.
1.3 Procedure B is applicable to residual fuel oils, cutback residua, used lubricating oils, mixtures of petroleum liquids with
solids, petroleum liquids that tend to form a surface film under test conditions, or are petroleum liquids of such kinematic viscosity
that they are not uniformly heated under the stirring and heating conditions of Procedure A.
1.4 Procedure C is applicable to biodiesel (B100). Since a flash point of residual alcohol in biodiesel is difficult to observe by
manual flash point techniques, automated apparatus with electronic flash point detection have been found suitable.
1.5 These test methods are applicable for the detection of contamination of relatively nonvolatile or nonflammable materials
with volatile or flammable materials.
1.6 The values stated in SI units are to be regarded as the standard.
1.6.1 Exception—The values given in parentheses are for information only.
NOTE 2—It has been common practice in flash point standards for many decades to alternately use a C-scale or an F-scale thermometer for temperature
measurement. Although the scales are close in increments, they are not equivalent. Because the F-scale thermometer used in this procedure is graduated
in 5 °F increments, it is not possible to read it to the 2 °C equivalent increment of 3.6 °F. Therefore, for the purposes of application of the procedure of
These test methods are under the joint jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and are the direct responsibility of
Subcommittee D02.08 on Volatility. In the IP, these test methods are under the jurisdiction of the Standardization Committee.
Current edition approved Nov. 1, 2019Aug. 1, 2020. Published November 2019August 2020. Originally approved in 1921. Last previous edition approved in 20182019
as D93 – 18.D93 – 19. DOI: 10.1520/D0093-19.10.1520/D0093-20.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D93 − 20
the test method for the separate temperature scale thermometers, different increments must be used. In this test method, the following protocol has been
adopted: When a temperature is intended to be a converted equivalent, it will appear in parentheses following the SI unit, for example 370 °C (698 °F).
When a temperature is intended to be a rationalized unit for the alternate scale, it will appear after “or,” for example, 2 °C or 5 °F.
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use. For specific warning statements, see 6.4, 7.1, 9.3, 9.4, 11.1.2, 11.1.4, 11.1.8, 11.2.2, and 12.1.2.
1.8 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D56 Test Method for Flash Point by Tag Closed Cup Tester
D3941 Test Method for Flash Point by the Equilibrium Method With a Closed-Cup Apparatus
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
E1 Specification for ASTM Liquid-in-Glass Thermometers
E300 Practice for Sampling Industrial Chemicals
E502 Test Method for Selection and Use of ASTM Standards for the Determination of Flash Point of Chemicals by Closed Cup
Methods
2.2 ISO Standards
Guide 34 General requirements for the competence of reference material producers
Guide 35 Reference material—General and statistical principles for certification
3. Terminology
3.1 Definitions:
3.1.1 biodiesel, n—a fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats,
designated B100.
3.1.2 biodiesel blends, n—a blend of biodiesel fuel with petroleum-based diesel fuel.
3.1.3 dynamic, adj—in petroleum products—in petroleum product flash point test methods—the condition where the vapor
above the test specimen and the test specimen are not in temperature equilibrium at the time that the ignition source is applied.
3.1.3.1 Discussion—
This is primarily caused by the heating of the test specimen at the constant prescribed rate with the vapor temperature lagging
behind the test specimen temperature.
3.1.4 equilibrium, n—in petroleum products—in petroleum product flash point test methods,—the the condition where the vapor
above the test specimen, and the test specimen are at the same temperature at the time the ignition source is applied.
3.1.4.1 Discussion—
This condition may not be fully achieved in practice, since the temperature may not be uniform throughout the test specimen, and
the test cover and shutter on the apparatus can be cooler.cooler or warmer.
3.1.5 flash point, n—in flash point test methods, the lowest temperature of the test specimen, adjusted to account for variations
in atmospheric pressure from 101.3 kPa, at which application of an ignition source causes the vapors of the test sample to ignite
under specified conditions of test.
4. Summary of Test Method
4.1 A brass test cup of specified dimensions, filled to the inside mark with test specimen and fitted with a cover of specified
dimensions, is heated and the specimen stirred at specified rates, using one of three defined procedures (A, B, or C). An ignition
source is directed into the test cup at regular intervals with simultaneous interruption of the stirring, until a flash is detected (see
11.1.8). The flash point is reported as defined in 3.1.5.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
D93 − 20
5. Significance and Use
5.1 The flash point temperature is one measure of the tendency of the test specimen to form a flammable mixture with air under
controlled laboratory conditions. It is only one of a number of properties which must be considered in assessing the overall
flammability hazard of a material.
5.2 Flash point is used in shipping and safety regulations to define flammable and combustible materials. One should consult
the particular regulation involved for precise definitions of these classifications.
5.3 These test methods should be used to measure and describe the properties of materials, products, or assemblies in response
to heat and an ignition source under controlled laboratory conditions and should not be used to describe or appraise the fire hazard
or fire risk of materials, products, or assemblies under actual fire conditions. However, results of these test methods may be used
as elements of a fire risk assessment which takes into account all of the factors which are pertinent to an assessment of the fire
hazard of a particular end use.
5.4 These test methods provide the only closed cup flash point test procedures for temperatures up to 370 °C (698 °F).
6. Apparatus
6.1 Pensky-Martens Closed Cup Apparatus (manual) —This apparatus consists of the test cup, test cover and shutter, stirring
device, heating source, ignition source device, air bath, and top plate described in detail in Annex A1. The assembled manual
apparatus, test cup, test cup cover, and test cup assembly are illustrated in Figs. A1.1-A1.4, respectively. Dimensions are listed
respectively.
6.2 Pensky-Martens Closed Cup Apparatus (Automated) —This apparatus is an automated flash point instrument that is capable
of performing the test in accordance with Section 11 (Procedure A), Section 12 (Procedure B), and Section 13 (Procedure C) of
these test methods. The apparatus shall use the test cup, test cover and shutter, stirring device, heating source, and ignition source
device described in detail in Annex A1.
6.3 Temperature Measuring Device—Thermometer having a range as shown in Table 1 and conforming to the requirements
prescribed in Specification E1 or in Annex A3, or an electronic temperature measuring device, such as resistance thermometers
or thermocouples. The device shall exhibit the same temperature response as the mercury thermometers.
6.4 Ignition Source—Natural gas flame, bottled gas flame, and electric ignitors (hot wire) have been found acceptable for use
as the ignition source. The gas flame device described in detailed in Fig. A1.4 requires the use of the pilot flame described in
A1.1.2.3. The electric ignitors shall be of the hot-wire type and shall position the heated section of the ignitor in the aperture of
the test cover in the same manner as the gas flame device. (Warning—Gas pressure supplied to the apparatus should not be
allowed to exceed 3 kPa (12 in.) of water pressure.)
6.5 Barometer—With accuracy of 60.5 kPa.
NOTE 3—The barometric pressure used in this calculation is the ambient pressure for the laboratory at the time of the test. Many aneroid barometers,
such as those used at weather stations and airports, are precorrected to give sea level readings and would not give the correct reading for this test.
7. Reagents and Materials
7.1 Cleaning Solvents—Use suitable solvent capable of cleaning out the specimen from the test cup and drying the test cup and
cover. Some commonly used solvents are toluene and acetone. (Warning—Toluene, acetone, and many solvents are flammable
and a health hazard. Dispose of solvents and waste material in accordance with local regulations.)
8. Sampling
8.1 Obtain a sample in accordance with instructions given in Practices D4057, D4177, or E300.
TABLE 1 Temperature Measuring Device
Temperature Range Thermometer Number Temperature Range Thermometer Number
ASTM IP
−5 °C to 110 °C 9C (9F) −5 °C to 110 °C 15C
(20 °F to 230 °F)
+10 °C to 200 °C 88C (88F) +20 °C to 150 °C 101C
(50 °F to 392 °F)
+90 °C to 370 °C 10C (10F) +90 °C to 370 °C 16C
(200 °F to 700 °F)
Supporting data regarding a variant of the cover locking mechanism have been filed at ASTM International Headquarters and may be obtained by requesting Research
Report RR:D02-1706. Contact ASTM Customer Service at [e-mail].
D93 − 20
8.2 Ensure at least 75 mL of sample is available so there is sufficient material for the test. When obtaining a sample of residual
fuel oil, the sample container shall be from 85 % to 95 % full. For other types of samples, the size of the container shall be chosen
such that the container is not more than 85 % full or less than 50 % full prior to any sample aliquot being taken. For biodiesel
(B100) samples, a typical one liter container filled to 85 % volume is recommended.
8.3 Successive test specimens can be taken from the same sample container. Repeat tests have been shown to be within the
precisions of the method when the second specimen is taken with the sample container at least 50 % filled. The results of flash
point determinations can be affected if the sample volume is less than 50 % of sample container capacity.
8.4 Erroneously high flash points may be obtained if precautions are not taken to avoid the loss of volatile material. Do not open
containers unnecessarily, to prevent loss of volatile material or possible introduction of moisture, or both. Avoid storage of samples
at temperatures in excess of 35 °C or 95 °F. Samples for storage shall be capped tightly with inner seals. Do not make a transfer
unless the sample temperature is at least the equivalent of 18 °C or 32 °F below the expected flash point.
8.5 Do not store samples in gas-permeable containers, since volatile material may diffuse through the walls of the enclosure.
Samples in leaky containers are suspect and not a source of valid results.
8.6 Samples of very viscous materials shall be heated in their containers, with lid/cap slightly loosened to avoid buildup of
dangerous pressure, at the lowest temperature adequate to liquefy any solids, not exceeding 28 °C or 50 °F below the expected flash
point, for 30 min. If the sample is then not completely liquefied, extend the heating period for additional 30 min periods as
necessary. Then gently agitate the sample to provide mixing, such as orbiting the container horizontally, before transferring to the
specimen cup. No sample shall be heated and transferred unless its temperaturestemperature is more than 18 °C or 32 °F below
its expected flash point. When the sample has been heated above this temperature, allow the sample to cool until its temperature
is at least 18 °C or 32 °F below the expected flash point before transferring.
NOTE 4—Volatile vapors can escape during heating when the sample container is not properly sealed.
NOTE 5—Some viscous samples may not completely liquefy even after prolonged periods of heating. Care should be exercised when increasing the
heating temperature to avoid unnecessary loss of volatile vapors, or heating the sample too close to the flash point.
8.7 Samples containing dissolved or free water may be dehydrated with calcium chloride or by filtering through a qualitative
filter paper or a loose plug of dry absorbent cotton. Warming the sample is permitted, but it shall not be heated for prolonged
periods or greater than a temperature of 18 °C or 32 °F below its expected flash point.
NOTE 6—If the sample is suspected of containing volatile contaminants, the treatment described in 8.6 and 8.7 should be omitted.
9. Preparation of Apparatus
9.1 Support the manual or automated apparatus on a level steady surface, such as a table.
9.2 Tests are to be performed in a draft-free room or compartment.
NOTE 7—A shield, of the approximate dimensions 460 mm (18 in.) square and 610 mm (24 in.) high, or other suitable dimensions, and having an open
front is recommended to prevent drafts from disturbing the vapors above the test cup.
NOTE 8—With some samples whose vapors or products of pyrolysis are objectionable, it is permissible to place the apparatus along with a draft shield
in a ventilation hood, the draft of which is adjustable so that vapors can be withdrawn without causing air currents over the test cup during the ignition
source application period.
9.3 Prepare the manual apparatus or the automated apparatus for operation in accordance with the manufacturer’s instructions
for calibrating, checking, and operating the equipment. (Warning—Gas pressure should not be allowed to exceed 3 kPa (12 in.)
of water pressure.)
9.4 Thoroughly clean and dry all parts of the test cup and its accessories before starting the test, to ensure the removal of any
solvent which had been used to clean the apparatus. Use suitable solvent capable of removing all of the specimen from the test
cup and drying the test cup and cover. Some commonly used solvents are toluene and acetone. (Warning—Toluene, acetone, and
many solvents are flammable. Health hazard. Dispose of solvents and waste material in accordance with local regulations.)
10. Verification of Apparatus
10.1 Adjust the automated flash point detection system (when used) in accordance with the manufacturer’s instructions.
10.2 Verify that the temperature measuring device is in accordance with 6.3.
10.3 Verify the performance of the manual apparatus or the automated apparatus at least once per year by determining the flash
point of a certified reference material (CRM) such as those listed in Annex A4, which is reasonably close to the expected
temperature range of the samples to be tested. The material shall be tested according to Procedure A of these test methods and the
observed flash point obtained in 11.1.8 or 11.2.2 shall be corrected for barometric pressure (see Section 14). The flash point
obtained shall be within the limits stated in Table A4.1 for the identified CRM or within the limits calculated for an unlisted CRM
(see Annex A4).
D93 − 20
10.4 Once the performance of the apparatus has been verified, the flash point of secondary working standards (SWSs) can be
determined along with their control limits. These secondary materials can then be utilized for more frequent performance checks
(see Annex A4).
10.5 When the flash point obtained is not within the limits stated in 10.3 or 10.4, check the condition and operation of the
apparatus to ensure conformity with the details listed in Annex A1, especially with regard to tightness of the lid (A1.1.2.2), the
action of the shutter, the position of the ignition source (A1.1.2.3), and the angle and position of the temperature measuring device
(A1.1.2.4). After any adjustment, repeat the test in 10.3 using a fresh test specimen, with special attention to the procedural details
prescribed in these test methods.
10.6 The numerical values obtained during the verification check (10.3) shall not be used to provide a bias statement, nor shall
they be used to make any correction to the flash points subsequently determined using the apparatus.
PROCEDURE A
11. Procedure
11.1 Manual Apparatus:
11.1.1 Ensure that the sample container is filled to the volume capacity requirement specified in 8.2. Fill the test cup with the
test specimen to the filling mark inside of the test cup. The temperature of the test cup and test specimen shall be at least 18 °C
or 32 °F below the expected flash point. If too much test specimen has been added to the test cup, remove the excess using a syringe
or similar device for withdrawal of fluid. Place the test cover on the test cup and place the assembly into the apparatus. Be sure
the locating or locking device is properly engaged. If the temperature measuring device is not already in place, insert the device
into its holder.
11.1.2 Light the test flame, and adjust it to a diameter of 3.2 mm to 4.8 mm (0.126 in. to 0.189 in.), or switch on the electric
igniter and adjust the intensity in accordance with the manufacturer’s instructions. (Warning—Gas pressure should not be allowed
to exceed 3 kPa (12 in.) of water pressure.) (Warning—Exercise care when using a gas test flame. If it should be extinguished it
will not ignite the vapors in the test cup, and the gas for the test flame that then enters the vapor space can influence the result.)
(Warning—The operator should exercise and take appropriate safety precautions during the initial application of the ignition
source, since test specimens containing low-flash material can give an abnormally strong flash when the ignition source is first
applied.) (Warning—The operator should exercise and take appropriate safety precautions during the performance of these test
methods. The temperatures attained during these test methods, up to 370 °C (698 °F), are considered hazardous.) (Warning—As
a safety practice, when using automated or manual apparatus, it is strongly advised, before heating the test cup and specimen, to
dip the ignitor to check for the presence of unexpected volatile material.)
11.1.3 Apply the heat at such a rate that the temperature, as indicated by the temperature measuring device, increases 5 °C to
6 °C (9 °F to 11 °F) ⁄min.
NOTE 9—In practice the rate is not achieved immediately after application of the heat due to the thermal inertia in the apparatus.
11.1.4 Turn the stirring device at 90 r ⁄min to 120 r ⁄min, stirring in a downward direction. (Warning—Meticulous attention to
all details relating to the ignition source, size of test flame or intensity of the electric ignitor, rate of temperature increase, and rate
of dipping the ignition source into the vapor of the test specimen is desirable for good results.)
11.1.5 Application of Ignition Source:
11.1.5.1 If the test specimen is expected to have a flash point of 110 °C or 230 °F or below, apply the ignition source when the
temperature of the test specimen is 23 °C 6 5 °C or 41 °F 6 9 °F below the expected flash point and each time thereafter at a
temperature reading that is a multiple of 1 °C or 2 °F. Discontinue the stirring of the test specimen and apply the ignition source
by operating the mechanism on the test cover which controls the shutter so that the ignition source is lowered into the vapor space
of the test cup in 0.5 s, left in its lowered position for 1 s, and quickly raised to its upward position.
11.1.5.2 If the test specimen is expected to have a flash point above 110 °C or 230 °F, apply the ignition source in the manner
described in 11.1.5.1 at each temperature increase of 2 °C or 5 °F, beginning at a temperature of 23 °C 6 5 °C or 41 °F 6 9 °F
below the expected flash point. (Warning—As a safety practice, when using automated or manual apparatus, it is strongly advised
that, for an expected flash point above 130 °C, to dip the ignitor every 10 °C throughout the test until the sample temperature
reaches 28 °C below the expected flash point and then follow the prescribed dipping procedure. This practice has been shown to
reduce the possibility of a fire, and, on average, not to significantly affect the result. A limited study has shown that this dipping
practice has no observable effect on test method repeatability.)
11.1.6 When testing materials to determine if volatile material contamination is present, it is not necessary to adhere to the
temperature limits for initial ignition source application as stated in 11.1.5.
11.1.7 When testing materials where the expected flash point temperature is not known, bring the material to be tested and the
tester to a temperature of 15 °C 6 5 °C or 60 °F 6 10 °F. When the material is known to be very viscous at this temperature, heat
Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D02-1652. Contact ASTM Customer
Service at [e-mail].
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the specimen to a starting temperature as described in 8.6. Apply the ignition source, in the manner described in 11.1.5.1, beginning
at least 5 °C or 10 °F higher than the starting temperature.
NOTE 10—Flash Point results determined in an “unknown expected flash point mode” should be considered approximate. This value can be used as
the expected flash point when a fresh specimen is tested in the standard mode of operation.
11.1.8 Record as the observed flash point the reading on the temperature measuring device at the time ignition source
application causes a distinct flash in the interior of the test cup. The sample is deemed to have flashed when a large flame appears
and instantaneously propagates itself over the entire surface of the test specimen. (Warning—For certain mixtures containing
halogenated hydrocarbons, such as, methylene chloride or trichloroethylene, no distinct flash, as defined, is observed. Instead a
significant enlargement of the test flame (not halo effect) and change in color of the test flame from blue to yellowish-orange
occurs. Continued heating and testing of these samples above ambient temperature can result in significant burning of vapors
outside the test cup, and can be a potential fire hazard. See Appendix X1 and Appendix X2 for more information.)
11.1.9 When the ignition source is a test flame, the application of the test flame can cause a blue halo or an enlarged flame prior
to the actual flash point. This is not a flash and shall be ignored.
11.1.10 When a flash point is detected on the first application, the test shall be discontinued, the result discarded, and the test
repeated with a fresh test specimen. The first application of the ignition source with the fresh test specimen shall be 23 °C 6 5 °C
or 41 °F 6 9 °F below the temperature at which a flash point was detected on the first application.
11.1.11 When a flash point is detected at a temperature which is greater than 28 °C or 50 °F above the temperature of the first
application of the ignition source, or when a flash point is detected at a temperature which is less than 18 °C or 32 °F above the
temperature of the first application of the ignition source, the result shall be considered approximate, and the test repeated with
a fresh test specimen. Adjust the expected flash point for this next test to the temperature of the approximate result. The first
application of the ignition source with the fresh test specimen shall be 23 °C 6 5 °C or 41 °F 6 9 °F below the temperature at
which the approximate result was found.
11.1.12 When the apparatus has cooled down to a safe handling temperature, less than 55 °C (130 °F), remove the test cover
and the test cup and clean the apparatus as recommended by the manufacturer.
NOTE 11—Exercise care when cleaning and positioning the lid assembly so not to damage or dislocate the flash detection system or temperature
measuring device. See the manufacturer’s instructions for proper care and maintenance.
11.2 Automated Apparatus:
11.2.1 The automated apparatus shall be capable of performing the procedure as described in 11.1, including control of the
heating rate, stirring of the test specimen, application of the ignition source, detection of the flash point, and recording the flash
point.
11.2.2 Start the automated apparatus in accordance with the manufacturer’s instructions. (Warning—Failure to install the
sample temperature measuring device correctly, when using automated apparatus, can result in uncontrolled heating of the test
portion and potentially a fire. Some automated apparatus include provisions to avoid this occurrence.) The apparatus shall follow
the procedural details described in 11.1.3 through 11.1.8.
PROCEDURE B
12. Procedure
12.1 Manual Apparatus:
12.1.1 Ensure that the sample container is filled to the volume capacity requirement specified in 8.2. Fill the test cup with the
test specimen to the filling mark inside of the test cup. The temperature of the test cup and test specimen shall be at least 18 °C
or 32 °F below the expected flash point. If too much test specimen has been added to the test cup, remove the excess using a syringe
or similar device for withdrawal of fluid. Place the test cover on the test cup and place the assembly into the apparatus. Be sure
the locating or locking device is properly engaged. If the temperature measuring device is not already in place, insert the device
into its holder.
12.1.2 Light the test flame and adjust it to a diameter of 3.2 mm to 4.8 mm (0.126 in. to 0.189 in.), or switch on the electric
igniter and adjust the intensity in accordance with the manufacturer’s instructions. (Warning—Gas pressure should not be allowed
to exceed 3 kPa (12 in.) of water pressure.) (Warning—Exercise care when using a gas test flame. If it should be extinguished it
will not ignite the vapors in the test cup and the gas for the test flame that then enters the vapor space can influence the result.)
(Warning—The operator should exercise and take appropriate safety precautions during the initial application of the ignition
source, since test specimens containing low-flash material may give an abnormally strong flash when the ignition source is first
applied.) (Warning—The operator should exercise and take appropriate safety precautions during the performance of these test
methods. The temperatures attained during these test methods, up to 370 °C (698 °F), are considered hazardous.)
12.1.3 Turn the stirring device at 250 r ⁄min 6 10 r ⁄min, stirring in a downward direction.
12.1.4 Apply the heat at such a rate that the temperature as indicated by the temperature measuring device increases 1 °C to
1.6 °C (2 °F to 3 °F) ⁄min.
NOTE 12—In practice the rate is not achieved immediately after application of the heat due to the thermal inertia in the apparatus.
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12.1.5 Proceed as prescribed in Section 11, with the exception of the preceding requirements for rates of stirring and heating.
12.2 Automated Apparatus:
12.2.1 The automated apparatus shall be capable of performing the procedure as described in 12.1, including control of the
heating rate, stirring of the test specimen, application of the ignition source, detection of the flash point, and recording the flash
point.
12.2.2 Start the automated apparatus in accordance with the manufacturer’s instructions. The apparatus shall follow the
procedural details in accordance with 12.1.3 through 12.1.5.
Procedure C
13. Procedure
13.1 Automated Apparatus—Ensure that the apparatus is equipped with an electronic measuring system for the detection of the
flash point.
13.2 Ensure that the sample container is filled to the volume capacity requirement specified in 8.2. Fill the test cup with the test
specimen to the filling mark inside of the test cup. The temperature of the test cup and test specimen shall be at least 24 °C below
the expected flash point. If too much test specimen has been added to the test cup, remove the excess using a syringe or similar
device for withdrawal of fluid. Place the test cover on the test cup and place the assembly into the apparatus. Be sure the locating
or locking device is properly engaged. If the temperature measuring device is not already in place, insert the device into its holder.
13.3 Light the test flame, and adjust it to a diameter of 3.2 mm to 4.8 mm (0.126 in. to 0.189 in.) or switch on the electric igniter
and adjust the intensity in accordance with the manufacturer’s instructions. (Warning—Gas pressure should not be allowed to
exceed 3 kPa (12 in. of water pressure.) (Warning—Exercise care when using a gas test flame. If it should be extinguished it will
not ignite the vapors in the test cup, and the gas for the test flame that then enters the vapor space can influence the result.)
(Warning—The operator should exercise and take appropriate safety precautions during the initial application of the ignition
source, since test specimens containing low-flash material can give an abnormally strong flash when the ignition
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