ASTM D86-23ae1

Standard Test Method for Distillation of Petroleum Products and Liquid Fuels at Atmospheric Pressure

SIGNIFICANCE AND USE
5.1 The basic test method of determining the boiling range of a petroleum product by performing a simple batch distillation has been in use as long as the petroleum industry has existed. It is one of the oldest test methods under the jurisdiction of ASTM Committee D02, dating from the time when it was still referred to as the Engler distillation. Since the test method has been in use for such an extended period, a tremendous number of historical data bases exist for estimating end-use sensitivity on products and processes.  
5.2 The distillation (volatility) characteristics of hydrocarbons have an important effect on their safety and performance, especially in the case of fuels and solvents. The boiling range gives information on the composition, the properties, and the behavior of the fuel during storage and use. Volatility is the major determinant of the tendency of a hydrocarbon mixture to produce potentially explosive vapors.  
5.3 The distillation characteristics are critically important for both automotive and aviation gasolines, affecting starting, warm-up, and tendency to vapor lock at high operating temperature or at high altitude, or both. The presence of high boiling point components in these and other fuels can significantly affect the degree of formation of solid combustion deposits.  
5.4 Volatility, as it affects rate of evaporation, is an important factor in the application of many solvents, particularly those used in paints.  
5.5 Distillation limits are often included in petroleum product specifications, in commercial contract agreements, process refinery/control applications, and for compliance to regulatory rules.
SCOPE
1.1 This test method covers the atmospheric distillation of petroleum products and liquid fuels using a laboratory batch distillation unit to determine quantitatively the boiling range characteristics of such products as light and middle distillates, automotive spark-ignition engine fuels with or without oxygenates (see Note 1), aviation gasolines, aviation turbine fuels, diesel fuels, biodiesel blends up to 30 % volume, marine fuels, special petroleum spirits, naphthas, white spirits, kerosines, and Grades 1 and 2 burner fuels.
Note 1: An interlaboratory study was conducted in 2008 involving 11 different laboratories submitting 15 data sets and 15 different samples of ethanol-fuel blends containing 25 % volume, 50 % volume, and 75 % volume ethanol. The results indicate that the repeatability limits of these samples are comparable or within the published repeatability of the method (with the exception of FBP of 75 % ethanol-fuel blends). On this basis, it can be concluded that Test Method D86 is applicable to ethanol-fuel blends such as Ed75 and Ed85 (Specification D5798) or other ethanol-fuel blends with greater than 10 % volume ethanol. See ASTM RR:D02-1694 for supporting data.2  
1.2 The test method is designed for the analysis of distillate fuels; it is not applicable to products containing appreciable quantities of residual material.  
1.3 This test method covers both manual and automated instruments.  
1.4 Unless otherwise noted, the values stated in SI units are to be regarded as the standard. The values given in parentheses are provided for information only.  
1.5 WARNING—Mercury has been designated by many regulatory agencies as a hazardous substance that can cause serious medical issues. Mercury, or its vapor, has been demonstrated to be hazardous to health and corrosive to materials. Use Caution when handling mercury and mercury-containing products. See the applicable product Safety Data Sheet (SDS) for additional information. The potential exists that selling mercury or mercury-containing products, or both, is prohibited by local or national law. Users must determine legality of sales in their location.  
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilit...

General Information

• Status: Published
• Publication Date: 30-Nov-2023
• ICS: 75.080 - Petroleum products in general
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.08 - Volatility

Relations

• Replaces: ASTM D86-23a - Standard Test Method for Distillation of Petroleum Products and Liquid Fuels at Atmospheric Pressure
• Effective Date: 01-Dec-2023
• Refers: ASTM D6300-24 - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Mar-2024
• Refers: ASTM D6708-24 - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-Mar-2024
• Refers: ASTM D6300-23a - Standard Practice for Determination of Precision and Bias Data for Use in Test Methods for Petroleum Products, Liquid Fuels, and Lubricants
• Effective Date: 01-Dec-2023
• Refers: ASTM D5842-23 - Standard Practice for Sampling and Handling of Fuels for Volatility Measurement
• Effective Date: 01-Oct-2023
• Refers: ASTM D6708-21 - Standard Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport to Measure the Same Property of a Material
• Effective Date: 01-May-2021
• Refers: ASTM D5842-19 - Standard Practice for Sampling and Handling of Fuels for Volatility Measurement
• Effective Date: 01-Nov-2019
• Referred By: ASTM D7583-16(2023) - Standard Test Method for John Deere Coolant Cavitation Test
• Effective Date: 01-Dec-2023
• Referred By: ASTM D6709-24 - Standard Test Method for Evaluation of Automotive Engine Oils in the Sequence VIII Spark-Ignition Engine (CLR Oil Test Engine)
• Effective Date: 01-Dec-2023
• Referred By: ASTM D7468-22 - Standard Test Method for Cummins ISM Test
• Effective Date: 01-Dec-2023
• Referred By: ASTM D2425-23 - Standard Test Method for Hydrocarbon Types in Middle Distillates by Mass Spectrometry
• Effective Date: 01-Dec-2023
• Referred By: ASTM D8276-19 - Standard Test Method for Hydrocarbon Types in Middle Distillates, including Biodiesel Blends by Gas Chromatography/Mass Spectrometry
• Effective Date: 01-Dec-2023
• Referred By: ASTM D3338/D3338M-20a - Standard Test Method for Estimation of Net Heat of Combustion of Aviation Fuels
• Effective Date: 01-Dec-2023
• Referred By: ASTM D4814-24 - Standard Specification for Automotive Spark-Ignition Engine Fuel
• Effective Date: 01-Dec-2023
• Referred By: ASTM D2880-23 - Standard Specification for Gas Turbine Fuel Oils
• Effective Date: 01-Dec-2023

Overview

ASTM D86-23ae1 is the internationally recognized standard test method for determining the distillation characteristics of petroleum products and liquid fuels at atmospheric pressure. Developed by ASTM Committee D02, this test method is fundamental for quality control and specification of fuels, solvents, and other hydrocarbon products. By simulating a simple batch distillation in a laboratory setting, ASTM D86 quantitatively establishes the boiling range of various light and middle distillates, such as gasoline, jet fuel, diesel, biodiesel blends, naphthas, spirits, and burner fuels.

The procedure and requirements outlined in ASTM D86 provide critical information on product volatility, composition, and behavior, contributing to performance, safety, regulatory compliance, and process optimization in the petroleum industry. Both manual and automated procedures are covered, ensuring broad applicability with modern laboratory equipment.

Key Topics

• Boiling Range Determination: Outlines systematic batch distillation for quantifying the range between the initial and final boiling points of samples.
• Product Scope: Applicable to automotive and aviation fuels (including oxygenated blends like ethanol-fuel), diesel, biodiesel up to 30% volume, marine fuels, naphthas, kerosenes, spirits, and burner fuels, but not to products with substantial residual material.
• Safety & Volatility: Evaluates volatility characteristics, which are central to understanding fuel evaporation, tendency for explosive vapor formation, combustion residue, and evaporation rates in solvents.
• Sampling & Conditioning: Recommends guidelines for representative sampling, storage, and temperature conditioning to ensure accurate and repeatable results.
• Manual and Automated Testing: Describes requirements for both traditional and automated apparatus, including temperature measurement verification and calibration.
• Regulatory & Specification Use: Frequently referenced in commercial contracts, product specifications, process controls, and regulatory submissions for compliance verification.

Applications

The ASTM D86 standard underpins many areas critical to the petroleum and fuel industries:

• Quality Control: Used in refineries, distribution, and end-use to ensure products conform to boiling range specifications, affecting performance, safety, and emissions.
• Product Development and Blending: Guides formulation and blending operations by profiling distillation curves, ensuring fuels meet specific volatility and boiling requirements.
• Specification Compliance: Integral for meeting regulatory mandates and contractual obligations, particularly concerning product volatility, emissions, and safety limits.
• Engine and Equipment Performance: Volatility profile obtained by this test directly impacts cold start, warm-up, vapor lock, and deposit formation in vehicles and aircraft.
• Solvent and Paint Industry: Determines evaporation rates and drying characteristics important for industrial solvent applications.
• Data Consistency: Provides a uniform metric for comparing products across laboratories and historical data, supporting industry-wide product standardization.
• Ethanol-Blended Fuels: Validated for use with ethanol blends (e.g., Ed75, Ed85), an increasingly important area as alternative fuels gain market share.

Related Standards

ASTM D86-23ae1 is part of a suite of standards dedicated to the quality and characterization of petroleum products and fuels. Related documents include:

• ASTM D97: Test Method for Pour Point of Petroleum Products
• ASTM D323: Test Method for Vapor Pressure of Petroleum Products (Reid Method)
• ASTM D5798: Specification for Ethanol Fuel Blends for Flexible-Fuel Automotive Spark-Ignition Engines
• ASTM D4057/D4177: Practices for Manual and Automatic Sampling of Petroleum and Petroleum Products
• ISO 17034: General requirements for the competence of reference material producers
• IP 123: Determination of Distillation Characteristics (UK equivalent standard)

Reference to these and other volatility or physical property methods ensures comprehensive coverage of fuel behavior and compliance with international requirements.

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Implementing ASTM D86 in your testing protocol ensures reliable, repeatable distillation data essential for the production, handling, and regulation of petroleum products and fuels worldwide. For further information, refer to ASTM’s official documentation and updates.

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.
´1
Designation: D86 − 23a
Standard Test Method for
Distillation of Petroleum Products and Liquid Fuels at
Atmospheric Pressure
This standard is issued under the fixed designation D86; 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.
ε NOTE—Editorially updated Section 7 in February 2024.
1. Scope* 1.5 WARNING—Mercury has been designated by many
regulatory agencies as a hazardous substance that can cause
1.1 This test method covers the atmospheric distillation of
serious medical issues. Mercury, or its vapor, has been dem-
petroleum products and liquid fuels using a laboratory batch
onstrated to be hazardous to health and corrosive to materials.
distillation unit to determine quantitatively the boiling range
Use Caution when handling mercury and mercury-containing
characteristics of such products as light and middle distillates,
products. See the applicable product Safety Data Sheet (SDS)
automotive spark-ignition engine fuels with or without oxy-
for additional information. The potential exists that selling
genates (see Note 1), aviation gasolines, aviation turbine fuels,
mercury or mercury-containing products, or both, is prohibited
diesel fuels, biodiesel blends up to 30 % volume, marine fuels,
by local or national law. Users must determine legality of sales
special petroleum spirits, naphthas, white spirits, kerosines,
in their location.
and Grades 1 and 2 burner fuels.
1.6 This standard does not purport to address all of the
NOTE 1—An interlaboratory study was conducted in 2008 involving 11
safety concerns, if any, associated with its use. It is the
different laboratories submitting 15 data sets and 15 different samples of
responsibility of the user of this standard to establish appro-
ethanol-fuel blends containing 25 % volume, 50 % volume, and 75 %
priate safety, health, and environmental practices and deter-
volume ethanol. The results indicate that the repeatability limits of these
samples are comparable or within the published repeatability of the mine the applicability of regulatory limitations prior to use.
method (with the exception of FBP of 75 % ethanol-fuel blends). On this
1.7 This international standard was developed in accor-
basis, it can be concluded that Test Method D86 is applicable to
dance with internationally recognized principles on standard-
ethanol-fuel blends such as Ed75 and Ed85 (Specification D5798) or other
ization established in the Decision on Principles for the
ethanol-fuel blends with greater than 10 % volume ethanol. See ASTM
Development of International Standards, Guides and Recom-
RR:D02-1694 for supporting data.
mendations issued by the World Trade Organization Technical
1.2 The test method is designed for the analysis of distillate
Barriers to Trade (TBT) Committee.
fuels; it is not applicable to products containing appreciable
quantities of residual material. 2. Referenced Documents
1.3 This test method covers both manual and automated 2.1 All standards are subject to revision, and parties to
agreement on this test method are to apply the most recent
instruments.
edition of the standards indicated below, unless otherwise
1.4 Unless otherwise noted, the values stated in SI units are
specified, such as in contractual agreements or regulatory rules
to be regarded as the standard. The values given in parentheses
where earlier versions of the method(s) identified may be
are provided for information only.
required.
2.2 ASTM Standards:
D97 Test Method for Pour Point of Petroleum Products
This test method is under the jurisdiction of ASTM Committee D02 on
D323 Test Method for Vapor Pressure of Petroleum Products
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
(Reid Method)
Subcommittee D02.08 on Volatility.
In the IP, the equivalent test method is published under the designation IP 123.
D4057 Practice for Manual Sampling of Petroleum and
It is under the jurisdiction of the Standardization Committee.
Petroleum Products
Current edition approved Dec. 1, 2023. Published February 2024. Originally
approved in 1921. Last previous edition approved in 2023 as D86 – 23. DOI:
10.1520/D0086-23AE01. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Supporting data have been filed at ASTM International Headquarters and may contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
be obtained by requesting Research Report RR:D02-1694. Contact ASTM Customer Standards volume information, refer to the standard’s Document Summary page on
Service at [e-mail]. the ASTM website.
*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
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D86 − 23a
D4175 Terminology Relating to Petroleum Products, Liquid 3.1.2 check standard, n—in QC testing, material having an
Fuels, and Lubricants accepted reference value used to determine the accuracy of a
D4177 Practice for Automatic Sampling of Petroleum and measurement system.
Petroleum Products
3.1.3 decomposition, n—of a hydrocarbon, the pyrolysis or
D4953 Test Method for Vapor Pressure of Gasoline and
cracking of a molecule yielding smaller molecules with lower
Gasoline-Oxygenate Blends (Dry Method)
boiling points than the original molecule.
D5190 Test Method for Vapor Pressure of Petroleum Prod-
3.1.4 decomposition point, n—in distillation, the corrected
ucts (Automatic Method) (Withdrawn 2012)
temperature reading that coincides with the first indications of
D5191 Test Method for Vapor Pressure of Petroleum Prod-
thermal decomposition of the specimen.
ucts and Liquid Fuels (Mini Method)
D5798 Specification for Ethanol Fuel Blends for Flexible-
3.1.5 dry point, n—in distillation, the corrected temperature
Fuel Automotive Spark-Ignition Engines
reading at the instant the last drop of liquid evaporates from the
D5842 Practice for Sampling and Handling of Fuels for
lowest point in the flask.
Volatility Measurement
3.1.6 dynamic holdup, n—in D86 distillation, the amount of
D5949 Test Method for Pour Point of Petroleum Products
material present in the neck of the flask, in the sidearm of the
(Automatic Pressure Pulsing Method)
flask, and in the condenser tube during the distillation.
D5950 Test Method for Pour Point of Petroleum Products
(Automatic Tilt Method)
3.1.7 emergent stem effect, n—the offset in temperature
D5985 Test Method for Pour Point of Petroleum Products reading caused by the use of total immersion mercury-in-glass
(Rotational Method)
thermometers in the partial immersion mode.
D6299 Practice for Applying Statistical Quality Assurance
3.1.7.1 Discussion—In the partial immersion mode, a por-
and Control Charting Techniques to Evaluate Analytical
tion of the mercury thread, that is, the emergent portion, is at
Measurement System Performance
a lower temperature than the immersed portion, resulting in a
D6300 Practice for Determination of Precision and Bias
shrinkage of the mercury thread and a lower temperature
Data for Use in Test Methods for Petroleum Products,
reading.
Liquid Fuels, and Lubricants
3.1.8 end point (EP) or final boiling point (FBP), n—the
D6708 Practice for Statistical Assessment and Improvement
maximum corrected thermometer reading obtained during the
of Expected Agreement Between Two Test Methods that
test.
Purport to Measure the Same Property of a Material
3.1.8.1 Discussion—This usually occurs after the evapora-
E1 Specification for ASTM Liquid-in-Glass Thermometers
tion of all liquid from the bottom of the flask. The term
E77 Test Method for Inspection and Verification of Ther-
maximum temperature is a frequently used synonym.
mometers
E1272 Specification for Laboratory Glass Graduated Cylin-
3.1.9 front end loss, n—loss due to evaporation during
ders
transfer from receiving cylinder to distillation flask, vapor loss
E1405 Specification for Laboratory Glass Distillation Flasks
during the distillation, and uncondensed vapor in the flask at
2.3 Energy Institute Standards:
the end of the distillation.
IP 69 Determination of Vapour Pressure—Reid Method
3.1.10 initial boiling point (IBP), n—in D86 distillation, the
IP 123 Petroleum Products—Determination of Distillation
corrected temperature reading at the instant the first drop of
Characteristics
condensate falls from the lower end of the condenser tube.
IP 394 Determination of Air Saturated Vapour Pressure
3.1.11 percent evaporated, n—in distillation, the sum of the
IP Standard Methods for Analysis and Testing of Petroleum
percent recovered and the percent loss.
and Related Products 1996—Appendix A
2.4 ISO Standards:
3.1.11.1 percent loss, n— in distillation, one hundred minus
ISO Guide 34
the percent total recovery.
ISO 17034 General requirements for the competence of
3.1.11.2 corrected loss, n—percent loss corrected for baro-
reference material producers
metric pressure.
3. Terminology
3.1.12 percent recovered, n—in distillation, the volume of
condensate collected relative to the sample charge.
3.1 Definitions:
3.1.1 For definitions of terms used in this test method, refer
3.1.12.1 percent recovery, n—in distillation, maximum per-
to Terminology D4175.
cent recovered relative to the sample charge.
3.1.12.2 corrected percent recovery, n—in distillation, the
percent recovery, adjusted for the corrected percent loss.
The last approved version of this historical standard is referenced on
www.astm.org.
5 3.1.12.3 percent total recovery, n—in distillation, the com-
Available from Energy Institute, 61 New Cavendish St., London, WIG 7AR,
bined percent recovery and percent residue.
U.K., http://www.energyinst.org.uk.
Available from International Organization for Standardization (ISO), ISO
3.1.13 percent residue, n—in distillation, the volume of
Central Secretariat, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,
Switzerland, https://www.iso.org. residue relative to the sample charge.
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D86 − 23a
3.1.14 rate of change (or slope), n—the change in tempera- was still referred to as the Engler distillation. Since the test
ture reading per percent evaporated or recovered, as described method has been in use for such an extended period, a
in 14.2. tremendous number of historical data bases exist for estimating
end-use sensitivity on products and processes.
3.1.15 sample charge, n—the amount of sample used in a
test.
5.2 The distillation (volatility) characteristics of hydrocar-
bons have an important effect on their safety and performance,
3.1.16 temperature lag, n—the offset between the tempera-
especially in the case of fuels and solvents. The boiling range
ture reading obtained by a temperature sensing device and the
gives information on the composition, the properties, and the
true temperature at that time.
behavior of the fuel during storage and use. Volatility is the
3.1.17 temperature measurement device, n—a thermometer,
major determinant of the tendency of a hydrocarbon mixture to
as described in 6.3.1, or a temperature sensor, as described in
produce potentially explosive vapors.
6.3.2.
5.3 The distillation characteristics are critically important
3.1.17.1 temperature reading, n—the temperature obtained
for both automotive and aviation gasolines, affecting starting,
by a temperature measuring device or system that is equal to
warm-up, and tendency to vapor lock at high operating
the thermometer reading described in 3.1.17.3.
temperature or at high altitude, or both. The presence of high
3.1.17.2 corrected temperature reading, n—the temperature
boiling point components in these and other fuels can signifi-
reading, as described in 3.1.17.1, corrected for barometric
cantly affect the degree of formation of solid combustion
pressure.
deposits.
3.1.17.3 thermometer reading (or thermometer result),
5.4 Volatility, as it affects rate of evaporation, is an impor-
n—the temperature of the saturated vapor measured in the neck
tant factor in the application of many solvents, particularly
of the flask below the vapor tube, as determined by the
those used in paints.
prescribed thermometer under the conditions of the test.
3.1.17.4 corrected thermometer reading, n—the thermom- 5.5 Distillation limits are often included in petroleum prod-
uct specifications, in commercial contract agreements, process
eter reading, as described in 3.1.17.3, corrected for barometric
pressure. refinery/control applications, and for compliance to regulatory
rules.
4. Summary of Test Method
6. Apparatus
4.1 Based on its composition, vapor pressure, expected IBP
or expected EP, or combination thereof, the sample is placed in
6.1 Basic Components of the Apparatus:
one of four groups. Apparatus arrangement, condenser
6.1.1 The basic components of the distillation unit are the
temperature, and other operational variables are defined by the
distillation flask, the condenser and associated cooling bath, a
group in which the sample falls.
metal shield or enclosure for the distillation flask, the heat
4.2 A 100 mL specimen of the sample is distilled under
source, the flask support, the temperature measuring device,
prescribed conditions for the group in which the sample falls.
and the receiving cylinder to collect the distillate.
The distillation is performed in a laboratory batch distillation
6.1.2 Figs. 1 and 2 are examples of manual distillation units.
unit at ambient pressure under conditions that are designed to
6.1.3 In addition to the basic components described in 6.1.1,
provide approximately one theoretical plate fractionation. Sys-
automated units also are equipped with a system to measure
tematic observations of temperature readings and volumes of
and automatically record the temperature and the associated
condensate are made, depending on the needs of the user of the
recovered volume in the receiving cylinder.
data. The volume of the residue and the losses are also
6.2 A detailed description of the apparatus is given in Annex
recorded.
A2.
4.3 At the conclusion of the distillation, the observed vapor
6.3 Temperature Measuring Device:
temperatures can be corrected for barometric pressure and the
data are examined for conformance to procedural
6.3.1 Mercury-in-glass thermometers, if used, shall be filled
requirements, such as distillation rates. The test is repeated if with an inert gas, graduated on the stem and enamel backed.
any specified condition has not been met. They shall conform to Specification E1 or IP Standard Methods
for Analysis and Testing of Petroleum and Related Products
4.4 Test results are commonly expressed as percent evapo-
1996—Appendix A, or both, for thermometers ASTM 7C/IP
rated or percent recovered versus corresponding temperature,
5C and ASTM 7F for the low range thermometers, and ASTM
either in a table or graphically, as a plot of the distillation
8C/IP 6C and ASTM 8F for the high range thermometers.
curve.
6.3.1.1 Thermometers that have been exposed for an ex-
5. Significance and Use
tended period above an observed temperature of 370 °C shall
not be reused without a verification of the ice point or checked
5.1 The basic test method of determining the boiling range
as prescribed in Specification E1 and Test Method E77.
of a petroleum product by performing a simple batch distilla-
tion has been in use as long as the petroleum industry has
NOTE 2—At an observed thermometer reading of 370 °C, the tempera-
existed. It is one of the oldest test methods under the jurisdic-
ture of the bulb is approaching a critical range in the glass and the
tion of ASTM Committee D02, dating from the time when it thermometer may lose its calibration.
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D86 − 23a
the neck of the distillation column, as shown in Fig. 5 and described in
11.5.
NOTE 5—When running the test by the manual method, products with
a low IBP may have one or more readings obscured by the centering
device. See also 11.14.3.1.
6.5 Automated equipment manufactured in 1999 and later
shall be equipped with a device to automatically shut down
power to the unit and to spray an inert gas or vapor in the
chamber where the distillation flask is mounted in the event of
fire.
NOTE 6—Some causes of fires are breakage of the distillation flask,
electrical shorts, and foaming and spilling of liquid sample through the top
opening of the flask.
6.6 Barometer—A pressure measuring device capable of
measuring local station pressure with an accuracy of 0.1 kPa
(1 mm Hg) or better, at the same elevation relative to sea level
as the apparatus in the laboratory. (Warning—Do not take
readings from ordinary aneroid barometers, such as those used
at weather stations and airports, since these are precorrected to
give sea level readings.)
7. Reagents
7.1 Check Standards:
FIG. 1 Apparatus Assembly Using Gas Burner
7.1.1 Low Range—Formulation of chemical compounds as
specified (Annex A3) certified in accordance with ISO 17034
and ISO Guide 31 to be used as verification of the dynamic
6.3.2 Temperature measurement systems other than those
response of the low range temperature measurement system.
described in 6.3.1 are satisfactory for this test method, pro-
7.1.2 High Range—Formulation of chemical compounds as
vided that they exhibit the same temperature lag, emergent
specified (Annex A3) certified in accordance with ISO 17034
stem effect, and equal or better accuracy as the equivalent
and ISO Guide 31 to be used as verification of the dynamic
mercury-in-glass thermometer.
response of the high range temperature measurement system.
6.3.2.1 The electronic circuitry or the algorithms, or both,
7,8
7.1.3 Toluene —Minimum purity of 95.0 % by volume.
used shall include the capability to simulate the temperature lag
(Warning—Combustible. Vapor harmful.)
and emergent stem effect of a mercury-in-glass thermometer
7,8
7.1.4 Hexadecane —Minimum purity of 95.0 % by vol-
(see Appendix X4). A procedure for verification of the dynamic
ume. (Warning—Combustible. Vapor harmful.)
response of the temperature measurement system is described
in Annex A3.
7.2 Secondary Working Standard (SWS):
6.3.2.2 Alternatively, the sensor can also be placed in a
7.2.1 SWS is a stable mixture of pure hydrocarbons, or
casing with the tip of the sensor covered so that the assembly,
other petroleum product whose composition is known to
because of its adjusted thermal mass and conductivity, has a
remain appreciably stable. Establish the mean value of control
temperature lag time similar to that of a mercury-in-glass
points and the statistical control limits for the SWS using
thermometer.
standard statistical techniques. See Practice D6299.
NOTE 3—In a region where the temperature is changing rapidly during
7.2.2 The formulations described in Annex A3, Tables
the distillation, the temperature lag of a thermometer can be as much as
A3.2-A3.4 may be blended in-house for use in more frequent
3 s.
verification. Ensure attention to formulation quality to achieve
6.3.3 In case of dispute, the referee test method shall be
the ARV(s) shown in Annex A3, Tables A3.2 and A3.3.
carried out with the specified mercury-in-glass thermometer.
6.4 Temperature Sensor Centering Device:
6.4.1 The temperature sensor shall be mounted through a
Reagent grade toluene and hexadecane (cetane), conforming to the specifica-
snug-fitting device designed for mechanically centering the
tions of the Committee on Analytical Reagents of the American Chemical Society
sensor in the neck of the flask without vapor leakage. Examples shall be used. However, other grades may also be used, provided it is first
ascertained that the reagent is of sufficient purity to permit its use without lessening
of acceptable centering devices are shown in Figs. 3 and 4.
the accuracy of the determination.
(Warning—The use of a plain stopper with a hole drilled
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
through the center is not acceptable for the purpose described
Standard-Grade Reference Materials, American Chemical Society, Washington,
DC. For suggestions on the testing of reagents not listed by the American Chemical
in 6.4.1.)
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
NOTE 4—Other centering devices are also acceptable, as long as they U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
position and hold the temperature sensing device in the proper position in copeial Convention, Inc. (USPC), Rockville, MD.
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D86 − 23a
1–Condenser bath 11–Distillation flask
2–Bath cover 12–Temperature sensor
3–Bath temperature sensor 13–Flask support board
4–Bath overflow 14–Flask support platform
5–Bath drain 15–Ground connection
6–Condenser tube 16–Electric heater
7–Shield 17–Knob for adjusting level
8–Viewing window of support platform
9a–Voltage regulator 18–Power source cord
9b–Voltmeter or ammeter 19–Receiver cylinder
9c–Power switch 20–Receiver cooling bath
9d–Power light indicator 21–Receiver cover
10–Vent
FIG. 2 Apparatus Assembly Using Electric Heater
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FIG. 3 PTFE Centering Device for Ground Glass Joint
FIG. 5 Position of Thermometer in Distillation Flask
TABLE 1 Group Characteristics
Group 1 Group 2 Group 3 Group 4
Sample
characteristics
Distillate type
Vapor pressure at
37.8 °C, kPa $65.5 <65.5 <65.5 <65.5
100 °F, psi $9.5 <9.5 <9.5 <9.5
(Test Methods D323, D4953, D5190, D5191,
D5842, IP 69 or IP 394)
Distillation, IBP °C #100 >100
°F #212 >212
EP °C #250 #250 >250 >250
°F #482 #482 >482 >482
(Warning—Do not completely fill and tightly seal a cold
container of sample because of the likelihood of expansion and
breakage on warming.)
8.2.1.2 Groups 2, 3, and 4—Collect the sample at ambient
temperature. After sampling, close the sample container imme-
diately with a tight-fitting closure.
8.2.1.3 If the sample received by the testing laboratory has
been sampled by others and it is not known whether sampling
FIG. 4 Example of Centering Device Designs for Straight-Bore
has been performed as described in 8.2, the sample shall be
Neck Flasks
assumed to have been so sampled.
8.3 Sample Storage:
8. Sampling, Storage, and Sample Conditioning
8.3.1 If testing is not to start immediately after collection,
8.1 Determine the Group characteristics that correspond to
store the samples as indicated in 8.3.2, 8.3.3, and Table 2. All
the sample to be tested (see Table 1). Where the procedure is
samples shall be stored away from direct sunlight or sources of
dependent upon the group, the section headings will be so
direct heat.
marked.
8.3.2 Group 1—Store the sample at a temperature below
10 °C.
8.2 Sampling:
8.2.1 Sampling shall be done in accordance with Practice
NOTE 7—If there are no, or inadequate, facilities for storage below
D4057 or D4177 and as described in Table 2.
10°C, the sample may also be stored at a temperature below 20 °C,
8.2.1.1 Group 1—Condition the sample container to below provided the operator ensures that the sample container is tightly closed
and leak-free.
10 °C, preferably by filling the container with the cold liquid
sample and discarding the first sample. If this is not possible
8.3.3 Group 2—Store the sample at a temperature below
because, for instance, the product to be sampled is at ambient
10 °C.
temperature, the sample shall be drawn into a container and
NOTE 8—If there are no, or inadequate, facilities for storage below
then discarded, to condition the container, and then refilled in
10 °C, the sample may also be stored at a temperature below 20 °C,
such a manner that agitation is kept at a minimum. Close the
provided the operator ensures that the sample container is tightly closed
container immediately with a tight-fitting closure. and leak-free.
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TABLE 2 Sampling, Storage, and Sample Conditioning
Group 1 Group 2 Group 3 Group 4
A
Temperature of sample container °C <10
A
°F <50
B
Temperature of stored sample °C <10 <10 ambient ambient
B
°F <50 <50 ambient ambient
C C
Temperature of sample after °C <10 <10 Ambient or Ambient or
D
conditioning prior to analysis 9 °C to 21 °C above pour point
°F <50 <50 Ambient or Ambient or
D
48 °F to 70 °F above pour point
If sample is wet resample resample dry in accordance with 8.5.3
E
If resample is still wet dry in accordance with 8.5.2
A
If sample is warmer than 10 °C, see 8.2.1.1.
B
Under certain circumstances, samples can also be stored at temperatures below 20 °C (68 °F). See also 8.3.2 and 8.3.3.
C
If sample is to be immediately tested and is already at the temperature prescribed in Table 3, see 8.4.1.1.
D
If sample is (semi)-solid at ambient temperature, see also 11.3.1.1.
E
If sample is known to be wet, resampling may be omitted. Dry sample in accordance with 8.5.2 and 8.5.3.
8.3.4 Groups 3 and 4—Store the sample at ambient or lower drous sodium sulfate per 100 mL of sample, shaking the
temperature. mixture for approximately 2 min, and then allowing the mix-
ture to settle for approximately 15 min. Once the sample shows
8.4 Sample Conditioning Prior to Analysis:
no visible signs of water, use a decanted portion of the sample,
8.4.1 Samples shall be conditioned to the temperature
maintained between 1 °C and 10 °C, for the analysis. Note in
shown in Table 2 before opening the sample container.
the report that the sample has been dried by the addition of a
8.4.1.1 Groups 1 and 2—Samples shall be conditioned to a
desiccant.
temperature of less than 10 °C (50 °F) before opening the
sample container, except when the sample is to be immediately
NOTE 9—Suspended water in hazy samples in Groups 1 and 2 can be
removed by the addition of anhydrous sodium sulfate and separating the
tested and is already at the prescribed sample temperature in
liquid sample from the drying agent by decanting without statistically
Table 3.
affecting the results of the test.
8.4.1.2 Groups 3 and 4—If the sample is not fluid at ambient
8.5.3 Groups 3 and 4—In cases in which a water-free
temperature, it is to be heated to a temperature of 9 °C to 21 °C
sample is not practical, the suspended water can be removed by
above its pour point (Test Method D97, D5949, or D5985)
shaking the sample with anhydrous sodium sulfate or other
prior to analysis. If the sample has partially or completely
suitable drying agent and separating it from the drying agent by
solidified during storage, it shall be vigorously shaken after
decanting. Note in the report that the sample has been dried by
melting prior to opening the sample container to ensure
the addition of a desiccant.
homogeneity.
8.4.1.3 If the sample is not fluid at room temperature, the
9. Preparation of Apparatus
temperature ranges shown in Table 2 for the flask and for the
9.1 Refer to Table 3 and prepare the apparatus by choosing
sample do not apply.
the appropriate distillation flask, temperature measuring
8.5 Wet Samples:
device, and flask support board, as directed for the indicated
8.5.1 Samples of materials that visibly contain water are not
group. Bring the temperature of the receiving cylinder, the
suitable for testing. If the sample is not dry, obtain another
flask, and the condenser bath to the indicated temperature.
sample that is free from suspended water.
8.5.2 Groups 1 and 2—If such a sample cannot be obtained,
Supporting data have been filed at ASTM International Headquarters and may
the suspended water can be removed by maintaining the
be obtained by requesting Research Report RR:D02-1455. Contact ASTM Customer
sample at 0 °C to 10 °C, adding approximately 10 g of anhy-
Service at [e-mail].
TABLE 3 Preparation of Apparatus and Specimen
Group 1 Group 2 Group 3 Group 4
Flask, mL 125 125 125 125
ASTM distillation thermometer 7C (7F) 7C (7F) 7C (7F) 8C (8F)
IP distillation thermometer range low low low high
Flask support board B B C C
diameter of hole, mm 38 38 50 50
Temperature at start of test
Flask °C 13–18 13–18 13–18 not above
°F 55–65 55–65 55–65 ambient
Flask support and shield not above not above not above
ambient ambient ambient
Receiving cylinder and sample
A A
°C 13–18 13–18 13–18 13–ambient
A A
°F 55–65 55–65 55–65 55–ambient
A
See 11.3.1.1 for exceptions.
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system simulates the temperature lag of a liquid-in-glass thermometer.
9.2 Make any necessary provisions so that the temperature
of the condenser bath and the receiving cylinder will be
10.2.3 Verification of the calibration of the temperature
maintained at the required temperatures. The receiving cylin-
measuring devices at elevated temperature may be conducted
der shall be in a bath such that either the liquid level is at least
by distilling hexadecane (see Section 7) in accordance with
as high as the 100 mL mark or the entire receiving cylinder is
Group 4 of this test method and comparing the 50 % corrected
surrounded by an air circulation chamber.
recovered temperature with that shown in Table 4.
9.2.1 Groups 1, 2, and 3—Suitable media for low tempera-
NOTE 11—Because of the high melting point of hexadecane, Group 4
ture baths include, but are not limited to, chopped ice and
verification distillations will have to be carried out with condenser
water, refrigerated brine, and refrigerated ethylene glycol.
temperatures >20 °C.
9.2.2 Group 4—Suitable media for ambient and higher bath
10.2.4 When the verification temperature reading(s) is not
temperatures include, but are not limited to, cold water, hot
within the values shown in Table 4 for the respective apparatus
water, and heated ethylene glycol.
being used (see Note 12 and Table 4), the temperature
9.3 Remove any residual liquid in the condenser tube by
measurement system shall be considered defective and shall
swabbing with a piece of soft, lint-free cloth attached to a cord
not be used for the test. Replace the electronic temperature
or wire.
measuring device or adjust the temperature measuring system
electronics involved, or both, as needed. Consult the apparatus
10. Verification
manufacturer.
10.1 Temperature Measurement System—Temperature mea-
NOTE 12—At 101.3 kPa, toluene is shown in reference manuals as
surement systems using other than the specified mercury-in-
boiling at 110.6 °C when measured using a partial immersion thermom-
glass thermometers shall exhibit the same temperature lag,
eter. Because this test method uses thermometers calibrated for total
emergent stem effect, and accuracy as the equivalent mercury-
immersion, the results typically will be lower and, depending on the
in-glass thermometer.
thermometer and the situation, may be different for each thermometer. At
101.3 kPa, hexadecane is shown in reference manuals as boiling at
10.2 Confirmation of the calibration of these temperature
287.0 °C when measured using a partial immersion thermometer. Because
measuring systems shall be made at intervals of not more than
this test method uses thermometers calibrated for total immersion, the
six months, and after the temperature system or temperature
results typically will be lower, and, depending on the thermometer and the
measuring device has been replaced or repaired. situation, may be different for each thermometer.
10.2.1 The accuracy and the calibration of the electronic
10.3 Verification of the dynamic response of the tempera-
circuitry or computer algorithms, or both, shall be verified by
ture measurement system (including temperature lag, emergent
the use of a standard precision resistance bench. When per-
stem effect, and accuracy) shall be conducted at least once per
forming this verification, no algorithms shall be used to correct
year, or when the temperature measuring system is repaired or
the temperature for lag and the emergent stem effect (see
replaced, by distilling a check standard(s) (see Section 7) in the
manufacturer’s instructions).
temperature range(s) of typical use for the apparatus, in
10.2.2 Verification of the calibration of temperature measur-
accordance with Annex A3.
ing devices shall be conducted by distilling toluene (see
10.4 Once the performance of the apparatus has been
Section 7) in accordance with Group 1 of this test method and
verified, secondary working standards (SWS) can be deter-
comparing the 50 % corrected recovered temperature with that
mined. These secondary materials can then be utilized for more
shown in Table 4.
frequent performance checks (see 7.2).
NOTE 10—Toluene is used as a verification fluid for calibration; it will
yield almost no information on how well an electronic measurement 10.5 Automated Method:
10.5.1 Level Follower—For an automated distillation
apparatus, the level follower/recording mechanism of the
Supporting data have been filed at ASTM International Headquarters and may
apparatus shall have a resolution of 0.1 % volume or better
be obtained by requesting Research Report RR:D02-1580. Contact ASTM Customer
with a maximum error of 0.3 % volume between the 5 % and
Service at [e-mail].
A
TABLE 4 True and Min and Max D86 50 % Corrected Recovered Boiling Points (°C)
Manual Automated
Distillation con- Distillation Distillation condi- Distillation con-
ditions min D86 conditions tions min D86 ditions max
50 % boiling max D86 50 % boiling D86 50 % boil-
point 50 % boiling point ing point
point
ASTM/IP true boil- Group 1, 2, and Group 1, 2, Group 1, 2, and Group 1, 2,
Toluene ing point 3 and 3 3 and 3
110.6 105.9 111.8 108.5 109.7
ASTM/IP true boil- Group 4 Group 4 Group 4 Group 4
Hexadecane ing point
287.0 272.2 283.1 277.0 280.0
A
The manual and automated temperatures show in this table are the values for the 95 % tolerance interval for the 99 % population coverage. The proposed tolerance
is approximately 3× sigma. Information on the values in this table can be found in RR:D02-1580.
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D86 − 23a
100 % volume points. The calibration of the assembly shall be with the highest point on the bottom of the inner wall of the
verified in accordance with manufacturer’s instructions at vapor tube (see Fig. 5). In the case of a thermocouple or
intervals of not more than three months and after the system resistance thermometer, follow the manufacturer’s instructions
has been replaced or repaired. as to placement (see Fig. 6).
NOTE 13—The typical calibration procedure involves verifying the
NOTE 16—If vacuum grease is used on the mating surface of the
output with the receiver containing 5 % and 100 % volume of material centering device, use the minimum amount of grease that is practical.
respectively.
11.6 Fit the flask vapor tube, provided with a snug-fitting
10.5.2 Barometric Pressure—At intervals of not more than
cork or rubber stopper of silicone, or equivalent polymeric
six months, and after the system has been replaced or repaired,
material, tightly into the condenser tube. Adjust the flask in a
the barometric reading of the instrument shall be verified
vertical position so that the vapor tube extends into the
against a barometer, as described in 6.6.
condenser tube for a distance from 25 mm to 50 mm. Raise and
adjust the flask support board to fit it snugly against the bottom
11. Procedure
of the flask.
11.1 Record the prevailing barometric pressure.
11.7 Place the receiving cylinder that was used to measure
11.2 Groups 1 and 2—Ensure that the sample is conditioned
the specimen, without drying the inside of the cylinder, into its
in accordance with Table 2. Fit a low range thermometer
temperature-controlled bath under the lower end of the con-
provided with a snug-fitting cork or stopper of silicone rubber,
denser tube. The end of the condenser tube shall be centered in
or equivalent polymeric material, tightly into the neck of the
the receiving cylinder and shall extend therein for a distance of
sample container and bring the temperature of the sample to the
at least 25 mm, but not below the 100 mL mark.
temperature indicated in Table 3.
11.8 Initial Boiling Point:
11.3 Groups 1, 2, 3, and 4—Check that the temperature of
11.8.1 Manual Method—To reduce evaporation loss of the
the sample is as shown in Table 3. Pour the specimen precisely
distillate, cover the receiving cylinder with a piece of blotting
to the 100 mL mark of the receiving cylinder, and transfer the
paper, or similar material, that has been cut to fit the condenser
contents of the receiving cylinder as completely as practical
tube snugly. If a receiver deflector is being used, start the
into the distillation flask, ensuring that none of the liquid flows
distillation with the tip of the deflector just touching the wall of
into the vapor tube.
the receiving cylinder. If a receiver deflector is not used, keep
NOTE 14—It is important that the difference between the temperature of
the drip tip of the condenser away from the wall of the
the specimen and the temperature of the bath around the receiving cylinder
receiving cylinder. Note the start time. Observe and record the
is as small as practically possible. A difference of 5 °C can make a
IBP to the nearest 0.5 °C (1.0 °F). If a receiver deflector is not
difference of 0.7 mL.
being used, immediately move the receiving cylinder so that
11.3.1 Groups 3 and 4—If the sample is not fluid at ambient
the tip of the condenser touches its inner wall.
temperature, it is to be heated to a temperature between 9 °C
11.8.2 Automated Method—To reduce evaporation loss of
and 21 °C above its pour point (Test Methods D97, D5949,
the distillate, use the device provided by the instrument
D5950, or D5985) prior to analysis. If the sample has partially
manufacturer for this purpose. Apply heat to the distillation
or completely solidified in the intervening period, it shall be
flask and contents with the tip of the receiver deflector just
vigorously shaken after melting, and prior to sampling, to
touching the wall of the receiving cylinder. Note the start time.
ensure homogeneity.
Record the IBP to the nearest 0.1 °C (0.2 °F).
11.3.1.1 If the sample is not fluid at ambient temperatures,
11.9 Regulate the heating so that the time interval between
disregard the temperature range shown in Table 3 for the
the first application of heat and the IBP is as specified in
receiving cylinder and sample. Prior to analysis, heat the
Table 5.
receiving cylinder to approximately the same temperature as
the sample. Pour the heated specimen precisely to the 100 mL
11.10 Regulate the heating so that the time from IBP to 5 %
mark of the receiving cylinder, and transfer the contents of the
recovered is as indicated in Table 5.
receiving cylinder as completely as practical into the distilla-
11.11 Continue to regulate the heating so that the uniform
tion flask, ensuring that none of the liquid flows into the vapor
average rate of condensation from 5 % recovered to 5 mL
tube.
residue in the flask is 4 mL to 5 mL per minute. (Warning—
NOTE 15—Any material that evaporates during the transfer will
Due to the configuration of the boiling flask and the conditions
contribute to the loss; any material that remains in the receiving cylinder
of the test, the vapor and liquid around the temperature sensor
will contribute to the observed recovery volume at the time of the IBP.
are not in thermodynamic equilibrium. The distillation rate will
11.4 If the sample can be expected to demonstrate irregular
consequently have an effect on the measured vapor tempera-
boiling behavior, that is, bumping, add a few boiling chips to
ture. The distillation rate shall, therefore, be kept as constant as
the specimen. The addition of a few boiling chips is acceptable
possible throughout the test.)
for any distillation.
11.11.1 In the context of this test method, “uniform average
11.5 Fit the temperature sensor through a snug-fitting rate of condensation” has the following intention. Heating of
device, as described in 6.4, to mechanically center the sensor in the boiling flask shall be regulated to maintain as best as
the neck of the flask. In the case of a thermometer, the bulb is possible a uniform flow of condensation, which will then
centered in the neck and the lower end of the capillary is level provide the most desired precision for the test. However, some
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D86 − 23a
FIG. 6 Example of One Manufacturer’s Recommended Placement
of Pt-100 Probe Relative to Distillation Flask Sidearm for Auto-
mated D86 Distillation Instrument
TABLE 5 Conditions During Test Procedure
Group 1 Group 2 Group 3 Group 4
A
Temperature of cooling bath °C 0–1 0–5 0–5 0–60
°F 32–34 32–40 32–40 32–140
Temperature of bath around °C 13–18 13–18 13–18 ±3
receiving cylinder °F 55–65 55–65 55–65 ±5
of charge
temperature
Time from first application of heat to
initial boiling point, min 5–10 5–10 5–10 5–15
Time from initial boiling point
to 5 % recovered, s 60–100 60–100
Uniform average rate of condensation
from 5 % recovered to 5 mL
in flask, mL/min 4–5 4–5 4–5 4–5
Time recorded from 5 mL residue to
end point, min 5 max 5 max 5 max 5 max
A
The proper condenser bath temperature will depend upon the wax content of the sample and of its distillation fractions. The test is generally performed using one single
condenser temperature. Wax formation in the condenser can be deduced from (a) the presence of wax particles in the distillate coming off the drip tip, (b) a higher distillation
loss than what would be expected based on the initial boiling point of the specimen, (c) an erratic recovery rate and (d) the presence of wax particles during the removal
of residual liquid by swabbing with a lint-free cloth (see 9.3). The minimum temperature that permits satisfactory operation shall be used. In general, a bath temperature
in the 0 °C to 4 °C range is suitable for kerosine, Grade No. 1 fuel oil and Grade No. 1-D diesel fuel oil. In some cases involving Grade No. 2 fuel oil, Grade No. 2-D diesel
fuel oil, gas oils and similar distillates, it may be necessary to hold the condenser bath temperature in the 38 °C to 60 °C range.
distillation tests can have one or more short-term rates of occur over the entire range of condensation. Typically, these
condensation which deviate from the 4 mL ⁄min to 5 mL ⁄min short-term deviations should not occur for more than ten
indicated in 11.11 and Table 5, this is a common occurrence for contiguous percent volume. The precision of the temperature
some sample types. The periods of these short-term deviations readings will be significantly affected during these periods.
may last for several percent of material condensed until the When the overall calculated average rate of condensation
temperature slope becomes constant again, and may occur at between 5 % recovered and 5 mL residue is within the pre-
several periods along the entire condensation range. These scribed rate, the requirement of 11.11 and Table 5 is satisfied.
deviations will typically correct after the temperature slope As example, those samples containing a 10 % ethanol-fuel
again becomes constant. These short-term deviations shall not blend or those that exhibit a significant change of temperature
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D86 − 23a
slope at points during the distillation can have a short-term rate Change of Slope F 5 (2)
~ !
of condensation which deviates from the 4 mL ⁄min to
~F 2 F !/~V 2 V ! 2 ~F 2 F !/~V 2 V !
2 1 2 1 3 2 3 2
5 mL ⁄min indicated in 11.11 and Table 5.
where:
NOTE 17—When testing gasoline samples, it is not uncommon to see
the condensate suddenly form non-miscible liquid phases and bead up on C = temperature at the volume % recorded one reading
the temperature measuring device and in the neck of the boiling flask at a
prior to the volume % in question, °C,
vapor temperature of around 160 °C. This may be accompanied by a sharp
C = temperature at the volume % recorded in question, °C,
(about 3 °C) dip in the vapor temperature and a drop in the recovery rate.
The phenomenon, which may be due to the presence of trace water in the
C = temperature at the volume % recorded following the
sample, may last for 10 s to 30 s before the temperature recovers and the
volume % in question, °C,
condensate starts flowing smoothly again. This point is sometimes
colloquially referred to as the Hesitation Point.
F = temperature
...