ASTM D6377-20

Standard Test Method for Determination of Vapor Pressure of Crude Oil: VPCR<inf>x</inf > (Expansion Method)

SIGNIFICANCE AND USE
5.1 Vapor pressure of crude oil at various V/Ls is an important physical property for shipping and storage.
Note 2: A vapor-liquid ratio of 0.02:1 (X = 0.02) mimics closely the situation of an oil tanker.  
5.2 Vapor pressure of crude oil is important to crude oil producers and refiners for general handling and initial refinery treatment.  
5.3 The vapor pressure determined by this test method at a vapor-liquid ratio of 4:1 (VPCR4) of crude oil at 37.8 °C can be related to the vapor pressure value determined on the same material when tested by Test Method D323 (see Appendix X1).  
5.4 Air saturation of crude oil shall not be done to avoid potential vapor loss. However air saturation of the chilled verification fluid is mandatory (see 7.2 and Section 11).  
5.5 This test method can also be applied in online applications.
SCOPE
1.1 This test method covers the use of automated vapor pressure instruments to determine the vapor pressure exerted in vacuum of crude oils. This test method is suitable for testing samples that exert a vapor pressure between 25 kPa and 180 kPa at 37.8 °C at vapor-liquid ratios from 4:1 and 0.02:1 (X = 4 and 0.02).
Note 1: This test method is suitable for the determination of the vapor pressure of crude oils at temperatures from 0 °C to 100 °C and pressures up to 500 kPa, but the precision and bias statements (see Section 14) may not be applicable. The current precision of the method is limited at vapor-liquid ratios of 0.02 and 4. (Section 14 is inclusive of vapor-liquid ratios of 0.02 and 4).  
1.2 This test method also allows the determination of vapor pressure for crude oil samples having pour points above 15 °C provided the proper sample handling, transfer, and analysis procedures are followed.  
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 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 7.2.1 – 7.3.2.  
1.5 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.

General Information

• Status: Published
• Publication Date: 31-May-2020
• ICS: 75.040 - Crude petroleum
• Technical Committee: D02 - Petroleum Products, Liquid Fuels, and Lubricants
• Drafting Committee: D02.08 - Volatility

Relations

• 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 D2892-23 - Standard Test Method for Distillation of Crude Petroleum (15-Theoretical Plate Column)
• Effective Date: 01-Nov-2023
• Refers: ASTM D5842-23 - Standard Practice for Sampling and Handling of Fuels for Volatility Measurement
• Effective Date: 01-Oct-2023
• Refers: ASTM D2892-20 - Standard Test Method for Distillation of Crude Petroleum (15-Theoretical Plate Column)
• Effective Date: 01-Jun-2020
• Refers: ASTM D5842-19 - Standard Practice for Sampling and Handling of Fuels for Volatility Measurement
• Effective Date: 01-Nov-2019
• Refers: ASTM D6708-19 - 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-2019
• Refers: ASTM D5191-18a - Standard Test Method for Vapor Pressure of Petroleum Products and Liquid Fuels (Mini Method)
• Effective Date: 01-Dec-2018
• Refers: ASTM D2892-18 - Standard Test Method for Distillation of Crude Petroleum (15-Theoretical Plate Column)
• Effective Date: 01-Apr-2018
• Refers: ASTM D6708-18 - 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-Apr-2018
• Refers: ASTM D2892-17 - Standard Test Method for Distillation of Crude Petroleum (15-Theoretical Plate Column)
• Effective Date: 01-May-2017
• Refers: ASTM D5853-16 - Standard Test Method for Pour Point of Crude Oils
• Effective Date: 01-Dec-2016
• Refers: ASTM D2892-16 - Standard Test Method for Distillation of Crude Petroleum (15-Theoretical Plate Column)
• Effective Date: 01-Dec-2016
• Refers: ASTM D6708-16a - 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-Apr-2016
• Refers: ASTM D6708-16 - 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-Jan-2016
• Refers: ASTM D6708-15 - 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-Jul-2015

Overview

ASTM D6377-20 is the internationally recognized standard test method for the determination of vapor pressure of crude oil using automated vapor pressure instruments, specifically referencing the Vapor Pressure of Crude Oil (VPCR_x) by the expansion method. This standard is essential for crude oil producers, refiners, and those involved in shipping and storage, providing a reliable process to assess key volatility properties of crude oils under conditions simulating real-world handling and transport.

Vapor pressure is a critical physical property affecting the safety, handling, and compliance of crude oil during storage and shipment. ASTM D6377-20 covers procedures to determine vapor pressures for a wide range of crude oils, including those with high pour points, across vapor-liquid ratios (V/L) from 4:1 to 0.02:1 and at temperatures from 0 °C to 100 °C.

Key Topics

• Vapor Pressure Measurement: Determines the equilibrium pressure in an evacuated chamber at a specific V/L ratio and temperature using automated equipment.
• Applicability: Suitable for crude oil samples with vapor pressures between 25 kPa and 180 kPa at 37.8 °C and pour points above 15 °C when proper procedures are followed.
• Vapor-Liquid Ratio (V/L): Test results typically reported at V/L ratios of 0.02:1 (simulating oil tankers) and 4:1 (comparable to legacy methods), providing flexible relevance to various shipping and handling scenarios.
• Sample Handling: Emphasizes meticulous sampling techniques to preserve the integrity of live and dead crude oil samples, using practices such as D3700, D8009, or D4057 as appropriate.
• Automated Instrumentation: Uses a chamber with a movable piston, integrated temperature and pressure controls, and in-line sample management to ensure accurate reproducibility.
• Safety and Quality Control: Stresses the need for pure reagents and robust calibration and verification with known-standard fluids to maintain accuracy and operational safety.

Applications

ASTM D6377-20 finds practical value across several domains:

• Crude Oil Shipping and Storage: Accurate vapor pressure determination is crucial for regulatory compliance, transportation safety, and minimizing vapor losses under dynamic storage and shipping conditions.
• Refinery Operations: Assists in general handling and initial refinery treatment by predicting how crude oil will behave during storage, blending, and processing.
• Regulatory Reporting: The standardized vapor pressure data support compliance with regional and international health, safety, and environmental regulations.
• Testing Versatility: Suitable for both laboratory and on-line process monitoring, facilitating real-time process control and quality assurance.
• Compatibility: Provides a relationship between results from this method (VPCR₄ at 37.8 °C) and those obtained from other established standards (such as ASTM D323), aiding laboratories in transitioning between methods or comparing legacy results.
• Variety of Crude Oils: Can be applied to both live and dead crude oil, and accommodates samples with elevated pour points by stipulating appropriate handling protocols.

Related Standards

This method references and aligns with a suite of ASTM standards relevant to petroleum sampling and vapor pressure measurement, supporting comprehensive and harmonized petroleum testing programs:

• ASTM D323: Test Method for Vapor Pressure of Petroleum Products (Reid Method)
• ASTM D4057: Practice for Manual Sampling of Petroleum and Petroleum Products
• ASTM D4177: Practice for Automatic Sampling of Petroleum and Petroleum Products
• ASTM D5191: Test Method for Vapor Pressure of Petroleum Products and Liquid Fuels (Mini Method)
• ASTM D5842: Practice for Sampling and Handling of Fuels for Volatility Measurement
• ASTM D5853: Test Method for Pour Point of Crude Oils
• ASTM D6708: Practice for Statistical Assessment and Improvement of Agreement Between Test Methods
• ASTM D7975: Test Method for Vapor Pressure of Crude Oil - Manual Expansion Field Method
• ASTM D8009: Practice for Manual Piston Cylinder Sampling for Volatile Crude Oils

Keywords: ASTM D6377, vapor pressure, crude oil, VPCR, expansion method, volatility measurement, petroleum testing, shipping and storage compliance, refinery operations, vapor-liquid ratio.

By following ASTM D6377-20, organizations can ensure accurate, reliable, and standardized vapor pressure data for crude oil, supporting operational safety, regulatory compliance, and quality control in the petroleum industry.

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: D6377 − 20
Standard Test Method for
Determination of Vapor Pressure of Crude Oil:
VPCR (Expansion Method)
x
This standard is issued under the fixed designation D6377; 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.
1. Scope* 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method covers the use of automated vapor
D323 TestMethodforVaporPressureofPetroleumProducts
pressureinstrumentstodeterminethevaporpressureexertedin
(Reid Method)
vacuum of crude oils. This test method is suitable for testing
D2892 Test Method for Distillation of Crude Petroleum
samples that exert a vapor pressure between 25 kPa and
(15-Theoretical Plate Column)
180 kPa at 37.8 °C at vapor-liquid ratios from 4:1 and 0.02:1
D3700 Practice for Obtaining LPG Samples Using a Float-
(X = 4 and 0.02).
ing Piston Cylinder
NOTE 1—This test method is suitable for the determination of the vapor
pressure of crude oils at temperatures from 0 °C to 100 °C and pressures
D4057 Practice for Manual Sampling of Petroleum and
up to 500 kPa, but the precision and bias statements (see Section 14) may
Petroleum Products
not be applicable. The current precision of the method is limited at
D4177 Practice for Automatic Sampling of Petroleum and
vapor-liquid ratios of 0.02 and 4. (Section 14 is inclusive of vapor-liquid
Petroleum Products
ratios of 0.02 and 4).
D5191 Test Method for Vapor Pressure of Petroleum Prod-
1.2 This test method also allows the determination of vapor
ucts and Liquid Fuels (Mini Method)
pressure for crude oil samples having pour points above 15 °C
D5842 Practice for Sampling and Handling of Fuels for
provided the proper sample handling, transfer, and analysis
Volatility Measurement
procedures are followed.
D5853 Test Method for Pour Point of Crude Oils
1.3 The values stated in SI units are to be regarded as D6708 Practice for StatisticalAssessment and Improvement
standard. No other units of measurement are included in this of Expected Agreement Between Two Test Methods that
standard. Purport to Measure the Same Property of a Material
D7975 Test Method for Determination of Vapor Pressure of
1.4 This standard does not purport to address all of the
Crude Oil: VPCR -F(Tm°C) (Manual Expansion Field
x
safety concerns, if any, associated with its use. It is the
Method)
responsibility of the user of this standard to establish appro-
D8009 Practice for Manual Piston Cylinder Sampling for
priate safety, health, and environmental practices and deter-
Volatile Crude Oils, Condensates, and Liquid Petroleum
mine the applicability of regulatory limitations prior to use.
Products
For specific warning statements, see 7.2.1 – 7.3.2.
1.5 This international standard was developed in accor-
3. Terminology
dance with internationally recognized principles on standard-
3.1 Definitions:
ization established in the Decision on Principles for the
3.1.1 platinum resistance thermometer, n—temperature
Development of International Standards, Guides and Recom-
measuring device constructed with a length of platinum wire,
mendations issued by the World Trade Organization Technical
whose electrical resistance changes in relation to temperature.
Barriers to Trade (TBT) Committee.
3.1.2 vapor-liquid ratio (V/L), n—the ratio of the vapor
volumetotheliquidvolumeofspecimen,inequilibrium,under
specified conditions.
This test method is under the jurisdiction of ASTM Committee D02 on
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
Subcommittee D02.08 on Volatility. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved June 1, 2020. Published June 2020. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1999. Last previous edition approved in 2016 as D6377 – 16. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D6377-20. 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
D6377 − 20
NOTE 2—A vapor-liquid ratio of 0.02:1 (X = 0.02) mimics closely the
3.2 Definitions of Terms Specific to This Standard:
situation of an oil tanker.
3.2.1 dead crude oil, n—crude oil with sufficiently low
vapor pressure that, when exposed to normal atmospheric 5.2 Vapor pressure of crude oil is important to crude oil
pressure at room temperature, does not result in boiling of the producers and refiners for general handling and initial refinery
sample. treatment.
3.2.1.1 Discussion—Sampling and handling of dead crude
5.3 The vapor pressure determined by this test method at a
oils can usually be done without loss of sample integrity or
vapor-liquidratioof4:1(VPCR )ofcrudeoilat37.8 °Ccanbe
other problems by using normal, non-pressurized sample
related to the vapor pressure value determined on the same
containers such as cans.
materialwhentestedbyTestMethodD323(seeAppendixX1).
3.2.2 livecrudeoil,n—crudeoilwithsufficientlyhighvapor
5.4 Air saturation of crude oil shall not be done to avoid
pressure that it would boil if exposed to normal atmospheric
potential vapor loss. However air saturation of the chilled
pressure at room temperature.
verification fluid is mandatory (see 7.2 and Section 11).
3.2.2.1 Discussion—Sampling and handling live crude oils
5.5 This test method can also be applied in online applica-
requires a pressurized sample system and pressurized sample
tions.
containers to ensure sample integrity and prevent loss of
volatile components.
6. Apparatus
3.2.3 Reid vapor pressure equivalent (RVPE), n—a value
6.1 The apparatus suitable for this test method employs a
calculatedbyadefinedcorrelationequation(seeEqX1.1)from
small volume, cylindrically shaped measuring chamber with
VPCR at37.8 °Cthatisexpectedtobeequivalenttothevapor
associated equipment to control the chamber temperature
pressure value obtained by Test Method D323.
within the range from 0 °C to 100 °C. The measuring chamber
3.2.3.1 Discussion—As noted in 14.3 and Appendix X1,
shallcontainamovablepistonwithaminimumdeadvolumeof
subsection X1.2, since Eq X1.1 for estimating RVPE is not
lessthan1 %ofthetotalvolumeatthelowestpositiontoallow
universally applicable to all crude oils, it is recommended to
sampleintroductionintothemeasuringchamberandexpansion
report the VPCR (37.8 °C) result for a crude oil sample.
to the desired V/L. A static pressure transducer shall be
3.2.4 vapor pressure of crude oil (VPCR ,n—the pressure
x)
incorporated in the piston. The measuring chamber shall
exerted in an evacuated chamber at a vapor-liquid ratio of X:1
contain an inlet/outlet valve combination for sample introduc-
by conditioned or unconditioned crude oil, which may contain
tion and expulsion. The piston and the valve combination shall
gas, air or water, or a combination thereof, where X may vary
be at the same temperature as the measuring chamber to avoid
from 4 to 0.02.
any condensation or excessive evaporation.
3.3 Abbreviations: 6.1.1 The measuring chamber shall be designed to have a
3.3.1 ARV, n—accepted reference value total volume of 5 mL to 15 mL and shall be capable of
maintaining a V/L of 4:1 to 0.02:1. The accuracy of the
3.3.2 RVPE, n—Reid vapor pressure equivalent
adjusted V/L shall be within 0.01.
3.3.3 V/L, n—vapor liquid ratio
NOTE3—Themeasuringchambersemployedbytheinstrumentsusedin
3.3.4 VPCR,n—vapor pressure of crude oil at x vapor
x
generating the precision and bias statements were constructed of nickel
liquid ratio
plated aluminium, stainless steel and brass with a total volume of 5 mL.
Measuring chambers exceedinga5mL capacity and different design can
4. Summary of Test Method
be used, but the precision and bias statement (see Section 14) may not be
4.1 Employing a measuring chamber with a built-in piston,
applicable.
a sample of known volume is drawn from the sample container
6.1.2 The pressure transducer shall have a minimum opera-
into the temperature controlled chamber at 20 °C or higher.
tional range from 0 kPa to 500 kPa with a minimum resolution
After sealing the chamber, the volume is expanded by moving
of 0.1 kPa and a minimum accuracy of 60.5 kPa.The pressure
the piston until the final volume produces the desired V/L
measurement system shall include associated electronics and
value. The temperature of the measuring chamber is then
readout devices to display the resulting pressure reading.
regulated to the measuring temperature.
6.1.3 Electronic temperature control shall be used to main-
4.2 After temperature and pressure equilibrium, the mea-
tain the measuring chamber at the prescribed temperature
sured pressure is recorded as the VPCR of the sample. The
within 60.1 °C for the duration of the test.
X
test specimen shall be mixed during the measuring procedure
6.1.4 A platinum resistance thermometer shall be used for
by shaking the measuring chamber to achieve pressure equi-
measuring the temperature of the measuring chamber. The
librium in a reasonable time of 5 min to 30 min.
minimum temperature range of the measuring device shall be
from 0 °C to 100 °C with a resolution of 0.1 °C and an
4.3 For results related to Test Method D323, the final
accuracy of 60.1 °C.
volume of the measuring chamber shall be five times the test
6.1.5 Thevaporpressureapparatusshallhaveprovisionsfor
specimen volume and the measuring temperature shall be
rinsing the measuring chamber with the next sample to be
37.8 °C.
tested or with a solvent of low vapor pressure.
5. Significance and Use
6.1.6 Thevaporpressureapparatusshallhaveprovisionsfor
5.1 Vapor pressure of crude oil at various V/Ls is an shaking the sample during the measuring procedure with a
important physical property for shipping and storage. minimum frequency of 1.5 cycles per second.
D6377 − 20
6.2 Vacuum Pump for Calibration, capable of reducing the 7.2.1 2,2-Dimethylbutane, (Warning—2,2-dimethylbutane
pressure in the measuring chamber to less than 0.01 kPa is flammable and a health hazard.)
absolute.
7.2.2 2,3-Dimethylbutane, (Warning—2,3-dimethylbutane
is flammable and a health hazard.)
6.3 McLeod Vacuum Gage or Calibrated Electronic Vacuum
7.2.3 Pentane, (Warning—Pentane is flammable and a
Measuring Device for Calibration, to cover at least the range
health hazard.)
of 0.01 kPa to 0.67 kPa. The calibration of the electronic
measuringdeviceshallberegularlyverifiedinaccordancewith
7.3 Solvents:
Annex A of Test Method D2892.
7.3.1 Toluene, (Warning—Toluene is flammable and a
health hazard.)
6.4 Pressure Measuring Device for Calibration, capable of
7.3.2 Acetone, (Warning—Acetone is flammable and a
measuring local station pressure with an accuracy and a
health hazard.)
resolution of 0.1 kPa or better, at the same elevation relative to
sea level as the apparatus in the laboratory.
8. Sampling and Sample Introduction
NOTE 4—This standard does not give full details of instruments suitable
for carrying out this test. Details on the installation, operation and
8.1 General Requirements:
maintenance of each instrument may be found in the manufacturer’s
8.1.1 The extreme sensitivity of vapor pressure measure-
manual.
ments to losses through evaporation and the resulting changes
in composition requires the utmost precaution and the most
7. Reagents and Materials
meticulous care in the drawing and handling of samples.
7.1 Purity of Reagents—Use chemicals of at least 99 %
Sampling of live crude oil shall be performed in accordance
purity for verification of instrument performance (see Section
with Practice D3700 or Practice D8009. Sampling in accor-
11). Unless otherwise indicated, it is intended that all reagents
dance with Practice D4057 shall only be used for dead crude
conform to the specifications of the Committee on Analytical
oil and if Practice D3700 or Practice D8009 is impractical.
Reagents of the American Chemical Society where such
NOTE 5—Sampling in accordance with Practice D4177 may also be
specifications are available. Other grades may be used, pro-
used instead of Practice D4057.
videditisfirstascertainedthatthereagentisofsufficientpurity
to permit its use without lessening the accuracy of the
8.1.2 For sampling in accordance with Practice D3700,a
determination.
floating piston cylinder with a minimum sample volume of
7.1.1 The chemicals in 7.2.1, 7.2.2, and 7.2.3 are suggested
200 mLshallbeusediftheoverallvolumeofthetestspecimen
for verification of instrument performance (see Section 11),
required for the vapor pressure determination, including the
based on the air saturated reference fuels analyzed in the Test
rinsing procedure is not larger than 20 mL. Larger floating
MethodD51912003interlaboratorystudy(ILS) (seeTable1).
piston cylinders can be used. The minimum piston back-
P usedinTestMethodD5191isequivalenttoVPCR usedin
pressure shall be higher than the sample vapor pressure at the
tot 4
this test method). Such reference fuels are not to be used for
introduction temperature of the measuring chamber plus
instrumentcalibration.Table1identifiestheacceptedreference
100 kPa for the shifting of the piston. The maximum back-
value (ARV) and uncertainty limits, as well as the acceptable
pressure shall not exceed the maximum measurement pressure
testing range for each of the reference fuels listed.
of the apparatus pressure transducer. Compressed air, or any
7.1.2 The chemicals in 7.3.1 and 7.3.2 are suggested for use
other, non-flammable compressed gas, can be used as the
as rinsing solvents capable of cleaning the measuring chamber,
back-pressuring agent. The floating piston cylinder shall have
the valves and the inlet and outlet tubes.
provisions for mechanical stirring of the sample and a second
valve at the inlet for rinsing.
7.2 Verification Fluids:
8.1.3 Do not unnecessarily expose the samples to tempera-
tures exceeding 30 °C during sampling and storage. For
3 prolonged storage, store the samples in an appropriate room or
ACS Reagent Chemicals, Specifications and Procedures for Reagents and
Standard-Grade Reference Materials, American Chemical Society, Washington, refrigerator.
DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
8.1.4 Perform the vapor pressure determination on the first
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
test specimen withdrawn from the cylinder after the rinsing
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
step in 9.3. Do not use the remaining sample in the floating
copeial Convention, Inc. (USPC), Rockville, MD.
Supporting data have been filed at ASTM International Headquarters and may
piston cylinder for more than three repeat vapor pressure
beobtainedbyrequestingResearchReportRR:D02-1619.ContactASTMCustomer
determinations.
Service at [e-mail].
A
TABLE 1 Accepted Reference Value (ARV) and Acceptable Testing Range for Air Saturated Reference Fluids
Recommended Instrument Acceptable Testing Range
ARV [P ] ± Uncertainty,
tot
Reference Fluid Manufacturer Tolerance, for Reference Fuel [P ],
tot
(kPa)
(kPa) (kPa)
Pentane 112.8 ± 0.2 ± 1.0 112.8 ± 1.2 (111.6 to 114.0)
2,2 Dimethylbutane 74.1 ± 0.2 ± 1.0 74.1 ± 1.2 (72.9 to 75.3)
2,3 Dimethylbutane 57.1 ± 0.2 ± 1.0 57.1 ± 1.2 (55.9 to 58.3)
A
Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D02-1619.
D6377 − 20
8.1.5 In the case of quality control checks with pure volume of the chamber for each rinse. This rinsing procedure
compounds (see 11.1), smaller sample containers without shall always be carried out immediately before the measuring
applied pressure can be used. procedure (see Section 12).
8.2 Sampling Procedures:
10. Calibration
8.2.1 If the sample is contained in a pressurized source like
10.1 Pressure Transducer:
a pipeline, use a floating piston cylinder and obtain the sample
10.1.1 Perform a calibration check of the transducer as
directly from the source under pressure. Rinse the cylinder by
indicated from the quality control checks (see Section 11). The
opening the rinsing valve until the crude oil emerges at the
calibration of the transducer is checked using two reference
second inlet. Close the rinsing valve and let the piston move
points, zero pressure (<0.1 kPa) and the ambient barometric
slowly until at least 200 mLof sample has entered the cylinder.
pressure.
Close the inlet valve and apply the back pressure immediately.
NOTE 8—Calibration frequency of the pressure transducer may vary
Check the filling of the cylinder to be at least 200 mL.
with instrument type and frequency of use. A calibration check of the
NOTE 6—The current precision statements were derived from the 2005
pressure transducer at least once every six months is recommended.
ILS using samples in 250 mL floating piston cylinders (see 14.3).
10.1.2 Connect a McLeod gage or a calibrated electronic
8.2.2 If the sample is taken from a non-pressurized source
vacuummeasuringdevicetothevacuumsourceinlinewiththe
like a storage tank, oil tanker, drum or other container, obtain
measuring chamber (see Note 7). Apply vacuum to the mea-
asampleandtestspecimeninaccordancewithPracticeD4057.
suring chamber (see Note 9). When the vacuum measuring
Use either a 250 mLor 1 Lsized container filled between 70 %
device registers a pressure less than 0.1 kPa, adjust the
and 80 % with sample. For best testing precision
transducer control to zero or to the actual reading on the
(reproducibility), it is recommended that a 1 L sized container
vacuum measuring device as dictated by the instrument design
be used.
or manufacturer’s instructions.
NOTE 7—The current precision statements were derived from the 2005
NOTE 9—Refer toAnnexA6.3 ofTest Method D2892 for further details
ILS using samples in 1 L amber glass containers (see 14.3). However,
concerning the calibration of electronic vacuum measuring devices and
samples in containers of other sizes, as prescribed in Practice D4057, may
proper maintenance of McLeod gages.
be used with the same ullage requirement if it is recognized that the
precision can be a
...

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: D6377 − 16 D6377 − 20
Standard Test Method for
Determination of Vapor Pressure of Crude Oil:
VPCR (Expansion Method)
x
This standard is issued under the fixed designation D6377; 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.
1. Scope*
1.1 This test method covers the use of automated vapor pressure instruments to determine the vapor pressure exerted in vacuum
of crude oils. This test method is suitable for testing samples that exert a vapor pressure between 25 kPa and 180 kPa at 37.8 °C
at vapor-liquid ratios from 4:1 toand 0.02:1 (X = 4 toand 0.02).
NOTE 1—This test method is suitable for the determination of the vapor pressure of crude oils at temperatures from 0 °C to 100 °C and pressures up
to 500 kPa, but the precision and bias statements (see Section 14) may not be applicable. The current precision of the method is limited at vapor-liquid
ratios of 0.02 and 4. (Section 14 is inclusive of vapor-liquid ratios of 0.02 and 4).
1.2 This test method also allows the determination of vapor pressure for crude oil samples having pour points above 15 °C
provided the proper sample handling, transfer, and analysis procedures are followed.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. For specific warning statements, see 7.2.1 – 7.3.2.
1.5 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:
D323 Test Method for Vapor Pressure of Petroleum Products (Reid Method)
D2892 Test Method for Distillation of Crude Petroleum (15-Theoretical Plate Column)
D3700 Practice for Obtaining LPG Samples Using a Floating Piston Cylinder
D4057 Practice for Manual Sampling of Petroleum and Petroleum Products
D4177 Practice for Automatic Sampling of Petroleum and Petroleum Products
D5191 Test Method for Vapor Pressure of Petroleum Products and Liquid Fuels (Mini Method)
D5842 Practice for Sampling and Handling of Fuels for Volatility Measurement
D5853 Test Method for Pour Point of Crude Oils
D6708 Practice for Statistical Assessment and Improvement of Expected Agreement Between Two Test Methods that Purport
to Measure the Same Property of a Material
D7975 Test Method for Determination of Vapor Pressure of Crude Oil: VPCR -F(Tm°C) (Manual Expansion Field Method)
x
D8009 Practice for Manual Piston Cylinder Sampling for Volatile Crude Oils, Condensates, and Liquid Petroleum Products
3. Terminology
3.1 Definitions:
3.1.1 platinum resistance thermometer, n—temperature measuring device constructed with a length of platinum wire, whose
electrical resistance changes in relation to temperature.
This test method is under the jurisdiction of ASTM Committee D02 on Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of Subcommittee
D02.08 on Volatility.
Current edition approved April 1, 2016June 1, 2020. Published April 2016June 2020. Originally approved in 1999. Last previous edition approved in 20152016 as
D6377 – 15.D6377 – 16. DOI: 10.1520/D6377-16.10.1520/D6377-20.
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.
*A Summary of Changes section appears at the end of this standard
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D6377 − 20
3.1.2 vapor-liquid ratio (V/L), n—the ratio of the vapor volume to the liquid volume of specimen, in equilibrium, under specified
conditions.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 dead crude oil, n—crude oil with sufficiently low vapor pressure that, when exposed to normal atmospheric pressure at
room temperature, does not result in boiling of the sample.
3.2.1.1 Discussion—
Sampling and handling of dead crude oils can usually be done without loss of sample integrity or other problems by using normal,
non-pressurized sample containers such as cans.
3.2.2 live crude oil, n—crude oil with sufficiently high vapor pressure that it would boil if exposed to normal atmospheric
pressure at room temperature.
3.2.2.1 Discussion—
Sampling and handling live crude oils requires a pressurized sample system and pressurized sample containers to ensure sample
integrity and prevent loss of volatile components.
3.2.3 Reid vapor pressure equivalent (RVPE), n—a value calculated by a defined correlation equation (see Eq X1.1) from
VPCR at 37.8 °C that is expected to be equivalent to the vapor pressure value obtained by Test Method D323.
3.2.3.1 Discussion—
As noted in 14.3 and Appendix X1, subsection X1.2, since Eq X1.1 for estimating RVPE is not universally applicable to all crude
oils, it is recommended to report the VPCR (37.8 °C) result for a crude oil sample.
3.2.4 vapor pressure of crude oil (VPCR , n—the pressure exerted in an evacuated chamber at a vapor-liquid ratio of X:1 by
x)
conditioned or unconditioned crude oil, which may contain gas, air or water, or a combination thereof, where X may vary from
4 to 0.02.
3.3 Abbreviations:
3.3.1 ARV, n—accepted reference value
3.3.2 RVPE, n—Reid vapor pressure equivalent
3.3.3 V/L, n—vapor liquid ratio
3.3.4 VPCR , n—vapor pressure of crude oil at x vapor liquid ratio
x
4. Summary of Test Method
4.1 Employing a measuring chamber with a built-in piston, a sample of known volume is drawn from the sample container into
the temperature controlled chamber at 20 °C or higher. After sealing the chamber, the volume is expanded by moving the piston
until the final volume produces the desired V/L value. The temperature of the measuring chamber is then regulated to the measuring
temperature.
4.2 After temperature and pressure equilibrium, the measured pressure is recorded as the VPCR of the sample. The test
X
specimen shall be mixed during the measuring procedure by shaking the measuring chamber to achieve pressure equilibrium in
a reasonable time of 5 min to 30 min.
4.3 For results related to Test Method D323, the final volume of the measuring chamber shall be five times the test specimen
volume and the measuring temperature shall be 37.8 °C.
5. Significance and Use
5.1 Vapor pressure of crude oil at various V/Ls is an important physical property for shipping and storage.
NOTE 2—A vapor-liquid ratio of 0.02:1 (X = 0.02) mimics closely the situation of an oil tanker.
5.2 Vapor pressure of crude oil is important to crude oil producers and refiners for general handling and initial refinery
treatment.
5.3 The vapor pressure determined by this test method at a vapor-liquid ratio of 4:1 (VPCR ) of crude oil at 37.8 °C can be
related to the vapor pressure value determined on the same material when tested by Test Method D323 (see Appendix X1).
5.4 Air saturation of crude oil shall not be done to avoid potential vapor loss. However air saturation of the chilled verification
fluid is mandatory (see 7.2 and Section 11).
5.5 This test method can also be applied in online applications.
D6377 − 20
6. Apparatus
6.1 The apparatus suitable for this test method employs a small volume, cylindrically shaped measuring chamber with
associated equipment to control the chamber temperature within the range from 0 °C to 100 °C. The measuring chamber shall
contain a movable piston with a minimum dead volume of less than 1 % of the total volume at the lowest position to allow sample
introduction into the measuring chamber and expansion to the desired V/L. A static pressure transducer shall be incorporated in
the piston. The measuring chamber shall contain an inlet/outlet valve combination for sample introduction and expulsion. The
piston and the valve combination shall be at the same temperature as the measuring chamber to avoid any condensation or
excessive evaporation.
6.1.1 The measuring chamber shall be designed to have a total volume of 5 mL to 15 mL and shall be capable of maintaining
a V/L of 4:1 to 0.02:1. The accuracy of the adjusted V/L shall be within 0.01.
NOTE 3—The measuring chambers employed by the instruments used in generating the precision and bias statements were constructed of nickel plated
aluminium, stainless steel and brass with a total volume of 5 mL. Measuring chambers exceeding a 5 mL capacity and different design can be used, but
the precision and bias statement (see Section 14) may not be applicable.
6.1.2 The pressure transducer shall have a minimum operational range from 0 kPa to 500 kPa with a minimum resolution of
0.1 kPa and a minimum accuracy of 60.5 kPa. The pressure measurement system shall include associated electronics and readout
devices to display the resulting pressure reading.
6.1.3 Electronic temperature control shall be used to maintain the measuring chamber at the prescribed temperature within
60.1 °C for the duration of the test.
6.1.4 A platinum resistance thermometer shall be used for measuring the temperature of the measuring chamber. The minimum
temperature range of the measuring device shall be from 0 °C to 100 °C with a resolution of 0.1 °C and an accuracy of 60.1 °C.
6.1.5 The vapor pressure apparatus shall have provisions for rinsing the measuring chamber with the next sample to be tested
or with a solvent of low vapor pressure.
6.1.6 The vapor pressure apparatus shall have provisions for shaking the sample during the measuring procedure with a
minimum frequency of 1.5 cycles per second.
6.2 Vacuum Pump for Calibration, capable of reducing the pressure in the measuring chamber to less than 0.01 kPa absolute.
6.3 McLeod Vacuum Gage or Calibrated Electronic Vacuum Measuring Device for Calibration, to cover at least the range of
0.01 kPa to 0.67 kPa. The calibration of the electronic measuring device shall be regularly verified in accordance with Annex A
of Test Method D2892.
6.4 Pressure Measuring Device for Calibration, capable of measuring local station pressure with an accuracy and a resolution
of 0.1 kPa or better, at the same elevation relative to sea level as the apparatus in the laboratory.
NOTE 4—This standard does not give full details of instruments suitable for carrying out this test. Details on the installation, operation and maintenance
of each instrument may be found in the manufacturer’s manual.
7. Reagents and Materials
7.1 Purity of Reagents—Use chemicals of at least 99 % purity for verification of instrument performance (see Section 11).
Unless otherwise indicated, it is intended that all reagents conform to the specifications of the Committee on Analytical Reagents
of the American Chemical Society where such specifications are available. Other grades may be used, provided it is first
ascertained that the reagent is of sufficient purity to permit its use without lessening the accuracy of the determination.
7.1.1 The chemicals in 7.2.1, 7.2.2, and 7.2.3 are suggested for verification of instrument performance (see Section 11), based
on the air saturated reference fuels analyzed in the Test Method D5191 2003 interlaboratory study (ILS) (see Table 1). P used
tot
A
TABLE 1 Accepted Reference Value (ARV) and Acceptable Testing Range for Air Saturated Reference Fluids
Recommended Instrument Acceptable Testing Range
ARV [P ] ± Uncertainty,
tot
Reference Fluid Manufacturer Tolerance, for Reference Fuel [P ],
tot
(kPa)
(kPa) (kPa)
Pentane 112.8 ± 0.2 ± 1.0 112.8 ± 1.2 (111.6 to 114.0)
2,2 Dimethylbutane 74.1 ± 0.2 ± 1.0 74.1 ± 1.2 (72.9 to 75.3)
2,3 Dimethylbutane 57.1 ± 0.2 ± 1.0 57.1 ± 1.2 (55.9 to 58.3)
A
Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D02-1619.
Reagent Chemicals, American Chemical Society SpecificationsACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference
Materials, , American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for
Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC),
Rockville, MD.
Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D02-1619. Contact ASTM Customer
Service at [e-mail].
D6377 − 20
in Test Method D5191 is equivalent to VPCR used in this test method). Such reference fuels are not to be used for instrument
calibration. Table 1 identifies the accepted reference value (ARV) and uncertainty limits, as well as the acceptable testing range
for each of the reference fuels listed.
7.1.2 The chemicals in 7.3.1 and 7.3.2 are suggested for use as rinsing solvents capable of cleaning the measuring chamber, the
valves and the inlet and outlet tubes.
7.2 Verification Fluids:
7.2.1 2,2-Dimethylbutane, (Warning—2,2-dimethylbutane is flammable and a health hazard.)
7.2.2 2,3-Dimethylbutane, (Warning—2,3-dimethylbutane is flammable and a health hazard.)
7.2.3 Pentane, (Warning—Pentane is flammable and a health hazard.)
7.3 Solvents:
7.3.1 Toluene, (Warning—Toluene is flammable and a health hazard.)
7.3.2 Acetone, (Warning—Acetone is flammable and a health hazard.)
8. Sampling and Sample Introduction
8.1 General Requirements:
8.1.1 The extreme sensitivity of vapor pressure measurements to losses through evaporation and the resulting changes in
composition requires the utmost precaution and the most meticulous care in the drawing and handling of samples. Sampling of live
crude oil shall be performed in accordance with Practice D3700 or Practice D8009. Sampling in accordance with Practice D4057
shall only be used for dead crude oil and if Practice D3700 or Practice D8009 is impractical.
NOTE 5—Sampling in accordance with Practice D4177 may also be used instead of Practice D4057.
8.1.2 For sampling in accordance with Practice D3700, a floating piston cylinder with a minimum sample volume of 200 mL
shall be used if the overall volume of the test specimen required for the vapor pressure determination, including the rinsing
procedure is not larger than 20 mL. Larger floating piston cylinders can be used. The minimum piston back-pressure shall be higher
than the sample vapor pressure at the introduction temperature of the measuring chamber plus 100 kPa for the shifting of the piston.
The maximum back-pressure shall not exceed the maximum measurement pressure of the apparatus pressure transducer.
Compressed air, or any other, non-flammable compressed gas, can be used as the back-pressuring agent. The floating piston
cylinder shall have provisions for mechanical stirring of the sample and a second valve at the inlet for rinsing.
8.1.3 Do not unnecessarily expose the samples to temperatures exceeding 30 °C during sampling and storage. For prolonged
storage, store the samples in an appropriate room or refrigerator.
8.1.4 Perform the vapor pressure determination on the first test specimen withdrawn from the cylinder after the rinsing step in
9.3. Do not use the remaining sample in the floating piston cylinder for more than three repeat vapor pressure determinations.
8.1.5 In the case of quality control checks with pure compounds (see 11.1), smaller sample containers without applied pressure
can be used.
8.2 Sampling Procedures:
8.2.1 If the sample is contained in a pressurized source like a pipeline, use a floating piston cylinder and obtain the sample
directly from the source under pressure. Rinse the cylinder by opening the rinsing valve until the crude oil emerges at the second
inlet. Close the rinsing valve and let the piston move slowly until at least 200 mL of sample has entered the cylinder. Close the
inlet valve and apply the back pressure immediately. Check the filling of the cylinder to be at least 200 mL.
NOTE 6—The current precision statements were derived from the 2005 ILS using samples in 250 mL floating piston cylinders (see 14.3).
8.2.2 If the sample is taken from a non-pressurized source like a storage tank, oil tanker, drum or other container, obtain a
sample and test specimen in accordance with Practice D4057. Use either a 250 mL or 1 L sized container filled between 70 % and
80 % with sample. For best testing precision (reproducibility), it is recommended that a 1 L sized container be used.
NOTE 7—The current precision statements were derived from the 2005 ILS using samples in 1 L amber glass containers (see 14.3). However, samples
in containers of other sizes, as prescribed in Practice D4057, may be used with the same ullage requirement if it is recognized that the precision can be
affected.
8.3 Sample Transfer:
8.3.1 Transfer the sample at room temperature but at least 5 °C above the pour point (as determined by Test Method D5853)
of the sample from the container into the measuring chamber.
8.3.2 If the sample is contained in a pressurized floating piston cylinder, apply a back-pressure which is higher than the vapor
pressure of the sample at the introduction temperature plus a minimum of 100 kPa for the piston movement. The applied
back-pressure shall not exceed the maximum limit of the pressure transducer used in the vapor pressure apparatus.
8.3.3 If the sample is contained in a nonpressurized container, transfer the sample into the measuring chamber using a transfer
tube or a syringe. Warning—If the sample flashes or outgases in the inlet line, either before or after any inlet filter or regulator,
then liquid volume to the cell is reduced and measured vapor pressure is falsely low. If flashing or outgassing occurs, results are
no longer valid under D6377.
D6377 − 20
9. Preparation of Apparatus
9.1 Prepare the instrument for operation in accordance with the manufacturer’s instructions.
9.2 Rinse the measuring chamber, if necessary with a solvent.
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