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:
VPCRx (Expansion Method)1
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

1.1 This test method covers the use of automated vapor 2.1 ASTM Standards:2
pressure instruments to determine the vapor pressure exerted in D323 Test Method for Vapor Pressure of Petroleum Products
vacuum of crude oils. This test method is suitable for testing (Reid Method)
samples that exert a vapor pressure between 25 kPa and D2892 Test Method for Distillation of Crude Petroleum
180 kPa at 37.8 °C at vapor-liquid ratios from 4:1 and 0.02:1 (15-Theoretical Plate Column)
(X = 4 and 0.02). D3700 Practice for Obtaining LPG Samples Using a Float-
NOTE 1—This test method is suitable for the determination of the vapor ing Piston Cylinder
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
vapor-liquid ratios of 0.02 and 4. (Section 14 is inclusive of vapor-liquid
D4177 Practice for Automatic Sampling of Petroleum and
ratios of 0.02 and 4). Petroleum Products
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 Statistical Assessment 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
1.4 This standard does not purport to address all of the D7975 Test Method for Determination of Vapor Pressure of
safety concerns, if any, associated with its use. It is the Crude Oil: VPCRx-F(Tm°C) (Manual Expansion Field
responsibility of the user of this standard to establish appro- Method)
priate safety, health, and environmental practices and deter- D8009 Practice for Manual Piston Cylinder Sampling for
mine the applicability of regulatory limitations prior to use. Volatile Crude Oils, Condensates, and Liquid Petroleum
For specific warning statements, see 7.2.1 – 7.3.2. Products
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
volume to the liquid volume of specimen, in equilibrium, under
1
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
2
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 service@astm.org. 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
3.2 Definitions of Terms Specific to This Standard: NOTE 2—A vapor-liquid ratio of 0.02:1 (X = 0.02) mimics closely the
3.2.1 dead crude oil, n—crude oil with sufficiently low situation of an oil tanker.
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-liquid ratio of 4:1 (VPCR4) of crude oil at 37.8 °C can be
other problems by using normal, non-pressurized sample related to the vapor pressure value determined on the same
containers such as cans. material when tested by Test Method D323 (see Appendix X1).
3.2.2 live crude oil, n—crude oil with sufficiently high vapor
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
requires a pressurized sample system and pressurized sample 5.5 This test method can also be applied in online applica-
containers to ensure sample integrity and prevent loss of tions.
volatile components.
6. Apparatus
3.2.3 Reid vapor pressure equivalent (RVPE), n—a value
calculated by a defined correlation equation (see Eq X1.1) from 6.1 The apparatus suitable for this test method employs a
VPCR4 at 37.8 °C that is expected to be equivalent to the vapor small volume, cylindrically shaped measuring chamber with
pressure value obtained by Test Method D323. associated equipment to control the chamber temperature
3.2.3.1 Discussion—As noted in 14.3 and Appendix X1, within the range from 0 °C to 100 °C. The measuring chamber
subsection X1.2, since Eq X1.1 for estimating RVPE is not shall contain a movable piston with a minimum dead volume of
universally applicable to all crude oils, it is recommended to less than 1 % of the total volume at the lowest position to allow
report the VPCR4 (37.8 °C) result for a crude oil sample. sample introduction into the measuring chamber and expansion
to the desired V/L. A static pressure transducer shall be
3.2.4 vapor pressure of crude oil (VPCR x), n—the pressure 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
3.3.2 RVPE, n—Reid vapor pressure equivalent maintaining a V/L of 4:1 to 0.02:1. The accuracy of the
3.3.3 V/L, n—vapor liquid ratio adjusted V/L shall be within 0.01.
3.3.4 VPCRx, n—vapor pressure of crude oil at x vapor NOTE 3—The measuring chambers employed by the instruments used in
liquid ratio generating the precision and bias statements were constructed of nickel
plated aluminium, stainless steel and brass with a total volume of 5 mL.
4. Summary of Test Method 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
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 VPCRX of the sample. The within 60.1 °C for the duration of the test.
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
4.3 For results related to Test Method D323, the final from 0 °C to 100 °C with a resolution of 0.1 °C and an
volume of the measuring chamber shall be five times the test accuracy of 60.1 °C.
specimen volume and the measuring temperature shall be 6.1.5 The vapor pressure apparatus shall have provisions for
37.8 °C. rinsing the measuring chamber with the next sample to be
tested or with a solvent of low vapor pressure.
5. Significance and Use 6.1.6 The vapor pressure apparatus shall have provisions for
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.

2
 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
6.3 McLeod Vacuum Gage or Calibrated Electronic Vacuum is flammable and a health hazard.)
Measuring Device for Calibration, to cover at least the range 7.2.3 Pentane, (Warning—Pentane is flammable and a
of 0.01 kPa to 0.67 kPa. The calibration of the electronic health hazard.)
measuring device shall be regularly verified in accordance with 7.3 Solvents:
Annex A of Test Method D2892. 7.3.1 Toluene, (Warning—Toluene is flammable and a
6.4 Pressure Measuring Device for Calibration, capable of health hazard.)
measuring local station pressure with an accuracy and a 7.3.2 Acetone, (Warning—Acetone is flammable and a
resolution of 0.1 kPa or better, at the same elevation relative to health hazard.)
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
7. Reagents and Materials in composition requires the utmost precaution and the most
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
specifications are available.3 Other grades may be used, pro- NOTE 5—Sampling in accordance with Practice D4177 may also be
vided it is first ascertained that the reagent is of sufficient purity used instead of Practice D4057.
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 mL shall be used if the overall volume of the test specimen
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
Method D5191 2003 interlaboratory study (ILS)4 (see Table 1). piston cylinders can be used. The minimum piston back-
Ptot used in Test Method D5191 is equivalent to VPCR4 used in pressure shall be higher than the sample vapor pressure at the
this test method). Such reference fuels are not to be used for introduction temperature of the measuring chamber plus
instrument calibration. Table 1 identifies the accepted reference 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
7.2 Verification Fluids: valve at the inlet for rinsing.
8.1.3 Do not unnecessarily expose the samples to tempera-
tures exceeding 30 °C during sampling and storage. For
3
ACS Reagent Chemicals, Specifications and Procedures for Reagents and prolonged storage, store the samples in an appropriate room or
Standard-Grade Reference Materials, American Chemical Society, Washington, refrigerator.
DC. For suggestions on the testing of reagents not listed by the American Chemical 8.1.4 Perform the vapor pressure determination on the first
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma- test specimen withdrawn from the cylinder after the rinsing
copeial Convention, Inc. (USPC), Rockville, MD. step in 9.3. Do not use the remaining sample in the floating
4
Supporting data have been filed at ASTM International Headquarters and may piston cylinder for more than three repeat vapor pressure
be obtained by requesting Research Report RR:D02-1619. Contact ASTM Customer
determinations.
Service at service@astm.org.

TABLE 1 Accepted Reference Value (ARV) and Acceptable Testing Range for Air Saturated Reference FluidsA
Recommended Instrument Acceptable Testing Range
ARV [Ptot] ± Uncertainty,
Reference Fluid Manufacturer Tolerance, for Reference Fuel [Ptot],
(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.

3
 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 mL of sample has entered the cylinder.
pressure.
Close the inlet valve and apply the back pressure immediately.
Check the filling of the cylinder to be at least 200 mL. NOTE 8—Calibration frequency of the pressure transducer may vary
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 vacuum measuring device to the vacuum source in line with the
like a storage tank, oil tanker, drum or other container, obtain measuring chamber (see Note 7). Apply vacuum to the mea-
a sample and test specimen in accordance with Practice D4057. suring chamber (see Note 9). When the vacuum measuring
Use either a 250 mL or 1 L sized 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
ILS using samples in 1 L amber glass containers (see 14.3). However, NOTE 9—Refer to Annex A6.3 of Test Method D2892 for further details
samples in containers of other sizes, as prescribed in Practice D4057, may concerning the calibration of electronic vacuum measuring devices and
be used with the same ullage requirement if it is recognized that the proper maintenance of McLeod gages.
precision can be affected. 10.1.3 Open the measuring chamber of the apparatus to
8.3 Sample Transfer: atmospheric pressure, and observe the corresponding pressure
8.3.1 Transfer the sample at room temperature but at least value of the transducer. Ensure that the apparatus is set to
5 °C above the pour point (as determined by Test Method display the total pressure and not a calculated or corrected
D5853) of the sample from the container into the measuring value. Compare this pressure value with the pressure obtained
chamber. from a pressure measuring device (see 6.4), as the pressure
8.3.2 If the sample is contained in a pressurized floating reference standard. The pressure measuring device shall mea-
piston cylinder, apply a back-pressure which is higher than the sure the local station pressure at the same elevation as the
vapor pressure of the sample at the introduction temperature apparatus in the laboratory at the time of pressure comparison.
plus a minimum of 100 kPa for the piston movement. The When the instrument is used over the full pressure range, a
applied back-pressure shall not exceed the maximum limit of calibration with a dead weight balance shall be carried out.
the pressure transducer used in the vapor pressure apparatus. (Warning—Many aneroid barometers, such as those used at
8.3.3 If the sample is contained in a nonpressurized weather stations and airports, are pre-corrected to give sea
container, transfer the sample into the measuring chamber level readings; these shall not be used for calibration of the
using a transfer tube or a syringe. Warning—If the sample apparatus.)
flashes or outgases in the inlet line, either before or after any 10.1.4 Repeat 10.1.2 and 10.1.3 until the zero and baromet-
inlet filter or regulator, then liquid volume to the cell is reduced ric pressures read correctly without further adjustments.
and measured vapor pressure is falsely low. If flashing or 10.2 Temperature Sensor—Verify the calibration of the
outgassing occurs, results are no longer valid under D6377. platinum resistance thermometer used to monitor the measur-
ing chamber temperature at least every six months against a
9. Preparation of Apparatus thermometer which is traceable to National Institute of Stan-
9.1 Prepare the instrument for operation in accordance with dards and Technology (NIST) or to national authorities in the
the manufacturer’s instructions. country the equipment is used.
9.2 Rinse the measuring chamber, if necessary with a 11. Quality Control Checks
solvent. Toluene has a low vapor pressure and can be used 11.1 Use a verification fluid (see 7.2) of known volatility as
successfully. Rinsing is performed by drawing the solvent into an independent check against the instrument calibration each
the chamber by the piston and expelling the solvent into the day the instrument is in use. For pure compounds, multiple test
waste container. specimens may be taken from the same container over time.
9.3 To avoid contamination of the test specimen with the Air saturate the verification fluid at temperatures between 0 °C
previous sample or the solvent, rinse the measuring chamber a to 1 °C as described in Test Method D5191 (see 8.4). Transfer
minimum of three times with the sample to be tested. Fill the the verification fluid into the measuring chamber using a
measuring chamber with sample to at least half the total transfer tube or a syringe. The temperature of the verification

4
 D6377 − 20
fluid shall be at 0 °C to 3 °C during the sample introduction, ture of the measuring chamber shall be equal to the measuring
and the measuring procedure shall be in accordance with temperature to avoid any influence due to sample expansion.
Section 12 with a V/L ratio of 4:1 and a measuring temperature 12.2 Set the V/L to the desired value X:1 (for test results
of 37.8 °C. related to Test Method D323, set the V/L to 4:1).
11.2 Table 1 provides the accepted reference value (ARV) 12.3 If the sample is contained in a pressurized floating
[Ptot] and uncertainty limits (at least 95 % confidence interval) piston cylinder, mix it vigorously with the mechanical stirrer,
of reference fluids tested in the 2003 D5191 ILS.4 As stated in otherwise shake the container with the non-pressurized sample,
7.1.1, the “Ptot” reference used in Test Method D5191 (and to ensure a homogenous sample. For manual piston cylinders,
Table 1 of this test method) is equivalent to VPCR4 (37.8 °C) check for liquid filled by pushing on the piston rod. If the rod
in this test method. This information, combined with the is not solid it indicates that some vapor is in the sample
tolerance value recommended by instrument manufacturers, chamber. Add additional pressure to the precharge side while
was used to establish the acceptable testing range for the rocking the cylinder (using the vapor bubble for effective
reference fuels to verify instrument performance. mixing) until the rod is again firm and the sample homoge-
11.3 Values obtained within the acceptable testing range neous.
intervals in Table 1 indicate that the instrument is performing 12.4 Follow the manufacturer’s instructions for introducing
at the level deemed acceptable by this standard. If values the test specimen into the measuring chamber. The volume of
outside the acceptable testing range intervals are obtained, the specimen shall be such that after the expansion to the final
verify the quality of the pure compound(s) and re-check the volume the programmed V/L is achieved.
calibration of the instrument (see Section 10). (Warning—The
use of single component verification materials such as those 12.5 After closing the inlet valve, expand the volume of the
listed in Table 1 will only prove the calibration of the measuring chamber to the final volume.
equipment. It will not check the accuracy of the entire test 12.6 Switch-on the shaker, and leave it on during the entire
method, including sample handling, because losses due to measuring procedure.
evaporation will not decrease the sample vapor pressure as 12.7 Adjust the temperature control to the measuring tem-
happens with losses of light ends in multi component mixtures. perature (for results related to Test Method D323, adjust to a
The vapor pressure measurement process (including operator temperature of 37.8 °C) and apply heat to cell. The measuring
technique) can be checked periodically by performing this test temperature shall not be lower than at least 10 °C above the
method on previously prepared samples from one batch of pour point temperature of the sample.
product, as per procedure described in 8.1.2. Samples should
be stored in an environment suitable for long term storage 12.8 Wait for temperature equilibrium between measuring
without sample degradation. Analysis of result(s) from these chamber and specimen, and monitor the total vapor pressure
quality control samples can be carried out using control chart every 30 s 6 5 s. When three successive readings agree within
techniques.5) 0.3 kPa, record this resulting vapor pressure as VP-
NOTE 10—It is recommended that at least one type of verification fluid CRX (Tm°C).
used in 11.1 have a vapor pressure representative of the crude(s) regularly
tested by the equipment. 13. Report
13.1 Report the results to the nearest 0.1 kPa and specify the
12. Procedure test temperature and vapor-liquid ratio.
12.1 Set the sample introduction temperature of the measur- VPCRX ~ Tm°C ! 5 ##.# kPa (1)
ing chamber.
12.1.1 For samples contained in a pressurized floating where:
piston cylinder, set the sample introduction temperature of the X = vapor-liquid ratio, and
measuring chamber between 20 °C and the measuring tempera- Tm = measuring temperature.
ture.
14. Precision and Bias
12.1.2 For samples contained in a non-pressurized
container, set the sample introduction temperature of the 14.1 Precision—The precision of this test method as deter-
measuring chamber to 20 °C. mined by the statistical examination of interlaboratory test
12.1.3 For samples with a pour point higher than 15 °C, set results is as follows:
the sample introduction temperature of the measuring chamber 14.1.1 Repeatability—The difference between successive
at least 5 °C above the pour point temperature of the sample test results obtained by the same operator with the same
but no higher than the measuring temperature. apparatus under constant operating conditions on identical test
12.1.4 For measurements with V/L ratios < 1, the sample material would, in the long run, in the normal and correct
may not be exposed to the atmosphere and shall be contained operation of the test method, exceed the values calculated as
in a floating piston cylinder. The sample introduction tempera- per the following equations only in one case in twenty:
14.1.1.1 For samples in pressurized Floating Piston Cylin-
ders:
5
MNL 7, Manual on Presentation of Data Control Chart Analysis, “Section 3: V/L 5 4 and Tm 5 37.8°C:repeatability 5 2.48 kPa ~ 37.8°C ! (2)
Control Charts for Individuals,” 6th edition, ASTM International, W. Conshohocken,
PA. V/L 5 0.02 and Tm 5 37.8°C:repeatability 5 5.61 kPa ~ 37.8°C ! (3)

5
 D6377 − 20
14.1.1.2 For samples in nonpressurized sample containers: 14.3 Relative Bias to Test Method D323—A statistically
V/L 5 4 and Tm 5 37.8°C:repeatability 5 2.29 kPa ~ 37.8°C ! (4) significant relative bias was observed for crude oil in a limited
interlaboratory test program the 2005 ILS6 between
14.1.2 Reproducibility—The difference between two single VPCR4 (37.8 °C) obtained using this test method and the vapor
and independent results obtained by different operators work- pressure obtained using Test Method D323 (see Appendix X1).
ing in different laboratories on identical material would, in the
14.4 The precision statements were derived from a 2005
long run, in the normal and correct operation of the test
interlaboratory cooperative test program involving 7 laborato-
method, exceed the following values in only one case in
ries and 6 crude oil samples covering a vapor pressure range
twenty:
between 34 kPa and 117 kPa.6 The sample introduction tem-
14.1.2.1 For samples in pressurized Floating Piston Cylin-
perature for this test program was allowed to be set between
ders:
20 °C and 37.8 °C.
V/L 5 4 and Tm 5 37.8°C:reproducibility 5 4.26 kPa ~ 37.8°C ! (5)
V/L 5 0.02 and Tm 5 37.8°C:reproducibility 5 20.3 kPa ~ 37.8°C ! 15. Keywords
(6) 15.1 crude oil; expansion method; Reid vapor pressure;
vapor pressure
14.1.2.2 For samples in nonpressurized sample containers:
V/L 5 4 and Tm 5 37.8°C:reproducibility 5 5.26 kPa ~ 37.8°C ! (7)
6
Supporting data have been filed at ASTM International Headquarters and may
14.2 Bias—Since there is no accepted reference material
be obtained by requesting Research Report RR:D02-1643. Standard sampling
suitable for determining the bias for the procedures in this test procedures D7975 and D8009 Manual Piston Cylinders were developed after the
method, a bias cannot be determined. program to determine the precision of the method.

APPENDIXES

(Nonmandatory Information)

X1. RELATIVE BIAS TO TEST METHOD D323

X1.1 The degree of expected agreement between in Eq X1.1 is not universally valid for all crude oils and it is
VPCR4 (37.8 °C) results by this test method for samples in recommended to report the VPCR4 (37.8 °C) result for all
either pressurized floating piston cylinders and nonpressurized crude oils. If Eq X1.1 is used to estimate RVPE, confirm its
1 L containers, and RVP results by Test Method D323 using validity for the crude oil samples under test by analyzing
nonpressurized 1 L containers has been assessed in accordance samples by both Test Methods D323 and D6377. In any case,
with Practice D6708. Sample specific biases were observed. Eq X1.1 only applies to dead crude oil samples (see 3.2.1 and
The reproducibility of Test Method D323 for the 2005 ILS 3.2.1.1) with VPCR4 (37.8 °C) results between 34 kPa and
crude oil sample set was R=9 kPa.6 Due to the low number of 117 kPa (see 14.4), since live crude oil samples (see 3.2.2 and
the crude oil samples in the ILS, a direct comparison between 3.2.2.1) if tested by Test Method D323 in non-pressurized
the results of this test method and Test Method D323 is containers (for example, sample bottles or cans) will result in
suggestive. significant loss of vapors during the air saturation procedure in
Test Method D323 prior to analysis.
X1.2 As stated in 14.3, a statistically significant relative bias
was observed for crude oil in a limited 2005 interlaboratory test RVPE 5 A 3 VPCR4 ~ 37.8°C ! (X1.1)
program involving VPCR4 (37.8 °C) results obtained by this
where:
test method and results obtained using Test Method D323. For
the six crude oil samples evaluated in the limited interlabora- A = 0.834 (for samples in pressurized floating piston
tory test program, RVP results determined by Test Method cylinders), and
A = 0.915 (for samples in nonpressurized 1-L sample
D323, based on VPCR4 (37.8 °C) results obtained by this test
containers)
method, can be predicted by Eq X1.1. However, the correlation

6
 D6377 − 20

X2. VAPOR PRESSURE OF CRUDE OIL VERSUS TEMPERATURE

X2.1 For several purposes, for example, transport and X2.1.2 Increase the measuring temperature in steps to the
storage, it may be useful to measure the vapor pressure highest temperature of interest but not higher than 100 °C.
behavior of crude oil versus temperature. To obtain such Each step is measured according with 12.7 and 12.8.
information proceed as follows. X2.1.3 The result is either recorded as a series of values, or
X2.1.1 Follow the instructions outlined in 12.1 – 12.8. The plotted as log (VPCRX) versus 1/T, where T is the absolute
initial measuring temperature is programmed to the lowest measuring temperature in °K (°C + 273.2).
temperature of interest but not lower than the temperature NOTE X2.1—No precision data have been developed for temperatures
stated in 12.7. different from 37.8 °C.

X3. VAPOR PRESSURE OF CRUDE OIL VERSUS VAPOR/LIQUID (V/L) RATIO

X3.1 For several purposes, for example, to check an un- and Task 2 report from Sandia National Lab on the Dept. of
known sample for the presence of light hydrocarbon compo- Energy (DOE) public technical report server.8
nents (methane, ethane propane, butane) and fixed gases (Air,
O2, N2, etc.) it may be useful to measure the vapor pressure X3.2 Follow the instructions outlined in 12.1 – 12.8. The
behavior of crude oil versus V/L ratio over the range 0.02 to 4. initial V/L is programmed to the lowest V/L of interest.
The shape and slope of this curve is qualitatively diagnostic for X3.3 Increase the V/L in steps to the highest V/L of interest
the presence and distribution of the gases. but not higher than V/L=4. Follow the manufacturer’s recom-
X3.1.1 Samples that are fully air saturated will display a mendation for the sample volume to be used for different V/L
curve that increases exponentially toward barometric pressure levels. Each step is measured according with 12.7 and 12.8.
below about V/L < 1 and will asymptotically approach a near X3.3.1 Some D6377 instruments may be programmed to do
horizontal line at V/L = 4, when most of the air and methane/ multiple VP determinations with a single injection. The preci-
ethane is in the vapor phase under test conditions. sion using this method may be poorer that if multiple VP
X3.1.2 Samples that contain no or very low concentrations determinations are done with multiple injections.
of air, CO2, methane and ethane will not display the rapid X3.3.2 Some D6377 instrument vendors recommend that
exponential increase in VP below V/L = 1. the VP curve be obtained with two programmed ranges
X3.1.3 Samples that are supersaturated with light gases, for (high/low) of V/L to minimize degradation of precision by
example from excessive or incorrect use of “Pad Gases” will using a larger injection volume when measuring VP at very low
display the rapid exponential increase in VP below about V/L.
1.5 V ⁄L to 2 V ⁄L, and will asymptotically approach the pres-
sure up to that of the pad gas used. For example, if a tank is X3.4 The result is either recorded as a series of values, or
equilibrated to a pressure of 200 kPa, then the measured VP plotted as VPCRX,(T m) vs. T, where T is the measuring
will approach 200 kPa as the V/L approaches 0.02. temperature in °C, and x = V/L.
NOTE X3.1—No precision data have been developed for V/L different
X3.1.4 Additional information on the shape of the VP vs. from those in 13.1.
V/L curve can be found in the “Vapor Pressure Best Practice”7
8
Available from https://www.osti.gov/scitech/biblio/1414422-doe-dot-crude-
oilcharacterization-research-study-task-test-report-evaluating-crude-oil-sampling-
7
Available from www.ccqta.com. analysis-methods.

7
 D6377 − 20
SUMMARY OF CHANGES

Subcommittee D02.08 has identified the location of selected changes to this standard since the last issue
(D6377 – 16) that may impact the use of this standard. (Approved June 1, 2020.)

(1) Revised subsections 1.1, 8.1.1, 8.3.3, 12.3, and 12.7. (4) Revised Footnote 6.
(2) Revised Note 1. (5) Added Appendix X3.
(3) Added Practice D5842, Test Method D7975, and Practice
D8009 to Section 2.

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