ASTM D6378-99e1
(Test Method)Standard Test Method for Determination of Vapor Pressure (VPx) of Petroleum Products, Hydrocarbons, and Hydrocarbon-Oxygenate Mixtures (Triple Expansion Method)
Standard Test Method for Determination of Vapor Pressure (VP<sub>x</sub>) of Petroleum Products, Hydrocarbons, and Hydrocarbon-Oxygenate Mixtures (Triple Expansion Method)
SCOPE
1.1 This test method covers the use of automated vapor pressure instruments to determine the vapor pressure exerted in vacuum by volatile, liquid petroleum products, hydrocarbons, and hydrocarbon-oxygenate mixtures. This test method is suitable for testing samples with boiling points above 0°C (32°F) that exert a vapor pressure between 7 and 150 kPa (1.0 and 21 psi) at 37.8°C (100°F) at a vapor-to-liquid ratio of 4:1. Measurements are made on liquid sample sizes in the range from 1 to 10 mL.
Note 1-The test method is suitable for the determination of the vapor pressure of volatile, liquid petroleum products at temperatures from 0 to 100°C at vapor to liquid ratios of 4:1 to 1.1 (X = 4 to 1) and pressures up to 500 kPa (70psi), but the precision statement (see Section 15) may not be applicable.
1.2 The VPx determined by this test method at a vapor-liquid ratio of 4:1 (X = 4) of gasoline and gasoline-oxygenate blends at 37.8°C can be correlated to the dry vapor pressure equivalent (DVPE) value determined by Test Method D5191 (see Section 15.2).
1.3 The values stated in SI units are regarded as the standard. The inch-pound units given in parentheses are for information only.
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 and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see Note 6.
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An American National Standard
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Designation: D 6378 – 99
Standard Test Method for
Determination of Vapor Pressure (VP ) of Petroleum
X
Products, Hydrocarbons, and Hydrocarbon-Oxygenate
Mixtures (Triple Expansion Method)
This standard is issued under the fixed designation D 6378; 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 (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Note 17 was corrected editorially in September 1999.
1. Scope ucts (REID Method)
D 1160 Test Method for Distillation of Petroleum Products
1.1 This test method covers the use of automated vapor
at Reduced Pressure
pressure instruments to determine the vapor pressure exerted in
D 4057 Practice for Manual Sampling of Petroleum and
vacuum by volatile, liquid petroleum products, hydrocarbons,
Petroleum Products
and hydrocarbon-oxygenate mixtures. This test method is
D 4177 Practice for Automatic Sampling of Petroleum and
suitable for testing samples with boiling points above 0°C
Petroleum Products
(32°F) that exert a vapor pressure between 7 and 150 kPa (1.0
D 4953 Test Method for Vapor Pressure of Gasoline and
and 21psi) at 37.8°C (100°F) at a vapor-to-liquid ratio of 4:1.
Gasoline-Oxygenate Blends (Dry Method)
Measurements are made on liquid sample sizes in the range
D 5191 Test Method for Vapor Pressure of Petroleum Prod-
from1to10mL.
ucts (Mini Method)
NOTE 1—The test method is suitable for the determination of the vapor
D 5842 Practice for Sampling and Handling of Fuels for
pressure of volatile, liquid petroleum products at temperatures from 0 to
Volatility Measurements
100 °C at vapor to liquid ratios of 4:1 to 1.1 (X=4to1)and pressures up
D 5854 Practice for Mixing and Handling of Liquid
to 500 kPa (70 psi), but the precision statement (see Section 15.) may not
Samples of Petroleum and Petroleum Products
be applicable.
1.2 The VP determined by this test method at a vapor-
X 3. Terminology
liquid ratio of 4:1 (X = 4) of gasoline and gasoline–oxygenate
3.1 Definitions of Terms Specific to This Standard:
blends at 37.8°C can be correlated to the dry vapor pressure
3.1.1 dry vapor pressure equivalent (DVPE)—a value cal-
equivalent (DVPE) value determined by Test Method D 5191
culated by a correlation equation from the total pressure (Test
(see Section 15.2).
Method D 5191), which is equivalent to the value obtained on
1.3 The values stated in SI units are regarded as standard.
the sample by Test Method D 4953, Procedure A.
The inch-pound units given in parentheses are provided for
3.1.2 partial pressure from dissolved air (PPA), n—the
information only.
pressure exerted in vacuum from dissolved air that escapes
1.4 This standard does not purport to address all of the
from the liquid phase into the vapor phase.
safety concerns, if any, associated with its use. It is the
3.1.3 Reid vapor pressure equivalent (RVPE)— a value
responsibility of the user of this standard to establish appro-
calculated by a correlation equation from the TP , which is
X
priate safety and health practices and determine the applica-
equivalent to the value obtained on the same by Test Method
bility of regulatory limitations prior to use. For specific hazard
D 323.
statements, see Note 6.
3.1.4 total pressure (TP ), n— the pressure exerted in
X
vacuum by air- and gas-containing petroleum products, com-
2. Referenced Documents
ponents and feedstocks, and other liquids, in the absence of
2.1 ASTM Standards:
undissolved water at a vapor-liquid ration of X:1.
D 323 Test Method for Vapor Pressure of Petroleum Prod-
3.1.5 vapor pressure (VP ), n— the total pressure minus the
X
PPA in the liquid at a vapor-liquid ratio of X:1.
This test method is under the jurisdiction of ASTM Committee D-2 on
Petroleum Products and Lubricants and is the direct responsibility of Subcommittee Annual Book of ASTM Standards, Vol 05.01.
D02.08 on Volatility. Annual Book of ASTM Standards, Vol 05.02.
Current edition approved Jan. 10, 1999. Published April 1999. Annual Book of ASTM Standards, Vol 05.03.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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D6378–99
VP 5 TP 2 PPA (1)
nation shall be at the same temperature as the measuring
X X
chamber to avoid any condensation or excessive evaporation.
4. Summary of Test Method
6.1.1 The measuring chamber shall be designed to contain
4.1 Employing a measuring chamber with a built-in piston, between 5 and 15 mL of liquid and vapor and be capable of
a sample of known volume is drawn into the temperature
maintaining a vapor-liquid ratio of 4:1 to 1:1. The accuracy of
controlled chamber at 20°C or higher. After sealing the
the adjusted vapor-liquid ratio shall be within 0.05.
chamber, an expansion is performed in three steps to a final
NOTE 3—The measuring chamber employed by the instruments used in
volume of (X+1) times that of the test specimen. After each
generating the precision and bias statements were constructed of nickel
expansion, the TP is determined. The PPA and the solubility
X
plated aluminum and stainless steel with a total volume of 5 mL.
of air in the specimen are calculated from the three resulting
Measuring chambers exceeding a 5-mL capacity can be used, but the
pressures. The temperature of the chamber is then increased to
precision and bias statements (see Section 15) are not known to apply.
a specified value, and the TP is determined. The (VP )is
X X
6.1.2 The pressure transducer shall have a minimum opera-
calculated by subtracting the PPA in the liquid, which has been
gas corrected for the temperature, from TP . For DUPE results, tional range from 0 to 200 kPa (0 to 71 psi) with a minimum
X
in accordance with Test Method D 5191, the volume of the resolution of 0.1 kPa (0.01 psi) and a minimum accuracy of
measuring chamber shall be five times that of the total test
60.2 kPa (60.002 psi). The pressure measurement system
specimen and the measuring temperature shall be 37.8°C.
shall include associated electronics and readout devices to
display the resulting pressure reading.
NOTE 2—Caution: For liquids containing very low levels of high vapor
pressure contaminants, which behave like a gas, this test method of
6.1.3 Electronic temperature control shall be used to main-
determination of the PPA and gases may lead to wrong results since the
tain the measuring chamber at the prescribed temperature
partial pressure of the contaminants will be included in the PPA. This
within 60.1°C for the duration of the test.
effect is shown when the value of the PPA and gases exceeds the average
6.1.4 A platinum resistance thermometer shall be used for
maximum limit of 7 kPa (1 psi).
measuring the temperature of the measuring chamber. The
5. Significance and Use
minimum temperature range of the measuring device shall be
5.1 Vapor pressure is a very important physical property of
from 20 to 100°C with a resolution of 0.1°C and an accuracy
volatile liquids for shipping and storage.
of 60.1°C.
5.2 The vapor pressure of gasoline and gasoline-oxygenate
6.1.5 The vapor pressure apparatus shall have provisions
blends is regulated by various government agencies.
from rinsing the measuring chamber with a solvent of low
5.3 Specifications for volatile petroleum products generally
vapor pressure or with the next sample to be tested.
include vapor pressure limits to ensure products of suitable
6.2 Vacuum Pump for Calibration, capable of reducing the
volatility performance.
pressure in the measuring chamber to less than 0.01 kPa (0.001
5.4 In this test method, an air saturation procedure prior to
psi) absolute.
the measurement is not required, thus eliminating losses of
6.3 McLeod Vacuum Gage or Calibrated Electronic Vacuum
high volatile compounds during this step. This test method is
faster and minimizes potential errors from improper air satu- Measuring Device for Calibration, to cover at least the range
ration. This test method permits VP determinations in the from 0.01 to 0.67 kPa (0 to 5 mm Hg). The calibration of the
X
field.
electronic measuring device shall be regularly verified in
5.5 This test method can be applied in on-line applications
accordance with Annex A1 of Test Method D 1160.
in which an air saturation procedure prior to the measurement
6.4 Pressure Measuring Device for Calibration, capable of
cannot be performed.
measuring local station pressure with an accuracy and a
resolution of 0.1 kPa (1 mm Hg), or better, at the same
6. Apparatus
elevation relative to sea level as the apparatus in the laboratory.
6.1 The apparatus suitable for this test method employs a
NOTE 4—This test method does not give full details of instruments
small volume, cylindrically shaped measuring chamber with
suitable for carrying out this test. Details on the installation, operation, and
associated equipment to control the chamber temperature
maintenance of each instrument may be found in the manufacturer’s
within the range from 0 to 100 °C. The measuring chamber
manual.
shall contain a movable piston with a minimum dead volume of
less than 1 % of the total volume at the lowest position to allow
7. Reagents and Materials
sample introduction into the measuring chamber and expansion
7.1 Purity of Reagents—Use chemicals of at least 99 %
to the desired vapor-liquid ratio. A static pressure transducer
purity for quality control checks (see Section 10). Unless
shall be incorporated in the piston. The measuring chamber
otherwise indicated, it is intended that all reagents conform to
shall contain an inlet/outlet valve combination for sample
introduction and expulsion. The piston and the valve combi- the specifications of the Committee of Analytical Reagents of
Vapor pressure apparatus meeting these requirements are available from
Grabner Instruments, A-1220 Vienna, Dr. Neurathgasse 1, Austria.
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D6378–99
a useful procedure. If a statement for hazy sample is required, cooling to
the American Chemical Society where such specifications are
the required temperature is necessary.
available. Lower purities can be used, provided it is first
ascertained that the reagent is of sufficient purity to permit its
8.3 Verification of Sample Container Filling—With the
use without lessening the accuracy of the determination.
sample at a temperature below 10°C, take the container from
the cooling bath and wipe dry with absorbent material. If the
NOTE 5—The chemicals in this section are suggested for quality control
sample is contained in a transparent container, verify that the
procedures (see Section 11) and are not used for instrument calibration.
container is at least 70 % full by suitable means, such as by
2,2-Dimethylbutane (Warning–See Note 6)
2,3-Dimethylbutane (Warning—See (Note 6)
using a marked ruler or by comparing it to a like container that
Toluene (Warning–See Note 6)
has the 70 % levels clearly marked. If the container is not
Pentane (Warning–See Note 6)
transparent, unseal it and, using a suitable gage, confirm that
Methanol (Warning–See Note 6)
Acetone (Warning–See Note 6)
the sample volume equals at least 70 % of the container
capacity.
NOTE 6—Warning: 2,2–dimethylbutane, 2,3-dimethylbutane, toluene,
pentane, methanol, and acetone are flammable and health hazards. 8.3.1 Discard the sample if the container is filled to less than
70 %, by volume, of the container capacity.
8. Sampling and Sample Introduction
8.3.2 Reseal the container, if opened, and place it back in
8.1 General Requirements:
the cooling bath or refrigerator.
8.1.1 The extreme sensitivity of vapor pressure measure-
8.4 Verification of Single Phase Sample—After drawing the
ments to losses through evaporation and the resulting changes
test specimens and transferring them into the instrument for
in composition is such as to require the utmost precaution and
analysis, check the remaining sample for phase separation. If
the most meticulous care in the drawing and handling of
the sample is contained in a transport container, this observa-
samples.
tion can be made prior to sample transfer. If the sample is
8.1.2 Obtain a sample and test specimen in accordance with
contained in a non-transparent container, shake the sample
Practice D 4057, D 4177, D 5842, or D 5854 when appropriate,
thoroughly and immediately pour a portion of the remaining
except do not use the Sampling by Water Displacement section
sample into a glass container and observe for evidence of phase
for fuels containing oxygenates. Use a container not less than
separation. A hazy appearance is to be carefully distinguished
300 mL and not more than 1 L in size filled at least 70 % with
from separation into distinct phases. If the sample separates
sample.
into two distinct phases with a discernible common boundary,
then discard the test and the sample. If the sample has a hazy
NOTE 7—The present precision statement was derived using samples in
appearance, but does not have two distinct phases, then phase
1 L (1 qt) containers. However, samples in containers of other sizes as
separation has not occurred. The test is valid, but the precision
prescribed in Practice D 4057 can be used, with the same filling
requirement, but the precision can be affected. and bias in Section 15 may not apply (see Section 14).
8.1.3 Perform the VP determination, including the rinsing
X
9. Preparation of Apparatus
(see 9.4), on the first test specimen withdrawn from a sample
container. Do not use the remaining sample in the container for 9.1 Prepare the instrument for operation in accordance with
a second VP determination. If a second determination is
the manufacturer’s instructions.
X
necessary, obtain a new sample. 9.2 Rinse the measuring chamber, if necessary, with a
8.1.4 Protect samples from excessive temperatures prior to
solvent. Methanol has a low vapor pressure and can be used
testing. This can be accomplished by storage in an appropriate successfully. Rinsing is performed by drawing the solvent into
ice bath or refrigerator.
the chamber by the piston and expelling the solvent into the
8.1.5 Do not test samples stored in leaky containers. Discard
waste container.
and obtain a new sample if leaks are detected.
9.3 To avoid contamination of the test specimen with the
8.2 Sampling Handling Temperature—Cool the sample con-
previous sample or the solvent, rinse the measuring chamber a
tainer and contents in a ice bath or refrigerator to the 0 to 1°C
minimum of three times with the sample to be tested. Fill the
(32 to 34°F) range prior to opening the sample container. Allow
measuring chamber with sample to at least hal
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