ASTM D7171-05(2016)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D7171 − 05(Reapproved 2016)
Standard Test Method for
Hydrogen Content of Middle Distillate Petroleum Products
by Low-Resolution Pulsed Nuclear Magnetic Resonance
Spectroscopy
This standard is issued under the fixed designation D7171; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Low-Resolution Nuclear Magnetic Resonance Spectros-
copy
1.1 This test method covers the determination of the hydro-
D5291Test Methods for Instrumental Determination of
gen content of middle distillate petroleum products using a
Carbon, Hydrogen, and Nitrogen in Petroleum Products
low-resolution pulsed nuclear magnetic resonance (NMR)
and Lubricants
spectrometer. The boiling range of distillates covered by the
D6299Practice for Applying Statistical Quality Assurance
testmethodis150°Cto390°C.Whilethistestmethodmaybe
and Control Charting Techniques to Evaluate Analytical
applicable to middle distillates outside this boiling range, in
Measurement System Performance
such cases the precision statements may not apply. The test
D6708Practice for StatisticalAssessment and Improvement
methodisgenerallybasedonTestMethodsD3701andD4808,
of Expected Agreement Between Two Test Methods that
with a major difference being the use of a pulsed NMR
Purport to Measure the Same Property of a Material
spectrometerinsteadofacontinuouswaveNMRspectrometer.
2.2 Other Documents:
1.2 The values stated in SI units are to be regarded as
MIL-DTL-5624U Military Detail Specification, Turbine
standard. No other units of measurement are included in this
Fuel, Aviation, Grades JP-4 and JP-5
standard.
MIL-DTL-83133EMilitary Detail Specification, Turbine
1.2.1 The preferred units are mass%.
Fuels, Aviation, Kerosene Types, NATO F-34, (JP-8),
1.3 This standard does not purport to address all of the
NATO F-35, and JP-8+100
safety concerns, if any, associated with its use. It is the
MIL-PRF-16884K Military Performance Specification,
responsibility of the user of this standard to establish appro-
Fuel, Naval Distillate
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
3. Terminology
3.1 Definitions:
2. Referenced Documents
2 3.1.1 calibration, n—the determination of the values of the
2.1 ASTM Standards:
significant parameters by comparison with values indicated by
D3701Test Method for Hydrogen Content of Aviation
a set of calibration standards.
Turbine Fuels by Low Resolution Nuclear Magnetic
Resonance Spectrometry
3.1.2 calibration curve (or calibration line), n—the graphi-
D4057Practice for Manual Sampling of Petroleum and
cal or mathematical representation of a relationship between
Petroleum Products
the assigned (known) values of calibration standards and the
D4808 Test Methods for Hydrogen Content of Light
measured responses from the measurement system.
Distillates, Middle Distillates, Gas Oils, and Residua by
3.1.3 calibration standard, n—a standard having an as-
signed (known) value (reference value) for use in calibrating a
measurementinstrumentorsystem.Thisstandardisnotusedto
This test method is under the jurisdiction of ASTM Committee D02 on
determine the accuracy of the measurement instrument or
Petroleum Products, Liquid Fuels, and Lubricants and is the direct responsibility of
system (see check standard).
Subcommittee D02.03 on Elemental Analysis.
Current edition approved April 1, 2016. Published May 2016. Originally
approved in 2005. Last previous edition approved in 2011 as D7171–05 (2011).
DOI: 10.1520/D7171-05R16.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available from NavalAir Systems Command,AIR-4.4.5, Patuxent River, MD
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM 20670.
Standards volume information, refer to the standard’s Document Summary page on Available from ASC/ENSI, Wright-Patterson AFB, OH 45433-7107.
the ASTM website. Available from Naval Sea Systems Command, SEA03R42, Washington, DC.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7171 − 05 (2016)
3.1.4 check standard, n—a material having an assigned procurement requirement of the following military fuels: JP-5
(known) value (reference value) used to determine the accu- specified in MIL-DTL-5624U, JP-8 specified in MIL-DTL-
racyofthemeasurementinstrumentorsystem.Thisstandardis 83133E, and Naval Distillate specified in MIL-PRF-16884K.
not used to calibrate the measurement instrument or system
5.2 This test method provides a simple and precise alterna-
(see calibration standard).
tive to existing test methods (D3701, D4808, and D5291) for
3.1.5 low resolution nuclear magnetic resonance (NMR)
determining the hydrogen content of petroleum distillate prod-
spectroscopy, n—a form of NMR spectroscopy using a simple
ucts.
NMR analyzer that employs a low magnetic field and conse-
quentially low NMR frequency. An example is proton NMR
6. Apparatus
below 60 MHz. Resolution is expressed as time at half height
6.1 Nuclear Magnetic Resonance Spectrometer:
of signal and is typically 1 millisecond (ms) or less.
6.1.1 This test method requires a low-resolution pulsed
3.1.6 nuclear magnetic resonance (NMR) spectroscopy,
instrumentcapableofmeasuringanuclearmagneticresonance
n—that form of spectroscopy concerned with radio-frequency-
signal due to hydrogen atoms in the sample in a linear fashion
induced transitions between magnetic energy levels of atomic
over the filling volume of interest.The instrument includes the
nuclei.
following:
3.1.7 radio frequency, n—the range of frequencies of elec-
6.1.1.1 Permanent magnet to provide the necessary static
tromagnetic radiation between 3 kHz and 300 GHz.
magnetic field for the NMR test,
3.1.8 recycle delay, n—NMR spectrometer parameter set-
6.1.1.2 Sample compartment containing a radio frequency
ting for the time delay that allows magnetization recovery.
(RF) coil for excitation and detection, and
3.1.9 relaxation time constant (T ), n—a numerical value
6.1.1.3 Electronic unit to control and monitor the resonance
which is a measure of magnetization relaxation time following
conditioninvolvingmagnettemperaturecontrolandfieldoffset
an excitation pulse of an NMR spectrometer.
coils.
6.1.2 The test method also requires that the instrument have
4. Summary of Test Method
theabilitytoequilibratesampleswithintheprobeataconstant
4.1 AtestspecimenisanalyzedinapulsedNMRspectrom-
temperature (that is, 35°C or 40°C).
eter calibrated with reference standard materials. The analyzer
6.2 Conditioning Block—Block of aluminum alloy drilled
records in a nondestructive fashion the total NMR signal,
with holes of sufficient size to accommodate the nominal
which arises from the absolute amount of hydrogen atoms in
18mmdiametertestcellstoadepthofatleast42mmandwith
thereferencestandardsandtestsample.Theabsolutehydrogen
a centrally positioned well to house a temperature-sensing
signalintensityreportedbythepulsedNMRinstrumentforthe
device, such as a thermometer or thermocouple.
standard and test specimens is normalized by the correspond-
ing sample mass.The resulting signal-per-gram ratios are used
6.3 Conditioning Apparatus—Bath or other temperature
as a means of comparing theoretical hydrogen contents of the
control device (into which the conditioning block is inserted)
standardswiththatofthesample.Theresultisexpressedasthe
for controlling block temperature to 35°C 6 0.2°C or 40°C
hydrogen content (on a mass% basis) of the sample.
6 0.2°C.
4.2 Toensureanaccuratemeasureoftheabsolutehydrogen
6.4 Test Cell—Glass tube (with a flat or round bottom) with
contentofthereferencestandardsandsample,itisnecessaryto
an outside diameter of 17.6mm to 18.1mm and an inside
ensure that the measured hydrogen signal intensity is always
diameterof15.2mmto16.4mm.Anytubelengththatpermits
directly proportional to the absolute hydrogen content of the
easy insertion into and removal from the NMR sample cham-
standards and sample.
ber may be used.
4.3 Undercounting of the reference standard with respect to
6.5 Polytetrafluorethylene (PTFE) Plug—Device made of
the sample is avoided by a number of strategies, including
PTFE used to tightly fit and close the test cells.An example of
accurate filling into the linear response region of the sample
one type of PTFE plug design is shown in Fig. 1.
compartment so that the mass recorded for the sample repre-
sents the true amount measured by NMR, and use of a recycle 6.6 Insertion Rod—Straight, rigid rod with a threaded end
delay considerably greater than the longest relaxation time (to screw into the PTFE plug) for inserting and removing the
constant (T ) for the sample. PTFE plugs from the test cells. Any diameter and length rod
that facilitates easy plug insertion and removal may be used.
5. Significance and Use
6.7 Analytical Balance—Top loading pan-type balance, ca-
5.1 Hydrogen content represents a fundamental quality of a
pable of weighing the test cells in an upright position to an
petroleum distillate that has been correlated with many of the
accuracy of 0.001g or better.
performance characteristics of that product. Combustion prop-
erties of gas turbine fuels are related primarily to hydrogen 6.8 Volume Transferring Device—Capableofaccuratelyand
content. As hydrogen content of these fuels decreases, soot repeatedly delivering a fixed volume of material within 61%
deposits, exhaust smoke, and thermal radiation increase. Soot or better, for use in preparing test specimens and standards for
deposits and thermal radiation can increase to the point that analysis. A 10mL capacity serological pipet with 0.1mL
combustor liner burnout will occur. Hydrogen content is a marked subdivisions has been found suitable to use.
D7171 − 05 (2016)
TABLE 1 Hydrogen Content of Reference Standards
Compound Mass % Hydrogen
dodecane 15.386
pentadecane 15.185
2-nonanone 12.756
ethyl caprate 12.077
octyl acetate 11.703
ethyl heptanoate 11.466
3-cyclohexanepropionic acid 10.324
cyclohexyl acetate 9.924
diethyl malonate 7.552
2-phenylethyl acetate 7.367
7.3 Quality Control (QC) Samples, preferably are portions
ofoneormorepetroleumdistillatematerialsthatarestableand
representative of the samples of interest. These QC samples
canbeusedtomonitortheprecisionandstabilityofthetesting
process as described in Section 15.
8. Hazards
8.1 Wear appropriate personal protective equipment when
workingwiththematerialsinSection7.Transferallreagentsin
a fume hood and immediately seal containers tightly. Avoid
prolonged or repeated exposure to materials.
9. Sampling
9.1 Take a homogeneous sample in accordance with Prac-
tice D4057. Mix the sample prior to taking a representative
FIG. 1 Example of a PTFE Plug (not to scale)
aliquot as the test specimen.
10. Preparation of Test Specimens and Standards
7. Reagents and Materials
10.1 Fig. 1 is an example of a PTFE plug. Dimensions may
7.1 Purity of Reagents—Reagent grade chemicals shall be
be varied to best seal the chosen test cell. Drill and thread the
used in all tests. Unless otherwise indicated, it is intended that
plug hole to mate the insertion rod thread. All test cells and
all reagents conform to the specifications of the Committee on
PTFE plugs used shall be well cleaned and dry. Weigh a clean
Analytical Reagents of theAmerican Chemical Society where
emptytestcellandPTFEplug(W )onananalyticalbalanceto
such specifications are available. Other grades may be used,
the nearest 0.001g. Use of a jig for supporting the test cell on
provided it is first ascertained that the reagent is of sufficiently
the balance pan is recommended for flat bottom test cells and
high purity to permit its use without lessening the accuracy of
required for round bottom test cells. For round bottom test
the determination.
cells, a paper clip dispenser (with hole in top) works well for
7.2 List of Available Calibration, Reference, or Check
this function. Transfer a fixed volume (in accordance with the
Standards (see Table 1). (Warning—Irritant. Combustible.
tolerances specified in 6.8) of a reference standard or test
Avoid breathing vapor. Avoid contact with eyes, skin, and
specimen into the test cell to a fill height of nominally 32mm
clothing.) applies to all of the following:
(representing a nominal 6mL volume). The choice of fill
7.2.1 3-cyclohexanepropionic acid, 99% minimum purity.
height is not critical, but fill height shall be the same for all
7.2.2 cyclohexyl acetate, 99% minimum purity.
standardsandsamplestoensuregoodresults.Usethesametest
7.2.3 diethyl malonate, 99% minimum purity.
cell source (that is, manufacturer and part number) for all
7.2.4 dodecane, 99% minimum purity.
standards and test specimens. This will ensure uniformity of
7.2.5 ethyl caprate, 99% minimum purity.
fluid height in the NMR sample compartment, an important
7.2.6 ethyl heptanoate, 99% minimum purity.
parameter in the test method. Take care to not introduce the
7.2.7 2-nonanone, 99% minimum purity.
fluid down the side of the test cell. Seal the reference standard
7.2.8 octyl acetate, 99% minimum purity.
container immediately after the material transfer to minimize
7.2.9 pentadecane, 99% minimum purity.
moisture pickup. Using the insertion rod with a PTFE plug
7.2.10 2-phenylethyl acetate, 99% minimum purity.
attached, push the PTFE plug into the test cell until it is just
above the liquid surface (that is, nominal 1 cm), keeping the
tube upright. Gently twisting the plug as it is inserted will aid
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For Suggestions on the testing of reagents not
theescapeofairfromthetestcellandnormallyensurethatthe
listed by the American Chemical Society, see Annual Standards for Laboratory
lip of the plug is turned up around the entire circumference.
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
Unscrew the insertion rod carefully without disturbing the
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
MD. plug. Weigh the filled, sealed test cell (W ) on the analytical
D7171 − 05 (2016)
balance to the nearest 0.001g. Determine the sample mass Follow the instrument manufacturer’s instructions for estab-
from the difference (W − W ) of the two weighings. lishing the calibration line. Remove the test cell from the
2 1
instrument. Similarly, run the other calibration standards to
...