1、Designation: D 7171 05An American National StandardStandard Test Method forHydrogen Content of Middle Distillate Petroleum Productsby Low-Resolution Pulsed Nuclear Magnetic ResonanceSpectroscopy1This standard is issued under the fixed designation D 7171; the number immediately following the designat
2、ion indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the deter
3、mination of the hydro-gen content of middle distillate petroleum products using alow-resolution pulsed nuclear magnetic resonance (NMR)spectrometer. The boiling range of distillates covered by thetest method is 150 to 390C. While this test method may beapplicable to middle distillates outside this b
4、oiling range, insuch cases the precision statements may not apply. The testmethod is generally based on Test Methods D 3701 andD 4808, with a major difference being the use of a pulsed NMRspectrometer instead of a continuous wave NMR spectrometer.1.2 The values stated in SI units are to be regarded
5、as thestandard. The preferred units are mass %.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regu
6、latory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 3701 Test Method for Hydrogen Content of AviationTurbine Fuels by Low Resolution Nuclear Magnetic Reso-nance SpectrometryD 4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD 4808 Test Methods for Hydrogen
7、 Content of Light Dis-tillates, Middle Distillates, Gas Oils, and Residua byLow-Resolution Nuclear Magnetic Resonance Spectros-copyD 5291 Test Methods for Instrumental Determination ofCarbon, Hydrogen, and Nitrogen in Petroleum Productsand LubricantsD 6299 Practice for Applying Statistical Quality A
8、ssuranceTechniques to Evaluate Analytical Measurement SystemPerformanceD 6708 Practice for Statistical Assessment and Improve-ment of the Expected Agreement Between Two TestMethods That Purport to Measure the Same Property of aMaterial2.2 Other Documents:MIL-DTL-5624U Military Detail Specification,
9、TurbineFuel, Aviation, Grades JP-4 and JP-53MIL-DTL-83133E Military Detail Specification, TurbineFuels, Aviation, Kerosene Types, NATO F-34, (JP-8),NATO F-35, and JP-8+1004MIL-PRF-16884K Military Performance Specification,Fuel, Naval Distillate53. Terminology3.1 Definitions:3.1.1 calibration, nthe d
10、etermination of the values of thesignificant parameters by comparison with values indicated bya set of calibration standards.3.1.2 calibration curve (or calibration line), nthe graphi-cal or mathematical representation of a relationship betweenthe assigned (known) values of calibration standards and
11、 themeasured responses from the measurement system.3.1.3 calibration standard, na standard having an as-signed (known) value (reference value) for use in calibrating ameasurement instrument or system.This standard is not used todetermine the accuracy of the measurement instrument orsystem (see check
12、 standard).3.1.4 check standard, na material having an assigned(known) value (reference value) used to determine the accu-racy of the measurement instrument or system. This standard isnot used to calibrate the measurement instrument or system(see calibration standard).3.1.5 low resolution nuclear ma
13、gnetic resonance (NMR)spectroscopy, na form of NMR spectroscopy using a simple1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and is the direct responsibility of SubcommitteeD02.03 on Elemental Analysis.Current edition approved June 1, 2005. Publ
14、ished July 2005.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Naval Air Systems Command, AI
15、R-4.4.5, Patuxent River, MD20670.4Available from ASC/ENSI, Wright-Patterson AFB, OH 45433-7107.5Available from Naval Sea Systems Command, SEA03R42, Washington, DC.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.NMR analyzer that empl
16、oys a low magnetic field and conse-quentially low NMR frequency. An example is proton NMRbelow 60 MHz. Resolution is expressed as time at half heightof signal and is typically 1 millisecond (ms) or less.3.1.6 nuclear magnetic resonance (NMR) spectroscopy,nthat form of spectroscopy concerned with rad
17、io-frequency-induced transitions between magnetic energy levels of atomicnuclei.3.1.7 radio frequency, nthe range of frequencies of elec-tromagnetic radiation between 3 kHz and 300 GHz.3.1.8 recycle delay, nNMR spectrometer parameter set-ting for the time delay that allows magnetization recovery.3.1
18、.9 relaxation time constant (T1), na numerical valuewhich is a measure of magnetization relaxation time followingan excitation pulse of an NMR spectrometer.4. Summary of Test Method4.1 Atest specimen is analyzed in a pulsed NMR spectrom-eter calibrated with reference standard materials. The analyzer
19、records in a nondestructive fashion the total NMR signal,which arises from the absolute amount of hydrogen atoms inthe reference standards and test sample. The absolute hydrogensignal intensity reported by the pulsed NMR instrument for thestandard and test specimens is normalized by the correspond-i
20、ng sample mass. The resulting signal-per-gram ratios are usedas a means of comparing theoretical hydrogen contents of thestandards with that of the sample. The result is expressed as thehydrogen content (on a mass % basis) of the sample.4.2 To ensure an accurate measure of the absolute hydrogenconte
21、nt of the reference standards and sample, it is necessary toensure that the measured hydrogen signal intensity is alwaysdirectly proportional to the absolute hydrogen content of thestandards and sample.4.3 Undercounting of the reference standard with respect tothe sample is avoided by a number of st
22、rategies, includingaccurate filling into the linear response region of the samplecompartment so that the mass recorded for the sample repre-sents the true amount measured by NMR, and use of a recycledelay considerably greater than the longest relaxation timeconstant (T1) for the sample.5. Significan
23、ce and Use5.1 Hydrogen content represents a fundamental quality of apetroleum distillate that has been correlated with many of theperformance characteristics of that product. Combustion prop-erties of gas turbine fuels are related primarily to hydrogencontent. As hydrogen content of these fuels decr
24、eases, sootdeposits, exhaust smoke, and thermal radiation increase. Sootdeposits and thermal radiation can increase to the point thatcombustor liner burnout will occur. Hydrogen content is aprocurement requirement of the following military fuels: JP-5specified in MIL-DTL-5624U, JP-8 specified in MIL
25、-DTL-83133E, and Naval Distillate specified in MIL-PRF-16884K.5.2 This test method provides a simple and precise alterna-tive to existing test methods (D 3701, D 4808, and D 5291) fordetermining the hydrogen content of petroleum distillate prod-ucts.6. Apparatus6.1 Nuclear Magnetic Resonance Spectro
26、meter:6.1.1 This test method requires a low-resolution pulsedinstrument capable of measuring a nuclear magnetic resonancesignal due to hydrogen atoms in the sample in a linear fashionover the filling volume of interest. The instrument includes thefollowing:6.1.1.1 Permanent magnet to provide the nec
27、essary staticmagnetic field for the NMR test,6.1.1.2 Sample compartment containing a radio frequency(RF) coil for excitation and detection, and6.1.1.3 Electronic unit to control and monitor the resonancecondition involving magnet temperature control and field offsetcoils.6.1.2 The test method also r
28、equires that the instrument havethe ability to equilibrate samples within the probe at a constanttemperature (that is, 35C or 40C).6.2 Conditioning BlockBlock of aluminum alloy drilledwith holes of sufficient size to accommodate the nominal 18mm diameter test cells to a depth of at least 42 mm and w
29、itha centrally positioned well to house a temperature-sensingdevice, such as a thermometer or thermocouple.6.3 Conditioning ApparatusBath or other temperaturecontrol device (into which the conditioning block is inserted)for controlling block temperature to 35 6 0.2C or 40 6 0.2C.6.4 Test CellGlass t
30、ube (with a flat or round bottom) withan outside diameter of 17.6 to 18.1 mm and an inside diameterof 15.2 to 16.4 mm.Any tube length that permits easy insertioninto and removal from the NMR sample chamber may be used.6.5 Polytetrafluorethylene (PTFE) PlugDevice made ofPTFE used to tightly fit and c
31、lose the test cells. An example ofone type of PTFE plug design is shown in Fig. 1.6.6 Insertion RodStraight, rigid rod with a threaded end(to screw into the PTFE plug) for inserting and removing thePTFE plugs from the test cells. Any diameter and length rodthat facilitates easy plug insertion and re
32、moval may be used.6.7 Analytical BalanceTop loading pan-type balance, ca-pable of weighing the test cells in an upright position to anaccuracy of 0.001 g or better.6.8 Volume Transferring DeviceCapable of accuratelyand repeatedly delivering a fixed volume of material within61 % or better, for use in
33、 preparing test specimens andstandards for analysis.A10-mL capacity serological pipet with0.1 mL marked subdivisions has been found suitable to use.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall rea
34、gents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specifications are available.6Other grades may be used,6Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the
35、testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Conventions, Inc. (USPC), Rockville,MD.D7171052provided it is first ascertained th
36、at the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.7.2 List of Available Calibration, Reference, or CheckStandards (see Table 1). (WarningIrritant. Combustible.Avoid breathing vapor. Avoid contact with eyes, skin, andclothing.) applies t
37、o all of the following:7.2.1 3-cyclohexanepropionic acid, 99 % minimum purity.7.2.2 cyclohexyl acetate, 99 % minimum purity.7.2.3 diethyl malonate, 99 % minimum purity.7.2.4 dodecane, 99 % minimum purity.7.2.5 ethyl caprate, 99 % minimum purity.7.2.6 ethyl heptanoate, 99 % minimum purity.7.2.7 2-non
38、anone, 99 % minimum purity.7.2.8 octyl acetate, 99 % minimum purity.7.2.9 pentadecane, 99 % minimum purity.7.2.10 2-phenylethyl acetate, 99 % minimum purity.7.3 Quality Control (QC) Samples, preferably are portionsof one or more petroleum distillate materials that are stable andrepresentative of the
39、 samples of interest. These QC samplescan be used to monitor the precision and stability of the testingprocess as described in Section 15.8. Hazards8.1 Wear appropriate personal protective equipment whenworking with the materials in Section 7.Transfer all reagents ina fume hood and immediately seal
40、containers tightly. Avoidprolonged or repeated exposure to materials.9. Sampling9.1 Take a homogeneous sample in accordance with Prac-tice D 4057. Mix the sample prior to taking a representativealiquot as the test specimen.10. Preparation of Test Specimens and Standards10.1 Fig. 1 is an example of a
41、 PTFE plug. Dimensions maybe varied to best seal the chosen test cell. Drill and thread theplug hole to mate the insertion rod thread. All test cells andPTFE plugs used shall be well cleaned and dry. Weigh a cleanempty test cell and PTFE plug (W1) on an analytical balance tothe nearest 0.001 g. Use
42、of a jig for supporting the test cell onthe balance pan is recommended for flat bottom test cells andrequired for round bottom test cells. For round bottom testcells, a paper clip dispenser (with hole in top) works well forthis function. Transfer a fixed volume (in accordance with thetolerances spec
43、ified in 6.8) of a reference standard or testspecimen into the test cell to a fill height of nominally 32 mm(representing a nominal 6 mL volume). The choice of fillheight is not critical, but fill height shall be the same for allstandards and samples to ensure good results. Use the same testcell sou
44、rce (that is, manufacturer and part number) for allstandards and test specimens. This will ensure uniformity offluid height in the NMR sample compartment, an importantparameter in the test method. Take care to not introduce thefluid down the side of the test cell. Seal the reference standardcontaine
45、r immediately after the material transfer to minimizemoisture pickup. Using the insertion rod with a PTFE plugattached, push the PTFE plug into the test cell until it is justabove the liquid surface (that is, nominal 1 cm), keeping thetube upright. Gently twisting the plug as it is inserted will aid
46、the escape of air from the test cell and normally ensure that thelip of the plug is turned up around the entire circumference.Unscrew the insertion rod carefully without disturbing theplug. Weigh the filled, sealed test cell (W2) on the analyticalbalance to the nearest 0.001 g. Determine the sample
47、massfrom the difference (W2 W1) of the two weighings.10.2 Repeat 10.1 for all standards and test specimens.11. Preparation of Apparatus11.1 Place the conditioning block in the conditioning appa-ratus. Select a testing temperature of 35C or 40C based onthe NMR instrument manufacturers recommendation
48、for thesample type to be tested. Adjust the conditioning apparatussetting to the selected 35 6 0.2 or 40 6 0.2C reading on acalibrated thermocouple or thermometer placed in a test cellFIG. 1 Example of a PTFE Plug (not to scale)TABLE 1 Hydrogen Content of Reference StandardsCompound Mass % Hydrogend
49、odecane 15.386pentadecane 15.1852-nonanone 12.756ethyl caprate 12.077octyl acetate 11.703ethyl heptanoate 11.4663-cyclohexanepropionic acid 10.324cyclohexyl acetate 9.924diethyl malonate 7.5522-phenylethyl acetate 7.367D7171053filled with a test fluid and placed in the conditioning block/apparatus. Allow at least 30 min for temperature equilibriumafter a setting adjustment. After adjustment, measure thealuminum block temperature at the thermometer/thermocouplewell in the block, and control the conditioning apparatus at thisblock temperature.11.2 Set the NMR
