1、Designation: D 4377 00 (Reapproved 2006)Designation: Manual of Petroleum Measurement Standards (MPMS), Chapter 10.7Designation: 356/99An American National StandardStandard Test Method forWater in Crude Oils by Potentiometric Karl Fischer Titration1This standard is issued under the fixed designation
2、D 4377; the number immediately following the designation 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 rea
3、pproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This test method covers the determination of water inthe range from 0.02 to 2 % in crude oils. Mercaptan and sulfide(Sor H2S) sulfur are known to interfere with this test method(see Section 5).1.2 Th
4、is test method is intended for use with standard KarlFischer reagent or pyridine-free Karl Fischer reagents.1.3 The values stated in SI units are to be regarded as thestandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsib
5、ility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use. Specific precau-tionary statements are given in Section 7.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent Wate
6、rD 4006 Test Method for Water in Crude Oil by Distillation(API MPMS Chapter 10.2)D 4057 Practice for Manual Sampling of Petroleum andPetroleum Products (API MPMS Chapter 8.1)D 4177 Practice for Automatic Sampling of Petroleum andPetroleum Products (API MPMS Chapter 8.2)E 203 Test Method forWater Usi
7、ngVolumetric Karl FischerTitration2.2 API Standards:3MPMS Chapter 8.1 Manual Sampling of Petroleum andPetroleum Products (ASTM Practice D 4057)MPMS Chapter 8.2 Automatic Sampling of Petroleum andPetroleum Products (ASTM Practice D 4177)MPMS Chapter 10.2 Determination of Water in Crude Oilby Distilla
8、tion (ASTM Test Method D 4006)3. Summary of Test Method3.1 After homogenizing the crude oil with a mixer, analiquot of the crude, in a mixed solvent, is titrated to anelectrometric end-point using Karl Fischer reagent.4. Significance and Use4.1 A knowledge of the water content of crude oil isimporta
9、nt in the refining, purchase, sale, or transfer of crudeoils.5. Interferences5.1 A number of substances and class of compounds asso-ciated with condensation or oxidation-reduction reactions in-terfere in the determination of water by Karl Fischer. In crudeoils, the most common interferences are merc
10、aptans andsulfides. At levels of less than 500 g/g (ppm) (as sulfur) theinterference from these compounds is insignificant. For moreinformation on substances that interfere in the determination ofwater using the (Karl Fischer reagent) titration method see TestMethod E 203.6. Apparatus6.1 Karl Fische
11、r Apparatus, using electrometric end-point.A suggested assembly of the apparatus is described in AnnexA2.1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products and Lubricants and the API Committee on Petroleum Measure-ment, and is the direct responsibility of Subcommi
12、ttee D02.02.0B /COMQ, the jointASTM-API Committee on Sampling, Sediment, Water.Current edition approved Nov. 1, 2006. Published December 2006. Originallyapproved in 1984. Last previous edition approved in 2000 as D 4377 00e1.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcon
13、tact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Published as Manual of Petroleum Measurement Standards. Available fromAmerican Petroleum Institute (API), 1220 L. St., NW,Washington, D
14、C 20005-4070,http:/api-ec.api.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.1.1 Presently there is available on the market commercialKarl Fischer titration assemblies, some of which automaticallystop the titration at the end-
15、point. Instructions for operation ofthese devices are provided by the manufacturer and notdescribed herein. This test method is not intended for use withcoulometric Karl Fischer titrators.6.2 Mixer, to homogenize the crude sample.6.2.1 Non-Aerating, High-Speed, Shear Mixer,4capable ofmeeting the hom
16、ogenization efficiency test described inAnnexA1. The sample size is limited to that suggested by themanufacturer for the size of the probe.6.3 Syringes:6.3.1 Samples and base liquid are most easily added to thetitration vessel by means of accurate glass syringes with LUERfittings and hypodermic need
17、les of suitable length. The boresof the needles used should be kept as small as possible, butlarge enough to avoid problems arising from back pressure/blocking whilst sampling. Suggested syringe sizes are asfollows:6.3.1.1 Syringe, 10 L, with a needle long enough to dipbelow the surface of the base
18、solution in the cell during thestandardization procedure (see Section 9).6.3.1.2 Syringes, 2.5 mL, 5 mL, and 10 mL for crude oilsamples (see Section 10).6.3.1.3 Syringe, 20 mL or larger for sample solvent.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused in all test
19、s. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.5Other grades may beused, provided it is first ascertained that the reagent is ofsuffic
20、iently high purity to permit its use without lessening theaccuracy of the determination.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water as definedby Type IV of Specification D 1193.7.3 1-Ethylpiperidine (99 + percent). (WarningIrritant.Flam
21、mable.)7.4 Karl Fischer Reagents, Standard reagent containingpyridine (7.4.1) or pyridine-free reagent (7.4.2).7.4.1 Karl Fischer Reagent Ethylene Glycol MonomethylEther Solution, stabilized, containing pyridine, (1 mL = 5 mgof water)Fresh Karl Fischer reagent must be used. Must beused with solvent
22、in 7.6.1.(WarningCombustible. Harmfulif swallowed, inhaled, or absorbed through the skin.)7.4.2 Pyridine-Free Karl Fischer (one-component) reagentdiluted with xyleneDilute three parts pyridine-free KarlFischer (one-component) reagent6(1 mL = 5 mg water) to 1part xylene. Fresh Karl Fischer reagent mu
23、st be used.(WarningSee 7.4.1) Must be used with solvent in 7.6.2.7.5 Methanol (anhydrous), Maximum 0.1 % water but pref-erably less than 0.05 % water. (WarningFlammable. Vaporharmful. May be fatal or cause blindness if swallowed orinhaled. Cannot be made nonpoisonous.)7.6 Sample SolventUse 7.6.1 for
24、 standard Karl Fischerreagent containing pyridine and 7.6.2 for pyridine-free KarlFischer reagent.7.6.1 Sample SolventMix 40 mL of 1-ethylpiperidine, 20mL of methanol, and 40 mL of Karl Fischer reagent in asealable glass bottle.Allow this mixture to sit overnight beforeadding 200 mL of xylene. Addit
25、ional methanol may berequired in some cases for the proper function of the elec-trodes. (Warningsee 7.3.)7.6.2 Sample Solvent for Pyridine-Free ReagentsMix 3parts chloroform to 1 part pyridine-free solvent using solventpart of two-component reagent6(contains SO2and odorlessamine dissolved in methano
26、l) and store in a sealable glassbottle. An evaluation of a number of crude oils has demon-strated that xylene can be substituted for chloroform with noapparent change in accuracy of this test method. (WarningFlammable. Vapor harmful.) (Also, see 7.4.1.)7.7 Xylene, reagent grade. Less than 0.05 % wat
27、er.7.8 Chloroform, reagent grade. (WarningHarmful if in-haled or swallowed. Carcinogen (animal positive). Skin andeye irritant. May produce toxic vapors if burned.8. Sampling and Test Samples8.1 Sampling, is defined as all the steps required to obtain analiquot representative of the contents of any
28、pipe, tank, or othersystem, and to place the sample into the laboratory testcontainer. The laboratory test container and sample volumeshall be of sufficient dimensions and volume to allow mixing asdescribed in 8.1.2.1.8.1.1 Laboratory SampleOnly representative samples ob-tained as specified in Pract
29、ice D 4057 (API MPMS Chapter8.1) and Practice D 4177 (API MPMS Chapter 8.2) shall beused for this test method.8.1.2 Test SamplesThe following sample handling proce-dure shall apply in addition to those covered in 8.1.1.8.1.2.1 Mix the test sample of crude oil immediately (within15 min) before analys
30、is to insure complete homogeneity. Mixthe test sample at room temperature (25C) in the originalcontainer.NOTE 1The sample should be mixed at room temperature (25C) orless. Mixing of the sample should not increase the temperature of thesample more than 10C, or a loss of water may occur. The type of m
31、ixerdepends on the quantity of crude. Before any unknown mixer is used, thespecifications for the homogenization test, Annex A1, must be met. The4The following mixers were used in a cooperative program and have been foundsatisfactory for samples under 300 mL; Ultra Turrax Model TP 18/10, availablefr
32、om Tekmar Co., P. O. Box 37202, Cincinnati, OH 45222; Brinkman PolytronModel PT 35,Available from Brinkman Instruments Inc., Cantiagu Road, Westbury,NY 11590; and Kraft Apparatus Model S-25, SGA, Bloomfield, NJ.5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, W
33、ashington, DC. For suggestions on the 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 Convention, Inc. (USPC), Rockville,MD.6Pyri
34、dine-free Karl Fischer reagent and two-component solvent used in thecooperative program and found to be satisfactory are available from CrescentChemical Co., Inc., 1324 Motor Parkway, Hauppauge, NY11788 under the name ofHydranal a registered trademark of Riedel DehaenComposite 5 and Hydranalsolvent.
35、D 4377 00 (2006)2mixer must be re-evaluated for any changes in the type of crude, quantityof crude, or shape of the sample container.8.1.2.1.1 For small sample volumes, 50 to 500 mL, anon-aerating, high speed, shear mixer is required. Use themixing time, mixing speed, and height above the bottom of
36、thecontainer found to be satisfactory to Annex A1. Clean and drythe mixer between samples.8.1.2.2 The test sample size is selected as indicated in Table1 based on the expected water content.9. Calibration and Standardization9.1 Standardize the Karl Fischer reagent at least once daily.9.2 Add enough
37、solvent to the clean, dry titration vessel tocover the electrodes. The volume of solvent depends on thesize of the titration vessel. Seal all openings to the vessel andstart the magnetic stirrer for a smooth stirring action. Turn onthe indicating circuit and adjust the potentiometer to give areferen
38、ce point with approximately 1 A of current flowing.Add Karl Fischer reagent in suitable amounts to the solvent tocause the needle to deflect from the reference point.At first theneedle will deflect due to local concentration of the unreactedreagent about the electrodes but will fall back to near the
39、reference point.As the end-point is approached, the needle willfall back more slowly after each addition of Karl Fischerreagent. The end-point is reached when, after the addition of asingle drop of reagent, the needle remains deflected at least 1Afrom the reference point for at least 30 s. Swirl the
40、 titrationvessel to dry the inside walls of the vessel. Add more KarlFischer reagent, if needed, until a steady end-point is reachedfor at least 30 s.9.3 Standardize the Karl Fischer reagent with distilled waterby one of the following methods:9.3.1 From a water filled weighing pipet or syringe previ
41、-ously weighed to the nearest 0.1 mg, add 1 drop of distilledwater (about 20 mg) to the sample solvent at end-pointconditions and reweigh the syringe. Record the weight of thewater added. Titrate the water with Karl Fischer reagent addedfrom the buret until a steady end point is reached for at least
42、 30s. Record to the nearest 0.01 mLthe volume of the Karl Fischerreagent needed to reach the end-point.NOTE 2After adding water do not shake the cell.NOTE 3When wiping the needle exercise care, so not to siphon liquidthrough the tip of the needle.9.3.2 Fill a 10-L syringe with water taking care to e
43、limi-nate air bubbles, wipe the needle with a paper tissue to removeany residual water from the needle and accurately determinethe weight of syringe plus water to 0.1 mg.Add the contents ofthe syringe to the sample solvent in the cell which has beenadjusted to the end point ensuring that the tip of
44、the needle isbelow the surface of the sample solvent. Reseal the vesselimmediately. Remove any solvent from the needle by wipingwith a paper tissue and reweigh the syringe to 0.1 mg. Titratethe water with Karl Fischer reagent as in 9.3.1.9.4 Calculate the water equivalence of the Karl Fischerreagent
45、 as follows:F 5 W/T (1)where:F = water equivalence of the Karl Fischer reagent, mg/mL,W = water added, mg, andT = reagent required for titration of the added water, mL.9.5 Duplicate values of water equivalence should agreewithin 2 % relative. If the variation between the two titrationsis greater tha
46、n 2 % relative, discard the contents of the titrationvessel. Introduce a further portion of sample solvent into thevessel and repeat the standardization procedure. If the titrationsfor two further portions of distilled water still vary by morethan 2 %, it is likely that either the Karl Fischer reage
47、nt or thesample solvent, or both, have aged. Replace these with freshreagents and repeat the procedure for calibration and standard-ization.9.6 Determine and record the mean water equivalencevalue.10. Procedure10.1 Add the fresh sample solvent to the titration vessel andbring the solvent to end-poin
48、t conditions as described in 9.2.10.2 Add the crude to the titration vessel immediately afterthe mixing step described in 8.1.2.1 using one of the followingmethods:10.2.1 Starting with a clean, dry syringe (10 or 5 mL), rinsethe syringe two times with the sample and discharge to waste.Withdraw the r
49、equired amount of sample and discharge any airbubbles. Weigh the syringe to the nearest 0.1 mg. Inject thesample into the titration vessel, clean the needle with a papertissue, and reweigh the syringe. Titrate the sample until asteady end-point for at least 30 s is reached and record thevolume of Karl Fischer reagent to the nearest 0.01 mL (seeNote 2 and Note 4).NOTE 4The solvent should be changed when the sample contentexceeds2gofcrude per 15 mL of solvent or when 4 mL of titrant per 15mL of solvent has been added to the titration vessel.10.2.2 For vi
