ASTM D4377-2000(2011) Standard Test Method for Water in Crude Oils by Potentiometric Karl Fischer Titration《卡耳 费歇尔电势滴定法测量原油中含水量的标准试验方法》.pdf

《ASTM D4377-2000(2011) Standard Test Method for Water in Crude Oils by Potentiometric Karl Fischer Titration《卡耳 费歇尔电势滴定法测量原油中含水量的标准试验方法》.pdf》由会员分享，可在线阅读，更多相关《ASTM D4377-2000(2011) Standard Test Method for Water in Crude Oils by Potentiometric Karl Fischer Titration《卡耳 费歇尔电势滴定法测量原油中含水量的标准试验方法》.pdf（7页珍藏版）》请在麦多课文档分享上搜索。

1、Designation: D4377 00 (Reapproved 2011)Designation: Manual of Petroleum Measurement Standards (MPMS), Chapter 10.7Designation: 356/99Standard Test Method forWater in Crude Oils by Potentiometric Karl Fischer Titration1This standard is issued under the fixed designation D4377; the number immediately

2、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 () indicates an editorial change since the last revision or reapproval.This standard has been a

3、pproved 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 This test method is intended for u

4、se with standard KarlFischer reagent or pyridine-free Karl Fischer reagents.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its

5、 use. It is theresponsibility 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:2D1193 Specifi

6、cation for Reagent WaterD4006 Test Method for Water in Crude Oil by DistillationD4057 Practice for Manual Sampling of Petroleum andPetroleum ProductsD4177 Practice for Automatic Sampling of Petroleum andPetroleum ProductsE203 Test Method for Water Using Volumetric Karl FischerTitration2.2 API Standa

7、rds:3MPMS Chapter 8.1 Manual Sampling of Petroleum andPetroleum Products (ASTM Practice D4057)MPMS Chapter 8.2 Automatic Sampling of Petroleum andPetroleum Products (ASTM Practice D4177)MPMS Chapter 10.2 Determination of Water in Crude Oilby Distillation (ASTM Test Method D4006)3. Summary of Test Me

8、thod3.1 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 isimportant in the refining, purchase, sale, or transfer of

9、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 mercaptans andsulfides. At levels of less than 500 g/g

10、(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 E203.6. Apparatus6.1 Karl Fischer Apparatus, using electrometric end-point.A suggest

11、ed 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 Subcommittee D02.02.10 on Sediment andWater (API MPMS Chapte

12、r 10.0).Current edition approved June 1, 2011. Published August 2011. Originallyapproved in 1984. Last previous edition approved in 2006 as D437700(2006).DOI: 10.1520/D4377-00R11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org.

13、 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, DC 20005-4070,http:/api-ec.api.org.1Copyright A

14、STM 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-point. Instructions for operation ofthese devi

15、ces 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 homogenization efficiency test described inAnnexA

16、1. 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 needles of suitable length. The boresof the needle

17、s 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 solution in the cell during thestandardization

18、 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 tests. Unless otherwise indicated, it is intended

19、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 ofsufficiently high purity to permit its use without l

20、essening 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 D1193.7.3 1-Ethylpiperidine (99 + percent). (WarningIrritant.Flammable.)7.4 Karl Fischer Reagents, Standard reag

21、ent 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 in 7.6.1.(WarningCombustible. Harmfulif swallow

22、ed, 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 must be used.(WarningSee 7.4.1) Must be used with

23、 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 standard Karl Fischerreagent containing pyridi

24、ne 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. Additional methanol may berequired in some cases for

25、 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 methanol) and store in a sealable glassbottle. An eval

26、uation 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 % water.7.8 Chloroform, reagent grade. (WarningHarmf

27、ul 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 pipe, tank, or othersystem, and to place the sa

28、mple 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 Practice D4057 (API MPMS Chapter 8.1)and Practice D4

29、177 (API MPMS Chapter 8.2) shall be used forthis 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 analysis to insure complete homogeneity. Mixthe test sa

30、mple 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 mixerdepends on the quantity of crude. Before any

31、unknown mixer is used, thespecifications for the homogenization test, Annex A1, must be met. Themixer must be re-evaluated for any changes in the type of crude, quantityof crude, or shape of the sample container.4The following mixers were used in a cooperative program and have been foundsatisfactory

32、 for samples under 300 mL; Ultra Turrax Model TP 18/10, availablefrom 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, Am

33、erican Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formula

34、ry, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.6Pyridine-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 reg

35、istered trademark of Riedel DehaenComposite 5 and Hydranalsolvent.D4377 00 (2011)28.1.2.1.1 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 thecontainer found to be satisfactory to Annex A1.

36、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 solvent to the clean, dry titration vessel tocover

37、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 areference point with approximately 1 A of current flowing.

38、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 thereference point.As the end-point is approached, the

39、 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 titrationvessel to dry the inside walls of the ves

40、sel. 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-ously weighed to the nearest 0.1 mg, add 1 drop of

41、 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 30s. Record to the nearest 0.01 mLthe volume of th

42、e 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 elimi-nate air bubbles, wipe the needle with a paper

43、 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 the needle isbelow the surface of the sample solven

44、t. 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 as follows:F 5 W/T (1)where:F = water equivalence

45、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 than 2 % relative, discard the contents of the titrati

46、onvessel. 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 reagent or thesample solvent, or both, have aged. Replac

47、e 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-point conditions as described in 9.2.10.2 Add the crude

48、 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 required amount of sample and discharge any airbubbl

49、es. 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 viscous crudes, add the sample to a clean, drydropper