1、Designation: D1123 99 (Reapproved 2015)Standard Test Methods forWater in Engine Coolant Concentrate by the Karl FischerReagent Method1This standard is issued under the fixed designation D1123; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、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 approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 These test
3、 methods cover the determination of the waterpresent in new or unused glycol-based coolant concentratesusing a manual (Test Method A) or an automatic (Test MethodB) coulometric titrator procedure.1.2 Many carbonyl compounds react slowly with the Fis-cher reagent, causing a fading end point and leadi
4、ng to highresults. A modified Fischer reagent procedure is included thatminimizes these undesirable and interfering reactions.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
5、of thesafety problems, 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 regulatory limitations prior to use. For specific hazardsstatements see Sections 8 and 16.2. Referenc
6、ed Documents2.1 ASTM Standards:2D156 Test Method for Saybolt Color of Petroleum Products(Saybolt Chromometer Method)D1176 Practice for Sampling and Preparing Aqueous Solu-tions of Engine Coolants or Antirusts for Testing PurposesD1193 Specification for Reagent WaterE203 Test Method for Water Using V
7、olumetric Karl FischerTitration3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 color end pointthat point during the titration whenthe color change from yellow to orange-red is sharp and easilyrepeated. The orange-red color must persist for at least 30 s inorder to indicate an
8、end point.3.1.1.1 DiscussionView the color by transmitted daylightor by transmitted light from an artificial daylight lamp, such asone that complies with the specification given in Test MethodD156.3.1.2 instrument end pointfor the purpose of these tests,that point in the titration when two small pla
9、tinum electrodes,upon which a potential of 20 to 50 mV has been impressed, aredepolarized by the addition of 0.05 mL of Fischer reagent (6mg of water/mL), causing a change of current flow of 10 to 20A that persists for at least 30 s.3.1.2.1 DiscussionThis end point is sometimes incorrectlycalled the
10、 “dead stop,” which is the reverse of the above.4. Summary of Test Method4.1 These test methods are based essentially on the reduc-tion of iodine by sulfur dioxide in the presence of water. Thisreaction can be used quantitatively only when pyridine and analcohol are present to react as follows:I21SO
11、21H2OSO312HI (1)4.2 In order to determine water, Karl Fischer reagent isadded to a solution of the sample in anhydrous high-puritymethanol until all water present has been consumed. This isevidenced by the persistence of the orange-red end point color,or alternatively by an indication on a galvanome
12、ter or similarcurrent-indicating device that records the depolarization of apair of noble metal electrodes. The reagent is standardized bythe titration of water.NOTE 1It is believed that these methods give all the informationrequired for determining the water in coolant formulations. Shouldadditiona
13、l information on water determinations be needed, referenceshould be made to Test Method E203.5. Significance and Use5.1 The total apparent water in engine coolant concentrateas determined by Karl Fischer titrations consists of the follow-ing: (1) water present in the original glycol base; (2) watera
14、dded (for example, inhibitor solutions); (3) water of hydration1These test methods are under the jurisdiction of ASTM Committee D15 onEngine Coolants and Related Fluids and are the direct responsibility of Subcom-mittee D15.04 on Chemical Properties.Current edition approved May 1, 2015. Published Ju
15、ne 2015. Originallyapproved in 1950. Last previous edition approved in 2009 as D1123 99(2009).DOI: 10.1520/D1123-99R15.2For 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
16、to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1of inhibitors (for example, Na2B4O75H2O); (4) water formedin the chemical reaction between borate and ethylene glycol,producing
17、boratediol condensate and water; and (5) quantita-tive interference by the reaction of the reagent with inhibitorssuch as tetraborate or sodium hydroxide.TEST METHOD AMANUAL TITRATION6. Apparatus6.1 Titration VesselFor color end point titrations, use a100 or 250-mL volumetric flask, which need not b
18、e calibrated.For instrument end point, a 250-mL flask fitted with inter-changeable electrodes (Fig. 1)3may be used. This is particu-larly good for titrations of coolant concentrate that is deeplycolored from dye or any other cause. For permanently mountedassemblies, the vessel should have a capacity
19、 about equal tothat of a 300-mL tall-form beaker and should be provided witha tight-fitting closure to protect the sample and reagent fromatmospheric moisture, a stirrer, and a means of adding sampleand reagents and removing spent reaction mixture. It isdesirable to have a means for cooling the titr
20、ation vessel to icetemperature.6.2 Instrument Electrodes, platinum with a surface equiva-lent to two No. 26 wires, 4.76-mm long. The wires should be3 to 8 mm apart and so inserted in the vessel that the liquid willcover them.6.3 Instrument Depolarization Indicator, having an internalresistance of le
21、ss than 5000 and consisting of a means ofimpressing and showing a voltage of 20 to 50 mV across theelectrodes and capable of indicating a current flow of 10 to 20A by means of a galvanometer or radio tuning eye circuit.46.4 Buret Assembly for Fischer reagent, consisting of a 25 or50-mL buret connect
22、ed by means of glass (not rubber) con-nectors to a source of reagent; several types of automaticdispensing burets5may be used. Since the reagent losesstrength when exposed to moist air, all vents must be protectedagainst atmospheric moisture by adequate drying tubes con-taining anhydrous calcium sul
23、fate.6All stopcocks and jointsshould be lubricated with a lubricant not particularly reactive7with the reagent.6.5 Weighing Bottle, of the Lunge or Grethen type, orequivalent.6.6 Some laboratory equipment suppliers offer a Karl Fis-cher apparatus. The noted model or its equivalent has beenfound to b
24、e suitable.87. Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. 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 avai
25、lable.9Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.7.2 Unless otherwise indicated, references to water shall beunderstood to mean reagent water, Type IV, conforming toSpe
26、cification D1193.7.3 Karl Fischer Reagent, equivalent to 5 mg of water/mL.107.4 Methanol (WarningSee 8.1.)Anhydrous, high pu-rity.8. Hazards8.1 MethanolPoison; flammable; may be fatal or causeblindness if swallowed; cannot be made non-poisonous; harm-ful if inhaled.3Flasks made by Rankin Glass Blowi
27、ng Co., 3920 Franklin Canyon Rd.,Martinez, CA have been found satisfactory for this purpose.4A type similar to the Precision Scientific Co. “Aquatrator” or Fisher ScientificCo. “Fisher Titrimeter,” is suitable for the measurement of the instrument end point.5A type similar to Catalog No. J-821 of Sc
28、ientific Glass Apparatus Co.,Bloomfield, NJ, or Catalog No. 750 of Eck and Krebs, New York, NY, has beenspecifically designed for this purpose and presents the minimum contact of reagentwith stopcock lubricant.6Indicating Drierite has been found satisfactory for this purpose.7Suitable lubricants inc
29、lude Apiezon N. (James G. Biddle and Co., Philadelphia,PA); High Vacuum Silicone Grease (Dow Corning Co., Midland, MI); Sisco 300(Swedish Iron and Steel Co., New York, NY).8Metrohm Herisau, Karl Fischer Titrator Type E-452 available from BrinkmannInstruments, Inc., Cantaigue Road, Westbury, NY 11590
30、.9Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, 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 Pharmacop
31、eiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.10Reagents, as the pyridine-free hydranal reagent, available from FisherScientific, Pittsburgh, PA 15219.NOTE 1All dimensions in millimetres.FIG. 1 Titration Flask AssemblyD1123 99 (2015)29. Sampling9.1 A representat
32、ive sample of the contents of the originalcontainer shall be obtained as directed in Practice D1176; evenif two phases are present, the water-insoluble phase should notbe separated.10. Standardization of Reagent10.1 Standardize the Fischer reagent at least once, prior touse, each day the procedure i
33、s used, by either the color orinstrument end point (see Section 3) method, using the proce-dure as used for titrating the sample (Section 11).10.1.1 Add to each 250 mL flask 25 mL of anhydrous, highpurity methanol. Stir rapidly. Titrate with Karl Fischer reagentaccording to 11.2. Add to the solution
34、 0.15 to 0.18 g of water(to 60.1 mg) by use of an accurately sized syringe. Titrateagain and record the volume of titrant used. Repeat standard-ization two more times.10.1.2 Calculate the equivalency factor of the reagent interms of water content per millilitre as follows:Equivalency factor, F , mg
35、of water/mL 5 A/B (2)where:A = mg of water used in the standardization, andB = Karl Fischer reagent required, mL.11. Procedure11.1 Introduce 30 to 50 mL of the anhydrous high-puritymethanol into a 250 mL Erlenmeyer flask, making sure, if aninstrument end point apparatus is used, that the electrodes
36、arecovered by this amount of methanol. If the color end point is tobe determined, make up a second flask as well.11.2 Adjust the stirrer, if any, to provide adequate mixingwithout splashing. Titrate the mixture to the instrument endpoint (3.1.2), or the color end point (3.1.1), with Karl Fischerreag
37、ent. If the color end point is to be observed, titrate one flaskto match the first. Set aside the first flask as a comparisonstandard for titrating the sample.11.3 To the titration mixture thus prepared, add an amountof sample as indicated in Table 1. Exercise care when thesample is transferred so t
38、hat water is not absorbed from the air,particularly under conditions of high humidity. Again, titratethe mixture with Karl Fischer reagent to the same instrument orcolor end point previously employed. Record the amount ofreagent used to titrate the water in the sample.NOTE 2When using the volumetric
39、 flask-type titration vessel in humidclimate, place a piece of thin paraffin wax over the mouth of the vessel.Provide a small hole for introducing the buret tip. In less humid climatesit is sufficient to lower the tip of the buret deeply into the long neck of thetitration flask.NOTE 3In titrating wi
40、th the volumetric flask-type titration vessel,avoid wetting the stopper and upper end of the flask with either the reagentor the sample solvent. Each time the titration is interrupted, touch the burettip to the neck of the flask to remove droplets which, if not removed,would absorb moisture from the
41、 atmosphere. When the flask is removedfrom under the buret tip, wipe the tip with a clean dry cloth in a downwardmotion.12. Calculation12.1 Calculate the total water content (free plus apparent) ofthe sample as follows:Water, weight% 5 VF/10M (3)where:V = mL of Karl Fischer reagent required by the s
42、ample,F = equivalency factor for Karl Fischer reagent, mg ofwater per mL of reagent, andM = sample used, g.13. Precision and Bias13.1 PrecisionThe following data should be used forjudging the acceptability of results (95 % probability):13.1.1 RepeatabilityDuplicate results by the same opera-tor shou
43、ld be considered suspect if they differ by more than thefollowing amount:Repeatability 0.5 mL of titrant13.1.2 ReproducibilityThe result submitted by one labo-ratory should not be considered suspect unless it differs fromthat of another laboratory by more than the following amount:Water Content, % R
44、eproducibility, % of mean0.1to1.0 151.0to10 513.2 BiasSince there is no accepted reference materialsuitable for determining the bias for the procedure in this testmethod, bias has not been determined.TEST METHOD BCOULOMETRIC TITRATION14. Apparatus14.1 Coulometric Titrator11,12A complete control unit
45、with titration chamber and clamp, platinum sensing electrodes,generator, magnetic stirrer, and meeting requirements 14.2 and18.1.14.2 The instrument used for determining water in liquids isdesigned and calibrated to deliver a known number of milli-amperes of current which generates sufficient iodine
46、 to neu-tralize a known number of micrograms of water per minute.14.3 In order to determine the water content of enginecoolants, this method requires a two-part titration solution thatis brought to zero dryness by iodine produced by the generator11This procedure is patented by the Photovolt Corp. un
47、der U. S. Patent 3,726,778and has been included in the standard under Paragraph 11.2 of the RegulationsGoverning ASTM Technical Committees. Procedure A is a non-patented alternativemethod.12A detailed drawing is available from ASTM Headquarters. Request AdjunctNo. 12-415330-00.TABLE 1 Recommended Sa
48、mple SizesWater Content,weight %SampleSize,gSample Method2.5 to 10 0.3 Introduce samples by using weigh bottles ordisposable, accurate syringes. Obtain sampleweight by difference.0.5to2.5 3Below 0.5 20D1123 99 (2015)3when the instrument is powered up. The sample is added andthe water content is read
49、 directly in micrograms.14.4 Glass Syringe, 50-mL, for removing excess solutionfrom the titration chamber.14.5 Syringe, 25-L, fitted with a 11.5-cm hypodermicneedle for introduction of samples into the titration chamber.14.6 Syringe, 1-L, fitted with a 11.5-cm hypodermic needlefor standardization of instrument.14.7 Fluorocarbon Sealing Grease,13to seal the titrationchamber against atmospheric moisture.14.8 Septums, to seal sample port but allow introduction ofsamples by a needle with a minimum of moisture contamina-tion. Septum caps should be replaced a
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