1、Designation: D1287 09Standard Test Method forpH of Engine Coolants and Antirusts1This standard is issued under the fixed designation D1287; 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 pare
2、ntheses 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 Department of Defense.1. Scope1.1 This test method covers the determination of the pH ofunused engine
3、coolants and antirusts, and used or unusedaqueous dilutions of the concentrated products.NOTE 1Antirusts in solid form are not included in this test method.NOTE 2It is believed that this procedure gives all the informationrequired for determining the pH of samples of engine coolant or antirustlikely
4、 to be encountered. Should additional information on pH determi-nations be needed, reference should be made to Test Method E70.1.2 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 a
5、ppro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1176 Practice for Sampling and Preparing Aqueous Solu-tions of Engine Coolants or Antirusts for Testing PurposesE70 Test Method for pH of Aqueou
6、s Solutions With theGlass Electrode3. Summary of Test Method3.1 A sample, as received or after dilution with a specifiedvolume of distilled water, is placed in a beaker or sample cupand the pH measured with a pH meter and combinationelectrode or associated glass-saturated calomel electrode pair.NOTE
7、 3The readings of the meter in the case of the concentratedproducts are not pH values according to the accepted definition, but areapparent pH values which are useful in the interpretation of the conditionof the product.4. Significance and Use4.1 pH is a measure of the hydrogen ion concentration and
8、indicates whether an engine coolant, antirust, or a solution ofthese compounds is acidic, alkaline, or neutral.4.2 The pH range includes values from 0 to 14. Values from0 to 7 represent the acidic half of the scale. Values from 7 to 14represent the alkaline or basic half of the scale. The pH value7
9、is considered neutral, as it is neither acidic nor alkaline.4.3 pH is sometimes used for production quality control. Itis generally desirable that engine coolants have an alkaline pH.4.4 pH is not significant from the standpoint of predictingservice life. The pH of used engine coolants or antirustso
10、lutions is not a dependable indication of either existingeffectiveness or remaining life of the solution.5. Apparatus5.1 The pH meter, glass electrode, and calomel electrode,shall be as specified in the Annex.NOTE 4In pH operation, the meter may be set up to perform one-,two- or up to five-point sta
11、ndardizations or may be set up to automaticallyrecognize U.S. standard (pH 4, 7 and 10) buffers, NIST/International (pH1.68, 4.01, 6.86, 9.18 and 12.46) buffers, or a custom user-centered set ofbuffers, or both.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unles
12、s 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.3Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently h
13、igh purity to permit its use without lessening theaccuracy of the determination.6.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean distilled water or water of1This test method is under the jurisdiction of ASTM Committee D15 on EngineCoolants and is the dire
14、ct responsibility of Subcommittee D15.04 on ChemicalProperties.Current edition approved Nov. 1, 2009. Published December 2009. Originallyapproved in 1953 as D1287 53 T. Last previous edition approved in 2002 asD1287 91(02). DOI: 10.1520/D1287-09.2For referenced ASTM standards, visit the ASTM website
15、, 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.3Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society, Washington, DC. For sugges
16、tions 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.1Copyright ASTM International,
17、100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.equal purity. Distilled water shall be boiled thoroughly, orpurged with carbon dioxide-free air, to remove carbon dioxideand shall be protected with a soda-lime tube or its equivalentwhile cooling and in storage. The
18、 pH of the water shall bebetween 6.2 and 7.2 at 25C.6.3 Standard Buffer SolutionsThe buffer solutions forcalibrating the pH meter and electrode pair shall be preparedfrom salts sold specifically for use, either singly or in combi-nation, as pH standards. The salts shall be dried for 1 h at110C befor
19、e use, except in the case of borax which shall beused as the decahydrate. The solutions with pH less than 9.5shall be stored in chemically resistant bottles. The alkalinephosphate solution shall be stored in glass bottles coated on theside with paraffin.NOTE 5Commercially available buffer tablets or
20、 prepared buffersolutions may be used.6.4 Standard Buffer Solution pH = 1.68, (Buffer pH 1.68from Fisher Scientific FC Part Number 13620836) orequivalent could be used.6.5 Potassium Hydrogen Phthalate Buffer Solution (0.05M, pH = 4.01 at 25C)Dissolve 10.21 g of potassiumhydrogen phthalate (KHC8H4O4)
21、 in water, and dilute to 1 L.Standard Buffer Solution pH = 4.0, Potassium HydrogenPhthalate (Red, pH 4.01) from Fisher Scientific (FC PartNumber: SB 101500; NISTSRM 185 g) or equivalent couldbe used.6.6 Neutral Phosphate Buffer Solution (0.025 M with re-spect to each phosphate salt, pH = 6.86 at 25C
22、)Dissolve3.40 g of potassium dihydrogen phosphate (KH2PO4) and 3.55g of anhydrous disodium hydrogen phosphate (Na2HPO4)inwater and dilute to 1 L. Standard Buffer Solution pH = 6.86,Potassium Phosphate (pH 6.86 from Fisher Scientific, orNISTSRM 186 le/lle) or equivalent could be used.6.7 Standard Buf
23、fer Solution pH = 7.0, Potassium Phos-phate Monobasic (Yello, pH 7.00) from Fisher Scientific (FCPart Number: SB 107500) or equivalent could be used.6.8 Borax Buffer Solution (0.01 M, pH = 9.18 at 25C)Dissolve 3.81 g of disodium tetraborate decahydrate(Na2B4O710H2O) in water, and dilute to 1 L. Prot
24、ect thissolution from atmospheric carbon dioxide; stopper the bottle atall times except when actually in use. Standard Buffer SolutionpH=9.18, Sodium Tetraborate 3 10 H2O (borax) (pH 9.18)from Fisher Scientific or NISTSRM 187c) or equivalent couldbe used.6.9 Standard Buffer Solution pH=10.00, Potass
25、ium Carbon-ate, Potassium (Blue, Buffer pH 10.00 from Fisher ScientificFC Part Number SB 115-500) or equivalent could be used.6.10 Alkaline Phosphate Buffer Solution (0.01 M trisodiumphosphate, pH = 11.72 at 25C)Dissolve 1.42 g of anhy-drous disodium hydrogen phosphate (Na2HPO4) in 100 mL ofa 0.1 M
26、carbonate-free solution of sodium hydroxide and diluteto 1 L with water.6.11 Standard Buffer Solution pH=12.46, (Buffer pH 12.46from Fisher Scientific FC Part Number 13-620-837) or equiva-lent could be used.6.12 Potassium Chloride ElectrolytePrepare a saturatedsolution of potassium chloride (KCl) in
27、 water.7. Sampling7.1 Sample material in accordance with Practice D1176.8. Preparation of Electrode System8.1 Maintenance of ElectrodesClean the glass electrode atfrequent intervals (not less than once every week duringcontinual use) in accordance with the manufacturers instruc-tions. Drain the calo
28、mel electrode at least once each week andfill with KCl electrolyte. Keep the electrolyte level in thecalomel electrode above that of the solution being tested at alltimes. When not in use, immerse the lower halves of theelectrodes in distilled water, or the appropriate buffer solutionrecommended by
29、the manufacturer. Do not immerse theelectrodes in the solution being tested for any appreciableperiod of time between determinations. Although the elec-trodes are not extremely fragile, they should be handledcarefully at all times.8.2 Preparation of ElectrodesBefore and after using,wipe the electrod
30、e thoroughly with a clean cloth, or a softabsorbent tissue, and rinse with distilled water. Follow themanufacturers recommendations if further preparation is re-quired. Prior to each pH determination, soak the preparedelectrode in distilled water for at least 2 min. Immediatelybefore use, touch the
31、tips of the electrodes with a dry cloth ortissue to remove excess water.9. Standardization and Testing of Electrode System inpH Units9.1 The assembly shall always be standardized with morethan one of the standard buffer solutions. A single standardiza-tion point serves to establish the electrodes ac
32、tual zero poten-tial, but the electrodes slope is assumed to be a default oralready known value. A pH measurement with one-pointstandardization should be restricted to a narrow pH range, verynear the standardization point. A second standard buffer solu-tion shall be used to check the linearity of th
33、e response of theelectrodes at different pH values and to detect a faulty glasselectrode or incorrect temperature compensation. The twobuffer solutions selected should bracket the anticipated pH ofthe solutions being tested.9.1.1 Turn on the instrument, allow it to warm up, andadjust according to th
34、e manufacturers instructions. Immersethe tips of the electrodes in the standard buffer solution chosenand allow sufficient time for the temperature of the buffersolution and the electrodes to equalize. Set the temperatureknob at the temperature of the buffer solution. Adjust thestandardization or as
35、ymmetry potential control until the meterregisters a scale reading, in pH units, equal to the known pH ofthe standardizing buffer solution.9.1.2 Rinse the electrodes with distilled water and touch thetips with a dry cloth or tissue to remove excess water. Immersethe electrodes in a second standard b
36、uffer solution. The readingof the meter shall agree with the known pH of the secondstandard buffer solution within 60.05 unit without changingthe setting of the standardization of asymmetry potentialcontrol. If it does not agree or if the meter gives a slowresponse time and drifts, the electrode sho
37、uld be cleaned inaccordance with the manufacturers instructions.D1287 0929.1.3 The presence of a faulty electrode is indicated byfailure to obtain a correct value for the pH of the secondstandard buffer solution after the meter has been standardizedwith the first. A cracked electrode will often yiel
38、d pH valuesthat are essentially the same for both standard buffer solutions.9.2 Multi-point standardization allows measurements to beperformed over a very broad pH range, but required theadditional effort of carrying out further standardizations. Withmultiple buffer points, the meter uses the electr
39、ode slopeapplicable to the pH range of the current sample. This linearsegments method is always in pH operation. When standard-ization by auto recognition of U.S. standard buffers or custombuffers is selected, three buffer points are usable. With auto-recognition of NIST buffers or a combination of
40、U.S. standard,custom, and NISTbuffers, or manual entry of buffers, up to fivestandardization buffers are permitted.10. Procedure10.1 Make the pH determination on (1) the unused concen-trated engine coolant or antirust (as received), or (2) anydesired dilution, with distilled water, of the concentrat
41、edproduct, or (3) used engine coolant or antirust solution. Fordilute solutions, suggested engine coolant concentrations are50 and 33 volume %; antirust solution concentration should bein the range of proposed usage. Prepare solutions as follows:Unused engine coolant or antirust solution samples to
42、be testedshould be obtained following the applicable portions of theprocedure outlined in Practice D1176.10.1.1 When a small, insoluble liquid layer is present,remove it prior to testing the unused sample or preparingdiluted samples for testing. Using a 100-mL mixing cylinderand a pipet or other sui
43、table measuring device, make up asolution of the concentration desired for testing by measuringthe necessary amount of antifreeze or antirust solution into thecylinder and adding sufficient distilled water to bring thesolution volume to 100 mL.10.1.2 Thoroughly mix the contents of the cylinder bysha
44、king, and transfer into a 250-mLtall-form spoutless or othersuitable beaker.NOTE 6Some pH apparatus is equipped with a sample cup. It issatisfactory to use these cups and the smaller sample required with them,as an alternative to the 100-mL sample and beaker specified.10.2 Prepare the calomel and gl
45、ass electrodes as directed inSection 8. Immerse the tip of the electrode in the solution andagitate.Where the instrument has a mechanical stirrer, this maybe used. Allow the system to come to equilibrium, and recordthe pH value. Remove and wash the electrodes with distilledwater and immerse them in
46、distilled water until the nextdetermination is made.NOTE 7In the event that the glass electrodes become coated with anoil film, as the result of testing two-phase products, it is necessary toremove such film with a suitable solvent, such as for inorganic deposits-wash with EDTA, ammonia, or acids; f
47、or grease and similar films-washwith acetone or methanol.NOTE 8With silicate-containing engine coolant, it is important tospecify that the pH reading be taken either immediately after preparing thedilution or after a specified period of time, such as 30 min. In contrast toan immediate pH, the 30-min
48、 value has been shown to be approximately0.2 units lower and a measurement made after 24 h can be from 0.3 to 0.5pH units lower.11. Report11.1 Report the pH.12. Precision and Bias12.1 RepeatabilityDuplicate results by the same operatorshould not be considered suspect unless they differ by morethan 6
49、0.1 pH units.12.2 ReproducibilityThe results submitted by two or morelaboratories should not be considered suspect unless the resultsdiffer by more than 60.2 pH units.13. Keywords13.1 antirusts; engine coolants; pH of engine coolantsANNEX(Mandatory Information)A1. APPARATUSA1.1 MeterA1.1.1 A voltmeter or potentiometer that will operate withan accuracy of 60.005 V and a sensitivity of 60.002 V, overa range of at least 60.5 V, when the meter is used with theelectrodes specified in A1.2 and A1.3 and when the resistancebetween the electrodes fall
