1、Designation: D 5931 96 (Reapproved 2007)Standard Test Method forDensity and Relative Density of Engine CoolantConcentrates and Aqueous Engine Coolants by DigitalDensity Meter1This standard is issued under the fixed designation D 5931; the number immediately following the designation indicates the ye
2、ar 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 determination of the dens
3、ityor relative density of engine coolant concentrates and aqueousengine coolants.1.2 This test method should not be applied to samples sodark in color that the absence of air bubbles in the sample cellcannot be established with certainty.1.3 The accepted units of measure for density are grams permil
4、liliter or kilograms per cubic meter.1.4 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 regulatory lim
5、itations prior to use. For specific hazardstatements, see Note 1.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterD 4052 Test Method for Density and Relative Density ofLiquids by Digital Density Meter3. Terminology3.1 Definitions:3.1.1 relative density, nthe ratio of
6、the density of amaterial at a stated temperature to the density of water at thesame stated temperature.4. Summary of Test Method4.1 A small volume of liquid sample is introduced into anoscillating sample tube, and the change in oscillating frequencycaused by the change in the mass of the tube is use
7、d inconjunction with calibration data to determine the density ofthe sample.5. Significance and Use5.1 Density is a fundamental physical property that can beused in conjunction with other properties to characterize enginecoolant concentrates and aqueous engine coolants.5.2 Determination of the densi
8、ty or relative density of theseproducts is necessary for the conversion of measured volumesto volumes at the standard temperature of 20C (68F).6. Apparatus6.1 Digital Density Analyzer, consisting of a U-shaped,oscillating sample tube and a system for electronic excitation,frequency counting, and dis
9、play. The analyzer must accommo-date the accurate measurement of the sample temperatureduring measurement or must control the sample temperature asdescribed in 6.2. The instrument must meet the precisionrequirements described in this test method.6.2 Circulating ConstantTemperature Bath, (optional) c
10、a-pable of maintaining the temperature of the circulating liquidconstant to 60.05C in the desired range. Temperature controlcan be maintained as part of the density analyzer instrumentpackage.6.3 Syringes, at least 2 mL in volume with a tip or anadapter tip that will fit the opening of the oscillati
11、ng tube.1This test method is under the jurisdiction of ASTM Committee D15 on EngineCoolants and is the direct responsibility of Subcommittee D15.03 on PhysicalProperties.Current edition approved Oct. 1, 2007. Published October 2007. Originallyapproved in 1996. Last previous edition approved in 2002
12、as D 593196(2002)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.1Copyright ASTM International, 100 Barr Harb
13、or Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.4 Flow-Through or Pressure Adapter, for use as analternative means of introducing the sample into the densityanalyzer either by a pump or by vacuum.6.5 Thermometer, calibrated and graduated to 0.1C, with athermometer holder tha
14、t can be attached to the instrument forsetting and observing the test temperature. In calibrating thethermometer, the freeze point should be estimated to thenearest 0.05C.7. Reagents and Materials7.1 Purity of ReagentsUse reagent grade chemicals in alltests. Unless otherwise indicated, all reagents
15、shall conform tothe specifications of the Committee on Analytical Reagents ofthe American Chemical Society, where such specifications areavailable.3Other grades may be used, provided it is firstascertained that the reagent is of sufficiently high purity topermit its use without lessening the accurac
16、y of the determi-nation.7.2 Purity of WaterUnless otherwise indicated, referencesto water mean reagent water as defined by Type II ofSpecification D 1193.7.3 Water, redistilled, freshly boiled and cooled reagentwater for use as a primary calibration standard.7.4 Acetone, for flushing and drying the
17、sample tube.NOTE 1Warning: Acetone is extremely flammable.7.5 Dry Air, for drying the oscillator tube.8. Preparation of Apparatus8.1 Set up the density analyzer and constant temperaturebath following the manufacturers instructions. Adjust the bathor internal temperature control so that the desired t
18、est tempera-ture is established and maintained in the sample compartmentof the analyzer. Calibrate the instrument at the same tempera-ture at which the density of the sample is to be measured.NOTE 2Precise setting and control of the test temperature in thesample tube is extremely important. An error
19、 of 1.0C can result in achange in density of one in the third decimal place.9. Calibration of Apparatus9.1 Calibrate the instrument when first set up and wheneverthe test temperature is changed. Thereafter, conduct calibrationchecks at weekly intervals during routine operation.9.2 Initial calibratio
20、n, or calibration after a change in testtemperature, necessitates calculation of the values of theconstants A and B from the periods of oscillation (T) observedwhen the sample cell contains air and redistilled, freshly boiledand cooled reagent water.9.2.1 While monitoring the oscillator period, (T),
21、 flush thesample tube with distilled water followed by an acetone flushand drying with dry air. Contaminated or humid air can affectthe calibration. When these conditions exist in the laboratory,pass the air used for calibration through a suitable purificationand drying train. In addition, the inlet
22、 and outlet ports for theU-tube must be plugged during measurement of the calibrationair to prevent ingress of moist air.9.2.2 Allow the dry air in the U-tube to come to thermalequilibrium with the test temperature and record the T-valuefor air.9.2.3 Introduce a small volume of redistilled, freshly
23、boiledand cooled reagent water into the sample tube opening using asuitable syringe. The test portion must be homogeneous andfree of even the smallest air or gas bubbles. The sample tubedoes not have to be completely full as long as the liquidmeniscus is beyond the suspension point. Allow the displa
24、y toreach a steady reading and record the T-value for water.9.2.4 Record the density of air at the temperature andatmospheric pressure of the test. Calculate the density of air atthe temperature of test using the following equation:da, g/mL 5 0.001293273.15/TP/760 (1)where:T = temperature, degrees K
25、elvin, K, andP = barometric pressure, torr.9.2.5 Determine the density of water at the temperature oftest by reference to Table 1.9.2.6 Using the observed T-values and the reference valuesfor water and air, calculate the values of the constants A and Busing the following equations:A 5 Tw22 Ta2#/dw2
26、da# (2)B 5 Ta22 A 3 da! (3)where:Tw= observed period of oscillation for cell containingwater,Ta= observed period of oscillation for cell containing air,dw= density of water at test temperature, C, andda= density of air at test temperature, C.Alternatively, use the T and d values for the other refere
27、nceliquid if one is used.9.2.7 If the instrument is equipped to calculate density fromthe constants A and B and the observed T-value from thesample, enter the constants in the instrument memory inaccordance with the manufacturers instructions.3Reagent Chemicals, American Chemical Society Specificati
28、ons , 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 Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention,
29、 Inc. (USPC), Rockville,MD.TABLE 1 Density of WaterATemper-ature,CDensity,g/mLTemper-ature,CDensity,g/mLTemper-ature,CDensity,g/mL0 0.99987 21 0.99802 40 0.992243 0.99999 22 0.99780 45 0.990254 1.00000 23 0.99756 50 0.988075 0.99999 24 0.99732 55 0.9857310 0.99973 25 0.99707 60 0.9832415 0.99913 26
30、0.99681 65 0.9805915.56 0.99904 27 0.99654 70 0.9778116 0.99897 28 0.99626 75 0.9748917 0.99880 29 0.99597 80 0.9718318 0.99862 30 0.99567 85 0.9686519 0.99843 35 0.99406 90 0.9653420 0.99823 37.78 0.99307 100 0.95838AFrom Test Method D 4052.D 5931 96 (2007)29.2.8 Check the calibration and adjust if
31、 needed by perform-ing the routine calibration check described in 9.3.9.2.9 To calibrate the instrument to display relative density,that is, the density of the sample at a given temperature relativeto the density of water at the same temperature, follow9.2.1-9.2.7, but substitute 1.000 for dwin perf
32、orming thecalculations described in 9.2.6.9.3 Weekly calibration adjustments to constants A and B canbe made if required without repeating the calculation proce-dure.NOTE 3The need for a change in calibration generally is attributableto deposits in the sample tube that are not removed by the routine
33、 flushingprocedure. Although this condition can be compensated for by adjusting Aand B, it is good practice to clean the tube sequentially with water,petroleum ether, and acetone.9.3.1 Flush and dry the sample tube as described in 9.2.1and allow the display to reach a steady reading. If the displayd
34、oes not exhibit the correct density for air at the temperature oftest, repeat the cleaning procedure or adjust the value ofconstant B commencing with the last decimal place until thecorrect density is displayed.9.3.2 If adjustment to constant B was necessary in 9.3.1,continue the recalibration by in
35、troducing redistilled, freshlyboiled and cooled reagent water into the sample tube asdescribed in 9.2.3 and allow the display to reach a steadyreading. If the instrument has been calibrated to display thedensity, adjust the reading to the correct value for water at thetest temperature (see Table 1)
36、by changing the value ofconstant A, commencing with the last decimal place. If theinstrument has been calibrated to display the relative density,adjust the reading to the value 1.000.NOTE 4In applying this weekly calibration procedure, it can be foundthat more than one value for A and B, differing i
37、n the fourth decimal place,will yield the correct density reading for the density of air and water. Thesetting chosen then would be dependent upon whether it is approachedfrom a higher or lower value. The setting selected by this test methodcould have the effect of altering the fourth place of the r
38、eading obtainedfor a sample.9.4 Some analyzer models are designed to display themeasured period of oscillation only (T-values) and theircalibration requires the determination of an instrument constantK, which must be used to calculate the density or relativedensity from the observed data.9.4.1 Flush
39、 and dry the sample tube as described in 9.2.1and allow the display to reach a steady reading. Record theT-value for air.9.4.2 Introduce redistilled, freshly boiled and cooled reagentwater into the sample tube as described in 9.2.3, and allow thedisplay to reach a steady reading and record the T-val
40、ue forwater.9.4.3 Using the observed T-values and the reference valuesfor water and air (9.2.4 and 9.2.5), calculate the instrumentconstant K using the following equations:For density:K15 $dw2 da%/$Tw22 Ta2% (4)For relative density:K25 $1.0000 2 da%/$Tw22 Ta2% (5)where:Tw= observed period of oscilla
41、tion for cell containingwater,Ta= observed period of oscillation for cell containing air,dw= density of water at test temperature, C, andda= density of air at test temperature, C.10. Procedure10.1 Mix the sample, if required, to be completely homo-geneous. If suspended solids are present in the samp
42、le, filterthrough a 0.5 m filter. Introduce a small amount (about 0.7mL) of sample into the clean, dry sample tube of the instrumentusing a suitable syringe.10.2 Turn on the illumination light and examine the sampletube carefully. Make sure that no bubbles are trapped in thetube and that it is fille
43、d to just beyond the suspension point. Thesample must be homogeneous and free of even the smallestbubbles.NOTE 5If the sample is too dark in color to determine the absence ofbubbles with certainty, the density cannot be measured within the statedprecision limits of Section 13.10.3 Turn the illuminat
44、ion light off immediately aftersample introduction because the heat generated can affect themeasurement temperature.10.4 After the instrument displays a steady reading to foursignificant figures for density and five for T-values, indicatingthat temperature equilibrium has been reached, record theden
45、sity or T-value.11. Calculation11.1 Calculating Density AnalyzersThe recorded value isthe final result, expressed either as density in g/mL, kg/m3or asrelative density. Note that kg/m3= 1000 3 g/mL.11.2 Noncalculating Density AnalyzersUsing the ob-served T-value for the sample and the T-value for wa
46、ter andappropriate instrument constants determined in 9.4.3, calculatethe density or relative density using (Eq 6) and (Eq 7). Carryout all calculations to six significant figures and round the finalresults to five.For density:density, g/mL kg/dm3! at t 5 dw1 K1Ts22 Tw2! (6)For relative density:rela
47、tive density, t/t 5 1 1 K2Ts22 Tw2! (7)where:Tw= observed period of oscillation for cell containingwater,Ts= observed period of oscillation for cell containingsample,dw= density of water at test temperature,K1= instrument constant for density,K2= instrument constant for relative density, andt = temp
48、erature of test, C.D 5931 96 (2007)312. Report12.1 In reporting density, give the test temperature and theunits, for example, density at 20C = 1.0360 g/mL or 1036kg/m3.12.2 In reporting relative density, give both the test tem-perature and the reference temperature but no units, forexample, relative
49、 density at 20/20C = 1.0361.12.3 Report the final results to the five significant figures.13. Precision and Bias413.1 The precision of this test method as obtained bystatistical examination of interlaboratory test results at testtemperature of 20C is as follows:13.1.1 RepeatabilityThe difference between successivetest results obtained by the same operator with the sameapparatus under constant operating conditions on identical testmaterial would, in the long run, in the normal and correctoperation of this test method, be expected to be as fol
