ASTM D5682-1995(2002) Standard Test Methods for Electrical Resistivity of Liquid Paint and Related Materials《液体涂料及有关材料电阻率的标准试验方法》.pdf

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1、Designation: D 5682 95 (Reapproved 2002)Standard Test Methods forElectrical Resistivity of Liquid Paint and Related Materials1This standard is issued under the fixed designation D 5682; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio

2、n, 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 These test methods cover the determination of specificresistance (resistivity) of liquid paints, solve

3、nts, and otherfluids in the range of 0.6 to 2640 MV-cm.1.2 Test Method A describes a procedure for making resis-tance tests with a commonly used paint application2testassembly (Fig. 1).1.3 Test Method B describes a procedure for making resis-tance tests with a conductivity meter3(Fig. 2).1.4 This st

4、andard 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 limitations prior to use.2. Terminology2.1 Definiti

5、ons:2.1.1 specific resistance (resistivity)The ratio of the d-cpotential gradient in volts per centimeter paralleling the currentflow within the specimen to the current density in amperes persquare centimeter at a given instant of time and underprescribed conditions.2.1.1.1 DiscussionThis is numeric

6、ally equal to the resis-tance between opposite faces of a centimeter cube of the liquid.The units are ohm centimeters (or megohm centimeters).2.2 Definitions of Terms Specific to This Standard:2.2.1 kilohms (KV)resistance value equal to 1000 V(103).2.2.2 megohms (MV)resistance value equal to 1 000 0

7、00V (106).2.2.3 ohm-centimeters (or megohm-centimeters)unit ofspecific resistance (resistivity).3. Summary of Test Methods3.1 Test Methods A and B measure direct current throughconcentric cylinder electrodes immersed in a liquid paintspecimen.4. Significance and Use4.1 These tests are suitable for t

8、esting paints adjusted forcompatibility with various electrostatic spray coating applica-tions, and by their use, spray performance can be optimized.5. Interferences5.1 Contamination of the specimen is the most likely causeof error. Very small amounts of water, acids, or polar solventswill lower the

9、 resistance of high resistivity solvents and paints.5.2 High humidity is not known to interfere with the testitself but can lead to water pickup by the specimen. Forrepeatable results, tests should be made under the sameatmospheric conditions and specimens should be stored andhandled so as to keep w

10、ater pickup to a minimum.5.3 Resistivity varies with temperature. A standard testtemperature of 25C is recommended. Other temperatures arepossible on agreement between the producer and the user.5.4 Electrification time must be the same for every test dueto ion migrations that cause current flow to d

11、ecrease with time.Variations with time of electrification can result in appreciablevariation in the test results.5.5 Equipment outlined in Test Methods A and B applydifferent test voltages (45 V and 15 V, respectively). Because of1These test methods are under the jurisdiction of ASTM Committee D01 o

12、nPaint and Related Coatings, Materials, and Applications and is the direct responsi-bility of Subcommittee D01.24 on Physical Properties of Liquid Paints and PaintMaterials.Current edition approved March 15, 1995. Published May 1995.2Paint application test assembly such as the Ransburg 70408-00 Test

13、er orequivalent may be obtained from ITW Ransburg Electrostatic Systems, P.O. Box913, Toledo, OH 43697-0913.3Conductivity meter such as the Byk-Gardner LC2 conductivity meter, Model1722/1710 or equivalent may be obtained from Byk-Gardner, Inc., 2435 LindenLane, Silver Spring, MD 20910.FIG. 1 Paint A

14、pplication Test Assembly1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.this, some variation in results may be expected.6. Apparatus6.1 Paint Application Test Assembly2designed to providemeasurement of the electrical resistance of pa

15、int formulationsfor all electrostatic applications. To provide greater accuracy inmeasuring low resistance paints, the meter is equipped withdual range selection. Range “A” is .005 to 1 MV, Range “B”is .05 to 20 MV.7. Reagents and Materials7.1 Low Resistivity Cell Constant Standards (see AppendixX1

16、for cell constant determination method).7.2 Potassium chloride, 1000 V/cm.47.3 Cleaning Solvents and SolutionsIt is essential tothoroughly clean the probe before and after tests. The cleaningsolvent should be chosen on the basis of the paint tested. Duecare must be exercised in cleaning to ensure al

17、l cleaningsolvents are removed from the probe before reusing. The probemust be dry and free from contaminates or results will vary.TEST METHOD A8. Standardization8.1 For maximum accuracy, the probe should be standard-ized to determine the exact cell constant. For routine measure-ments a cell constan

18、t (K) of 132 may be used (see AppendixX1).8.2 The electronic-resistance measuring assembly may bechecked by use of a standard-resistance decade box (12 %accuracy or better).9. Procedure9.1 Prior to tests, make sure that the probe is thoroughlycleaned (see Section 9.2).9.2 Insert the paint test probe

19、 into the jack in the lower rightside of the meter case.9.3 Set the scale select switch (top center) to the Scale Bposition.9.4 Move the mode select switch (top right) to the ZeroAdjust position and rotate the zero adjust knob (top left) untilthe dial indicator needle centers on the adjust position

20、(farright). Maximum accuracy will be realized with the meter lyingflat, meter face up.NOTE 1If the needle will not adjust to zero, replace the battery.9.5 Move the mode select switch to the Paint Test position.9.6 Immerse the probe vertically into a well-mixed, visuallyuniform specimen of the subjec

21、t material until the holes at thebottom of the slots in the probe sleeve are submerged.CautionDo NOT immerse the probe past the top ofsleeve.9.7 Read the paint resistance from Scale B. If the reading isless than 0.5 on the B scale, move the scale select switch to theScale A position, repeat 9.4, the

22、n read the paint resistance fromScale A.9.8 Read the scale value at 10 s after immersion in the testsample. Ignore any slow drift that may occur after this time.9.9 To convert the megohms reading on the tester toresistivity in megohm-centimeters, multiply by constant “K”found in 8.1 or 132.9.10 Clea

23、n the probe thoroughly. Allow the apparatus andspecimen to stand for 1 h (keep lids on specimens tightlyclosed to prevent loss of volatiles). Repeat the measurement,making certain to remix the specimen.9.11 Report the result as the mean value of the twomeasurements.TEST METHOD B10. Apparatus10.1 Con

24、ductivity Meter,3provides measurement of electri-cal resistivity of solvents and pain formulations for electro-static spray applications. This meter permits evaluation ofsolvents and liquid paints in the resistance range of 0.0520MV.11. Standardization11.1 For maximum accuracy, the probe should be s

25、tandard-ized to determine the cell constant. For routine measurement, acell constant (K) of 132 may be used (see Appendix X1).11.2 The electronic resistance measuring assembly may bechecked by use of a standard resistance decade box (12 %accuracy or better).4One thousand V/cm test solutions are avai

26、lable from scientific supplycompanies (see5).FIG. 2 Conductivity MeterD 5682212. Procedure12.1 Prior to tests, thoroughly clean the probe. See Section12.12.2 Connect the measuring cable of the probe to the socketin the back of the instrument.12.3 Immerse the measuring cell into a well mixed, visuall

27、yuniform specimen. The specimen should reach the two holes inthe probe.12.4 Press the measuring button. After 10 s the measuredvalue is displayed in megohms.12.5 To convert the megohms readings to specific resistivityin megohm-centimeters, multiply by 132.5 cm.12.6 Clean the probe thoroughly. Allow

28、the apparatus andspecimen to stand for 1 h (keep lids of specimen tightly closedto prevent loss of volatiles). Repeat the measurement, makingcertain to remix the specimen.12.7 Report the result as the mean value of the twomeasurements.13. Report13.1 Report the following information:13.1.1 Identifica

29、tion of the material under test,13.1.2 Identification of the tester used,13.1.3 The test temperature, and13.1.4 The resistivity in megohm-centimeters (the meanvalue of two measurements).14. Precision and Bias14.1 PrecisionThe precision estimates are based on aninterlaboratory study in which one oper

30、ator in each of sevendifferent laboratories (five using the first tester2, two the secondtester)3measured the resistivity in duplicate on two differentdays for three solvent specimens ranging in resistivity from 40to 818 MV-cm (0.36.2 MV resistance). The within-laboratorycoefficient of variation was

31、 found to be 4.0 % with 16 df andthe between-laboratory coefficient of variation 23.0 % with 13df. Based on these coefficients, the following criteria should beused for judging the acceptability of results at the 95 %confidence level.14.1.1 RepeatabilityTwo results, each the mean of dupli-cate deter

32、minations, obtained by the same operator on differentdays should be considered suspect if they differ by more than12 % relative.14.1.2 ReproducibilityTwo results, each the mean of du-plicate determinations, obtained by operators in different labo-ratories should be considered suspect if they differ

33、by morethan 70 % relative.14.2 BiasSince there is no accepted reference materialsuitable for determining the bias for the procedures in these testmethods, bias has not been determined.15. Keywords15.1 conductivity meter; electrical resistance; electrical re-sistivity; electrostatic spray application

34、compatibility; paintapplication test assembly; specific resistanceAPPENDIX(Nonmandatory Information)X1. TESTING THE PROBE (CELL CONSTANT DETERMINATION)X1.1 These cells depend on concentricity of the inner andouter section for accuracy and repeatability. The cell constantmay be tested by the followin

35、g method. Both cells haveidentical cell constants by design, so may be tested in samemanner. The main reason for doing this is to determine whetherthe cell is in good condition, clean, and operating properly. Ifthe cell is dirty or damaged, it will not give the correct cellconstant.X1.2 Obtain a sta

36、ndard solution of approximately 1000V/cm.5X1.3 Measure the resistance of the standard solution (inohms) using the probe and an ohmmeter with full scale readingof about 25 V, since the test meters normally used in thesemethods are not suitable for measuring this low value ofresistance.X1.4 The cell c

37、onstant may be found by substituting in thefollowing equation:K 5 P/R (X1.1)where:K = the cell constant in cm,P = the resistance in MV-cm, andR = the resistance in MV.X1.5 This value is typically 132, but may vary slightlybecause of manufacturing tolerances, or slight damage while inuse. If the cell

38、 constant is 133, reclean the cell andrecheck the constant. If it is still outside the range 128 to 133,then the outer sleeve probably has been damaged and must bereplaced.5Test solutions may be obtained from chemical supply companies such asAmerican Scientific Products, 1210 Waukegan Road, McGraw P

39、ark, Illinois 60085,or Ricca Chemical Company, 448 W. Fork Drive, Arlington, Texas 76013.D 56823ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determin

40、ation of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or wit

41、hdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that yo

42、ur comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 56824