1、Designation: D5682 08 (Reapproved 2012)Standard Test Methods forElectrical Resistivity of Liquid Paint and Related Materials1This standard is issued under the fixed designation D5682; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision,
2、 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.1. Scope*1.1 These test methods cover the determination of specificresistance (resistivity) of liquid paints, solvent
3、s, and otherfluids in the range of 0.6 to 2640 M-cm.1.2 Test Method A describes a procedure for making resis-tance tests with a commonly used paint application testassembly (Fig. 1 and Fig. 2).1.3 Test Method B describes a procedure for making resis-tance tests with a conductivity meter (Fig. 3).1.4
4、 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 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-p
5、riate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Terminology2.1 Definitions:2.1.1 specific resistance (resistivity), nthe ratio of the d-cpotential gradient in volts per centimetre paralleling the currentflow within the specimen to the curr
6、ent density in amperes persquare centimetre at a given instant of time and underprescribed conditions.2.1.1.1 DiscussionThis is numerically equal to the resis-tance between opposite faces of a centimetre cube of the liquid.The units are ohm centimetres (or megohm centimetres).2.2 Definitions of Term
7、s Specific to This Standard:2.2.1 kilohm (K), nresistance value equal to 1000 (103).2.2.2 megohm (M), nresistance value equal to 1 000 000 (106).2.2.3 ohm-centimetre (or megohm-centimetre), nunit ofspecific resistance (resistivity).3. Summary of Test Methods3.1 Test Methods A and B measure direct cu
8、rrent throughconcentric cylinder electrodes immersed in a liquid paintspecimen.4. Significance and Use4.1 These tests are suitable for testing paints adjusted forcompatibility with various electrostatic spray coatingapplications, and by their use, spray performance can beoptimized.5. Interferences5.
9、1 Contamination of the specimen is the most likely causeof error. Very small amounts of water, acids, or polar solventswill lower the 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. Forre
10、peatable results, tests should be made under the sameatmospheric conditions and specimens should be stored andhandled so as to keep water pickup to a minimum.5.3 Resistivity varies with temperature. A standard testtemperature of 25C is recommended. Other temperatures arepossible on agreement between
11、 the producer and the user.5.4 Electrification time must be the same for every test dueto ion migrations that cause current flow to decrease with time.Variations with time of electrification can result in appreciablevariation in the test results.5.5 Devices described in Test Methods A and B applydif
12、ferent test voltages (45 V and 15 V, respectively). Because ofthis, some variation in results may be expected.6. Reagents and Materials6.1 Low Resistivity Cell Constant Standards (see AppendixX1 for cell constant determination method).6.1.1 Potassium Chloride, 1000 /cm.26.2 Cleaning Solvents and Sol
13、utionsIt 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 all cleaning1These test methods are under the jurisdiction of ASTM Committee D01 onPaint and Related Coati
14、ngs, Materials, and Applications and are the directresponsibility of Subcommittee D01.24 on Physical Properties of Liquid Paints andPaint Materials.Current edition approved Nov. 1, 2012. Published November 2012. Originallyapproved in 1995. Last previous edition approved in 2008 as D5682 - 08. DOI:10
15、.1520/D5682-08R12.21000 /cm test solutions are available from scientific supply companies.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1solvents are removed from the p
16、robe before reusing. The probemust be dry and free from contaminates or results will vary.TEST METHOD A7. Apparatus7.1 Paint Application Test Assemblydesigned to providemeasurement of the electrical resistance of paint formulationsfor all electrostatic applications. To provide greater accuracy inmea
17、suring low resistance paints, the meter is equipped withdual range selection. Range “A” is .005 to 1 M , Range “B”is .05 to 20 M. The original version of this device was ananalog instrument with a pointer and scale as shown in Fig. 1and many such instruments are in use. It has been replaced bya digi
18、tal version, a diagram of which is in Fig. 2.8. Standardization8.1 For maximum accuracy, the probe should be standard-ized to determine the exact cell constant. For routine measure-ments a cell constant (K) of 132 may be used (see AppendixX1).8.2 The electronic-resistance measuring assembly may bech
19、ecked 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 6.2).9.2 Insert the paint test probe into the jack in the lower rightside of the meter case.9.3 Set the scale select switch (top center) to the
20、 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 (farright). Maximum accuracy will be realized with the meter lyingflat, meter face up.NOTE 1If the needle w
21、ill 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 subject material until the holes at thebottom of the slots in the probe sleeve are submerged.FIG. 1 Analog Paint
22、Application Test AssemblyFIG. 2 Diagram of Digital Application Test AssemblyFIG. 3 Conductivity MeterD5682 08 (2012)2WarningDo 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 theSca
23、le A position, repeat 9.4, then 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-centimetres, multiply by constant “K
24、”found in 8.1 or 132.9.10 Clean 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
25、 METHOD B10. Apparatus10.1 Conductivity Meter provides measurement of electricalresistivity of solvents and paint formulations for electrostaticspray applications (Fig. 3). This meter permits evaluation ofsolvents and liquid paints in the resistance range of 0.05 to 20M.11. Standardization11.1 For m
26、aximum accuracy, the probe should be standard-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).12.
27、Procedure12.1 Prior to tests, thoroughly clean the probe. See 6.2.12.2 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, visuallyuniform specimen. The specimen should reach the two holes inthe probe.12.4 Press the m
28、easuring button. After 10 s the measuredvalue is displayed in megohms.12.5 To convert the megohms readings to specific resistivityin megohm-centimetres, multiply by 132.5 cm.12.6 Clean the probe thoroughly. Allow the apparatus andspecimen to stand for 1 h (keep lids of specimen tightly closedto prev
29、ent 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 Identification of the material under test,13.1.2 Identification of the tester used,13.1.3 The tes
30、t temperature, and13.1.4 The resistivity in megohm-centimetres (the meanvalue of two measurements).14. Precision and Bias14.1 PrecisionThe precision estimates are based on aninterlaboratory study in which one operator in each of sevendifferent laboratories (five using an analong version of the first
31、tester, two the second tester) measured the resistivity induplicate on two different days for three solvent specimensranging in resistivity from 40 to 818 M-cm (0.3 to 6.2 Mresistance). The within-laboratory coefficient of variation wasfound to be 4.0 % with 16 df and the between-laboratorycoefficie
32、nt of variation 23.0 % with 13 df. Based on thesecoefficients, the following criteria should be used for judgingthe acceptability of results at the 95 % confidence level.14.1.1 RepeatabilityTwo results, each the mean of dupli-cate determinations, obtained by the same operator on differentdays should
33、 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 by morethan 70 % relative.14.2 BiasSince there is no accepted re
34、ference 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 applicationcompatibility; paintapplication test assembly; specific resistan
35、ceD5682 08 (2012)3APPENDIX(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 following method. Both cells haveidentical cell constant
36、s 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 standard solution of approximately 1000/cm.X1.3 Mea
37、sure the resistance of the standard solution (inohms) using the probe and an ohmmeter with full scale readingof about 25 , since the test meters normally used in thesemethods are not suitable for measuring this low value ofresistance.X1.4 The cell constant may be found by substituting in thefollowin
38、g equation:K 5 P/R (X1.1)where:K = the cell constant in cm,P = the resistance in M-cm, andR = the resistance in M.X1.5 This value is typically 132, but may vary slightlybecause of manufacturing tolerances, or slight damage while inuse. If the cell constant is 133, reclean the cell andrecheck the con
39、stant. If it is still outside the range 128 to 133,then the outer sleeve probably has been damaged and must bereplaced.SUMMARY OF CHANGESCommittee D01 has identified the location of selected changes to this standard since the last issue(D5682 - 95 (2002) that may impact the use of this standard. (Ap
40、proved June 1, 2008.)(1) Information on specific suppliers of instruments has beenremoved in keeping with ASTM policy.(2) The section on Apparatus has been split in two and movedto the two different test methods.(3) The section on Reagents and Materials has been renum-bered.(4) A sentence has been a
41、dded to the Apparatus section forMethod A indicating that the meter that is currently available isdigital.(5) A diagram of the digital apparatus for Method A has beenadded (Figure 2) and the previous Figure 2 has been renumberto Figure 3.(6) Several typographical errors have been corrected.ASTM Inte
42、rnational 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 determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely
43、 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 withdrawn. Your comments are invited either for revision of this standard or for additional standardsand sho
44、uld 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 your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Sta
45、ndards, 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). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D5682 08 (2012)4
