1、Designation: D 7358 07Standard Test Method forWater Content of Paints by Quantitative Calcium HydrideReaction Test Kit1This standard is issued under the fixed designation D 7358; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the
2、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 describes the determination of the totalwater content of paints using a calcium hydride reac
3、tion testkit, or water content between 2 and 85 % water.1.2 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresp
4、onsibility 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. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterD 3925 Practice for Sampling Liquid Paints and Relate
5、dPigmented CoatingsD 4017 Test Method for Water in Paints and Paint Materialsby Karl Fischer MethodE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with Specifications3. Summary of Test Method3.1 A0.25 mL sample is reacted with a specially formulatedcalcium hydride reag
6、ent to convert water in the sample tohydrogen gas. The reaction is carried out in a sealed pressurevessel and the resulting pressure is then measured using aspecially designed meter programmed to convert gas pressureinto water content. The results are displayed in milligrams ofwater in the reacted s
7、ample extract. The actual weight percentwater in the whole paint sample is manually calculated usingthe exact weights of the paint sample and the diluted extractsample, if used.4. Significance and Use4.1 Although Test Method D 4017 is widely used for thedetermination of water in paints and related m
8、aterials, thismethod may overcome some of the variability found in theKarl Fischer method.4.2 Control of water content is often important in control-ling the performance of paints, and it is critical in determiningvolatile organic compound (VOC) content when VOC contentis measured by difference from
9、 total volatile matter and watercontent as required in certain federal and state regulations.5. Interferences5.1 The following compounds, tested at twice the samplesize, have been found to produce no measurable response to thecalcium hydride reaction test kit and, therefore, cause nointerference at
10、levels up to 40 %:3EthanolMethanolAcetoneAMethyl Ethyl KetoneTetrahydrofuranDiethylene Glycol Dimethyl EtherEthylene GlycolADiethylene GlycolDipropylene GlycolStearic Acid2Ethyl Hexanoic AcidLead Oxide (II and III)Aluminum Oxide (Brockman I)A0.25 mL sample size program A and B.5.2 When using the 5 m
11、L sample size programs, that is,programs C, D, or E, ethylene glycol and acids have beenfound to produce a positive result in the presence of a small1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsib
12、ility ofSubcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.Current edition approved Nov. 1, 2007. Published November 2007.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards vol
13、ume information, refer to the standards Document Summary page onthe ASTM website.3HydroSCOUT Users Manual.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.amount of water. Ethylene glycol responds at approximately7 % of the volumetric
14、 equivalent.6. Apparatus6.1 HydroSCOUT4SystemA test kit system consisting ofthe HydroSCOUT meter, reaction tubes, sampling syringes anddilution vials.5The entire analytical sequence, including sam-pling, sample dilution, chemical reactions and quantification, isavailable in kit form using pre-dispen
15、sed and encapsulatedreagents. An analytical balance is required in order to obtainthe most precise results. In addition, a mechanical shaker maybe necessary to obtain a representative sample.7. Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.All reagents
16、 shall conform to the specificationsof the Committee on Analytical reagents of the AmericanChemical Society, where such specifications are available.67.2 Purity of WaterUnless otherwise indicated, referenceto water shall mean reagent water conforming to SpecificationD 1193, Type II.7.3 Calcium Hydri
17、de (20 %) in HI SOL 10contained in acrushable glass ampule.7.4 Watercontained in a crushable glass ampule.7.5 Diethylene Glycol Dimethyl Ether (Diglyme)2.25 mLcontained in a glass vial.8. Hazards8.1 Store ampules in a cool, dry place. Keep away fromheat, sparks, water and open flames.8.2 See manufac
18、turers instructions and Material SafetyData Sheet (MSDS) before use.8.3 The gray ampule in the tube contains calcium hydride,which is a flammable solid and water reactive.8.4 Perform test only in a well ventilated area.8.5 Always wear rubber gloves and safety glasses.8.6 Take care to ensure that fin
19、gers are not cut by glass inthe kits. Each ampule should be crushed only once to reducethe risk of glass pieces piercing the sides of the tube.8.7 When venting reaction tube after completion of test,point tube upright and away from user and bystander.8.8 When breaking the green water ampule after co
20、mpletionof test, the tube must be shaken vigorously for the full 15seconds to ensure that the water contacting the remainingcalcium hydride does not overheat the side of the tube,otherwise tube failure can result.9. Sampling, Test Specimens, and Test Units9.1 Sample CollectionTake a representative s
21、ample of theliquid coatings in accordance with Practice D 3925. Mixthoroughly before taking specimens for individual tests.10. Preparation10.1 PreparationRemove a sampling syringe with capand a test tube from the kit box. Check the contents to ensurethat all items are present and intact. If a diluti
22、on is to be used,remove a dilution vial and an additional sampling syringe andcap. Remove the screw cap and rubber septum from the tubeand the cap from the dilution vial, if used. Insert one greenwater ampule into the top of the polypropylene ampule sleeveand replace the holder in the tube.11. Calib
23、ration and Standardization11.1 The commercially available meter is calibrated at thefactory over the pressure range of 0 to 60 psig. Each time themeter is turned on, the pressure transducer recalibrates the 0psig point. If this changes significantly from the factory setpoint, an error message will b
24、e displayed. This error will alsoappear if a tube is accidentally inserted into the meter beforethe meter is turned on.12. Procedure12.1 Sample Introduction for Expected Water Content LessThan 15 % (No Dilution)Work the plunger on an emptysampling syringe a few times to ensure that it slides easily.
25、Place the tip of the syringe into the paint sample to be testedand slowly pull back on the plunger until it reaches the stop andcannot be pulled further. Remove the syringe from the paintsample and wipe any excess paint from the outside of thesyringe with a tissue wipe provided with the kit. Cap the
26、syringe with the cap provided and weigh; record the weight(gross sample weight) to the nearest 0.1 mg. Dispense thesample into the reaction tube. Recap the syringe withoutwiping, reweigh it, and record this weight (sample tare weight).The difference in the two weights becomes the sample weight(S1) t
27、o be used in Eq 1. Replace the rubber septum (hole ontop) by gripping the tube firmly and pressing the septum downwith the thumb. (NOTE: Do not squeeze the sides of the tubewhile inserting the septum.) Replace the screw cap tightly,turning it until it cannot be turned further. Proceed to step 12.3.1
28、2.2 Sample Introduction for Expected Water ContentGreater Than 15 % (With Dilution)Work the plunger on anempty sampling syringe a few times to ensure that it slideseasily. Place the tip of the syringe into the paint sample to betested and slowly pull back on the plunger until it reaches thestop and
29、cannot be pulled further. Remove the syringe from thepaint sample and wipe any excess paint from the outside of thesyringe with a tissue wipe provided with the kit. Cap thesyringe with the cap provided and weigh; record the weight(gross sample weight) to the nearest 0.1 mg. Dispense thesample into t
30、he dilution vial containing a premeasured amountof solvent (2.15 g). (Do not allow the syringe to contact thedilution solvent when dispensing the sample.) Recap thesyringe without wiping, reweigh it, and record this weight(sample tare weight). The difference in the two weights4HydroSCOUT is a tradem
31、ark of the Dexsil Corporation.5The sole source of supply of this kit known to the committee at this time isDexsil Corporation, One Hamden Park Drive, Hamden, CT 06517. If you are awareof alternative suppliers, please provide this information to ASTM InternationalHeadquarters. Your comments will rece
32、ive careful consideration at a meeting of theresponsible technical committee,1which you may attend.6Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Anala
33、r Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D7358072becomes the sample weight S1to be used in Eq 2. Replace thecap on the dilution vial and shake the vial vigoro
34、usly for atleast 10 seconds. Remove the cap and quickly, using a newsyringe, draw up a sample from the solution. Wipe any excesssolution from the outside of the syringe, cap and weigh thesyringe. Record this weight (diluted sample gross weight).Dispense this sample into the reaction tube. Recap the
35、syringe,without wiping it, and reweigh the syringe and record thisweight (diluted sample tare weight). The difference in the twoweights becomes the diluted sample weight (S2) to be used inEq 2. Replace the rubber septum (hole on top) by gripping thetube firmly and pressing the septum down with the t
36、humb.(NOTE: Do not squeeze the sides of the tube while insertingthe septum.) Replace the screw cap tightly, turning it until itcannot be turned further.12.3 ReactionBreak the bottom (gray) ampule in the tubeby compressing the sides of the tube. Mix thoroughly byshaking the tube vigorously for 30 sec
37、onds. The mixture willbe seen to bubble and perhaps foam. Allow the reaction toproceed for 2 minutes. Shake the reaction tube again for 10seconds and let stand for an additional 1 minute.12.4 AnalysisEnsure the meter is set for the correctprogram for determining water in paint and that the meter isr
38、eady for measurement. Insert the reaction tube firmly into theopening at the bottom of the meter. The hole in the white capmust be lined up with the metal pin extending from the insideof the hole in the meter. Press the “READ” button on the faceof the meter. The display will flash the word “CALC,” t
39、hen theresults will be displayed in milligrams of water in the sample.Record the results. Keep the meter and tube upright at all times.12.5 DisposalCarefully remove the reaction tube from themeter. Vent tube by inserting completely into venting cap andremoving. Tube and cap must be upright and point
40、ed awayfrom user and bystanders. Tap the tube on the bench top toshake any loose glass to the bottom of the tube, then break thetop (green) ampule in the reaction tube by compressing thesides of the tube. Shake the tube for 15 seconds.After any foamhas settled, vent the tube again. Discard the tube
41、and vial aslaboratory waste. Do not remove cap.13. Calculations13.1 Calculations for Direct Sample (No Dilution)Themeter is programmed to display the weight, in milligrams, ofthe water contained in the sample introduced into the reactiontube (in this case the paint sample). Calculate the water conte
42、ntin the original paint sample in weight percent using Eq 1:Water in paint, wt. percent 5 R/10*S1! (1)where:R = meter reading in milligrams of waterS1= actual weight of whole paint sample, grams13.2 Calculations for Diluted Sample (With Dilution)Themeter is programmed to display the weight, in milli
43、grams, ofthe water contained in the sample introduced into the reactiontube (in this case the diluted sample). Calculate the watercontent in the original paint sample in weight percent using Eq2:Water in paint, wt. percent 5 R/S2!1 1 2.15/S1!/10 (2)where:R = meter reading in milligrams of waterS1= a
44、ctual weight of whole paint sample, gramsS2= actual weight of diluted paint sample, grams2.15 = weight of the dilution solvent, grams14. Report14.1 Report calculated water content in weight percent tothree significant figures (see Practice E29for guidance). Thereport should also include the method u
45、sed to determine thewater content: Test Method D 7358.15. Precision and Bias715.1 The precision of this test method is based on aninterlaboratory study of Test Method D 7358, conducted in2006. Each of six laboratories tested six different materialsusing two analyses for the determination of water co
46、ntent; KarlFischer and a calcium hydride test. Every “test result” repre-sents an individual determination. Each laboratory obtainedtwo replicate test results (from one operator) for each material/analysis combination.15.1.1 RepeatabilityTwo test results obtained within onelaboratory shall be judged
47、 not equivalent if they differ by morethan 5.7 % of the measured value; Repeatability “ r” is theinterval representing the critical difference between two testresults for the same material, obtained by the same operatorusing the same equipment on the same day in the samelaboratory. For more detailed
48、 information on the repeatabilitydata for the individual samples tested, see Table 1.15.1.2 ReproducibilityTwo test results shall be judged notequivalent if they differ by more than 15.5 % of the measuredvalue; Reproducibility “R” is the interval representing thedifference between two test results f
49、or the same material,obtained by different operators using different equipment indifferent laboratories. For more detailed information on thereproducibility data for the individual samples tested, see Table2.15.1.3 Any judgment in accordance with these two state-ments would have an approximate 95 % probability of beingcorrect.15.2 BiasAt the time of the study, there was no acceptedreference material suitable for determining the bias for this testmethod, therefore no statement on bias is being made.15.3 Relative BiasThe interlaboratory study (ILS) wasnot specif
