ASTM_D_7358_-_07_2013.pdf

Designation:D735807(Reapproved 2013)Standard Test Method forWater Content of Paints by Quantitative Calcium HydrideReaction Test Kit1This standard is issued under the fixed designation D7358;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 parentheses indicates the year of last reapproval.Asuperscript epsilon()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 reaction testkit,or water content between 2 and 85%water.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 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 limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD3925 Practice for Sampling Liquid Paints and RelatedPigmented CoatingsD4017 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 reagent 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 sample 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 D4017 is widely used for thedetermination of water in paints and related materials,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 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 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 mL 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 smallamount of water.Ethylene glycol responds at approximately7%of the volumetric equivalent.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.Current edition approved June 1,2013.Published June 2013.Originallyapproved in 2007.Last previous edition approved in 2007 as D7358 07.DOI:10.1520/D7358-07R13.2For 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.3HydroSCOUT Users Manual.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.Apparatus6.1 HydroSCOUT4SystemA test kit system consisting ofthe HydroSCOUT meter,reaction tubes,sampling syringes anddilution vials.5The entire analytical sequence,includingsampling,sampledilution,chemicalreactionsandquantification,is available in kit form using pre-dispensed andencapsulated reagents.An analytical balance is required inorder to obtain the most precise results.In addition,a mechani-cal shaker may be necessary to obtain a representative sample.7.Reagents and Materials7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.All reagents 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 SpecificationD1193,Type II.7.3 Calcium Hydride(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