ASTM_D_4940_-_10.pdf

Designation:D494010Standard Test Method forConductimetric Analysis of Water Soluble IonicContamination of Blasting Abrasives1This standard is issued under the fixed designation D4940;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 a procedure for rapid evalu-ation of abrasives for the presence of ionic contamination bydetermining the total concentration of water soluble ioniccontaminants by means of a conductivity test.1.2 This test method does not identify the ionic speciespresent nor provide quantitative results on each species.1.3 This test method is based on a volume comparisonamong abrasives of similar sizes.A volume comparison ismore closely related to surface area of the abrasives than is aweight comparison.1.4 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-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 WaterE832 Specification for Laboratory Filter Papers2.2 Other Standard:ISO 11127-6 Preparation of Steel Substrates before Applica-tion of Paints and Related Products-Test Methods forNon-Metallic Blast Cleaning Abrasives-Part 6:Determi-nation of Water-Soluble Contaminants by ConductivityMeasurement32.3 SSPC:The Society for Protective CoatingsSSPC-AB 1 Specification for Mineral and Slag Abrasives43.Summary of Test Method3.1 Abrasive and pure water are combined into a slurry thatis stirred to leach the soluble salts from the abrasive.Thisslurry is filtered and conductance of the filtrate is measured.The conductivity,which is related to the concentration ofsoluble ionic materials contaminating the abrasive surface,iscalculated from the conductance and the cell constant.4.Significance and Use4.1 By-product abrasives manufactured from slags that areair cooled or quenched with pure water,normally contain lowconcentrations of ionic materials,as do mined mineral abra-sives.However,slags quenched with seawater or other con-taminated water,contain high amounts of ionic material asdoes seashore sand.This contamination of the abrasive cantransfer to the steel surfaces being blasted,where it mayaccelerate corrosion.This test is useful in establishing thecleanliness of the abrasive at the jobsite.4.2 This test method provides a value that indicates theconcentration of total water soluble ions based on theirelectrolytic mobility.Thus,it provides an indication of ioniccorrosion potential.NOTE1A typical value of conductivity for a high level of contami-nation is 500 mho/cm.A typical value for a low level of contaminationis 50 mho/cm.5.Apparatus5.1 Conductivity Bridge and CellAny commercial con-ductivity bridge and conductivity cell typically having a rangeof at least 5 mho/cm to 10 000 mho/cm is satisfactory.Eithera dip-type,pipet-type,or cup-type cell may be used.A meansof adjusting for temperature or controlling the temperature isessential.While some instruments have an adjustment tocompensate for temperature(automatic temperature compen-sation),one means is to use a 25C constant temperature bath.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.46 on Industrial Protective Coatings.Current edition approved June 1,2010.Published June 2010.Originallyapproved in 1989.Last previous edition approved in 2003 as D4940-98(2003).DOI:10.1520/D4940-10.2For 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.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.4Available from Society for Protective Coatings(SSPC),40 24th St.,6th Floor,Pittsburgh,PA 15222-4656,http:/www.sspc.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 Another method is to stir the solution with a clean thermometerwhile the vessel is warmed or cooled by an external source.NOTE2ISO 11127-6 is another method for assessing the level ofsoluble salt contamination present in an abrasive.It differs from this testmethod in two major areas:(1)The ISO method uses a weight to volume ratio between the abrasiveand the fluid(deionized water)used to extract soluble salts from theabrasive.The ASTM