Designation:E128−99(Reapproved2011)StandardTestMethodforMaximumPoreDiameterandPermeabilityofRigidPorousFiltersforLaboratoryUse1ThisstandardisissuedunderthefixeddesignationE128;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodcoversthedeterminationofmaximumporediameterandpermeabilityofrigidporousfiltersusedinthelaboratoryforfiltrationordiffusion.Theyareapplicabletofiltersmadeofsinteredglass,ceramic,metal,orplastic.Thistestmethodestablishesauniformdesignationformaximumporediameterandalsoprovidesameansofdetectingandmeasuringchangeswhichoccurthroughcontinueduse.1.2ThevaluesstatedinSIunitsaretoberegardedasstandard.Nootherunitsofmeasurementareincludedinthisstandard.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyproblems,ifany,associatedwithitsuse.Itistheresponsibilityoftheuserofthisstandardtoestablishappro-priatesafetyandhealthpracticesanddeterminetheapplica-bilityofregulatorylimitationspriortouse.2.ReferencedDocuments2.1ASTMStandards:2D845SpecificationforFive-DegreeXylene(Withdrawn1980)33.Terminology3.1Definitions:3.1.1maximumporediameter—thediameterinmicrometresofacapillaryofcircularcrosssectionthatisequivalent(withrespecttocharacteristicsrelatedtosurface-tensioneffects)tothelargestporeinthefilterunderconsideration.NOTE1—Itisrecognizedthatthemaximumporediameterasdefinedhereindoesnotnecessarilyindicatethephysicaldimensionsofthelargestporeinthefilter,andfurthermore,thattheporesarehighlyirregularinshape.Becauseofthisirregularityinshapeandotherphenomenacharacteristicoffiltration,afiltermaybeexpectedtoretainallparticleslargerthanthemaximumporediameterasdefinedanddeterminedbythistestmethod,andwillgenerallyretainparticleswhicharemuchsmallerthanthedetermineddiameter.3.1.2permeability—theflowofair,inmillimetrespermin-utepersquarecentimetre...
