BS 7874-1998 Microbiological deterioration of elas

|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||BRITISHSTANDARDBS7874:1998ICS23.040.80NOCOPYINGWITHOUTBSIPERMISSIONEXCEPTASPERMITTEDBYCOPYRIGHTLAWMethodoftestforMicrobiologicaldeteriorationofelastomericsealsforjointsinpipeworkandpipelinesBS7874:1998ThisBritishStandard,havingbeenpreparedunderthedirectionoftheSectorBoardforMaterialsandChemicals,waspublishedundertheauthorityoftheStandardsBoardandcomesintoeffecton15March1998©BSI1998ThefollowingBSIreferencesrelatetotheworkonthisstandard:CommitteereferencePRI/70DraftannouncedinUpdateStandards,February1998ISBN0580262995AmendmentsissuedsincepublicationAmd.No.DateTextaffectedCommitteesresponsibleforthisBritishStandardThepreparationofthisBritishStandardwasentrustedtoTechnicalCommitteePRI/70,Elastomericsealsforjointsinpipeworkandpipelines,uponwhichthefollowingbodieswererepresented:BritishGasplcBritishPlasticsFederationBritishPrecastConcreteFederationLtd.BritishRubberManufacturers'AssociationLtd.CharteredInstitutionofWaterandEnvironmentalManagementClayPipeDevelopmentAssociationLimitedConcretePipeAssociationDuctileIronProducers'AssociationFibreCementManufacturers'AssociationLimitedMalaysianRubberProducers'ResearchAssociationRAPRATechnologyLtd.SocietyofBritishWaterIndustriesWaterCompaniesAssociationWaterServicesAssociationofEnglandandWalesBS7874:1998©BSI1998iContentsPageCommitteesresponsibleInsidefrontcoverForewordiiMethod1Scope12Informativereferences13Principle14Materials15Apparatus16Preparationoftestpieces17Procedure38Calculationofresults39Testreport4Figures1Typicalarrangementoftanksforbiodeteriorationtest22Testpiecedimensionsforbiodeteriorationtest4ListofreferencesInsidebackcoverii©BSI1998BS7874:1998ForewordThisBritishStandardhasbeenpreparedbyTechnicalCommitteePRI/70.ThismethodwaspreviouslycontainedinannexBofBS2494:1990,fromwhichithasbeendeletedasaconsequenceofthepublicationofBSEN681-1:1996.NOTE.SealsoftypeD,H,SandW,asspecifiedpreviouslyinBS2494:1990,conformedtothefollowingrequirements:a)theaveragelossinmass(Z)ofthetestsetoftestpiecesdoesnotexceed3.5%;b)thereisnogreaterreleaseofcarbonblackorotherfillersfromthetestsetthanfromthecontrolsetwhenthesurfaceofthespecimensislightlyrubbed.Inthecaseofcompositesealstherequirementsappliedonlytothosecomponentsexposedtothecontentsofthepipelineorpipework.WithinBSEN681-1thereisnomicrobiologicalrequirementforelastomericseals.However,theUKhasfoundtheaboverequirementsandmethodtobeacceptable.CompliancewithaBritishStandarddoesnotofitselfconferimmunityfromlegalobligations.SummaryofpagesThisdocumentcomprisesafrontcover,aninsidefrontcover,pagesiandii,pages1to4,aninsidebackcoverandabackcover.©BSI19981BS7874:1998Method1ScopeThisBritishStandarddetailsthetestmethodformicrobiologicaldeteriorationforelastomericjointseals.Themethodisapplicabletoelastomericcomponentsofcompositeornon-compositerings,seals,jointinggasketsandsimilarcomponentsusedtosealaqueousfluidsinpipesandfittings.Itisapplicabletoallcategoriesofaqueousfluid,includingrawandtreatedpotablewater,sewerageanddrainagewater.2InformativereferencesThisBritishStandardreferstootherpublicationsthatprovideinformationorguidance.Editionsofthesepublicationscurrentatthetimeofissueofthisstandardarelistedontheinsidebackcover,butreferenceshouldbemadetothelatesteditions.3PrincipleTestpiecesundertensilestrainareexposedtorawriverwater,inoculatedwithsuitableorganismsandmaintainedatahighdissolvedoxygenconcentration.Lossesinmassaremeasuredattheendoftheexposureperiodandanyreleaseofcarbonblackorotherfillersnoted.4Materials4.1Asourceofrawriverwaterhavingallthefollowingcharacteristics:a)anoxygensaturationgreaterthan60%;b)abiologicaloxygendemand(BOD)of#8.5mg/l;c)anammoniacontent,asammoniumions,#0.9mg/l.4.2Aninoculumofrubberdegradingorganismsisprovidedbyintroducingintotheheadertank(5.2)asuspendedrubbersealshowingactivesignsofbiologicaldeterioration.5Apparatus5.1Stainlesssteelframe,containingtwostainlesssteelrodsof4.7mmto4.8mmdiameter,maintainedinparallel(110±1)mmapart(seefigure1).NOTE.Spacerplatesmaybelocatedatintervalsasnecessarytobracetherodsatthespecifiedspacingifthetensionexertedbythetestpieceswouldotherwisecauseexcessiveflexureoftherods.5.2Headertank,constructedofnon-metallicmaterialandincludingacoverwhichpermitsventilation.Thetankisconstructedorenclosedsuchthatlightisexcludedfromthecontentsofthetank.Thetankshallcontainwaterofthetypedescribedin4.1,inwhichasourceofinoculuminaccordancewith4.2ismaintainedfollowinganinitialresidenceperiodofnotlessthan7days.Thetankshalldischargecontinuouslyintothetesttank(5.3)viaaflowcontroldevicewhichmaintainstherateofoverflowdischargefromthetesttankequivalentto(0.4±0.1)volumechange/dayofthewatercontentofthetesttank.Theheadertankshallbereplenishedwithwaterinaccordancewith4.1sothatthesourceofinoculumintheheadertankremainssubmerged.NOTE.Thesystemforreplenishmentoftheheadertankwilldependupontherateofdischargeusedwhenfillingthetesttankandwhenmaintainingtherequiredrateofoverflowdischargefromthetesttank.5.3Te