Designation:B78−90(Reapproved2013)StandardTestMethodofAcceleratedLifeofIron-Chromium-AluminumAlloysforElectricalHeating1ThisstandardisissuedunderthefixeddesignationB78;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope1.1Thistestmethodcoversthedeterminationoftheresis-tancetooxidationofiron-chromium-aluminumelectricalheat-ingalloysatelevatedtemperaturesunderintermittentheatingusingaconstant-temperaturecycletest.Thistestisusedforinternalcomparativepurposesonly.1.2Thevaluesstatedininch-poundunitsaretoberegardedasstandard.ThevaluesgiveninparenthesesaremathematicalconversionstoSIunitsthatareprovidedforinformationonlyandarenotconsideredstandard.1.3Thisstandarddoesnotpurporttoaddressallofthesafetyconcerns,ifany,associatedwithitsuse.ItistheresponsibilityoftheuserofthisstandardtobecomefamiliarwithallhazardsincludingthoseidentifiedintheappropriateMaterialSafetyDataSheet(MSDS)forthisproduct/materialasprovidedbythemanufacturer,toestablishappropriatesafetyandhealthpractices,anddeterminetheapplicabilityofregulatorylimitationspriortouse.2.SignificanceandUse2.1Thistestmethodisusedbyproducersofelectricalheatingalloystomeasurethecyclicoxidationresistanceofthesealloys.2.2Becauseoftheeffectofenvironment,designanduse,thelifevaluesobtainedfromthistestmethodmaynotcorrelatewiththatofanapplianceorindustrialheatingunit.3.TestPanel3.1SizeandLocation—ThedimensionsofthetestpanelshallbesimilartothoseshowninFig.1.Thetestpanelshallbelocatedinapositionfreefromdraftsofair.3.1.1Theenclosureshallfittightlyonthepanelandtheglassslideshallfitsnuglytopreventleakageofairatthispointduringtheoperationofthetest,asevenaslightdraftofairincontactwiththespecimenwillcauseexcessivevariationinlengthoflife.Ascreenof40wiremesh,0.010-in.(0.025mm)wirediameter,marketgrade,maybeusedasacoverovertheindividual...
