NFPA 253 Standard Method of Test for Critical Radiant Flux of Floor Covering Systems Using a Radiant Heat Energy Source, 2000 ed. http://catalog.nfpa.org/NFPA-253-Standard-Method-o f-Test-for-Critical-Radiant-Flux-of-Floor-Covering -Systems-Using-a-Radiant-Heat-Energy-Source-Prior- Years-P4185.aspx, (Std: Meth of Tst for Critical Rad Flux of Floor Covering Sys Using a Rad Heat Enrg Source - Amer) {272 NFC}