Riello C7001038 BF NPT To NPTF Adapter For BF3 And BF5 Burners Screws Into The Bulk Head Fitting To Convert To Standard NPT Thread This fitting is the connection point for the oil linefrom the oil tank or the in-line oil filter. In some locations, fit-tings with the NPTF male thread are difficult to obtain.In these areas, a more common NPT thread male fitting orpipe may be used. To accommodate this NPT thread, the BFNPT-NPTF adapter is supplied.