Tank, Oil Burner Auxiliary : A tank having a capacity of not more than 60 gal (227 L) that is listed for installation in the supply piping between a burner and its main fuel supply tank. See: Oil Burner, Integral Tank
NFPA 31 Standard for the Installation of Oil-Burning Equipment, 2001 ed. https://www.nfpa.org/Assets/files/AboutTheCodes/31 /LPI-AAA_ROPagenda_06-09.pdf, (Std: Install of Oil-Burn Equip - Amer) {195 NFC}