Dvf : A drop diameter such that the cumulative volume, from zero diameter to this respective diameter, is the fraction, f, of the corresponding sum of the total distribution
NFPA 750 Standard on Water Mist Fire Protection Systems, 2003 ed. https://www.nfpa.org/Assets/files/AboutTheCodes/75 0/750_FKT-AAA_SDAgenda_01-13.pdf, (Std: Wtr Mist Fr Prac Sys - Amer) {346 NFC}