Loss coefficients for pipe appurtenances used in stormwater pump station discharge line hydraulic calculations, from FHWA HEC-24 Table 8-2 (adapted from Brater et al., Handbook of Hydraulics, 7th Edition). Covers 8 diameter-dependent fittings (flanged elbows, tees, return bend, gate valve, swing check valve) and 3 constant-K elements (restrictor, enlarger, sudden enlargement). Formula: K = a * D^b where D is in mm (metric) or inches (English); loss = K * V^2 / (2g).